Advanced therapy in thoracic surgery - part 9 potx

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440 / Advanced Therapy in Thoracic Surgery

The majority of acute mediastinal infections result from

complications of cardiac surgery or perforations of the

esophagus Less commonly, acute mediastinitis can result

from spread of cervical or odontogenic infections

Suppurative infections of the oropharynx extending to

the mediastinum have become rare since the advent of

antibiotics When this does occur, the most severe

infec-tion is descending necrotizing mediastinitis

Descending necrotizing mediastinitis (DNM) is a

fulminant infection leading to uncontrolled sepsis and

death if not promptly recognized and appropriately

treated It is frequently the result of odontogenic

infec-tions or unrecognized injuries to the aerodigestive tract

These virulent infections dissect through and travel along

the fascial planes of the neck to reach the mediastinum

The diagnosis of DNM is almost always delayed and is

often not made until sepsis persists or develops following

inadequate surgical drainage of the cervical infection

Early diagnosis and aggressive treatment is paramount in

salvaging these patients as the reported mortality can

reach 40%.1–3 We review the pertinent anatomy and

pathophysisolgy, clinical manifestations, diagnostic

work-up, and recommended treatment of DNM

Anatomy and Pathophysiology

DNM is an aggressive, suppurative mediastinitis

associ-ated with odontogenic or cervicofacial infections A

review by Estrera and colleagues in 1983 defined criteria

for diagnosis of DNM The criteria included:

1 Clinical manifestations of severe infection

2 Demonstration of characteristic roentgenographic

features

3 Documentation of the necrotizing mediastinal

infection at operation or postmortem examination

4 Establishment of the relationship of oropharyngealinfection with the development of the necrotizingmediastinal process

Although established for the purposes of a tive review, these criteria are a useful framework for theclinical diagnosis of DNM

retrospec-Appreciating the pathophysiology of DNM preparesone to suspect this life-threatening infection Theprimary source is often an oropharyngeal abscess origi-nating from an odontogenic infection of a second orthird molar.3–5The infections spread along the deep cervi-cal fascial planes on the way to the mediastinum and maycause cellulitis, abscess formation, pericardial and pleuraleffusions, empyemas, tissue necrosis, mediastinitis, andsepsis Other sources are peritonsillar or retropharyngealabscesses and Ludwig’s angina.6–8Traumatic endotrachealintubation or endoscopic procedures can result inpharyngeal perforations, which become a portal forinfection to reach the mediastinum.9–11

Anatomy

Understanding the anatomy of the neck and the variouspathways from the oropharynx and aerodigestive tractinto the mediastinum is necessary to make the associa-tion between the source of infection and resulting medi-astinitis The neck contains viscera, muscles, nerves,blood vessels, and a bony skeleton As in the limbs andtorso, these structures are contained and supported byfascial coverings of connective tissue organized as sheetsand membranes These fasciae wrap around the struc-tures of the neck, forming cylindrical connective tissueplanes that span from the face and base of the skull to themediastinum and thoracic inlet These cylindrical sheets

of fascia confine and compartmentalize the deep

struc-tures of the neck, defining the cervicomediastinal region

The cervicomediastinal region is traversed in its length by

three major deep fascial layers: the superficial layer, the

visceral layer, and the prevertebral layer The superficial

layer invests the sternocleidomastoid muscle, trapezius

muscle, strap muscles, and parotid and submandibular

glands The visceral layer surrounds the thyroid gland,

esophagus, and trachea Its upper limit attaches to the

hyoid bone and extends inferiorly to the mediastinum

The prevertebral layer is immediately adjacent to the

vertebral column and runs from the base of the skull to

the coccyx The alar layer, just anterior to the prevertebral

layer, is intimate with the prevertebral layer but extends

only to the second thoracic vertebra.12

These three deep fascial layers (Figure 36-1),

individu-ally and as a group, surround and define five potential

spaces of the neck: the pretracheal space, the perivascular

space, the retrovisceral space, the submandibular space,

and the lateral pharyngeal space Of these five spaces, the

first three (pretracheal, perivascular, and retrovisceral)

provide avenues for infections that originate in the head

and neck to descend into the mediastinum.3,4,13,14 The

latter two spaces (submandibular and lateral pharyngeal)

communicate with the first three, allowing infections of

the oropharynx a pathway to the mediastinum Each of

these five spaces will be described below

The pretracheal space is anterior to the trachea and

posterior to the strap muscles and pretracheal fascia The

pretracheal fascia, together with the buccopharyngeal

fascia, encloses the pharynx, esophagus, larynx, trachea,

thyroid, and parathyroid The buccopharyngeal fasciaexternally invests the upper part of the alimentary tract

It covers the pharynx, the buccinator muscle, and theposterior esophagus The buccopharyngeal fascia,together with the pretracheal fascia blends along thepharyngeal constrictors, the hyoid, the thyroid cartilage,and the thyroid The pretracheal fascia descends from thethyroid, covering the trachea anteriorly and the sternumposteriorly The inferior extent of the pretracheal fasciaand pretracheal space is the aorta, pericardium, and pari-etal pleura at the level of the carina Perforations of thetrachea and lateral pharyngeal walls allow infections toenter this space The infections can descend into theanterior mediastinum, causing purulent pericarditis,empyema, and mediastinitis

The perivascular space is surrounded by the carotidsheath This sheath invests the internal and commoncarotid arteries, the internal jugular vein, and the vagusnerve The cervical sympathetic trunk lies behind, butnot within, the sheath The areolar tissue of the sheathseparates and invests the nerves and vessels mentioned.The sheath is adherent to the thyroid, the sternocleido-mastoid muscle, and prevertebral fascia The sheathblends with the fascia of the stylohyoid and digastricmuscles in the upper neck and is attached to the base ofthe skull at the jugular foramen and carotid canal.Infections can track along the vascular structuresthrough this space to reach the mediastinum and pleuralspaces

The retrovisceral (or retropharyngeal) space is thelargest and most important interfascial interval in theneck, when considering a pathway of infection for DNM.This potential space is areolar in nature and is bordered

by the buccopharyngeal fascia anteriorly and the tebral fascia posteriorly The lateral borders are thecarotid sheaths The potential space extends from thebase of the skull superiorly to the posterior mediastinuminferiorly This loose areolar connective tissue supportsthe movements of the pharynx during swallowing Theretopharyngeal lymph nodes are in the lateral aspects ofthe retrovisceral space near the base of the skull Thesenodes are part of the superior deep cervical chain Theretrovisceral space is further divided by the alar fascia.The alar fascia is usually delicate; however, it sometimes

prever-is a definitive fascial plane that, along with the bral fascia, descends to the seventh cervical vertebra.The retrovisceral space communicates with the lateralpharyngeal spaces above via the styloglossus muscles.This muscular avenue allows infections from the base ofthe tongue, the teeth, the tonsils, and the pharynx, whicherupt into the lateral pharyngeal space, to descend intothe retrovisceral space and beyond This is the mostcommon route for descending mediastinitis

preverte-442 / Advanced Therapy in Thoracic Surgery

Buccopharyngeal fascia

Prevertebral fascia Retrovisceral space

Angle of

Dissection

Sternocleidomastoid m.

FIGURE 36-1 The different fascial planes of the neck Infection may

descend through these planes into the mediastinum The arrow

demonstrates the standard surgical approach to the prevertebral

fascia medial to the sternocleidomastoid muscle and thyroid gland.

Reproduced with permission from Wheatley et al 4

The submandibular space spans from the floor of the

mouth to the hyoid bone The mandible provides the

anterior and lateral borders of this space with the

super-ficial layer of the deep cervical fascia bordering the space

inferiorly The mylohyoid muscle crosses the mandible

and is responsible for directing the spread of dental

infections, most importantly those from abscesses of the

second and third molars The buccopharyngeal gap is a

connection between the submandibular and lateral

pharyngeal spaces that results when the styloglossus

muscle passes between the middle and superior

pharyn-geal constrictors Infections from the submandibular

space may travel the styloglossus into the lateral

pharyn-geal space, which in turn communicates with all the

major spaces of the neck In 1836, Wilhelm von Ludwig

described a gangrenous infection of the neck

character-ized by cellulitis, chest pain, and asphyxiation as a result

of a submandibular abscess Today, Ludwig’s angina

implies bilateral infections involving this space

The lateral pharyngeal (or parapharyngeal) space, as

mentioned, communicates with all major spaces of the

neck The space is defined by the skull above, the hyoid

below, the prevertebral fascia posteriorly, and the

bucci-nator and superior pharyngeal constrictor muscles

ante-riorly The lateral borders are the parotid glands and the

mandible The anterior aspects of the lateral pharyngeal

space contain lymph nodes and fat The posterior aspects

of this space include cranial nerves IX, X, XI, and XII as

well as the carotid artery and jugular vein When

infec-tion invades this space, symptoms of trismus or cranial

nerve palsies suggest its involvement

Pathophysiology

The potential spaces defined by the major fascial planes

of the cervicomediastinal region provide a pathway for

the spread of infection into the mediastinum Once a

cervical infection has been established, invasion of any or

all of these spaces can lead to life-threatening DNM

Approximately 70% of the reported cases of DNM are

thought to have spread via the retrovisceral space, 20%

through the perivascular space, and the rest by way of the

pretracheal space.1 , 3 , 4 , 6 , 1 5 – 1 8 Gravity and the negative

intrathoracic pressure favor the descent of infection into

the mediastinum

Odontogenic infection is the most common source for

DNM.1,3,4,6Other reported sources include peritonsillar

abscess, retropharyngeal abscess, epiglottitis, parotitis,

lymphadenitis, and trauma.19–26Some reports have

impli-cated endotracheal intubation resulting in tracheal or

esophageal injury as a source for infection leading to

DNM.9–11

Commonly, odontogenic abscesses from second and

third molars rupture into the submandibular or lateral

pharyngeal space The infection progresses through thefascial lined spaces, typically tracking into the retrovis-ceral space on the way to the posterior mediastinum.Iatrogenic pharyngeal injuries can introduce infectiondirectly into the retrovisceral space Most of these infec-tions are polymicrobial, representing the normal bacter-ial flora of the mouth and pharynx These organisms dohave the potential to become virulent and can be invasivewhen normal barriers have been broken

Most odontogenic infections are polymicrobial,comprised of organisms that reflect the indigenousmicroflora of the oropharyngeal cavity Anaerobes gener-ally outnumber the aerobes by a factor of 10:1.15,27,28

Synergistic effects in this mixed population can promoteinvasiveness and contribute to the virulence of theseinfections Some gram-positive cocci and gram-negativerods can cause tissue damage by gas production, resulting

in a nonclostridial gas gangrene The organisms isolated

in the various case reports on DNM reflect this crobial oropharyngeal population Common isolates

polymi-recovered from the mediastinum were Bacteroides fragilis,

Enterobacter cloacae, Escherichia coli, Serratia marcescens, Staphylococcus aureus, and
-hemolytic streptococcusspecies.3,4,27,28Other series identified Pseudomonas aerugi-

nosa, Klebsiella pneumoniae, Peptostreptococcus, Actinomyces, and Clostridia.14,29

The necrotizing infections in the cervicomediastinalregion share similarities with other necrotizing soft tissueinfections in the body The infections are rapid, progres-sive, and lethal The infections are polymicrobial, syner-gistic, and virulent Some microorganisms possessvirulence factors that enhance the fulminant nature ofthe process Fascial planes provide means of travel fromspace to space and cavity to cavity Patients with impairedimmune systems (diabetics, alcoholics, patients withacquired immunodeficiency syndrome, cancer patients)are at increased risk for this necrotizing infection Theinfections spread rapidly, resulting in septic shock, multi-system organ failure, and death The aggressive nature ofthis type of infection requires an astute clinician torapidly diagnose the condition and respond with anaggressive surgical approach

Clinical Manifestations

The clinical presentation of DNM depends on the origins

of the infection and the time course of the diseaseprocess An odontogenic infection is the most commoncause of DNM, followed by peritonsillar and retropha-ryngeal abscesses Abscess from a second or third molar isthe odontogenic infection most typically reported inassociation with DNM The majority of these odonto-genic infections are successfully treated by root canal,

tooth extraction, or other periodontal procedures before

they become serious However, a rare few become a

rapidly progressing life-threatening infection

Patients initially present to a local dentist or

emer-gency room Early symptoms include fever and pain If

the infection persists and abscess develops, signs and

symptoms might suggest the fascial space that is

involved The submandibular space may be involved

when an abscessed molar erupts The patient might

expe-rience mouth pain, dysphagia or drooling The tongue

and floor of the mouth can swell with infection and

asso-ciated edema The tongue may be displaced anteriorly,

and as the infection migrates into the neck, patients will

complain of neck pain and stiffness Involvement of both

submandibular spaces is referred to as Ludwig’s angina

Airway compromise is the most common cause of early

death in this rare infection

Infection involving the lateral pharyngeal space may

cause pain, neck swelling, and trismus The

sternocleido-mastoid muscle can become involved, making rotation of

the neck painful and difficult If the perivascular space

becomes involved, palsies of cranial nerves IX to XII may

be apparent, and in severe cases, Horner’s syndrome may

develop Thrombophlebitis of the jugular vessels is

possi-ble, as is carotid artery erosion or thrombosis.30

The infection progresses if untreated or if the patient

does not respond to initial therapy The infection can

migrate from the portal of infection into one of the three

critical fascial spaces: the pretracheal space, the

perivas-cular space, or the retrovisceral space Having reached

one of these spaces, the infection can continue to

descend, aided by both gravity and the negative pressure

generated by the thorax, into the mediastinum As

medi-astinitis begins, the inflammatory process causes swelling

of the mediastinal structures The pericardium may be

involved, resulting in pericarditis or pericardial effusion

The pleural spaces may develop sympathetic effusions or

become directly infected Empyemas may develop

Pneumomediastinum or pneumothorax may also be part

of the evolving inflammatory and infective process

lead-ing to hemodynamic derangement

The localized infection may evolve into a systemic

process Tachycardia, tachypnea, pyrexia, and

leukocyto-sis suggest systemic inflammatory response syndrome

(SIRS) This syndrome evolves from a complex sequence

of events initiated by proinflammatory cytokines such as

tumor necrosis factor, interleukin (IL)-1, IL-2, IL-6, and

interferon- The body attempts to regulate this initial

response with a series of anti-inflammatory cytokines

and other soluble factors Secondary mediators such as

nitric oxide, thromboxanes, leukotrienes,

platelet-activating factor, prostaglandins, and the complement

system are also triggered as SIRS progresses This milieu

of primary and secondary mediators can cause lial cell damage leading to tissue and organ damage Asthe inflammatory process tumbles out of control, end-organ dysfunction, sepsis, septic shock, and hemody-namic collapse are the result Multiorgan system failureand death is the final course if the inflammatory processcannot be arrested and reversed.31–33

endothe-Diagnosis

When called to evaluate a patient with suspected DNM,the patient is usually late in the course of the diseaseprocess Mediastinal sepsis is the reason these patients are

so ill; however, the diagnosis is delayed because the cal presentation suggests an infection isolated to the headand neck Mediastinitis can present as quickly as 24 to 48hours after the odontogenic infection or procedure, or itmay take 1 to 2 weeks before mediastinitis evolves.3–5

clini-Many of these patients are elderly or mised Some have undergone surgical drainage of theneck but have not improved or have worsened A thor-ough and detailed history usually reveals a recent dentalprocedure or cervical trauma or procedure involving thehypopharynx or aerodigestive tract

immunocompro-On initial inspection, the patient is generally lethargicwith uncontrolled fevers despite the use of broad-spectrum antibiotics On physical exam there may besevere pain and induration over the neck, trismus, anddeviation of the tongue In the most severe cases, airwaycompromise secondary to cervical swelling and venouscongestion may necessitate intubating the patient Inpatients who have undergone prior surgical intervention,there may be pus emanating from the wounds eventhough drains are still in place Further evaluation maydemonstrate chest wall crepitus and chest pain in thosewith a delayed diagnosis Decreased breath sound may bepresent at the bases secondary to pleural effusion

Blood work should include complete blood count,electrolytes, and blood cultures If SIRS or sepsis is evident,liver function tests, arterial blood gas, and lactic acid levelwill be helpful Invasive hemodynamic monitoring including arterial access, central access, and pulmonaryartery catheter may be indicated Cultures usually reveal

a mixed flora of anaerobic and aerobic bacteria and,

in many cases, fungal elements Broad-spectrum antibiotics, resuscitation, and supportive measures arenecessary as the diagnostic process continues

A chest radiograph is always part of the work-up.Findings may include widening of the superior mediasti-nal shadow, widening of the retrocervical space, anteriordisplacement of the trachea, mediastinal emphysema,and air–fluid levels However, these findings are difficult

to recognize when the process presents late The single

444 / Advanced Therapy in Thoracic Surgery

most important and influential diagnostic evaluation for

a patient with suspected DNM is the computed

tomogra-phy (CT) scan.3–5,15–18CT scanning allows for evaluation of

the mediastinum and surrounding structures (Figure

36-2) The CT will help define the extent of the infection,

which is necessary when planning the surgical approach

to the mediastinum Frequently, if the disease is

diag-nosed early, only the upper mediastinum is involved and

limited drainage may be appropriate CT scanning is also

necessar y to determine if the infection has been

adequately drained after initial intervention since fevers

and signs of sepsis may lag a progressing infection for

days One retrospective review averaged six CT scans per

patient after the initial surgical intervention.18Although

laboratory testing with a complete blood count and

cultures are important, interval resolution of fevers and

sepsis may not completely correlate with adequate

drainage

Treatment

DNM is an aggressive infection with reported mortalities

of 40 to 50% in the postantibiotic era.1,3,4If left untreated,

it is universally fatal With aggressive surgical tion, the mortality can be reduced to less than 20%.5,15–18

interven-This improvement in survival is the result of earlier nosis, broad-spectrum antibiotic therapy, and thoroughsurgical débridement and drainage

diag-Early in the course of DNM, the clinical picture issimilar to that of a localized acute cervical infection Theclinical progression is dramatically different with DNM,resulting in death if left untreated Clinical suspicion isnecessary to recognize this disease early in its evolution,thereby improving the chances of arresting and reversingthe inflammatory process The CT scan is the criticaldiagnostic study that differentiates DNM from a local-ized cervical infection The CT defines the extent of thedisease process and the amount of destruction of medi-

FIGURE 36-2 Computed tomography scans of the neck of a 40-year-old man 6 days after self-extracting a lower second molar with a pair of

pliers The patient had fevers, shaking chills, and woody edema of the neck A, Air in the deep neck spaces B, Mediastinal air–fluid levels C, Mediastinal inflammation and edema D, Bilateral effusions The patient underwent tracheostomy, cervical drainage, and mediastinal drainage

through a transhiatal approach The patient survived to be discharged 42 days after original presentation.

A

B

C

D

astinal tissue Determining the extent of the disease is

important because this dictates the magnitude of surgical

débridement.15–18 The single most important aspect of

successfully treating a patient with DNM is that of

adequate surgical drainage and débridement

Patients typically present well into the course of

DNM They are often septic or in septic shock Some will

have been inadequately drained Initial treatment

involves resuscitation and stabilization The

inflamma-tion, venous congesinflamma-tion, and edema cause dramatic neck

swelling that threatens the patient’s airway This swelling

and edema is unpredictable, and should the airway be

lost, regaining control would be virtually impossible For

this reason, early tracheostomy is felt to be essential and

is recommended in many reports.3,4,34Others feel a

surgi-cal airway should be used selectively.35 Broad-spectrum

antibiotics against aerobic and anaerobic organisms

should be administered until cultures are returned and

appropriate directed therapy can begin

Once the patient has been stabilized, definitive

surgi-cal débridement and drainage can be performed The CT

scan defines the extent of the infection and directs the

surgical approach For deep neck infections, the surgical

approach to the various spaces is well established The

surgical approach to DNM, however, remains

controver-sial When the infection is above the tracheal bifurcation

anteriorly or the fourth thoracic vertebra posteriorly,

most agree that cervical drainage is the appropriate first

step as long as all fascial planes are opened and drained

adequately A unilateral or bilateral approach may be

used, and soft drains are recommended to minimize the

potential of erosion into vascular structures.36When the

infection descends below these margins, a more

aggres-sive surgical approach is required

The CT scan will identify those patients with more

extensive mediastinitis For these patients, in addition to

the cervical drainage, drainage and débridement of the

mediastinum is required When the DNM is limited to

the anterior mediastinum, a subxyphoid approach may

be used A subxyphoid incision is used to access the

ante-rior mediastinum.3Blunt manual retrosternal dissection

is followed by placement of a retrosternal drain The

anterior mediastinum may also be reached via a

paraster-nal incision, standard thoracotomy,37–39or even

medi-ansternotomy.4 0 Transpleural drainage violates and

contaminates the pleural space The posterolateral

thora-cotomy allows access to the ipsilateral mediastinum, the

pleural spaces, and the prevertebral and paraesophageal

spaces.15,17,18,27Controversy exists as to whether it is

neces-sary to access and drain the pleural spaces The pleural

effusions are often sympathetic, and entering theses

spaces risks contaminating them, thereby enhancing the

risk of empyema formation.3,27 One approach to avoid

contaminating these spaces is to sample the fluid bythoracentesis A sterile collection can be safely observed.Other recent reports have suggested thoracoscopic orCT-guided percutaneous drainage as an alternative to theaggressive surgical approach.41,42The necrotizing nature

of this infection mandates débridement of involvedtissue, and this cannot be adequately achieved with aminimalist approach

Endo and colleagues have suggested a classification ofDNM to help direct the treatment of this lethal infection.For infections localized to the space above the carina,cervical drainage could be used to treat the infection Forinfections that have involved the anterior mediastinumalone, a subxyphoid approach could be added Fordiffuse mediastinitis that involves the anterior and poste-rior mediastinum, a thoracotomy needs to be part of thesurgical approach.43

Results

DNM is perhaps the most aggressive and lethal form ofmediastinitis Early case reports and reviews suggested amortality rate approaching 50%.1Even into the postan-tibiotic era, the mortality rate remained near 40%.3–5

With the widespread use of CT scanning, the diagnosis ofDNM became better defined and more easily recognized.Early use of this modality has been stressed by variousreviews as a crucial and necessary step in improving theoutcome of this fulminant infection Along with earlydiagnosis, it has also become clear that aggressive andrepeated surgical drainage and débridement is required

to improve the survival of this group of patients.Employing this approach, reviews over the past decadehave demonstrated mortality rates of 0 to 23%.5,15–18

DNM remains a rare but aggressive form of tinitis With early recognition, adequate surgicaldrainage, and appropriate antibiotics, the disease may besuccessfully treated

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4 Wheatley MJ, Stirling MC, Kirsh MM, et al Descending necrotizing mediastinitis: transcervical drainage is not enough Ann Thorac Surg 1990;49:780–4.

446 / Advanced Therapy in Thoracic Surgery

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25 Watanabe M, Ohshika Y, Aoki T, et al Empyema and astinitis complicating retropharyngeal abscess Thorax 1994;49:1179–80.

medi-26 Zeitoun IM, Dhanarajani PJ Cervical cellulitis and tinitis caused by odontogenic infections: report of two cases and a review of literature J Oral Maxillofac Surg 1995;24:60–3.

medias-27 Marty-Ane C-H, Berthet J-P, Alric P, et al Management of descending necrotizing mediastinitis: an aggressive treatment for an aggressive disease Ann Thorac Surg 1999; 68:212–7.

28 Sancho LMM, Minamoto H, Fernandez A, et al Descending necrotizing mediastinitis: a retrospective surgi- cal experience Eur J Cardiovasc Surg 1999;16:200–5.

29 Brook I, Frazier E Microbiology of mediastinitis Arch Intern Med 1996;156:333–6.

30 Mathieu D, Neviere R, Teillon J, et al Cervical necrotizing fasciitis: clinical manifestations and management Clin Infect Dis 1995;21:51–6.

31 Oberholzer A, Oberholzer C, Moldawer LL Sepsis syndromes: understanding the role of innate and acquired immunity Shock 2000;14:59023.

32 Pinsky MR Organ-specific therapy in critical illness: facing molecular mechanisms with physiological interven- tions J Crit Care 1996;11:95–107.

inter-33 Livingston DH Management of the surgical patient with multiple system organ failure Am J Surg 1993;165(2A Suppl):8S–13S.

34 Alexander DW, Leonard JR, Trail ML Vascular tions of deep neck abscesses A report of four cases Laryngoscope 196;78:361–70.

complica-35 Allen D, Loughnan TE, Ord RA A reevaluation of the role

of tracheotomy in Ludwig’s angina J Oral Maxillofac Surg 1985;43:436–9.

36 Ichimura H, Ishikawa S, Hiramatsu Y, et al Innominate artery rupture after transcervical draining for descending necrotiz- ing mediastinitis Ann Thorac Surg 2001;71:1028–30.

37 Brunelli A, Sabbatini A, Catalini G, Fianchini A Descending necrotizing mediastinitis: cervicotomy or thoracotomy? J Thorac Cardiovasc Surg 1996;111:485–6.

38 Kim JT, Kim KH, Lee SW, Sun K Descending necrotizing

mediastinitis: mediastinal drainage with or without

thora-cotomy Thorac Cardiovasc Surg 1999;47:333–5.

39 Ris HB, Banik A, Furrer M, et al Descending necrotizing

mediastinitis: surgical treatment via a clamshell approach.

Ann Thorac Surg 1996;62:1650–4.

40 Izumoto H, Komoda K, Okada O, et al Successful

utiliza-tion of the mediansternotomy approach in the

manage-ment of descending necrotizing mediastinitis: report of a

case Surg Today 1996;26:286–8.

41 Roberts JR, Smythe WR, Weber RW, et al Thorascopic management of descending necrotizing mediastinitis Chest 1997;112:850–4.

42 Gobien RP, Stanley JH, Gobien BS, et al Percutaneous catheter aspiration and drainage of suspected mediastinal abscess Radiology 1984;151:69–71.

43 Endo S, Murayama F, Hasegawa T, et al Guideline of cal management based on diffusion of descending necrotiz- ing mediastinitis Jpn J Thorac Cardiovasc Surg 1999;47:14–9.

surgi-448 / Advanced Therapy in Thoracic Surgery

In his 1777 treatise on the uses of electricity for human

ailments, Cavallo noted that electricity may be of use to

assist respiration However, it was not until after Galvani

discovered animal electricity in 1787, that Ure in 1818

applied Galvanic electricity to the phrenic nerve of a

recently hanged criminal and first observed the powerful

contractions that resulted “The chest heaved and fell; the

belly was protruded and again collapsed, with the

relax-ing and retirrelax-ing diaphragm.”1

Sarnoff and colleagues coined the term

“elec-trophrenic respiration” as he began to investigate what is

now recognized as diaphragmatic pacing as a possible

treatment to aid respiration in victims of bulbar

poliomyelitis.2,3Sarnoff ’s early work remains critical to

the understanding of diaphragmatic pacing; however,

Glenn and colleagues and Farmer and colleagues are

credited for developing the modern systems, employing

chronic diaphragmatic stimulation using radiofrequency

signals to stimulate phrenic nerves through intact skin.4,5

Moreover, this group initiated investigations regarding

muscle fatigue and conditioning, and they are

responsi-ble for the implementation of safety guidelines for

effec-tive use of diaphragmatic pacing

Diaphragmatic Pacing

Long-term electrical stimulation of motor nerves has been

successful only in pacing the diaphragm The durability

and fatigue resistance of the diaphragm is owing to its high

oxidative capacity and blood flow The critical

condition-ing phase of diaphragmatic paccondition-ing further molds the

muscle into an even more fatigue-resistant state through

long-term application of slow stimulation frequencies.6

Normal diaphragmatic muscle fiber has been shown to be

55% slow-twitch resistant, 21% fast-twitch resistant, and 24% fast-twitch fatigable.7

fatigue-Although diaphragmatic dysfunction may be theresult of a variety of disease processes, only a select feware eligible for treatment with diaphragmatic pacing Anintact peripheral (phrenic) ner ve and muscle(diaphragm) are prerequisites for potential pacing candi-dates Some patients with intrinsic paralysis of the acces-sory respiratory muscles (high cervical spine injuries)and those with central alveolar hy poventilation(Ondine’s curse) may be candidates for diaphragmaticpacing Patients with respiratory insufficiency secondary

to lower motor neuron (phrenic nerve) dysfunction,amyotrophic lateral sclerosis, muscular dystrophy, orextensive pulmonary parenchymal disease have tradition-ally not been candidates Although the potential patientpool is limited, diaphragmatic pacing offers a clearadvantage in quality of life, compared with traditionalventilatory systems, for appropriately selected patients.8

Apparatus

There are currently three commercially available phragmatic pacing devices Though each has uniquecharacteristics, there are four common basic compo-nents: receiver, electrode, antennae, and transmitter Thereceiver and electrode assembly require permanent surgi-cal implantation, whereas the transmitter and antennaeare external devices The basic components of a typicaldevice are detailed in Figure 37-1 (Avery Laboratories ofFarmingdale, New York)

dia-The subcutaneously implanted receiver transformsradiofrequency signals from the transmitter into electri-cal impulses carried to electrodes placed in the proximity

ate 24-hour support but instead respond better with

pacing during the day and ventilation during sleep.15–17In

the patients with anatomical defects causing respiratory

insufficiency, most are able to maintain normal

respira-tory physiology while awake, but develop significant

apnea and hypoventilation during sleep This subset of

patients is unique in that they have a somewhat

func-tional respiratory system while awake and some refuse

surgery fearing that medical and surgical complications

related to diaphragmatic pacing could leave them worse

off than before.18,19However, Glenn and his colleagues

have shown in a series of 36 patients with

hypoventila-tion syndromes significant benefit in raising pO2and

lowering pCO2without an unacceptably high

complica-tion rate

Diaphragmatic pacing has been feasible only in

patients with intact lower motoneurons, a prerequisite

which excluded a significant group of patients in the

past, including C3–5 quadriplegics, owing to axonal loss

of the phrenic nerve A recently developed procedure,

involving the transfer of an intercostal nerve to the

phrenic nerve, has been described by Krieger and

colleagues.20An end-to-end anastomosis is performed

from the harvested fourth intercostal nerve to the

phrenic nerve, approximately 5 cm above the diaphragm

At the time of the procedure, a phrenic nerve pacemaker

is implanted distal to the anastomosis After diaphragm

movement is documented, pacing is instituted The

aver-age interval from surgery to pacing is 9 months In a

series of 6 patients, 10 total nerve transfers were

per-formed, successfully reanimating the diaphragm and

allowing pacing in all 6 patients

Preoperative Screening

Careful patient selection and preoperative evaluation is

crucial to long-term success in diaphragmatic pacing

This assessment should include diaphragm

electromyog-raphy, radiologic evaluation of diaphragmatic excursion,

and pulmonary function tests The gold standard for

test-ing the integrity of the phrenic nerve, neuromuscular

junction, and diaphragm has traditionally been

percuta-neous electrical stimulation of the nerve at the neck.21

However, magnetic stimulation has recently been shown

to produce similar data in a less invasive manner and is

not dependent on precise localization of the phrenic

nerve.22,23 The pitfalls of this screening test are that

acces-sory muscles of respiration are also activated and it is

difficult to lateralize function, as the contralateral side

often contracts to a small extent.24 Some believe that by

using cortical magnetic stimulation one may predict the

eventual spontaneous recovery of respiratory function

and help avoid unnecessary diaphragmatic pacing.25

Surgical Technique for Implantation

Although techniques for implantation of electrodes inthe cervical region are well described, this approach isseldom used, as accessory nerve fibers have been shown

to join the phrenic nerve as it courses through thethoracic inlet The exception to this rule is in patientswith severe thoracic deformity or pleural disease, wherecervical implantion is the only safe option

The thoracic approach, most commonly used, involvesincision in the second intercostal space If bilateral elec-trodes are needed, the operations are performed 10 to 14days apart, to lower the rate of infection from a longerone-stage operation.26 After sterile preparation of thechest, a transverse incision in the second intercostal space

is made, from the sternal border to the anterior axillaryline The incision is carried through the pectoralis major,and internal mammary veins are then ligated Alterna-tively, some clinicians use minimally invasive techniques,according to anecdotal reports

The pleural cavity is entered and the mediastinum isexposed The section of phrenic nerve between the base

of the heart and the apex of the chest is the preferred site

of electrode implantation.27 Anatomically, on the right,this site is immediately above the junction of the azygosvein and the superior vena cava, where the phrenic nervepasses across the cava.28 On the left, the site where thenerve passes between the aortic arch and left pulmonaryartery is often chosen

When dissecting the phrenic nerve, it is important tokeep a 2 to 3 mm cuff of perineural tissue intact sur-rounding the nerve to preserve its blood supply Oncedissection is complete, the electrode cuff (monopolar) isthen inserted beneath the nerve and secured in place tosurrounding structures Critical to successful propaga-tion of stimulus is contact of the platinum electrode tothe perineurium of the phrenic nerve The lead wires arethen tunneled to a subcutaneous pocket containing thereceiver The receiver is placed in a pocket whose posi-tioning depends on the underlying reason for pacing.The optimal location of the receiver in patients withcentral alveolar hypoventilation is the lower chest in themidaxillary line; in quadriplegic patients, the optimallocation is the upper chest over the midclavicular line;and in children, the optimal location is the lateralabdomen It is important that no part of the receiver liedirectly underneath the incision and that the copper coilfaces outward toward the undersurface of the skin Inpatients with bilateral implants, the receivers should be

no closer than 15 cm Testing of the system before nation of the operation is critical for both contractionand threshold (should be between 0.1 to 2 mA).26,27

termi-Diaphragmatic Pacing / 451

Another surgical alternative to diaphragmatic pacing

in patients with phrenic nerve dysfunction is diaphragm

plication This surgical option has been extensively used

in patients after cardiac surgery with postoperative

phrenic nerve palsy, usually secondary to intraoperative

trauma or cold-induced injury These patients have

respi-ratory dysfunction and prolonged ventilatory

depen-dence unless treated Some studies suggest early

intervention when phrenic nerve division has taken place

during the operation.29

Pacing Schedule

The selection of the appropriate parameters of pacing is

dependent on the underlying reason for ventilatory

support Patients with quadriplegia who require support

usually have undergone mechanical ventilation for

months and have significant disuse atrophy of the

diaphragm.30 Once pacing parameters have been set and

maximal determination of diaphragm motion has been

achieved, pacing is begun 2 to 3 minutes per hour while

the patient is awake This is increased daily by a few

minutes, as long as the minute-volume does not decrease

by more than 25% during pacing.31If bilateral

stimula-tion is needed, condistimula-tioning must be performed to

prevent fatigue, by converting muscle fibers to a

nonfa-tiguing status This conditioning is done by gradually

lowering respiratory rate, frequency, and amplitude

For patients requiring pacing support while sleeping

(as with central alveolar hypoventilation and apnea) a

more aggressive schedule can be instituted These

patients often have only unilateral pacing electrodes and

therefore must be paced more forcefully This is usually

well tolerated, owing to the long rest period these

patients are able to tolerate during waking hours Sample

settings have been frequency 50 msec (20Hz), respiratory

rate of 12 to 14, pacing time of 12 to 14 hours.32 Pacing

can be started as early as the second postoperative week.33

A new mode of stimulation proposed by Talonen and

colleagues use principles of sequential stimulation.6 This

strategy is designed to limit fatigue and capitalizes on the

ability to stimulate muscle compartments selectively The

use of unipolar electrodes has been criticized for

stimu-lating the same part of the nerve each time, allowing no

recovery Sequential stimulation uses a four-pole

elec-trode to split the nerve into four equal components, each

stimulated using a lower frequency in a sequential

fash-ion, allowing optimal contraction with time for rest for

most of the muscle fibers during the actual contraction

Sequential stimulation has been reported to shorten

conditioning in quadriplegic patients from 6 to 8 months

at the external and internal level Internal failure, usuallyrequiring surgical intervention to correct, occurred at arate of approximately 25% per patient-year in one study

of children.17 Most commonly, this internal failure isreceiver malfunction, which requires a minimally inva-sive exchange

Malfunction of other components, including the wiresand electrodes, has been reported as well.19 Electrodemalfunction can occur with growth, vigorous activity, orfibrous ner ve entrapment, but the incidence hasdecreased since bipolar cuff–shaped electrodes havedeclined in use.36

Rarely, the etiology of failure is at the neuromuscularjunction or phrenic nerve level These have been linked

to diabetes, toxins, nutritional deficiencies,

Infections have been reported over the receiver site,sometimes long after surgery.37

Physicians should inspect all pacing equipment ally In addition to this physical exam, polysomnographyshould be performed in a well-equipped sleep laboratory.During this exam, arterial blood gas sampling should beincluded.21 Transtelephonic monitoring is available withthe Avery/Dobelle system

annu-Outcome

Patients who can successfully rely on diaphragmaticpacing have been shown to have an improved quality oflife as measured by their ability to attain simplified nurs-ing care, restored speech and olfactory sense, andimprovement in their self-assessed psychological comfortlevel.38Children have been shown to pursue activitiessuch as soccer, tennis, and football; moreover, adultquadriplegics have been able to operate computers.39

When compared with mechanical ventilation, the needfor artificial humidification is reduced, secretions arereduced, and equipment is less cumbersome.40 Thoughnot formally studied, there also appears to be a trendtoward long-term savings in health care costs.21

Latest Trends

Coordination of upper airway muscles to maintain

completely implantable system with its own power

source that can be programmed externally is still a goal

of manufacturers.19Pacemakers that can adjust to the

patient’s level of activity may be developed in the future.41

However, by far the most exciting area of continued

success and research is in diaphragm reanimation using

microsurgical techniques of nerve transfer These

tech-niques enlarge the patient pool and make available a

better quality of life for many quadriplegic patients for

whom diaphragmatic pacing was not formerly available.20

References

1 Elefteriades JA, Quin JA Diaphragm pacing Chest Surg

Clin North Am 1998;8:331–57.

2 Sarnoff SJ, Hardenbergh E, Whittenberger JL.

Electrophrenic respiration Am J Physiol 1948;155:1.

3 Sarnoff SJ, Hardenbergh E, Whittenberger JL.

Electrophrenic respiration Science 1948;108:482.

4 Glenn WWL, Holcomb WG, McLaughlin AJ, et al Total

ventilatory support in a quadriplegic patient with

radiofre-quency electrophrenic respiration N Engl J Med

1972;286:513.

5 Farmer WC, Glenn WWL, Gee JBL Alveolar

hypoventila-tion syndrome: studies of ventilatory control in patients

selected for diaphragm pacing Am J Med 1978;64:39–49.

6 Talonen PP, Baer GA, Hakkinen V, Ojala JK.

Neurophysiological and technical considerations for the

design of an implantable phrenic nerve stimulator Med

Biol Eng Comput 1990;28:31–7.

7 Lieberman DA, Faulkner JA, Craig AB, Maxwell AC.

Perfusion and histochemical composition of guinea pig and

human diaphragm J Appl Physiol 1973;34:233.

8 Brouillette RT, Marzocchi M Diaphragm pacing: clinical

and experimental results Biol Neonate 1994;65:265–71.

9 Nochomovitz ML, Peterson DK, Stellato TA Electrical

acti-vation of the diaphragm Clin Chest Med 1988;9:349.

10 Bellemare E, Bigland-Ritchie B Central components of

diaphragmatic fatigue assessed by phrenic nerve

stimula-tion J Appl Physiol 1987;62:1307.

11 Baer GA, Talonen PP International symposium on

implanted phrenic nerve stimulators for respiratory

insuffi-ciency Ann Clin Res 1987;19:399.

12 Girsch W, Koller R, Holle J, et al Vienna phrenic

pacemaker-experience with diaphragm pacing in children Eur J Pediatr

Surg 1996;6:140–3.

13 Nochomovitz ML, Montenegro HD, editors Diaphragm

pacing Ventilatory support in respiratory failure 1987 p

85–107.

14 Danon J, Druz WS, Goldberg NB, Sharp JT Relative

contri-butions of ribcage and abdomen to breathing in normal

subjects J Appl Physiol 1979;119:909.

15 Radecki LL, Tomatis LA Continuous bilateral trophrenic pacing in an infant with total diaphragmatic paralysis J Pediatr 1976;88:969–71.

elec-16 Ilbawi MN, Hunt CE, DeLeon SY, Idriss F Diaphragm pacing in infants and children: report of a simplified tech- nique and results Ann Thorac Surg 1981;31:61–5.

17 Flageole H, Adolph VR, Davis GM, et al Diaphragmatic pacing in children with central alveolar hypoventilation syndrome Surgery 1995;118:25–8.

18 Glenn WWL, Holcomb WG, Hogan J Diaphragm pacing by radiofrequency transmission in the treatment of chronic ventilatory insufficiency; present status J Thorac Cardiovasc Surg 1973;66:505–20.

19 Glenn WWL, Phelps ML, Elefteriades JA, et al Twenty years

of experience in phrenic nerve stimulation to pace the diaphragm PACE 1986;9:780.

20 Krieger LM, Krieger AJ The intercostal to phrenic nerve transfer: an effective means of reanimating the diaphragm

in patients with high cervical spine injury, plastic and structive surgery Plast Reconstr Surg 2000;105:1255–61.

recon-21 Chervin RD, Guilleminault C Diaphragm pacing in ratory insufficiency J Clin Neurophysiol 1997;14:369–77.

respi-22 Muller-Felber W, Riepl R, Reimers CD, et al Combined ultrasonographic and neurographic examination: a new technique to evaluate phrenic nerve function Electromyogr Clin Neurophysiol 1993;33:335–40.

23 Hamnegard CH, Wragg SD, Mills GH, et al Clinical ment of diaphragm strength by cervical magnetic stimula- tion of the phrenic nerves Thorax 1996;51:1239–42.

assess-24 Mills GH, Kyroussis D, Hamnegard CH, et al Unilateral magnetic stimulation of the phrenic nerve Thorax 1995;50:1162–72.

25 Similowski T, Straus C, Attali V, et al Assessment of the motor pathway to the diaphragm using cortical and cervi- cal magnetic stimulation in the decision-making process of phrenic pacing Chest 1996;110:1551–7.

26 Glenn WWL, Phelps ML Diaphragm pacing by electrical stimulation of the phrenic nerve Neurosurg 1985;17:974.

27 Van Trigt P III Diaphragm and diaphragmatic pacing In: Sabiston, Spencer, editors Surgery of the chest 1997.

28 Wetstein L Technique for implantation of phrenic nerve electrodes Ann Thorac Surg 1987;43:335.

29 Illze EW, Metz R, Jekel L, Woolley SR Post cardiac surgery phrenic nerve palsy: value of plication and potential for recovery Eur J Cardiothorac Surg 1998;14:179–84.

30 Nochomovitz ML, Hopkins M, Brodkey J, et al Conditioning of the diaphragm with phrenic nerve stimu- lation after prolonged disuse Am Rev Respir Dis 1984;130:684.

31 Harprin RP, Gignac SP, Epstein SW, et al Diaphragm pacing and continuous positive airway pressure Am Rev Respir Dis 1986;134:1321.

Diaphragmatic Pacing / 453

32 Oda T, Glenn WWL, Fukuda Y, et al Evaluation of electrical

parameters for diaphragm pacing: an experimental study J

Surg Res 1981;30:142–53.

33 Miller JI, Farmer JA, Stuart W, Apple D Phrenic nerve

pacing of the quadriplegic patient J Thorac Cardiovasc

Surg 1990;99:35–40.

34 Weese-Mayer DE, Hunt CE, Brouillette RT, Silvestri JM.

Diaphragm pacing in infants and children J Pediatr

1992;120:1–8.

35 Marzocchi M, Brouillette RT, Weese-Mayer DE, et al.

Comparison of transthoracic impedance/heart rate

moni-toring and pulse oximetry for patient using diaphragm

pacemakers Pediatr Pulmonol 1990;8:29–32.

36 Hunt CE, Brouillette RT, Weese-Mayer DE, et al Diaphragm

pacing in infants and children PACE 1988;11L:2135–41.

37 Fodstad H Pacing of the diaphragm to control breathing in patients with paralysis of central nervous system origin Stereotact Funct Neurosurg 1989;53:209–22.

38 Oakes DD, Wilmot CB, Halverson D, Hamilton RD Neurogenic respiratory failure: a 5-year experience using implantable phrenic nerve stimulators Ann Thorac Surg 1980;30:188.

39 Fodstad H The Swedish experience in phrenic nerve lation PACE 1987;10:246–51.

stimu-40 Carter RE, Donovan WH, Halstead L, Wilkerson MA Comparative study of electrophrenic nerve stimulation and mechanical ventilatory support in traumatic spinal cord injury Paraplegia 1987;25:86–91.

41 Frey H, Baer GA, Talonen PP Patient selection for matic pacing by phrenic nerve stimulation (PNS) In: Baer

diaphrag-GA, Frey H, Talonen PP, editors Implanted phrenic nerve stimulators for respiratory insufficiency Tampere (Finland): Acta University Tamperensis; 1989 p 51–9.

Unlike other gastrointestinal organs, the esophagus is a

relatively simple lumen having no digestive, absorptive,

or endocrine function Rather, it is a pump that propels

liquids and foods from the hypopharynx into the

stom-ach Two valves, the upper and lower esophageal

sphinc-ters, are present to open in coordinated function with the

swallowing mechanism and close at appropriate times to

prevent gastroesophageal reflux and aspiration

Diseases of the esophagus, particularly gastroesophageal

reflux disease (GERD) and achalasia are quite common In

many cases, patients respond well to various medical

thera-pies (eg, proton pump inhibitors, pneumatic dilatation, or

botulinum toxin injection), but more complicated cases

and patient preference results in over 80,000 operations a

year in the United States for the treatment of benign

esophageal diseases (T.R DeMeester, personal

communica-tion).1Surgical repair of the esophagus and restoration of

its function are demanding and difficult operations In

part, these are the results of limited surgical options for

esophageal repair The lower esophageal sphincter (LES) in

reflux disease may be augmented and returned to the

abdomen or undergo myotomy in the patient with

achala-sia The esophageal body and upper esophageal sphincter

may be myotomized in cases of diffuse esophageal spasm or

cricopharyngeal muscle dysfunction Diverticulectomy of

either an epiphrenic or hypopharyngeal diverticulum may

be necessary along with a myotomy If esophageal function

is not salvageable, total esophagectomy and replacement is

the only surgical choice

To ensure the best operation, we at the Cleveland

Clinic Foundation in the Center for Swallowing and

Esophageal Disorders believe that interactive cooperation

between gastroenterologists and esophageal surgeons is

the “best menu” for successful esophageal surgery It is the

gastroenterologist’s responsibility to identify the “rightpatient” based on the history and carefully performedpreoperative esophageal function tests These results arethen carefully reviewed with our surgical colleagues sothat the “right operation” can be performed, eitherlaparoscopically or open through the abdomen or thechest As a result of this teamwork, our success rate forbenign esophageal disease over the last 8 years, whether it

be for initial operation or repeat surgery, exceeds 90%.This chapter discusses the approach taken at theCleveland Clinic in the preoperative evaluation of patientsfor GERD and primary esophageal motility disorders,especially achalasia.2Our success is predicated on a teamapproach including gastroenterologists, esophagealsurgeons, radiologists, and technicians in our esophagealfunction laboratory

Preoperative Evaluation of the Patient Prior to Antireflux Surgery

Meticulous evaluation prior to surgery is the first andmost important step in performing antireflux surgery.Simplifying the operation via laparoscopy does not liber-alize the indications for this procedure This was learnedwith the Angelchik fiasco; with the wide proliferation oflaparoscopic surgery we hope this unfortunate scenariowill not be repeated Furthermore, it is important thatthe gastroenterologist communicates to the surgeon theresults of these studies and any modifications in thesurgery that may be appropriate

Clinical History

A careful history will elicit the typical symptoms ofGERD, such as heartburn and acid regurgitation, as well

as atypical symptoms (hoarseness, throat clearing, cough,

or chest pain), which may require further clinical

correla-tion Paradoxically, the best surgical candidates are the

patients responding completely to proton pump

inhibitors.3 Therefore over the years, my group has

evolved a “golden rule” in referring patients for surgery

Those who respond dramatically to the proton pump

inhibitors are potential surgical candidates, while those

failing to show improvement, especially after twice-daily

dosing, likely have a problem other than GERD causing

their “intractable” symptoms or esophagitis (Table 38-1)

This rule is particularly important when evaluating

patients presenting primarily with atypical symptoms of

GERD For example, a recent series reported on 150

consecutive patients undergoing laparoscopic antireflux

surgery of which 35 (23%) patients had primarily atypical

symptoms.4Surgery relieved heartburn in 93% of the

patients, whereas only 56% of the patients had relief of

their atypical symptoms The only useful preoperative

predictors for relieving the atypical symptoms were the

positive response to acid suppression with proton pump

inhibitors and the presence of hypopharyngeal reflux on

pH testing in patients with laryngeal complaints Also

beware of the patients whose major complaints are nausea,

vomiting , belching, or hiccups Dyspeptic patients may

not do well with surgery because they have another

etiol-ogy for their symptoms (ie, gastroparesis or bulimia) or

their constant air-swallowing will increase their

postopera-tive chances for troubling gas-bloat symptoms

Endoscopy

A careful evaluation of the esophageal and gastric

mucosa is mandatory in all GERD patients prior to

antireflux surgery The esophagus needs to be carefully

evaluated for the location of both the esophagogastric

and squamocolumnar junctions, presence and type of

esophagitis, Barrett’s epithelium, peptic stricture or rings,

the presence and length of a hiatal hernia, and the

pres-ence of esophageal diverticula

The normal esophagogastric junction, defined by

either the beginning of the tubular esophagus or the

proximal edge of the gastric folds when a hiatal hernia ispresent, should be located at about 40 cm from the teeth.Identification of this landmark 5 cm or more above thediaphragmatic hiatus should raise suspicion about thepresence of a shortened esophagus

On the other hand, the squamocolumnar junctiondefines where the pale white squamous mucosa of theesophagus joins the salmon pink mucosa of the stomach

In the healthy patient, the esophagogastric junction andsquamocolumnar junction should be closely apposed.Classic esophagitis begins at the squamocolumnar junc-tion and usually extends orad in a linear orientationalong the distal esophageal folds Isolated ulcers oresophagitis sparing the squamocolumnar junctionshould suggest other etiologies, such as pill injury or viraldiseases The presence of Barrett’s esophagus is bestdefined after healing of esophagitis It is suspected whentongues or circumferential extension of gastric-appearingmucosa appear above the esophagogastric junction.However, the diagnosis is only made with biopsies show-ing the histologic presence of specialized intestinal meta-plasia with Alcian blue–positive goblet cells Other gastrictissues with characteristics of cardiac or fundic mucosa

do not make the diagnosis of Barrett’s epithelium, as theyare not associated with an increased risk of esophagealadenocarcinoma This issue is especially important inpatients appearing to have shorter segments (< 3 to

5 cm) of Barrett’s-appearing mucosa, as the biopsyconfirmation of specialized intestinal metaplasia occurs

in only 25 to 50% of these cases.5 Prior to antirefluxsurgery, patients with Barrett’s esophagus also needextensive esophageal biopsies to exclude the presence ofhigh-grade dysplasia or cancer If found, these patientsare treated with esophagectomy or possibly endoscopicablation therapies

Endoscopy can help to define the presence, extent, anddegree of scarring related to esophageal strictures Long

or tight firm strictures without associated inflammationsuggest severe submucosal scarring, a shortened esopha-gus, and complicated GERD On the other hand, manypatients with severe esophagitis will have a stricture, butmost of the esophageal narrowing is related to edema,which resolves with aggressive acid suppression It must

be remembered that subtle rings and peptic stricturessufficient to account for dysphagia may be missed byendoscopy, owing to poor esophageal distention, and can

be best assessed by barium esophagram

The presence of a hiatal hernia is determined bymeasuring the distance between the esophagogastricjunction and diaphragmatic hiatus; up to 2 cm is consid-ered normal A key endoscopic maneuver in evaluatingthese patients is to use considerable air insufflation toadequately demonstrate these landmarks The retroflex

TABLE 38-1 Common Reasons for GERD Treatment Failure

Incorrect diagnosis

Inadequate acid suppression

Much less common with use of PPIs

Noncompliance with drug regimen

Cost vs psychosocial issues

view of the fundus is essential to assess the presence of a

sliding hernia or a paraesophageal hernia Complex or

mixed hernias also are suggested by sharp angulations of

the lumen of the distal esophagus or difficulty in passing

the endoscope through the hernia into the stomach

Finally, endoscopy can be helpful in identifying the

shortened esophagus, which may be responsible for 20 to

33% of surgical failures after open or laparoscopic

fundo-plication.7A shortened esophagus should be suspected

preoperatively in patients with a hiatal hernia 5 cm or

larger in size, a nonreducible hernia, long-segment

Bar-rett’s esophagus, or a difficult-to-manage peptic stricture,7,8

This group of patients may require a Collis gastroplasty to

lengthen the esophagus, allowing for a tension-free

fundo-plication

Barium Esophagram

We believe that the barium esophagram is an important

test prior to antireflux surgery.9It allows for the detailed

assessment of esophageal anatomy and can identify subtle

strictures and rings, missed at the time of endoscopy, by

assuring good esophageal distention either with Valsalva’s

maneuver or by challenging the esophagogastric junction

with a 13 mm tablet or food (Figure 38-1).10

The esophagram is another study to assess the presence

and especially the extent of gastroesophageal reflux More

recent studies suggest that the presence of spontaneous

reflux or reflux provoked by various maneuvers (cough,

Valsalva’s, rolling, water siphon test) on the barium

esophagram has a sensitivity of 60 to 70% and a

speci-ficity in the same range when compared with 24-hour pH

monitoring.9,11Once reflux is observed, it is important to

assess the extent of the refluxed barium and approximate

time to clear reflux material from the esophagus If

esophageal motility is abnormal, nearly all patients show

poor clearance (> 1 minute) of refluxed material

The barium esophagram is the most accurate test for

assessing the presence of a hiatal hernia, its length, the

type of hernia (especially paraesophageal or Type III

mixed hernia), and the reducibility of a hiatal hernia

Some sliding hiatal hernias may not be identified on an

upright esophagram and will only be observed when the

patient is in the semiprone, right anterior oblique (RAO)

position while rapidly ingesting barium If the hernia

persists in the upright position, especially when

associ-ated with a stricture, esophageal foreshortening is

as-sumed (Figure 38-2).9

Finally, the barium esophagram is an important

adjunctive test, complementing manometry, for

evaluat-ing the adequacy of esophageal peristalsis.12This

assess-ment is best performed in the RAO semiprone position by

giving the subject a series of five swallows of barium to

ingest, separated by 30-second intervals Abnormal

motil-ity and poor clearance are suggested by the presence ofpoor propagation of the primary wave, analogous to low-amplitude contractions at esophageal manometry, withsignificant retrograde escape of the barium column and

no secondary stripping waves to clear the barium Insome patients, there are vigorous, nonpropulsive tertiarycontractions These abnormal barium features on three ormore swallows suggest the presence of a weak esophagealpump or possibly aperistalsis in association with achalasia

or scleroderma When supported by manometric studies,these changes might require modification to the tradi-tional Nissen fundoplication (ie, Toupet fundoplication)

or a Heller myotomy when achalasia is present

Esophageal Manometry

A careful study of the LES and esophageal body ismandatory prior to antireflux surgery, as much to evalu-ate the adequacy of the esophageal pump as to assess thepressure and length of the LES

Manometry can assess the location of the LES, its ing pressure, its ability to relax, its overall length, as well

rest-as the length of its intrathoracic and intra-abdominalcomponents Most patients undergoing antireflux

Preoperative Evaluation of Neuromotor Diseases of the Esophagus / 457

FIGURE 38-1 Gastroesophageal reflux disease patient with

heart-burn and solid food dysphagia Left, Upright esophagram suggesting possible narrowing of distal esophagus Right, After Valsalva’s

maneuver in the horizontal semiprone position, classic Schatzki’s ring and hiatal hernia are now seen with good esophageal distention.

debate Four studies18–21performed in medical centers

with expert esophageal surgeons found that the patients

with these motor abnormalities postoperatively reported

clinical results similar to those patients with normal

motor function of the esophagus These results suggested

that abnormal motility should not be a contraindication

to a properly performed “loose” Nissen fundoplication

However, a cautionary note is warranted as it must be

remembered that these reports come from high-volume

esophageal centers with expert surgeons performing

antireflux operations multiple times a month We and

others22 prefer to tailor our operation, performing the

incomplete Toupet fundoplication in patients with

significant esophageal motility, confirmed by both

manometr y and barium esophagram With this

approach, our postoperative dysphagia rate is only 10%,

well below the usual experience of up to 25%

24-Hour pH Monitoring

Esophageal pH testing, as well as the response to medicaltherapy, defines the disease state in reflux patients with-out esophagitis Therefore, ambulatory 24-hour pHmonitoring must be done prior to surgery in patientswithout esophagitis or in those where the diagnosis is indoubt Patients should be tested off their current antire-flux medications This requires stopping proton pumpinhibitors for at least 7 days and H2-receptor antagonists

up to 48 hours prior to the testing to ensure that a drugeffect is no longer present All pH studies should beperformed after accurately defining the proximal border

of the LES by manometry Failure to adhere to this detailmay result in the pH probe being placed too high, givingpossibly a false-negative study, or more importantlybeing placed too low, possibly in the hernia sac, giving afalse-positive study (Figure 38-4) The usefulness ofroutine pH testing in patients with esophagitis orBarrett’s esophagus is marginal, especially if they haveclassic symptoms and endoscopic findings.22,23 However,the presence of distal esophagitis, particularly if it doesnot involve the squamocolumnar junction, does notalways mean acid reflux disease Older patients withrecent onset of ulcerative esophagitis or strictures mayhave drug-induced disease from antibiotics, Quinaglute,vitamin C, or alendronate (ie, Fosamax) Their unusualacute presentation and normal 24-hour pH study will bethe only clue to the correct diagnosis.24

Patients with only upright gastroesophageal reflux by24-hour pH testing need to be carefully scrutinized prior

to antireflux surgery These patients usually have normalLES pressures, hiatal hernias are uncommon, and most

FIGURE 38-3 Esophageal motility tracings of ineffective esophageal

peristalsis A, All contractions are peristaltic but very low amplitude

(< 30 mm Hg) B, Normal-amplitude peristalsis that fails to transverse

the most distal esophagus (ie, nontransmitted [NT] contraction).

Reproduced with permission from Leite LP et al 15

FIGURE 38-4 Technical problem with lower (distal) pH probe placed in

a hiatal hernia because esophageal manometrc location of the lower esophageal sphincter not performed Characteristics suggesting this is not prolonged esophageal reflux: (1) esophageal pH is infrequently less than 2 and (2) distal pH rises rather than falls in response to meals

(dark arrows) as the result of gastric acid neutralization by food.

have either a normal endoscopy or only mild esophagitis.

Additionally, symptoms other than classic heartburn or

acid regurgitation may predominate, including nausea,

vomiting, bloating, or belching We believe all these

patients should have gastric emptying studies prior to

surgery to assess for delayed gastric emptying, which may

be the primary cause of their symptoms with reflux being

only a secondary issue These patients can undergo

antireflux surgery, but their overall success is less than

those with supine or bipositional reflux, and they have a

higher incidence of postoperative complications of

gas-bloat and increased flatus.25

We have routinely attempted to perform 24-hour pH

monitoring in all patients prior to and 3 months after

antireflux surgery to assess the adequacy of their

fundo-plication However, our recent experience suggests this

may not be indicated in all patients.26Rather, the selected

use of postoperative 24-hour pH testing may be most

helpful in patients with persistent symptoms after

surgery or those with a history of complicated GERD,

especially strictures or Barrett’s esophagus In this latter

group, symptom relief still may be associated with

substantial acid reflux, which if left untreated may

worsen their disease or possibly even lead to cancer.27

Gastric Emptying Studies

Abnormalities of gastric emptying, usually mild to

moder-ate slowing, are frequent in patients with GERD being

considered for surgery.28However, the Nissen

fundoplica-tion has been shown to augment gastric emptying,

proba-bly by interfering with receptive relaxation of the fundus,

thereby promoting rapid transfer of the meal from the

proximal to the distal stomach.28,29On the other hand,

severe gastroparesis (
12
of gastric emptying time exceeds

200 minutes) is a contraindication to antireflux surgery as

it will be associated with severe symptoms of gas-bloating,

pain, and forceful retching, ultimately resulting in

fundo-plication failure We do not perform gastric emptying

studies routinely on all our patients but believe it is

indi-cated in patients with a normal LES pressure, daily or

severe postprandial bloating, and frequent nausea and

vomiting and in patients with collagen-vascular diseases

It should be remembered that the postoperative

evalu-ation should make sense and accurately define the

patho-physiology behind the patient’s chronic reflux disease As

shown in Table 38-2, my experience has shown that

certain scenarios are “red flags,” requiring careful

scruti-nizing so as not to wrap the patient who has achalasia,

pill-induced esophagitis, or gastroparesis as the cause of

symptoms or more complicated GERD requiring

modifi-cation of the traditional fundoplimodifi-cation

Preoperative Evaluation of Primary Esophageal Motility Disorder

Primary motility disorders, especially achalasia anddiffuse esophageal spasm, commonly present withdysphagia and chest pain In patients with achalasia, theetiology of symptoms is well defined and secondary toincomplete LES relaxation and poor esophageal empty-ing, rather than the aperistalsis found in the esophagealbody As a result, therapies directed at correcting theseLES abnormalities, such as pneumatic dilatation, botu-linum toxin injections, or Heller myotomy, are successful

in relieving dysphagia and regurgitation, thus allowingthe patient to return to normal swallowing and eating,despite the rare return of esophageal peristalsis

On the other hand, the etiology of chest pain inpatients with diffuse esophageal spasm and its variant,nutcracker esophagus, is poorly understood In somepatients, the cause appears to be gastroesophageal reflux,which responds appropriately to proton pump inhibitors

On the other hand, other patients are treated with nitrates,calcium channel blockers, or antidepressants to decreasethe high-amplitude spastic contractions or the associatedanxiety states, but their response is much less predictable.Unfortunately, there are no drugs that can return a spasticesophagus back to one with normal peristalsis, andalthough drugs can decrease the high-amplitude peristalticcontractions seen in the nutcracker esophagus, chest pain

is infrequently cured Thus, surgery needs to be consideredvery carefully in this subset of patients, unless there is amajor complaint of dysphagia associated with LESdysfunction and poor esophageal emptying We advisegreat caution in considering a long myotomy for patientswith chest pain alone, because all peristaltic waves andnormal esophageal clearance are abolished It has been ourexperience that chest pain is not reliably alleviated in thesepatients, and the surgery runs the risk of adding dysphagia

to the patient’s complaints

Clinical History

460 / Advanced Therapy in Thoracic Surgery

TABLE 38-2 Preoperative Evaluation for GERD: It Should All Make Sense

Beware of the following Symptoms resistant to PPIs

“Intractable” esophagitis Normal endoscopy Normal LES pressure Upright refluxer Large hernia or tight stricture Bloaters or patients with nausea and vomiting GERD = gastroesophageal reflux disease; LES = lower esophageal sphincter; PPI = proton pump inhibitor.

The diagnosis of achalasia should be suspected in anyone

with dysphagia for solids and liquids with regurgitation

of food and saliva.30Although the dysphagia may initially

be for solids only, as many as 70 to 97% of patients with

achalasia have dysphagia for both solids and liquids at

presentation This contrasts with patients having

stric-tures or rings whose dysphagia is limited to solids

Achalasia patients localize their dysphagia to the cervical

or subxyphoid area Over the years, patients learn to

accommodate to their problem by using various

maneu-vers, including lifting the neck or drinking carbonated

beverages to help empty the esophagus

Regurgitation becomes a problem with progression of

the disease, especially when the esophagus begins to

dilate Regurgitation of bland, undigested, retained food,

or accumulated saliva occurs in about 75% of achalasia

patients It occurs more commonly in the recumbent

position, waking the patient from sleep because of

chok-ing and coughchok-ing In some patients, aspiration

pneumo-nia can occur

Chest pain occurs in some achalasia patients, being

more common in individuals with mild disease whose

esophagus is not dilated It may mimic angina by

loca-tion and character, but differs in not being aggravated by

exercise or relieved by rest About 60% of achalasia

patients have some degree of weight loss at presentation,

because of poor esophageal emptying and decreased or

modified food intake However, weight loss is usually

minimal and some patients are obese Surprisingly,

heart-burn is recorded by nearly 40% of achalasia patients The

cause of this symptom is speculative, but it is probably

linked to the production of lactic acid from retained food

or to ingested acidic material such as carbonated drinks

The patients with diffuse esophageal spasm and

nutcracker esophagus tend to have chest pain rather than

dysphagia as a predominant symptom Chest pain is

vari-able in frequency, intensity, and location and commonly

has a pattern indistinguishable from that of cardiac

angina, including response to nitroglycerin Pain can be

associated with meals and is rarely exertional Dysphagia

is intermittent, nonprogressive, and associated with

liquids and solids and can be precipitated by stress,

liquids of extreme temperatures, or rapid eating Many

patients with spastic motility disorders also have

symp-toms compatible with irritable bowel syndrome or

urinary and sexual dysfunction in women

Barium Esophagram

When the diagnosis of achalasia is suspected, a barium

esophagram with fluoroscopy should be the first test

performed.9It will reveal the loss of primary peristalsis in

the distal two-thirds of the esophagus with to-and-fro

movement in the supine position In the upright

posi-tion, there will be poor emptying with retained food andsaliva often producing a heterogeneous air-fluid level atthe top of the barium column Early in the disease, theesophagus may be minimally dilated, but more chronicdisease may be associated with a sigmoid-like tortuosity

In late stages, the esophagus becomes massively dilated (8

to 10 cm or more) These patients may be better treatedwith esophagectomy than myotomy

The distal esophagus is characterized by a smoothtapering leading to the closed LES, resembling a bird’s-beak When the esophagus is minimally dilated, this may

be misinterpreted as a peptic stricture The presence of

an epiphrenic diverticulum suggests the diagnosis ofachalasia.31Hiatal hernias are infrequent findings inpatients with achalasia with a reported prevalence of 1 to14% compared with 20 to 50% found in the generalpopulation.32 The presence of a hiatal hernia on bariumesophagram makes the diagnosis of achalasia less likely,but it does not rule it out and does not change themanagement of these patients

At the Cleveland Clinic Foundation, we have oped the “timed barium esophagram” to more accuratelyassess esophageal emptying and diameter in our patientswith achalasia.33It is usually performed as the first phase

devel-of the barium esophagram with the patient standing inthe upright position throughout the test The patientingests, according to personal tolerance, 100 to 250 mL oflow-density barium (45% weight by volume) over a 1-minute period Three-on-one spot films (14 inch by 14inch or 14 inch by 17 inch) are obtained at 1-, 2-, and 5-minute intervals after ingestion with the patient in theleft posterior oblique (LPO) position and the distance ofthe fluoroscopic carriage constant for all spot films Thedegree of emptying can be estimated by measuring theheight and width of the barium column after 1- and 5-minute intervals while assessing the change over the 5-minute time period (Figure 38-5)

We have found that the timed barium swallow lates well with the patient’s symptoms For example, theseverity of dysphagia parallels the rate of decline in thebarium column over 5 minutes, regurgitation is moresevere the higher the column of barium, and chest pain ismore common when the esophagus is not dilated.34Moreimportantly, this test has become an objective measure-ment along with symptoms to better assess the degree ofimprovement in esophageal emptying after either medical

corre-or surgical treatments Surprisingly, we have found that

up to 30% of patients feel remarkably better after

Therefore, we now believe the goal of effective achalasiatreatment is to promote complete or near completeemptying of the esophagus in 5 minutes with associateddecompression of the esophageal body as measured by a

subjects.40Apart from these high pressures, all

contrac-tions are peristaltic, although their duration can be

longer than normal About one-third of the patients with

nutcracker esophagus will also have high LES pressures,

but relaxation is normal

Endoscopy

Pseudoachalasia results from a tumor of the

esopha-gogastric junction or the adjacent area These patients

mimic classic achalasia clinically and manometrically

The diagnosis should be suspected in patients with

advanced age, shorter duration of symptoms, and

marked weight loss.41However, the predictive accuracy of

this triad of symptoms and signs is only 18%.42Although

the gastric cardia may be assessed radiographically, its

sensitivity is poor in detecting tumors of the

gastro-esophageal junction causing pseudoachalasia Therefore,

all patients with suspected achalasia should undergo

upper gastrointestinal endoscopy with a close

examina-tion of the cardia and the gastroesophageal juncexamina-tion

At endoscopy, the esophageal body usually appears

dilated, atonic, and often tortuous with normal-appearing

mucosa Sometimes, the mucosa is reddened, friable,

thickened, or even superficially ulcerated secondary to

chronic stasis, pills, or Candida esophagitis In the rare

patient with minimal esophageal dilatation, this may be

confused with reflux esophagitis Retained secretions,

usually saliva, liquids, or sometimes food debris, may be

encountered Patients with a markedly dilated esophagus

may need esophageal lavage or a clear liquid diet for

several days before endoscopy to avoid aspiration and to

allow adequate visualization of the esophagus

The LES region usually has a “rosette” appearance andremains closed with air insufflation; however, the endo-scope will easily traverse this area with gentle pressureallowing examination of the stomach If excess pressure isrequired, the presence of pseudoachalasia should behighly suspected, the gastroesophageal junction andcardia closely examined and biopsies taken

Tumors of the gastroesophageal junction may bemissed endoscopically in up to 60% of patients with

prove useful in patients with a nondiagnostic endoscopyand a high degree of suspicion for pseudoachalasia, but it

is not recommended as a routine test in achalasia.44Therole of computed tomography scans is limited in thediagnosis of achalasia.43 Rarely, this issue cannot beresolved before treatment We have elected to send thesepatients to surgery, performing a careful exploration ofthe upper abdomen and sampling any enlarged lymphnodes prior to undergoing myotomy

In the patients with diffuse esophageal spasm andnutcracker esophagus, the esophagus is generally normal

in appearance In some patients with secondary refluxcausing their spastic motility disorders, reflux esophagitisand a hiatal hernia may be noted

Miscellaneous Tests

Some authorities prefer to use scintigraphic methodswith oatmeal or egg sandwich to assess esophagealemptying.45However, we find the timed barium esopha-gram easier, more widely available, and more repro-ducible Occasionally, a 24-hour pH study may beperformed in a patient with achalasia Although the total

Preoperative Evaluation of Neuromotor Diseases of the Esophagus / 463

FIGURE 38-6 Esophageal manometry of achalasia A, In third from the bottom lead, lower esophageal sphincter pressure measures 60 mm Hg

with no relaxation to gastric baseline and exaggerated overshoot B, Aperistalsis of the esophageal body with simultaneous isobaric contractions

that have a mirror image appearance.

acid exposure time may be abnormal, the pH tends to

drift slowly down around pH 3 to 4, and the typical sharp

drops with gradual clearance are not seen.4 6 These

episodes of pseudoreflux probably represent the acidic

contents from the fermentation of retained food or

ingestion of acid beverages

Summary

Careful assessment of esophageal function prior to

surgery is the key for choosing the right patient to

undergo successful fundoplication or Heller myotomy

Even the best surgeon cannot expect a good operative

outcome if the patient has the wrong diagnosis or

complications requiring modification of the traditional

operation are not recognized prior to surgery A

multi-discipline team approach with good communication

between gastroenterologists and surgeons is the “best

menu” for successful esophageal surgery in GERD and

achalasia The best operation for these benign diseases is

usually the first operation; therefore, it benefits everyone

to ensure that everything makes perfect sense based upon

meticulous preoperative testing

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Gastroesophageal reflux (GER) is the most common

gastrointestinal disorder in Western countries Up to 10%

of the general American population experiences

heart-burn daily.1GER has become a common complaint to the

primary care provider, accounting for 1.3 million

outpa-tient visits a year in the United States This has resulted in

a surge of medical and surgical treatments for these

patients Lifestyle modifications include head-of-the-bed

elevation, weight loss in obese patients, diet change,

alco-hol and tobacco cessation, and avoiding tight-fitting

clothes The spectrum of medical treatment has

ad-vanced from antacids, to histamine-2 (H2) receptor

blockers, promotility agents, and most recently proton

pump inhibitors (PPIs) The current medical treatments

cure the majority of patients with mild disease, but more

than 50% of patients need lifelong medical therapy Since

the initial reports in 1991 of laparoscopic Nissen

fundo-plication by both Dallemagne and colleagues and Geagea,the use of laparoscopic antireflux surger y hasblossomed.2,3With the advent of minimally invasiveantireflux techniques many patients who need lifelongmedication or have intermittent symptoms on medicaltherapy are prime candidates for surgery Laparoscopictechniques have reduced morbidity and made surgicaltreatment an acceptable and appropriate treatmentchoice for GER A good response to the proper medicaltherapy predicts an excellent response to antirefluxsurgery.4Laparoscopic antireflux surgery has been shown

to be cost-effective when compared with medical therapy

A Canadian study compared the costs of laparoscopicNissen fundoplication and omeprazole (20 mg/d) At theend of the 5-year study period, surgery was less expensiveand became more cost effective at 3.3 years.5