Critical Care Obstetrics part 12 potx

Measured parameter Direction of change Values in normal pregnancy Effect on CPR Pharyngeal edema Increases – May need smaller endotracheal tube, increases diffi culty with intubation

In cases of a witnessed respiratory arrest when the airway is

known to be clear but the victim is not breathing, the airway must

be protected from aspiration and kept patent, and the BLS/ACLS

algorithms begun Endotracheal intubation by direct

laryngos-copy is the preferred method for maintaining airway patency for

the gravid arrest victim Alternative techniques for airway

man-agement include endotracheal intubation by light stylet,

esopha-geal tracheal combitube, larynesopha-geal mask airway, and transtracheal

ventilation Tracheal intubation offers advantages of securely

protecting the airway, facilitating oxygenation and ventilation,

and providing a route for drug administration during a cardiac

arrest

In the hospital setting immediate confi rmation of the tracheal

tube is typically done using non - physical examination

tech-niques, such as end - tidal (ET) carbon dioxide indicators The

presence of ET CO 2 is a reliable measure of pulmonary perfusion

and, therefore, can measure the effi cacy of CPR Esophageal

detector devices may also be used to confi rm tracheal tube

place-ment but false - negative results may be obtained in women in late

gestation False - negative results are due to decreased functional

residual capacity (FRC) and tracheal compression in late

preg-nancy Consequently, the gold standard for confi rmation in the

pregnant women remains repeat direct visualization [23]

Even with advanced airway techniques, airway access and

maintenance can be diffi cult in pregnancy due to enlarged breasts

and increased pharyngeal edema Rescuers may fi nd it necessary

to use a slightly smaller endotracheal tube than normal [24] Also,

progesterone relaxes the smooth muscle of the lower esophageal

sphincter and increases the propensity of the gravida to refl ux

and aspirate

Breathing

Rescue breathing may occur mouth - to - mouth, mouth - to - nose,

mouth - to - mask, bag valve - to - mask, or ultimately by

endotra-cheal intubation The current guidelines call for a ratio of 2

ven-tilations to 30 compressions in one - or two - person CPR, pausing

for ventilations in the absence of an advanced airway With a

protected airway, the 2005 guidelines call for continuous chest

compression with rescue breaths every 6 seconds [25]

In pregnancy, the expanding breast tissue decreases chest wall

compliance, making ventilation more diffi cult The enlarging

uterus results in upward displacement of the diaphragm leading

to a decrease in the functional residual capacity (FRC) of the

lungs Maternal minute ventilation increases, probably due to a

central effect of progesterone The decrease in FRC combined

with the increase in oxygen demand predisposes the pregnant

woman to rapid decreases in arterial and venous oxygen tension

during periods of decreased ventilation The chronic increase in

ventilation in pregnancy leads to a decline in arterial carbon

dioxide tension The maternal kidney compensates for this

respi-ratory alkalosis by reducing serum bicarbonate concentration

The maternal respiratory alkalosis enhances fetal excretion of

carbon dioxide Hence, increases in maternal carbon dioxide

levels promote fetal acidosis During periods of hypoxia there is

also decreased uteroplacental blood fl ow which further promotes fetal acidosis Thus, the demands of the fetus and normal mater-nal adaptations to those demands promote rapid matermater-nal hypoxia and acidosis in the presence of hypoventilation This makes it more diffi cult to resuscitate the mother and ultimately the fetus

Circulation

An adequately functioning heart and suffi cient quality and quan-tity of blood are necessary to deliver oxygen to the tissues In the pulseless patient, external chest compressions provide a means of circulation, as originally described by Kouwenhoven and col-leagues in 1960 [26] The initial belief that the chest compressions cause direct compression of the heart between the sternum and the spine, leading to a rise in ventricular pressure, closure of the mitral and tricuspid valves, forcing blood into the pulmonary artery and aorta, has been disproved We now understand the primary mechanism of blood movement involves compression mediated fl uctuations in the intrathoracic pressure that create an arteriovenous pressure gradient peripherally [27] External chest compressions cause a rise in intrathoracic pressure, which is dis-tributed to all the intrathoracic structures Competent venous valves prevent transmission of this pressure to extrathoracic veins, whereas the arteries transmit the increased pressure to extrathoracic arteries, creating an artifi cial venous pressure gradi-ent and forward blood fl ow Werner et al [28] used echocardiog-raphy to support the notion of the heart as a passive conduit, rather than a pump, by demonstrating that the mitral and tricus-pid valves remain open during CPR

With or without an advanced airway, when chest compressions are required, they should be given at a rate of approximately 100/min Chest compressions should only be interrupted for brief assessments and application of electrical therapy when indicated

by the specifi c rhythm and cardiac circulatory effectiveness The BLS algorithms include the use of automated external defi brilla-tors (AEDs) AED availability and rapid deployment has lead to improved survival ACLS involves additional electrical and phar-macologic therapy, invasive monitoring, and other therapeutic techniques to correct cardiac arrhythmias, metabolic imbalances, and other causes of cardiac arrest Defi brillators can be used without signifi cant complications to the fetus in pregnant women [29] The fetus has a relatively high fi brillation threshold and the electrical current density reaching the fetus is small Nanson and colleagues evaluated women during and after pregnancy and compared transthoracic impedance values Because there was no signifi cant difference, the authors concluded that no modifi ca-tions to the recommendaca-tions for non - pregnant patients were necessary [30]

Concurrent with establishing cardiac function, resuscitators must assure that arrest victims have adequate quality and quan-tity of blood remaining in the vascular tree for circulation Although volume administration, which can lead to decreased cerebral and coronary blood fl ow, is generally not recommended during treatment of cardiac arrest, it should be strongly

considered in cardiopulmonary arrest related to postpartum

hemorrhage or circulatory collapse as seen with amniotic fl uid

embolism Accordingly, early in the resuscitation, resources

should be mobilized to obtain blood products to refi ll the

vascu-lar tree and manage ongoing hemorrhage Current data suggest

that the optimal product for resuscitations involving massive

hemorrhage is whole blood or reconstitutes thereof However,

overzealous fl uid resuscitation, particularly with crystalloid

fl uids, before controlling hemorrhage and in the early phases of

resuscitation, actually decreases survival [31 – 35] Factor VII

con-centrates, now available in many medical centers in the United

States, provide an improved means of correcting coagulopathies

also common to obstetric hemorrhage There are now several

reports of using recombinant factor VII concentrates in

uncon-trolled obstetric hemorrhage [31 – 35] The reader is referred to

Chapter 22 in this text for more information regarding the

man-agement of hemorrhage in pregnancy

This stage of the primary and secondary survey of BLS/ACLS

should include an assessment of the fetal status and whether or

not delivery of the fetus would be of benefi t to mother and/or

fetus Morris and colleagues [36] evaluated neonatal survival

fol-lowing emergency cesarean section in trauma patients presenting

to nine Level I trauma centers The authors suggest adding

Doppler fetal heart tone (FHT) assessment to the primary survey

along with assessment of maternal circulation If FHTs are not

present, the authors suggest the fetus should otherwise be ignored

and treatment directed toward maternal survival Nonetheless,

delivery of the fetus can be considered in the secondary survey if

fetal distress is present More importantly, delivery may be a

means of improving effectiveness of maternal CPR efforts even

in cases of antecedent fetal death This has led to a

recommenda-tion by some to avoid using precious time for assessment of fetal

status when moving forward with cesarean section for maternal

benefi t [37]

The e ffect of p regnancy on c ardiopulmonary

r esuscitation

Pregnancy produces physiologic changes that have profound

effects on cardiopulmonary resuscitation Pregnancy - specifi c

physiologic changes and recommended intervention changes to

CPR are summarized in Tables 7.5 and 7.6 There are signifi cant

changes in the pulmonary, cardiovascular and renal systems

Some of these changes have been briefl y described above A more

comprehensive description of these changes and their impact on

CPR follows

From the circulatory perspective, pregnancy represents a high

fl ow, low - resistance state characterized by a high cardiac output

(CO) and low systemic vascular resistance (SVR) Cardiac output

increases by 50% of non - pregnant values The uterus receives up

to 30% of cardiac output compared with 2 – 3% in the non - gravid

patient The increase in CO satisfi es the increase in oxygen

demands of the growing fetus, the placenta, and the mother

In the latter half of pregnancy, aortocaval compression by the gravid uterus renders resuscitation more diffi cult in the pregnant woman than in her non - pregnant counterpart The pregnant uterus exerts pressure on the inferior vena cava common iliac vessels, and abdominal aorta In the supine position, such uterine obstruction may lead to sequestration of up to 30% of circulating blood volume [38] , decreasing venous return, causing supine hypotension, and decreasing effectiveness of thoracic compres-sions Furthermore, the enlarged uterus poses an obstruction to forward blood fl ow, particularly when arterial pressure and volume are decreased, as in cardiac arrest

The u se of d rugs for r esuscitation

Changes in the gravida woman ’ s response to drugs may also hinder effective resuscitation Vasopressors used in ACLS, espe-cially alpha - adrenergic or combined alpha and beta agents, are capable of producing uteroplacental vasoconstriction, leading to decreased fetal oxygenation and carbon dioxide exchange Clinical experience with the pharmacologic agents used in ACLS is limited in pregnancy, particularly when the drugs are used for acute life - threatening situations In the acute situation, absent or poor maternal cardiac output produces fetal hypoxia and hypercarbia Thus, despite the potential for uteroplacental vascular vasoconstriction, the benefi ts of these drugs in restoring maternal circulation outweigh their risks

Most of the data concerning fetal effects of these drugs come from chronic use rather than limited dosing in the acute arrest setting Beginning with the 2000 American Heart Association ACLS guidelines, amiodarone became the drug of choice for treatment of wide - complex tachycardia, stable narrow - complex tachycardia, monomorphic and polymorphic VT, and potentially for shock - refractory VF/VT Placental transfer occurs with amio-darone at approximately a quarter of the maternal dose Amiodarone has been labeled a category D drug by the manufac-turer With chronic use, fetal effects such as growth restriction, hypothyroid goiter, enlarged fontanels, and transient bradycardia

in the newborn have all been reported [39] The drug has been used to successfully treat resistant fetal tachycardia both transplacentally and by direct insertion into the umbilical cord [39] As with the vasopressors, the concerns raised about chronic use should not negate using amiodarone for maternal resuscitation

Vasopressin was added as a fi rst - line pressor agent in the 2000 CPR guidelines However, in the 2005 guidelines epinephrine remains the drug of choice as the fi rst - dose pressor agent given

in various scenarios given the available data Nonetheless vaso-pressin may have a lower adverse affect profi le than epinephrine and the 2005 guidelines allow its use primarily to use primarily when a second pressor dose is required [40,41] See Figure 7.2 Some controversy remains about high - dose ( > 1 mg and usually

4 – 5 mg) epinephrine in these scenarios [41 – 44] At present, the consensus appears to be to use regular - dose epinephrine initially

Table 7.5 Relevant maternal physiologic changes in pregnancy and their effect on CPR [66,70,71]

Measured parameter Direction of change Values in normal pregnancy Effect on CPR

Pharyngeal edema Increases – May need smaller endotracheal tube, increases diffi culty with

intubation and airway control Minute ventilation Increases 50% – Increased development of hypercarbia

Oxygen consumption Increases 20% – More rapid development of hypoxia

Serum bicarbonate Decreases 18 – 21 mEq/L Decreased acid buffering capability

Chest wall compliance Decreases – More diffi cult intubation, increased ventilation pressures

Cardiac output Increases 50% 6.2 ± 1.0 L/min Increases the circulatory demand during CPR

Blood volume Increases 30 – 50% – Dilutional anemia with decreased O 2 carrying capacity

Heart rate Increases 15 – 20% 83 ± 10 beats/min

SVR Decreases 20% 1210 ± 256 dynes/sec/cm − 5

COP Decreases 15% 18 ± 1.5 mmHg Propensity to pulmonary edema

Aortocaval compression Increases – Lateral uterine displacement required to maintain venous return and

hence cardiac output

Most clotting factors Increase – Propensity to thrombosis; thromboembolic disease high on

differential diagnosis

Motility Decreases – Increased risk of aspiration, need to protect airway

Lower esophageal sphincter tone Decreases – Increased risk of aspiration, need to protect airway

Compensated respiratory alkalosis Increases – Modifi cation of target values and increase ventilation required, avoid

bicarbinate in CPR Glomerular fi ltration rate Increases – Drug clearance may be modifi ed

but consider high dose for prolonged, resistant cardiac arrest

[45] Spohr et al recently summarized the current data regarding

drug therapy for CPR [45] Adenosine, lidocaine, procainamide,

and beta - blockers, also used in the treatment of

tachyarrhyth-mias, all appear to be safe in pregnancy [46]

Resuscitators should remember that during pregnancy, the

volume of distribution and drug metabolism may vary from non

pregnant norms Page [47] reviewed the multiple factors

contrib-uting to altered therapeutic blood levels of drugs in pregnancy

They include increased intravascular volume, reduced drug

protein binding, increased clearance of renally excreted drugs,

progesterone - activated increased hepatic metabolism, and altered

gastrointestinal absorption due to changes and gastric secretion

and gut motility The agents used in ACLS are recommended in

standard doses However, if the victim does not respond to

stan-dard doses, higher doses should be considered to account for the

expanded plasma volume of pregnancy

Modifi cations of b asic l ife s upport and

a dvanced c ardiac l ife s upport in p regnancy

The anatomic and physiologic changes of pregnancy require several modifi cations in ECC (Tables 7.5 & 7.6 ) Most important,

to affect an increase in venous return and reduced supine hypo-tension, the uterus must be displaced to the left Left lateral dis-placement can be achieved by: (i) manual disdis-placement of the uterus by a member of the resuscitation team; (ii) positioning of the patient on an operating room table that can be tilted laterally; (iii) positioning a wedge under the right hip; (iv) using a Cardiff resuscitation wedge or (v) using a human wedge [48] The human wedge kneels on the fl oor with the patient ’ s back placed on the thighs of the human wedge The human wedge uses one arm to stabilize the patient ’ s shoulder and the other arm to stabilize the pelvis The human wedge maneuver has the advantage that it may

Table 7.6 Primary and secondary ABCD surveys: modifi cations for pregnant women Reproduced from [72]

ACLS Approach Modifi cations to BLS and ACLS Guidelines

Primary ABCD Survey

Breathing No modifi cations

Circulation Place the woman on her left side with her back angled 15 ° to 30 ° back from the left lateral position Then start chest

compressions

or Place a wedge under the woman ’ s right side (so that she tilts toward her left side)

or Have one rescuer kneel next to the woman ’ s left side and pull the gravid uterus laterally This maneuver will relieve pressure on the inferior vena cava

Defi brillation No modifi cations in dose or pad position

Defi brillation shocks transfer no signifi cant current to the fetus

Remove any fetal or uterine monitors before shock delivery

Secondary ABCD Survey

Airway Insert an advanced airway early in resuscitation to reduce the risk of regurgitation and aspiration

Airway edema and swelling may reduce the diameter of the trachea Be prepared to use a tracheal tube that is slightly smaller than the one you would use for a non - pregnant woman of similar size

Monitor for excessive bleeding following insertion of any tube into the oropharynx or nasopharynx

No modifi cations to intubation techniques A provider experienced in intubation should insert the tracheal tube

Effective preoxygenation is critical because hypoxia can develop quickly

Rapid sequence intubation with continuous cricoid pressure is the preferred technique

Agents for anesthesia or deep sedation should be selected to minimize hypotension

Breathing No modifi cations of confi rmation of tube placement Note that the esophageal detector device may suggest esophageal

placement despite correct tracheal tube placement

The gravid uterus elevates the diaphragm:

Patients can develop hypoxemia if either oxygen demand or pulmonary function is compromised They have less reserve because functional residual capacity and functional residual volume are decreased Minute ventilation and tidal volume are increased

Tailor ventilatory support to produce effective oxygenation and ventilation

Circulation Follow standard ACLS recommendations for administration of all resuscitation medications

Do not use the femoral vein or other lower extremity sites for venous access Drugs administered through these sites may not reach the maternal heart unless or until the fetus is delivered

Differential diagnosis and decisions Decide whether to perform emergency hysterotomy

Identify and treat reversible causes of the arrest Consider causes related to pregnancy and causes considered for all ACLS patients (see the 6 H ’ s and 6 T ’ s, in Part 7.2: “ Management of Cardiac Arrest ” )

be employed without equipment, utilizing an untrained person

Its obvious disadvantage of the wedge is that it must be displaced

when defi brillation becomes necessary The back of an upside

down chair may also function as a leaning post to support a

woman in a laterally tilted position

The maternal propensity for hypoxia and hypercapnia (which

lead to decreases in utero placental perfusion) suggests that the

pregnant woman may benefi t from sodium bicarbonate in an

arrest situation in order to keep maternal pH greater than 7.10

This idea is hazardous and should be discarded Sodium

bicar-bonate crosses the placenta very slowly Accordingly, with rapid correction of maternal metabolic acidosis, her respiratory com-pensation will cease with normalization of her PCO 2 toward the non - pregnant state For example, if the maternal PCO 2 increases from 20 to 40 mmHg as a result of bicarbonate administration, fetal PCO 2 will also increase However, the fetus will not receive the benefi t of the bicarbonate If the fetal pH was 7.0 before maternal bicarbonate administration, the normalization of maternal pH will be achieved at the expense of increasing the fetal PCO 2 by 20 mmHg, resulting in a reduction in fetal pH to

approximately 6.84 Even in the non - pregnant state, sodium

bicarbonate is considered potentially harmful in patients with

hypoxic lactic acidosis, such as commonly occurs in non -

intu-bated patients undergoing prolonged cardiopulmonary arrest

Carbon dioxide generated in tissues is not well cleared by low

blood fl ow [49] Adequate ventilation and restoration of

perfu-sion are the mainstays of control of acid – base balance during

cardiac arrest The buffering of blood with bicarbonate does not

benefi t the patient [50]

Thrombolytic t herapy

Unfractionated and low molecular weight heparins have been

used extensively during pregnancy In cases of acute

cardiopul-monary thrombosis, therapy with these agents has proven helpful

in both non - pregnant and pregnant patients There is much less

data regarding the use of other thrombolytic therapies during

pregnancy including recombinant tissue plasminogen activators

(TPA) Generally, pregnancy is considered a contraindication to

TPA therapy but there are several case reports of successful use

during pregnancy [51 – 53] The use of such agents increases the

risk of hemorrhage, particularly in the scenario when operative

delivery has or is likely to occur Nonetheless, the use of these

agents should not be completely excluded when alternative

therapies have been unsuccessful

Complications and a ftercare of

c ardiopulmonary r esuscitation

d uring p regnancy

Unfortunately, CPR is rarely effective in restoring spontaneous

circulation and permitting neurologically intact recovery to

hos-pital discharge Successful resuscitation is reported in 6 – 15% of

patients suffering in - hospital cardiac arrest [54,55] In pregnancy,

survival may be even less likely given the maternal physiologic

changes that predispose her to rapid hypoxia and complicated

resuscitative efforts Fortunately, the paucity of underlying

disease may improve the likelihood of success

For survivors, cardiopulmonary resuscitation may impose

sec-ondary complications on both mother and fetus Ongoing

sup-portive and therapeutic care will be necessary, paying careful

attention to common areas of injury and ongoing risk Care is

best accomplished by a multidisciplinary team Neonatal and

maternal care providers should assess for injuries Maternal

inju-ries may include: (i) fractures of ribs and sternum; (ii)

hemotho-rax and hemopericardium; (iii) rupture of internal organs

(especially the spleen and uterus); and (iv) lacerations of organs

(most notably the liver) Damaging effects to the fetus consist of

central nervous toxicity from medications and reduced

uteropla-cental perfusion with possible fetal hypoxemia and acidemia

Fetal monitoring may be used to assess ongoing fetal status;

however, maternal resuscitation should be the primary goal

Perimortem c esarean d elivery

Historically, perimortem cesarean delivery (PMCD) was a widely

accepted practice In fact, the term cesarean developed from the

Roman period (715 – 763 BC) when PMCD was practiced under

the law of Caesar ( lex Cesare ), not for maternal or fetal benefi t,

rather to allow woman and children to be buried separately for religious ritual [56] In ancient Greek mythology the fi rst cesar-ean section was performed by Apollo, on his wife Coronois, as she was being burned on a funeral pyre Their son, Asclepius, is said to be the demigod of medicine and healing The Staff of Asclepius, a rod entwined with a single serpent, has become the symbol for physicians across the globe

The fi rst documented case of maternal survival from a PMCD took place in Switzerland, when a farmer named Jacob Nufer performed a cesarean delivery on his own wife [57] Since then, over 250 reports of maternal survival from PMCD have been described Recognition that the gravid uterus may prevent proper CPR techniques by restoring adequate cardiac output, has led many to theorize that immediate PMCD may assist in maternal resuscitation The theory is that the low - resistance, high - volume uteroplacental unit sequesters blood and hinders effective CPR Delivery leads to a decrease in aortocaval obstruction, and increase in effectiveness of compressions, and an increase in maternal cardiac output In a recent review by Katz et al., 12 of

22 case reports showed a sudden and often dramatic improve-ment in pulseless gravidas following uterine evacuation [58] When considering PMCD, several factors need to be addressed Clearly, the timing of the operation is critical for infant survival Survival appears to be inversely proportional to the time between the mother ’ s cardiac arrest and her delivery In 1986, Katz et al introduced the idea of the “ 4 - minute rule ” for PMCD, basing their recommendations on the idea that maternal neurologic injury would commence 6 minutes after the cessation of cerebral perfusion [59] If delivery is accomplished within 5 minutes of maternal cardiac arrest, intact neurologic survival is likely [15,59] Beyond 15 minutes, neonatal death or impaired survival is

gener-ally seen Primate studies confi rm brain damage in utero with as

little as 6 minutes of complete asphyxia and severe cellular damage occurring by 8 minutes [60] Nonetheless scattered reports describe infant survival at longer intervals following arrest, implying that cesarean delivery should be performed post arrest if signs of fetal life are still present [61,62]

In light of the evolving timing of the limits of fetal viability, one group of authors attempted to develop an algorithm to assist clinicians in determining when and who would benefi t from a postmortem cesarean section [36] The “ potentially salvageable ” infant was defi ned as an estimated gestational age of at least 26 weeks with the confi rmation of fetal cardiac activity by Doppler ultrasound In this group, 75% of the infants survived The authors postulated that 60% of the infant deaths may have been avoided by earlier recognition of fetal distress and earlier cesarean delivery With evolving technology, determination of what

gestational age defi nes fetal viability will be left to the discretion

of the delivering physician and the resources available for

neona-tal resuscitation To date, we have not identifi ed any lawsuits

brought against physicians for the wrongful performance of a

PMCD

The 4 - minute limit to initiate delivery, as advocated by Katz

and colleagues [58,59] and the American College of Obstetricians

and Gynecologists is derived from the theoretical physiologic

advantages for resuscitating the mother, as well as from

extrapo-lation of data on infant survival While such data suggests an ideal

arrest - to - delivery interval, in actual practice these goals are rarely

achieved It must be emphasized that no data exist to

prospec-tively document actual maternal benefi ts of perimortem cesarean

section There are many anecdotal examples of improved

mater-nal response to resuscitation after perimortem cesarean However,

maternal death remains the most likely outcome regardless of

arrest - to - delivery interval None - the - less, in light of both the

anecdotal experiences suggesting benefi t to mother and fetus, and

the dismal outcomes without intervention, we support the

concept of the 4 - minute rule based on the currently available

evidence In the setting of perimortem cesarean section

per-formed for the likely salvageable fetus, the staff should be well

versed in the techniques of neonatal resuscitation as these infants

are likely to suffer from respiratory and circulatory depression at

birth Women with chronic illnesses are less likely to have a

normal surviving infant by perimortem cesarean section,

com-pared to previously healthy women who suffer cardiac arrest

following an acute obstetric event

The n eurologically i mpaired p atient

f ollowing r esuscitation

On the rare occasion when a patient is successfully resuscitated

but left brain dead and a cesarean section has not been

per-formed, several medical, social, ethical and legal dilemmas follow

In most circumstances, advance directives are not available to

guide the physician in the decision - making process A decision

must be made, based on gestational age, family wishes (or medical

power of attorney), and available resources, on whether to extend

the maternal life for fetal benefi t

To arrive at a decision involving the prolongation of pregnancy

in a brain - dead pregnant patient, the physician must be guided

by basic ethical and legal principles If an advance directive is

available and deemed lawful, it must be interpreted within the

context of the situation and with the patient ’ s values in mind If

a durable power of attorney or next of kin are not available, or if

there is confl ict within the family, then legal counsel is

recom-mended Keep in mind that the decision to prolong maternal life

for the benefi t of the fetus must fi rst be consistent with the values

of the patient as determined by the next of kin Historically,

gestational age at the timing of the event was often cited as the

most important variable, with the assumption that prolongation

of a pregnancy was rarely successful beyond 2 – 4 weeks, and thus

should only be considered in the gravid women beyond 24 weeks gestational age [63] However, more recent cases have demon-strated that pregnancy can be prolonged for as long as 204 days following severe neurologic injury, and as early as 15 weeks gesta-tion in a brain - dead patient [64,65] Therefore, the more relevant questions for the physician and family are if prolongation of the pregnancy is what the patient would have wanted and if so, when

is the appropriate time for delivery to optimize the health of the neonate?

If the decision is made to prolong the pregnancy, a unique set of medical complications must also be addressed in anticipa-tion of expected physiologic changes following brain death Discussion of the somatic support of a brain dead gravida is beyond the scope of this chapter, but is covered comprehensively

in a review by Mallampalli and colleagues [66]

Case p resentation

A 22 - year - old primigravida was admitted to the hospital for mild pre - eclampsia and preterm contractions at 32 weeks Her preg-nancy was remarkable for a 12 - year history of insulin - dependent diabetes Her blood sugar control was reasonable on an insulin pump She had no overt consequences of microvascular injury She was given pneumatic compression stockings for use while in bed The 2 - week admission was remarkable for episodes of short-ness of breath associated with ambulation and with pneumatic compression stocking use She was evaluated clinically Chest

X - ray, pulse oximetry, and an ECG were performed Throm-boembolic disease was entertained but ultimately considered unlikely Because of the discomfort with the compression stock-ings they were discontinued and she was started on thrombopro-phylactic doses of heparin She labored spontaneously in the 36th week but had arrest of dilatation at 8 cm

After unsuccessful oxytocin labor stimulation, she was taken for cesarean section on a weekend morning The delivery occurred using the labor epidural from a recumbent position with a left lateral tilt Just as the rectus fascia was incised, she suddenly expressed great anxiety, attempted to sit up and then collapsed unresponsive Cardiac monitoring initially showed bradycardia

to the 40s and then became erratic There was no palpable pulse Within the fi rst 2 minutes of the event, a hospital “ code blue ” was initiated, the baby was quickly delivered, endotracheal intubation was attempted and chest compressions begun The initial intuba-tion was unsuccessful and bag/mask ventilaintuba-tion was performed Two 1 - mg doses of epinephrine followed by 1 mg of atropine were given intravenously without response Lidocaine and calcium were given and a second attempt at endotracheal intuba-tion was successful within 4 minutes into the resuscitaintuba-tion The cardiac monitors showed only a fl at line tracing

External cardiac monitors were disconnected Cardioversions with 200, 360 and 360 J were attempted with intermittent CPR and rhythm monitoring without a positive response Four mg of epinephrine was given intravenously; there was no response

Eight minutes into the resuscitation, the potential etiologies of

the arrest were reviewed Given the absence of an apparent

coagu-lopathy, anaphalactoid syndrome of pregnancy was considered

unlikely However, the history of previous events, now more

sus-picious for possible thromboembolic phenomenon, put a large

pulmonary embolism at the top of the differential diagnoses The

pulseless electrical activity (PEA) identifi ed earlier in the

resusci-tation supported this possibility

Left lateral thoracotomy and pericardotomy were performed

and open cardiac massage was initiated Within 30 seconds a

palpable beat was noted with subsequent beats following in

increasingly rapid succession By 12 – 15 minutes into the

resusci-tation the patient had a sustained rhythm and a blood pressure

of 70/40 Bilateral chest tubes were placed She was given 80

mg/kg of heparin An hour into the resuscitation a portable

pul-monary arteriogram demonstrated bilateral distal fi lling defects

in the pulmonary vasculature Ultimately, to maintain an

ade-quate blood pressure, the patient was given multiple 4 - mg doses

of epinephrine She needed levoephedrin, dopamine and

neosyn-ephrin drips and required cardiac massage on two subsequent

occasions to maintain an adequate cardiac output She received

a total of 10 units of packed red blood cells during the fi rst 4 hours

of the resuscitation and 2 units of FFP Crystalloid fl uids were

limited to 800 mL during the fi rst 3 hours Three hours into the

resuscitation her pupils were fi xed and dilated There was no

response to stimulation despite the fact that no pharmacologic

sedation had been given The patient was warmed, the wounds

closed and she was transferred to the ICU Within 18 hours of

the arrest she was appropriately responsive She was extubated

within 72 hours She was discharged from the hospital on post

arrest day 40 with moderate lower extremity spasticity and short

-term memory loss but otherwise neurologically intact Her

cardiac output at discharge was 25% Over the course of 2 years

her cardiac and neurologic function completely normalized The

baby has done well

Summary

Sudden cardiac arrest is uncommon in pregnancy and is usually

catastrophic when it occurs Because SCA arrest in pregnancy is

a rare event, medical facilities and personnel must maintain

com-petency by training and practice While successful resuscitation

is uncommon, early aggressive resuscitation by well - trained and

skilled attendants improves the likelihood of survival

The latest guidelines for CPR by the American Heart Association

make several recommendations for change from the previous

algorithms Pregnancy necessitates several modifi cations to

stan-dard CPR that include displacement of the uterus off the vena

cava to facilitate venous return Modifi cations to pharmacologic

or electrical therapy are usually not necessary

Immediate action is critical for both mother and baby In

preg-nant and non - pregpreg-nant individuals there is a window of

oppor-tunity in the fi rst 5 minutes after the arrest This short window

of time includes decisions about and performance of emergency cesarean section if that course is elected Urgent cesarean delivery

in SCA victims may be of benefi t to both mother and baby Precisely because SCA is an uncommon event on the labor and delivery unit, it is often unexpected Thus, training and drilling for such events should be a priority in order to maintain a state

of alert and readiness by hospital personnel We concur with Morris and colleagues [67] that the best opportunity for good outcome occurs when inertia can be avoided We must avoid (i) the inertia of fear that proven procedures and medications in non - pregnant patients will adversely affect the fetus, (ii) the inertia of indecision about emergent surgical delivery, (iii) the inertia of hopelessness for the desperately ill mother, delivered or undelivered, and (iv) the peculiarly American condition of medi-colegal dystocia

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Critical Care Obstetrics, 5th edition Edited by M Belfort, G Saade,

M Foley, J Phelan and G Dildy © 2010 Blackwell Publishing Ltd.

Christian Con Yost & Ron Bloom

Department of Neonatology, University of Utah Health Sciences, Salt Lake City, UT, USA

Introduction

Under normal circumstances, the transition from womb to world

is a series of dramatic and rapid physiologic changes leading to

the birth of an infant prepared to continue the processes of

growth and development The goal of delivering a healthy infant

intact ready to continue normal development is, unfortunately,

not always possible Pregnancies and/or deliveries complicated by

common and uncommon conditions, discussed throughout this

text, are at increased risk of failing to successfully make the

transi-tion to extrauterine life Modern diagnostic tools often, but not

always, allow for anticipation of infants at risk of not making a

successful transition, and, thus, permit the perinatal team to plan

for neonatal resuscitation and/or medically necessary

interven-tions However, more acute and often unanticipated conditions

such as a sudden prolapsed cord, an abruption or a previously

unrecognized congenital anomaly may result in the need for an

unanticipated, but nevertheless, skillful resuscitation

At birth, neonatal resuscitation may be necessary However,

because it is not possible to predict every infant who may require

resuscitation, the ability to conduct an effective resuscitation is

an integral part of the considerations and planning for any

deliv-ery Regardless of level of care, a trained and experienced team,

readily available, is an integral part of perinatal care These teams

must be provided with appropriate and well functioning

equip-ment needed to resuscitate a newborn [1] Skilled and

experi-enced personnel with the right equipment can usually intervene

successfully on a compromised infant ’ s behalf

The approach to neonatal resuscitation has continually changed

since the late 1980s when the teaching of neonatal resuscitation

became commonplace Over the last 20 years, we have

reconsid-ered our approach to resuscitation and have questioned some of

our previous assumptions We are now considering approaches

to assisted ventilation and the use of oxygen from a whole new perspective

This chapter will not address the details of exactly how to perform a resuscitation This is very well taught in the Neonatal Resuscitation Program of the American Academy of Pediatrics/ American Heart Association [2] and the details exceed the bounds

of this chapter What we will discuss are some of the new ideas, approaches and principles as well as some basic elements of neo-natal resuscitation In this context, we will discuss the role of continuous positive airway pressure versus intermittent manda-tory ventilation We will also discuss the growing dialogue regard-ing the use of oxygen in the resuscitative process

Elements of b irth d epression

Causes of b irth d epression

While all deliveries involve a complex physiologic transition at birth, infants of those mothers cared for by the high - risk obstetric team, especially if premature, are at a greater risk of birth depres-sion The newborn infant may be depressed at birth through a variety of mechanisms, some of which are unrelated to asphyxia Birth depression requiring resuscitation of a neonate cannot always be predicted, but at least among infants born of high - risk pregnancies, it should be expected

Maternal or placental conditions can result in birth depression For example, diminished uterine blood fl ow may result from maternal hypotension, eclampsia, regional anesthesia or uterine contractions Placental abnormalities such as an abruption, edema, or infl ammatory changes may reduce placental gas exchange Fetoplacental blood fl ow may also be compromised due to sustained and unrelieved cord compression from a nuchal

or prolapsed umbilical cord

Compromising conditions or events may also be primarily fetal

in origin These include drug - induced central nervous system (CNS) depression, CNS anomalies, spinal cord injury, mechani-cal airway obstruction, pulmonary immaturity, congenital anom-alies and infection All of these events or conditions, maternal and