Neuromuscular Disease Duchenne muscular dystrophy warrants thorough cardiac assessment The most common neuromuscular disease is Duchenne muscular dystrophy, with an incidence of one in 3
Trang 1Cardiac Assessment
Cardiovascular abnormalities are most commonly caused by pulmonary
hyper-tension (secondary to chronic hypoxia and hypercapnia) Right ventricular
hypertrophy and cor pulmonale may develop as a result of the elevated
pulmo-nary resistance ECG changes associated with pulmopulmo-nary hypertension and right
atrial enlargement (P wave greater than 2.5 mm, R greater than S in V1and V2)
may be seen but are usually not evident until late in the disease process
Mitral valve prolapse can be associated with idiopathic scoliosis
Scoliosis is also associated with congenital heart abnormalities [30] Mitral
valve prolapse is common in patients with idiopathic scoliosis with a prevalence
of about 25 % If a murmur is heard on physical examination, an echocardiogram
is recommended
Echocardiogram is recommended to assess pulmonary hypertension and congenital heart abnormalities
Marfan syndrome may be associated with mitral valve prolapse, dilatation of
the aortic root and aortic insufficiency Prophylaxis against infective
endocardi-tis should be administered to patients who have mitral valve prolapse or other
lesions resulting in disturbances of flow
Neuromuscular Disease
Duchenne muscular dystrophy warrants thorough cardiac assessment
The most common neuromuscular disease is Duchenne muscular dystrophy,
with an incidence of one in 3 300 male births It is inherited as a sex-linked
reces-sive condition affecting skeletal, cardiac and smooth muscle Over 90 % of these
patients develop a progressive scoliosis when they become wheelchair bound
Patients lack the membrane cytoskeletal protein dystrophin and typically
pre-sent between the ages of 2 and 6 years with progressive weakness of proximal
muscle groups Up to one-third of patients have intellectual impairment
Duchenne muscular dystrophy patients have a high incidence of deteriorating
lung function and cardiac abnormalities (50 ± 70 %) In the later stages of the
dis-ease, a dilated cardiomyopathy may occur associated with mitral valve
incompe-tence Dysrhythmias occur and up to 50 % of patients have cardiac conduction
defects [31] Cardiac arrest in patients with Duchenne muscular dystrophy has
been reported during spinal surgery [32]
Cerebral Palsy
Cerebral palsy is a non-progressive disorder of motion and posture and is the
result of an injury to the developing brain Clinical manifestations relate to the
area affected and these children require special consideration because of their
various disabilities Visual and hearing deficits are common and will make
com-munication difficult This often leads to anxiety, but premedication has to be
bal-anced with the unpredictable response These patients should be accompanied
by their carers at induction and in the recovery room, as they usually know how
to communicate with the patient Their understanding may be greater than
seems apparent on first meeting About one-third of these patients suffer from
Anticonvulsive therapy should be continued perioperatively
epilepsy and the anticonvulsive therapy should be continued Respiratory
prob-lems can include pulmonary aspiration from reflux, recurrent respiratory
infec-tions and reduced ability to cough The airway should be assessed for difficult
lar-yngoscopy because of loose teeth and temporomandibular joint dysfunction
Other problems during the perioperative period that require caution may include
hypothermia, nausea and vomiting and pain induced muscle spasm [33]
Trang 2Patients with primary or secondary malignant disease of the vertebral column and spinal cord are increasingly being considered for surgery Metastatic tumors occur three to four times more frequently than primary neoplasms within the vertebral column, and solitary vertebral lesions are often metastatic in the elderly The vast majority of neoplastic cord compressions derive from meta-static tumors of the breast, lung, prostate or hematopoietic system The thoracic spine is the most commonly affected [35]
Cancer patients are prone
to complications
These patients have commonly lost a large amount of weight and have reduced physiological reserve Respiratory complications of malignancy are common in
such patients Further risks include [36]:
) wound healing disturbance (protein loss)
) infection
) pleural effusion
) pulmonary toxicity (secondary to chemotherapy)
) increased risk for myocardial infarction (secondary to chemotherapy)
) metabolic derangements (e.g., hypercalcemia, SIADH)
) risk of coagulopathies (prostate cancer, hypernephroma) The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is associated with small cell lung tumors, carcinoma of the prostate, pancreas and bladder, and central nervous system neoplasms [37]
Surgery for malignant
tumors often requires
extensive blood transfusions
Prior to surgery enough units of packed red blood cells should be available since spinal decompressive surgery for malignant processes often leads to a large blood loss
Spinal Cord Injury
Spinal shock begins
immediately after the insult
and lasts up to 3 weeks
Patients with traumatic spinal injury frequently present for surgical spinal
stabi-lization during the period of spinal shock, which is the result of a traumatic sym-pathectomy It begins almost immediately after the insult and may last for up to
3 weeks [38] The clinical effects depend on the level of the lesion to the spinal cord and may involve several organ systems
A traumatic sympathectomy occurs below the level of the spinal cord lesion with the risk of hypotension secondary to arteriolar and venular vasodilatation Injuries
at or above T6 are particularly associated with hypotension, as the sympathetic out-flow to splanchnic vascular beds is lost Bradycardia will occur if the lesion is higher than the sympathetic cardioaccelerator fibers (T1–T4), with the parasympathetic cranial outflow being preserved A complete cervical cord injury produces a total sympathectomy and therefore hypotension will be more marked Above the level of the lesion, sympathetic outflow is preserved Vasoconstriction in the upper body vascular beds and tachycardia may be observed in response to the hypotension resulting from reduced systemic vascular resistance in the lower part of the body Hypotension associated with spinal cord injury responds poorly to i.v fluid
load-ing, which may cause pulmonary edema Vasopressors are the treatment of choice.
Hypoxia or manipulation of the larynx or trachea during intubation may cause
pro-found bradycardia or asystolia in these patients because of the unopposed vagal
tone In these situations atropine may be administered to attenuate the vagal effects Other causes of hypotension should be excluded such as blood loss associated with other injuries, since a hemorrhagic shock will not be accompanied by a compensa-tory tachycardia Positive pressure ventilation causes marked arterial hypotension
as the systemic vascular resistance cannot be raised to offset the changes in intra-thoracic pressure caused by positive pressure ventilation [38, 39]
Trang 3Ventilatory impairment increases with higher levels of spinal injury A high
cer-vical lesion that includes the diaphragmatic segments (C3–C5) will result in
Perioperative management
of spinal cord injured patients is demanding
respiratory failure and death unless artificial pulmonary ventilation is
insti-tuted Mid to low cervical spine injuries (C5–C8) spare the diaphragm but the
intercostal and abdominal muscles may be paralyzed Further complications [39]
of the paralysis due to a cervical spinal cord injury include:
) an inadequate cough mechanism
) ineffective secretion clearing
) paradoxical rib movement on spontaneous ventilation
) decreased vital capacity (20 – 50 %)
) decrease in functional residual capacity (10 – 20 %)
) loss of active expiration
) paralytic ileus
) gastric distension
) thromboembolism
The paralytic ileus and the gastric distension increase abdominal pressure,
fur-ther compromising diaphragmatic excursion This gastric distension can be
reduced by placement of a nasogastric tube and attaching it to suction
Autonomic dysreflexia is a syndrome associated with chronic spinal cord
injury and may be present after 3 – 6 weeks following the spinal cord injury This
condition is characterized by extreme autonomic responses such as:
) severe paroxysmal hypertension associated with bradycardia
) ventricular ectopy
) various degrees of heart block
Autonomic dysreflexia may
be present after 3 – 6 weeks following the spinal cord injury
The initiation of these events can be stimulation of nerves below the level of the
spinal cord lesion (for example, cutaneous, rectal, urological, peritoneal
stimula-tion) Injuries higher than T7 have an 85 % chance of producing serious
cardio-vascular derangement [40] Treatment involves removal of the noxious stimulus
(e.g., bladder distension), increasing the level of analgesia and/or anesthesia and
the administration of direct-acting vasodilators If left untreated, the syndrome
can provoke a hypertensive crisis causing seizures, myocardial ischemia or
cere-bral hemorrhage Avoidance of this phenomenon in scheduled patients with
chronic spinal injury necessitates either regional or general anesthesia despite a
lack of motor or sensory function in the area of the surgery
Recapitulation
Patient assessment The preanesthetic evaluation
of patients for spinal surgery follows the general
ap-proach used before any patient is given anesthesia
Particular care should be given to the respiratory,
cardiovascular, and neurological systems that can all
be affected by the spinal pathology The aim of the
preoperative visit is to explain the anesthetic
proce-dure and reduce the patient’s anxiety The need for
preoperative testings is determined by the patient’s
age and health and by the scope of the procedure
Organ-specific assessment. When assessing the
airway, difficulties should always be considered.
Traumatized patients or those with head injury are assumed to have an unstable cervical spine until this has been ruled out; the stability of the spine should be discussed preoperatively with the sur-geon These patients may be managed with awake
fiberoptic intubation after topical anesthesia Re-spiratory function should be assessed by a
thor-ough history, focusing on functional impairment, and reversible causes of pulmonary dysfunction should be optimized Because of the increased
prevalence of coronary heart disease, cardiac as-sessment is a challenge to the anesthesiologist.
Special attention should be paid to patients
Trang 4bear-ing an increased risk where coronary heart disease
has not been proven Most pediatric cardiac
com-promise is a result of the underlying pathology, e.g.,
in patients with Duchenne muscle dystrophy,
Mar-fan syndrome or scoliosis Preoperative
neurologi-cal examination should be documented since the
anesthesiologist is responsible for avoiding further
neurological deterioration during tracheal
intuba-tion and patient posiintuba-tioning In scoliosis the
tho-racic deformity causes restrictive lung disease that
can progress to irreversible pulmonary
hyperten-sion and cor pulmonale Duchenne muscle
dystro-phy is a neuromuscular disease with a high
inci-dence of lung function and cardiac abnormalities
Patients with malignancy have impaired
physiolog-ical reserves, and metabolic derangements and
sur-gery for malignant processes often lead to large
blood loss Spinal injury patients frequently present
during spinal shock, a traumatic sympathectomy
below the lesion which begins almost immediately after the insult and which may last up to 3 weeks Vasopressors are the treatment of choice for the
resulting hypotension Autonomic dysreflexia may
be present after 3 – 6 weeks following the spinal cord injury and is characterized by extreme auto-nomic responses such as severe paroxysmal hyper-tension Avoidance of this phenomenon necessi-tates regional or general anesthesia for patients with chronic spinal cord damage scheduled for sur-gery
Perioperative drug therapy. It is important to
decide which drugs to stop, continue or add
Peri-operative prophylaxis with beta-blocking agents in patients with increased cardiac risk can improve postoperative survival rate
Key Articles
Mangano DT ( 1999) Assessment of the patient with cardiac disease: an anesthesiolo-gist’s paradigm Anesthesiology 91:1521–6
Systematically presented suggestions for selection of preoperative tests and therapy, based on the presence of coronary artery disease (or risk factors) and the patient’s func-tional capacity.
Lee TH, Marcantonio ER, Mangione CM, Thomas EJ, Polanczyk CA, Cook EF, Sugar-baker DJ, Donaldson MC, Poss R, Ho KK, Ludwig LE, Pedan A, Goldman L ( 1999) Deriva-tion and prospective validaDeriva-tion of a simple index for predicDeriva-tion of cardiac risk of major noncardiac surgery Circulation 100:1043–9
Useful and clinically applicable index for cardiac risk stratification in the context of elec-tive major non-cardiac surgery The authors outlined six risk factors for cardiac compli-cations such as high risk type of surgery, ischemic heart disease, congestive heart failure, history of cerebrovascular insult, insulin dependent diabetes mellitus and increased pre-operative serum creatinine.
Hambly PR, Martin B ( 1998) Anaesthesia for chronic spinal cord lesions Anaesthesia 53:273–89
An excellent review of this topic.
Mangano DT, Layug EL, Wallace A, Tateo I ( 1996) Effect of atenolol on mortality and car-diovascular morbidity after noncardiac surgery Multicenter Study of Perioperative Ischemia Research Group N Engl J Med 335:1713–20
In patients who have or are at risk for coronary artery disease and who are undergoing non-cardiac surgery, it has been shown by these authors that the administration of ateno-lol throughout hospitalization can substantially reduce mortality and cardiovascular events after discharge from the hospital, particularly during the first 6 – 8 months after surgery, and the effects on survival persist for at least 2 years.
Trang 51 Ali FE, Al-Bustan MA, Al-Busairi WA, Al-Mulla FA, Esbaita EY (2006) Cervical spine
abnor-malities associated with Down syndrome Int Orthop 30:284 – 289
2 American Society of Anesthesiologists Task Force on Management of the Difficult Airway
(2003) Practice guidelines for management of the difficult airway: an updated report by the
American Society of Anesthesiologists Task Force on Management of the Difficult Airway.
Anesthesiology 98:1269 – 77
3 Amzallag M (1993) Autonomic hyperreflexia Int Anesthesiol Clin 31:87 – 102
4 Boushy SF, Billig DM, North LB, Helgason AH (1971) Clinical course related to preoperative
pulmonary function in patients with bronchogenic carcinoma Chest 59:383 – 91
5 Bramlage P, Pittrow D, Kirch W (2005) Current concepts for the prevention of venous
thromboembolism Eur J Clin Invest 35 (Suppl 1):4 – 11
6 Byrne TN (1992) Spinal cord compression from epidural metastases N Engl J Med 327:614 – 9
7 Cabana F, Pointillart V, Vital JM, S´en´egas J (2000) Postoperative compressive spinal epidural
hematomas: 15 cases and a review of the literature Rev Chir Orthop 86:335 – 345
8 Chen SH, Huang TJ, Lee YY, Hsu RW (2002) Pulmonary function after thoracoplasty in
ado-lescent idiopathic scoliosis Clin Orthop 399:152 – 61
9 Crosby ET, Cooper RM, Douglas MJ, Doyle DJ, Hung OR, Labrecque P, Muir H, Murphy MF,
Preston RP, Rose DK, Roy L (1998) The unanticipated difficult airway with
recommenda-tions for management Can J Anaesth 45:757 – 76
10 Dearborn JT, Serena SH, Clifford BT, Bradford DS (1999) Thromboembolic complications
after major thoracolumbar spine surgery Spine 24 (14):1471 – 1476
11 Desbordes JM, Mesz M, Maissin F, Bataille B, Guenot M (1993) Retrospective multicenter
study of prevention of thromboembolic complications after lumbar disc surgery
Neurochi-rurgie 39 (3):178 – 181
12 Dzankic S, Pastor D, Gonzalez C, Leung JM (2001) The prevalence and predictive value of
abnormal preoperative laboratory tests in elderly surgical patients Anesth Analg 93:301 – 8
13 Engelhardt T, Webster NR (1999) Pulmonary aspiration of gastric contents in anaesthesia.
Br J Anaesth 83:453 – 60
14 Faciszewski T, Winter RB, Lonstein JE, Denis F, Johnson L (1995) The surgical and medical
perioperative complications of anterior spinal fusion surgery in the thoracic and lumbar
spine in adults A review of 1 223 procedures Spine 20:1592 – 9
15 Ferguson MK (1999) Preoperative assessment of pulmonary risk Chest 115:58S–63S
16 Findlow D, Doyle E (1997) Congenital heart disease in adults Br J Anaesthesia 78:416 – 430
17 Geerts WH, Pineo GF, Heit JA, Bergqvist D, Lassen MR, Colwell CW, Ray JG (2004)
Preven-tion of venous thromboembolism The seventh ACCP conference on antithrombotic and
thrombolytic therapy Chest 126:338 – 400S
18 Gerlach R, Raabe A, Beck J, Woszczyk, Seifert V (2004) Postoperative nadroparin
adminis-tration for prophylaxis of thromboembolic events is not associated with an increased risk of
hemorrhage after spinal surgery Eur Spine J 13:9 – 13
19 Hall JC, Tarala RA, Tapper J, Hall JL (1996) Prevention of respiratory complications after
abdominal surgery: a randomised clinical trial BMJ 12:148 – 52
20 Hambly PR, Martin B (1998) Anaesthesia for chronic spinal cord lesions Anaesthesia
53:273 – 89
21 Kawakami N, Mimatsu K, Deguchi M, Kato F, Maki S (1995) Scoliosis and congenital heart
disease Spine 20:1252 – 5
22 Kearon C, Viviani GR, Kirkley A, Killian KJ (1993) Factors determining pulmonary function
in adolescent idiopathic thoracic scoliosis Am Rev Respir Dis 148:288 – 94
23 Kinnear WJ, Johnston ID (1993) Does Harrington instrumentation improve pulmonary
function in adolescents with idiopathic scoliosis? A meta-analysis Spine 18:1556 – 9
24 Kou J, Fischgrund J, Biddinger A, Herkowitz H (2002) Risk factors for spinal epidural
hema-toma after spinal surgery Spine 27 (15):1670 – 1673
25 Lee TH, Marcantonio ER, Mangione CM, Thomas EJ, Polanczyk CA, Cook EF, Sugarbaker
DJ, Donaldson MC, Poss R, Ho KK, Ludwig LE, Pedan A, Goldman L (1999) Derivation and
prospective validation of a simple index for prediction of cardiac risk of major noncardiac
surgery Circulation 100:1043 – 9
26 Mangano DT, Layug EL, Wallace A, Tateo I (1996) Effect of atenolol on mortality and
cardio-vascular morbidity after noncardiac surgery Multicenter Study of Perioperative Ischemia
Research Group N Engl J Med 335:1713 – 20
27 Mangano DT (1999) Assessment of the patient with cardiac disease: an anesthesiologist’s
paradigm Anesthesiology 91:1521 – 6
28 Mansel JK, Norman JR (1990) Respiratory complications and management of spinal cord
injuries Chest 97:1446 – 52
29 Matti MV, Sharrock NE (1998) Anesthesia on the rheumatoid patient Rheum Dis Clin
North Am 24:19 – 34
Trang 630 Meyer B, Jende C, Rikli D, Moerloose de P, Wuillemin WA (2003) Periinterventionelles Man-agement der oralen Antikoagulation: Fallbeispiele und Empfehlungen Schweiz Med Forum 9:213
31 Morris P (1997) Duchenne muscular dystrophy: a challenge for the anaesthetist Paediatr Anaesth 7:1 – 4
32 Munro J, Booth A, Nicholl J (1997) Routine preoperative testing: a systematic review of the evidence Health Technology Assessment 1:I – IV; 1 – 62
33 Nolan J, Chalkiadis GA, Low J, Olesch CA, Brown TC (2000) Anaesthesia and pain manage-ment in cerebral palsy Anaesthesia 55:32 – 41
34 Oda T, Fuji T, Kato Y, Fujita S, Kanemitsu N (2000) Deep venous thrombosis after posterior spinal surgery Spine 25 (22):2962 – 2967
35 Pehrsson K, Larsson S, Oden A, Nachemson A (1992) Long-term follow-up of patients with untreated scoliosis A study of mortality, causes of death, and symptoms Spine 17:1091 – 6
36 Poldermans D, Boersma E, Bax JJ, Thomson IR, van de Ven LL, Blankensteijn JD, Baars HF,
Yo TI, Trocino G, Vigna C, Roelandt JR, van Urk H (1999) The effect of bisoprolol on periop-erative mortality and myocardial infarction in high-risk patients undergoing vascular sur-gery Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography Study Group N Engl J Med 341:1789 – 94
37 Raskob GE, Hirsh J (2003) Controversies in timing of the first dose of anticoagulant prophy-laxis against venous thromboembolism after major orthopaedic surgery Chest 124:379S– 385S
38 Reid JM, Appleton PJ (1999) A case of ventricular fibrillation in the prone position during back stabilisation surgery in a boy with Duchenne’s muscular dystrophy Anaesthesia 54:364 – 7
39 Sethna NF, Rockoff MA, Worthen HM, Rosnow JM (1988) Anesthesia-related complications
in children with Duchenne muscular dystrophy Anesthesiology 68:462 – 5
40 Sidi A, Lobato EB, Cohen JA (2000) The American Society of Anesthesiologists’ Physical Status: category V revisited J Clin Anesth 12:328 – 34
41 Sorensen JB, Andersen MK, Hansen HH (1995) Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in malignant disease J Intern Med 238:97 – 110
42 Stiller K, Montarello J, Wallace M, Daff M, Grant R, Jenkins S, Hall B, Yates H (1994) Efficacy
of breathing and coughing exercises in the prevention of pulmonary complications after coronary artery surgery Chest 105:741 – 7
43 Supkis DE, Varon J (1998) Uncommon problems related to cancer In: Benumof J (ed) Anes-thesia and uncommon diseases, 4th edn Philadelphia: WB Sanders Co., 545 – 60
44 Vedantam R, Lenke LG, Bridwell KH, Haas J, Linville DA (2000) A prospective evaluation of pulmonary function in patients with adolescent idiopathic scoliosis relative to the surgical approach used for spinal arthrodesis Spine 25:82 – 90
45 Wolfs JF, Peul WC, Boers M, Tulder van MW, Brand R, Houwelingen van HC, Thomeer RT (2006) Rationale and design of The Delphi Trial – I(RCT)2: international randomized clini-cal trial of rheumatoid craniocerviclini-cal treatment, and intervention-prognostic trial compar-ing ’early’ surgery with conservative treatment BMC Musculoskelet Disord 7:14
46 Yentis SM (2002) Predicting difficult intubation – worthwhile exercise or pointless ritual? Anaesthesia 57:105 – 9
47 Zaugg M, Tagliente T, Lucchinetti E, Jacobs E, Krol M, Bodian C, Reich DL, Silverstein JH (1999) Beneficial effects from beta-adrenergic blockade in elderly patients undergoing non-cardiac surgery Anesthesiology 91:1674 – 86
Trang 7Intraoperative Anesthesia Management
Juan Francisco Asenjo
Core Messages
✔Communicate with your anesthetist Talk to him
before surgery if you have particular concerns
about the patient or the procedure you are
planning Let him know constantly about how
things are going during the surgery Share your
thoughts and team up
✔Patients having major spine procedures must
be properly assessed by the anesthesia team
beforehand to increase safety and success in
the perioperative period
✔Special airway management and positioning
could be challenging for the anesthesia team,
sometimes involving longer preparation
✔The anesthesia technique must allow for
reli-able neuromonitoring; SSEP recordings and
wake-up test, short-acting drugs, TIVA and
low-dose gases are indicated
✔Blood preservation is a must Careful surgical
technique and positioning, antifibrinolytics,
blood predeposit, cell recovery and controlled hypotension (CH) are the way to go CH is con-traindicated in the presence of spinal cord com-pression (tumor, trauma, etc.)
✔Some cervical spine surgeries, long cases or
those with massive transfusions might require postoperative ventilation
✔Good pain control after surgery is associated
with lower rates of postoperative chronic pain conditions and faster recovery Multimodal analgesia is the cornerstone NSAIDs could be controversial, but in low doses they are 17 times less likely than smoking to be linked to malunion
✔Anesthesia should be tailored to fast-track
min-imally invasive spine surgery, emphasizing pre-vention of nausea, vomiting and pain control
Historical Background
Precise information is not available about the first anesthesia for spine surgery
Definitive improvements began in the 1950s with the use of muscle relaxants,
oro-tracheal intubation, introduction of halothane and more generous use of
intrave-nous crystalloids In the 1970s the wake-up test was described to assess the
integ-rity of the spinal function At the same time larger doses of opiates became popular
to help maintain stable hemodynamic conditions and better pain control
intra-and postsurgery In the 1980s intra-and 1990s new short-acting drugs contributed to the
enhancement of the perioperative experience in patients having day surgery
pro-cedures, as well as permitting better neurophysiologic monitoring
Goals of Anesthesia in Spinal Surgery
Optimal teamwork between the surgeon and anesthetist
is a prerequisite for success-ful surgery
The role of anesthesia care in spinal surgery must be appreciated within the context
of comprehensive perioperative care where a dedicated team takes care of a patient
from preoperative planning and perioperative care to rehabilitation and discharge
In many places this is accomplished through the design of “Clinical Pathways,” a
Trang 8road map for a particular surgical procedure with standardization of each step to reduce variability, cost and errors The anesthesia contribution is a key component
in this continuum In a successful Clinical Pathway all players have agreed upon a road map, they have contributed the best evidence from their fields and everybody understands his or her own role and each other’s inputs In this chapter the most relevant features of anesthesia for spinal surgical procedures are discussed Partic-ular emphasis on trauma, scoliosis, and degenerative and cancer surgery is given
Preoperative Patient Assessment
Anesthesia for spine surgery
can only be as good as the
preoperative assessment
and optimization
Recommendations for preoperative assessment, diagnostic work-up and condi-tion dependent patient optimizacondi-tion have been provided in Chapter 14 Safe and efficient anesthesia for spinal interventions depends crucially on the quality
of the preoperative assessment and patient optimization A detailed preoperative assessment minimizes life-threatening risks and helps to avoid intra- and post-operative complications
Optimal communication
between surgeon and
anesthetist is mandatory
for successful surgery
The surgeon and anesthesiologist must team up, discuss and plan the opera-tive procedure in advance, particularly in nonroutine cases Good preoperaopera-tive communication and a clear bilateral understanding of the procedure and the overall condition of the patient are prerequisites to successful surgery Although seemingly trivial, the consequences of these rules being ignored are often seen in daily clinical practice
Induction of Anesthesia
Patients being admitted for surgery of the spine benefit from premedication with gabapentin Our experience confirms recent publications [80] supporting the use of
300 – 600 mg before going to the operating room It provides mild sedation and a
powerful antihyperalgesic effect If a wake-up test (WUT) is considered,
benzodiaz-epines or other amnesic drugs are not recommended since the patient will not retain the information about the WUT provided before the induction of general anesthesia Patient identification and
type and level of procedure
must be checked prior to anesthesia
Prior to starting the anesthetic procedures, the identification of the patient, the type of procedure and the level to be operated at (which is key in spine
sur-gery) must be checked and confirmed to avoid “wrong patient, wrong side and wrong site surgery” particularly if patients with identical surnames are on the
operating list
Before starting the anesthetics, the minimum standard monitoring for
gen-eral anesthesia in an otherwise healthy patient undergoing low risk spine surgery encompasses:
) hemoglobin-O2saturation
) noninvasive blood pressure
) end-tidal CO2
) continuous ECG The patient’s preoperative condition and type of surgery will dictate the use of other monitoring before starting the operation
At least one large bore i.v cannula should be in place prior to the induction of anesthesia and for major cases A second cannula is inserted after the patient is asleep unless a central venous catheter is considered
The choice of induction agent (propofol, thiopental, opiates, etomidate or inhaled agents in children) will depend on the general condition of the patient and the presence of trauma associated hypovolemia, cardiac conditions and cord
Trang 9com-pression with marginal blood perfusion The choice of muscle relaxants to facilitate
the intubation will be influenced by conditions like full stomach, gastroesophageal
reflux and trauma Nondepolarizing agents such as rocuronium, vecuronium and
cisatracurium have a safe record and are widely used today in spine surgery
Suc-Succinylcholine should be avoided in patients with muscular dystrophy and spinal cord injury
cinylcholine should be avoided in patients with muscular dystrophy as well as in
patients with spinal cord injury between 3 and 180 days postdenervation because
of the potential for hyperkalemia, secondary arrythmias, and cardiac arrest Acute
denervation induces an increment in the number of cholinergic receptors in the
perijunctional area Succinylcholine is a depolarizing type of muscle relaxant;
therefore in this condition it will release massive amounts of potassium [30, 70]
Airway Control and Endotracheal Intubation
A decision should be made whether to gain control of the airway in advance of or
after the induction of anesthesia to assess neurological status after airway
manipu-lation and positioning the patient on the table Patients with unstable C-spine or
using a halo vest might need fiberoptic intubation and awake positioning to ensure
preservation of neurological function If awake positioning is needed with traction
devices anchored to the skull (e.g., a skull clamp or Mayfield head support),
infiltrat-ing the area where the pins are goinfiltrat-ing to be placed (with 4 – 6 ml of bupivacaine 0.25 %
with epinephrine 5 μg/ml at each point) at least 10 min prior to pin insertion is
sug-gested Occasionally a low-dose infusion of remifentanyl (0.05 – 0.1 μg/kg/min) is
maintained during the whole procedure of intubation and positioning In the event
that the patient’s mental status is not reliable enough to ensure a safe surgical
posi-tioning, an alternative is to do a baseline somatosensory evoked potential (SSEP)/
motor evoked potential (MEP) recording before anesthesia and positioning and
compare it to the one immediately after installation on the surgical table (Table 1)
Table 1 Indications for awake fiberoptic intubation
Absolute Relative
There is controversy as to whether direct laryngoscopy is a major factor
contrib-uting to cord injury in patients with cervical spine instability [48] In this setting,
however, other factors such as hypotension and patient positioning may be even
more important Laryngoscopy with manual inline stabilization by the surgeon
Direct laryngoscopy should
be avoided in patients with spinal cord compromise
or with a stiff collar is an accepted means of intubation for many patients with an
unstable cervical spine as long as movement of the neck can be avoided [48]
Patients with difficult airways may require fiberoptic intubation, a GlideScope
device (a fiberoptic laryngoscope with a screen, seeFig 1) or a laryngeal airway
mask (the “fast track”) to gain airway control Careful freezing of the airway with
local anesthetic is important to avoid coughing during tube placement in patients
with unstable C-spine
In the case of anterior access to the thoracic spine, selective collapse of the
ipsilateral lung facilitates performance of the procedure by the surgeon Some
choices exist in this situation between:
) a regular orotracheal (OT) tube with a bronchial blocker, which is possibly
the first option It requires a regular OT tube to be placed, followed by
Trang 10fiber-Figure 1 GlideScope
Direct laryngoscopy without moving the head or C-spine Observe on the screen the deflated cuff of the endotra-cheal tube under the epi-glottis crossing the vocal cords.
optic deployment of a bronchial blocker (type Cohen or Arndt) similar to a Fogarty catheter to restrict the ventilation to the nondependent lung It is the simplest way of isolating and deflating the lung
) a Univent OT tube, which is a slightly larger tube because of a bronchial blocker channel built-in to its wall This tube is placed in the trachea like a regular OT tube The built-in bronchial blocker is advanced under direct fiberscopic vision through its channel to the main bronchus of the nonde-pendent lung It is the fastest way of isolating the lung
) a classic double lumen device which is very reliable, but which can be more
traumatic for the airway and vocal cords If the patient remains intubated in the postop, this is the only type of tube that will need to be changed for a regular one Placement of this type of tube may also be more difficult in patients with complex airways
Standard use of the more expensive reinforced armored orotracheal tube in patients operated on in the prone position is not clearly justified in the literature [34] Furthermore, if the patient bites the armored tube (for instance, face-down during a WUT or while on ventilator support in the recovery room or ICU), it will remain deformed and collapsed, diminishing or totally blocking the gas flow, causing a major problem to breathing Changing the tube with the patient in the prone or lateral position or during cervical spine surgery might be catastrophic A nasogastric or orogastric tube is routinely passed intraoperati-vely and removed before extubation in anterior C-spine procedures to help the surgeon identify the esophagus and decrease postoperative nausea and vomiting For anterior lumbar approaches, the stomach is decompressed of gas and secre-Careful eye and face
protection is crucial
tions by using the gastric tube Careful eye protection with cream, occlusive tape
and peripheral padding is mandatory in particular in patients positioned prone
or in anterior approaches to the cervical spine (Fig 2) In prepping the neck for posterior approaches, irritant solutions might reach the eyes from behind, remaining there for hours with the potential for severe corneal damage