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refractory failure. Death at the time of delivery or in the early
The greater demands on the pulmonary system peak by mid-third
postpartum period is common in parturients with pulmonary
trimester. However, because the uterus continues to grow
hypertension.38,39,41
through the last trimester, it may encroach further on the non-
compliant thorax and cause deterioration despite the fact that
respiratory demand has stabilized. The onset of new respiratory
Outcome of pregnancy in scoliotic parturients
symptoms or the exacerbation of preexistent symptoms during
Isolated cases of maternal death during pregnancy and the post-
the antepartum period is associated with an increased rate of
partum period have been reported with scoliosis, although preg-
maternal morbidity as well as a requirement for assisted ventila-
tion around the time of delivery.53 During labor, MV of the nancy is usually well tolerated with few medical or obstetric



135
2 Musculoskeletal disorders


complications.13,14 In the Reports on Confidential Enquiries into however, reporting on 25 C/S in women with severe kyphoscolio-
sis, noted that classic C/S was required in only one.4
Maternal Deaths in the United Kingdom covering the years
1985“1987 and 1988“1990, there were two cases of maternal mor- Patients with corrected scoliosis tolerate pregnancy, labor, and
tality associated with scoliosis, one in each report.56,57 Both delivery well, although some studies have demonstrated an
patients were admitted to hospital with deteriorating respiratory increased incidence of operative delivery compared with that in
normal parturients.61 In one study, the rate of vacuum extraction
status, underwent C/S, and died postoperatively. One death was
attributed to adult respiratory distress syndrome and multiorgan was higher in surgically treated women (16%) than it was in either
brace-treated (8%) or a control cohort (5%).13 Others have noted
failure, the other to air embolism. These deaths, viewed in light of
the comments regarding the usually benign course of pregnancy no increased requirement for operative delivery in patients with
in the scoliotic parturient, probably reflect the lack of homoge- corrected scoliosis. Orvomaa reported that rates of complications
neity in the population of parturients with scoliosis. There have of either pregnancy or labor were similar to national statistics and
been no similar cases detailed in subsequent reports. although there was an increased requirement for C/S, the indica-
tions for surgery were not typically scoliosis-related.14 In a report
The reproductive experiences of women with scoliosis depend
not only on the severity of the curve and the resulting cardiopul- of 355 patients with scoliosis and prior posterior fusion, C/S was
necessary in only 2.5% of deliveries.47 In another review of
monary sequelae but also on the presence of underlying neuro-
muscular disorders. Kafer suggested that complications are more 17 women with kyphoscoliosis who had 27 pregnancies: nine
likely to occur in the older parturient (>35 years) with severe had idiopathic scoliosis, and posttraumatic scoliosis was the lar-
gest single second etiologic factor.15 Again, the experience was
scoliosis, or in a parturient with scoliosis associated with an
underlying neuromuscular disease.3 Also at risk are primiparas similar to that seen in the nonaffected population.
who develop fatigue during long labors. Premature labor is
reported by some to occur more commonly in scoliotic parturi-
Management issues in the scoliotic parturient
ents and to be independent of the severity of the curve.12,50,53
However, this observation was not found in two of the largest
Antepartum assessment and medical management
series of parturients with treated idiopathic scoliosis.13,14
The incidence of low-birth-weight infants and congenital Prepregnancy planning in women with scoliosis serves two pur-
anomalies is not increased in women with moderate uncorrected poses. It allows for counseling regarding the risk of inheritable
or corrected curves, compared with population averages.12,13,14 The disease in offspring when there is a significant genetic component,
likelihood of intrauterine fetal compromise rises with the fre- and it allows for evaluation of maternal risk in carrying a gestation
quency and severity of maternal hypoxic episodes.55 Malposition to term. The majority of patients with scoliosis have mild to mod-
at delivery is not common; in patients without cephalopelvic dis- erate idiopathic curves, and the expectation is that they will toler-
proportion, vaginal delivery occurs uneventfully at a rate similar to ate pregnancy, labor, and delivery with an incidence of
controls. When scoliosis or other underlying disease distorts pelvic complications comparable to that in the normal population.
anatomy, operative or instrumented deliveries, perineal tears, and Maternal morbidity is predominantly due to cardiopulmonary
uterine prolapse occur with greater frequency, leading to a higher failure and is related to the site (thoracic) of the curvature and
rate of fetal and maternal morbidity. degree of cardiopulmonary compromise before pregnancy.
In the second stage of labor, the diaphragm not only acts as a Morbidity and mortality increase if the vital capacity is <1 to 1.25
respiratory muscle but also has a nonrespiratory function. With liters, if PaCO2 is elevated, or if pulmonary hypertension with
ventricular compromise is present.55,62,63,64,65 These are consid-
expulsive efforts, maximal isometric diaphragmatic contractions
are often sustained for 10 to 20 seconds. Diaphragmatic fatigue ered indications for recommending avoidance of, or termination
has been demonstrated in normal laboring women.53 In one of, the pregnancy. Pregnancy is well tolerated if antenatal lung
volumes exceed 50% of those predicted.45,48 Scoliosis secondary to
report the incidence of acute respiratory failure during delivery
was virtually zero in healthy parturients, but in the woman whose a primary neuromuscular disorder may be associated with higher
gestational morbidity than idiopathic scoliosis.55 Young women
diaphragm is weak due to neuromuscular disease, the potential for
respiratory difficulties increased.58 Expulsive forces are also with curves that are >258 and those that involve a double curve
decreased and may lead to a prolonged second stage or even fail- and are not yet stable should be advised that there is some risk of
ure of a trial of labor. Cesarean delivery is necessary in a significant progression of the curve from pregnancy. Conversely, there is little
proportion of scoliotic parturients. The incidence is likely to be risk of progression if the curve is <208 or has been stable, and no
risk if the curve has been surgically stabilized.13,14
related to the degree of skeletal deformity, resulting maternal
compromise, and cephalopelvic disproportion. In patients with Antepartum maternal assessment focuses on maternal cardio-
severe curves, the rates for C/S range up to 52%.4,59,60 Cesarean respiratory status with attention to the history and current status;
delivery may be technically more difficult in patients with severe presence of coexistent disease; and type, status, and patient prog-
curves, especially those with lumbar spinal involvement. This nosis of associated neuromuscular disorders. If respiratory com-
difficulty is due to the acute anteflexion of the uterus in the small promise is evident, a formal respiratory evaluation is carried out.
abdominal cavity resulting from the approximation of the xiphis- An assessment is made of the respiratory reserve, including
ternum and the symphysis pubis. The lower uterine segment may inspiratory and expiratory muscle function, and integrity of
be inaccessible, making classic C/S necessary.60 Kopenhager, the airway-protective reflexes. Special attention is given to the



136
Chapter 7


presence of dyspnea, tachypnea, and exercise tolerance; recent high-risk group for antepartum maternal decompensation.
pulmonary function assessments are noted. Further evaluation is Admission to hospital for the last weeks of pregnancy enhances
made with respect to the possible benefits of supplemental O2 the likelihood that maternal decompensation will be recognized
therapy, nocturnal continuous positive airway pressure (CPAP), early and morbidity or mortality prevented. Oxygen therapy
or assisted (negative-pressure) ventilation. Patients with (2“4 l/min by nasal prongs) intermittently during the day and
curves >608 or those with known cardiac disease require formal continuously overnight may improve maternal condition and
cardiologic evaluation to assess ventricular size and function as reduce fetal risk. Both negative- and positive-pressure noninva-
well as pulmonary vascular pressures. sive ventilatory support for respiratory insufficiency during preg-
If maternal cardiopulmonary status is so compromised that her nancy in parturients with severe kyphoscoliosis has been
reported.66,67 The patient whose diagnostic images are profiled
survival is jeopardized by continuation of the pregnancy, a
recommendation to terminate the pregnancy may be made. in Figures 7.2 and 7.6 underwent negative-pressure ventilation for
Despite the risk, many will choose to continue with pregnancy. several weeks before delivery, initially intermittently and noctur-
The value of a team approach to these high-risk patients cannot nally, then subsequently continuously. Chronic hypoxemia and
be overemphasized. The team includes medical, obstetric peri- polycythemia combined with the hypercoagulable state induced
by pregnancy increase the risk for thromboembolic events.39,63
natology, neonatology, and anesthesiology consultants; the team
can be complemented by nursing and social services personnel. Antiembolism stockings are recommended. Consideration
The team meets, in whole and in part, at regular intervals to should also be given to subcutaneous heparin therapy, with full
monitor both the condition of the mother and progress of the anticoagulation being reserved for the patient with more severe
pregnancy. A plan is generated regarding the management of the disease. Heparin may be reversed at induction or with onset of
pregnancy and delivery. The plan is relayed to the patient and is labor to allow for neuraxial analgesia.
shared with the departments involved. Such an approach to
management may reduce the incidence of morbidity and mortal-
Obstetric management
ity even in very high-risk parturients.62
Patients with underlying neuromuscular disease or cardiopul- In parturients with little or no cardiopulmonary compromise at
monary dysfunction related to scoliosis represent a particularly the outset of pregnancy, the expectation is for an uneventful




Figure 7.6 Pelvic x-ray study in a young woman with a progressive spinal muscular atrophy (Kugelberg-Welander syndrome) demonstrating an inadequate pelvic
outlet. She delivered two children by C/S under GA after failed attempts to perform regional anesthesia. Her chest film is detailed in Figure 7.2.



137
2 Musculoskeletal disorders


pregnancy and delivery. As the pregnancy advances, the cardio- Radiographic studies done before pregnancy and operative notes
pulmonary signs and symptoms of a normal course must be related to surgical procedures on the spine should be assessed in
differentiated from true deterioration in function. The obstetri- any patient with a significant scoliosis or previous major spinal
cian or perinatologist is in the best position to monitor for unto- surgery before consideration is given to regional anesthesia.
ward maternal responses to the advancing gestation by virtue of Reviewing films taken in the past, even before pregnancy, is
the frequency of contact with the woman. If there is concern that usually sufficient to determine not only the underlying anatomy
the maternal condition is deteriorating, a reevaluation by a med- but also the residua of previous surgical interventions. If further
ical consultant is in order to quantify the change and to initiate diagnostic imaging is required, it should be deferred until there is
therapy. Although right-sided heart failure may mimic pre- little threat to the fetus (late second or third trimester). The spine
eclampsia, peripheral edema being common in both, respiratory should be examined and note made of the surface landmarks and
symptoms are usually profound in cor pulmonale and are the interspaces least involved in the deformity.
uncommon in preeclampsia. Maternal decompensation early in
the pregnancy confers an ominous prognosis. Decompensation
Anesthetic care of parturients with scoliosis
in late pregnancy and during the early postpartum period is
complicated by pulmonary hypertension
common in the patient with borderline cardiopulmonary func-
tion. Obstetric intervention before the completion of gestation is The care of parturients with pulmonary hypertension is discussed
reserved for compelling maternal or fetal indications. in detail in Chapters 1 and 3 and will only be detailed briefly here.
At term, if maternal cardiopulmonary function and pelvic size The goals in the anesthetic management of parturients with pul-
are adequate and the fetal condition is good, a trial of labor is monary hypertension include (1) avoidance of pain, hyperten-
permitted and should be successful. Cesarean delivery is reserved sion, hypoxemia, hypercarbia, and acidosis, because these
for obstetric indications. A higher incidence of operative delivery increase PVR; (2) avoidance of myocardial depression because
may occur in patients with spinal fusion for scoliosis; but this has CO will be further decreased; (3) maintenance of intravascular
not been a consistently reported finding.12,13,14,56,62,65 volume and preload; and (4) maintenance of systemic vascular
In women without major lumbosacral deformity, there is little resistance (SVR) so as to ensure myocardial perfusion and pre-
alteration of the pelvic cavity, and malpresentation is no more vent right-to-left shunting. The use of regional block in parturi-
frequent.4,12 In patients in whom a lumbar spinal deformity is ents with pulmonary hypertension has been discouraged,
prominent, however, malpresentation is common.60,68 Pelvic historically.70 However, recent reports suggest that regional
abnormalities are also more common when scoliosis is associated anesthesia may be provided to these patients with relative safety,
with neuromuscular disorders, which predisposes the fetus to although this may depend on the degree of pulmonary hyperten-
malpresentation (see Figure 7.6).55 Uterine function is typically sion.62 Mortality, though considerable, seems dictated primarily
normal in scoliosis; labor is not prolonged and spontaneous vagi- by maternal condition at presentation and the intensity (major vs.
minor) of the surgical intervention.71 The concerns regarding the
nal delivery is to be anticipated. In patients with severe disease,
those with scoliosis resulting from neuromuscular disease and use of regional anesthesia include reducing venous return with
especially in those with gestational decompensation, C/S may be sympatholytic vasodilatation as well as the possibility of creating
indicated because of maternal compromise. Patients with signifi- or augmenting a right-to-left shunt and reducing myocardial
cant pulmonary hypertension should avoid bearing down, and a perfusion by reducing SVR. Systemic hypotension resulting
forceps-assisted vaginal extraction facilitates delivery in these from regional block may also lead to RV ischemia and profound
patients. Oxytocin is a systemic vasodilator, and bolus doses decreases in CO.
should be avoided in parturients with pulmonary hypertension.39 Invasive cardiac monitoring is recommended for those patients
with significant cardiopulmonary dysfunction. A radial arterial
line allows for continuous assessment of maternal blood pressure
Anesthetic management
(BP) and serial arterial blood gases. Central venous pressure
Antepartum assessment monitoring is also helpful in parturients with RV dysfunction.
Patients who require antepartum anesthetic consultation include Insertion of the central line through the antecubital fossa veins
those with pulmonary hypertension, thoracolumbar scoliosis prevents maternal distress resulting from the Trendelenburg
with a Cobb angle >308, and spinal instrumentation and fusion position for insertion through the vessels in the neck, particularly
for scoliosis. Initial anesthesiology contact should occur early in in those patients who are already experiencing symptomatic car-
gestation, not later than the second trimester. The more severe diopulmonary decompensation.
the maternal condition, the earlier first contact is advised.
Ongoing evaluation is carried out via team conferences and a
Analgesia for labor
plan for anesthetic management is formulated well before deliv-
ery. The plan is conveyed to the patient and other team members. Modes of analgesia and anesthesia for labor and delivery can be
The underlying etiology of the scoliosis as well as severity and discussed at the antepartum consultation. Patients with uncor-
stability of the curve should be elucidated. In patients with rected thoracolumbar scoliosis may be offered lumbar epidural
scoliosis resulting from neuromuscular disorders, anesthetic anesthesia (LEA) for labor and delivery, even if the deformity is
considerations specific to those disorders should be reviewed.69 severe. Placement of an epidural catheter is technically more



138
Chapter 7


2. Reliable surface landmarks are absent following surgery.
3. Degenerative changes occur in the spine below the area of
fusion at a rate greater than usual, and these changes may
increase the likelihood of technical difficulties entering the
space or achieving a block.75
4. Insertion of an epidural needle by either the midline or para-
median approach in the fused area may not be possible
because of the presence of instrumentation, scar tissue, and
bone graft material.72
5. A false loss of resistance is common.
6. The ligamentum flavum may be injured during surgery,
resulting in adhesions in the epidural space or obliteration
of the epidural space, which may interfere with spread of
local anesthetic (LA) injected into the epidural space.76
7. Obliteration of the epidural space may make accidental dural
Figure 7.7 Vertebral displacement and rotation in moderate to severe scoliosis. puncture inevitable in some patients.
The vertebral body deviates from the midline and undergoes rotation with the 8. It may not be possible to perform an epidural blood patch if a
spinous process remaining closer to the true midline (defined as a line drawn
significant postdural puncture headache results.
from C7 to the sacrum). The interlaminar space is deviated toward the curve
9. Persistent back pain is common in patients with surgically
convexity. A needle entering the palpated interspinous gap must be directed
corrected scoliosis (correlates with increasing time since the
toward the convexity of the curve to reach the interlaminar gap. Tracking the
surgery and extent of fusion).28,75
interspinous ligament can be used to determine the angle required; the angle is
10. Patients often manifest a high degree of anxiety about their
dependent on the magnitude of the curve.
backs and may be reluctant to have a regional block.
Once the epidural catheter is sited and its position verified, it
demanding than usual and an increased incidence of complica- may be activated with a solution of LA alone or with a LA-opioid
tions should be anticipated. The midline of the epidural space is mixture. In most parturients, and in particular those with signifi-
deviated toward the convexity of the curve, relative to the spinous cant cardiovascular compromise, a dilute LA-opioid mixture
process palpable at the skin level (see Figure 7.7).21 The degree of (bupivacaine 0.0625% À 0.1% with 2“4 mg/ml fentanyl at infusion
lateral deviation is determined by the severity of the deformity. rates of 8“15 ml/h) is more likely to provide excellent first-stage
The needle should enter the selected interspace and be directed and good second-stage analgesia with fewer hemodynamic con-
sequences compared with more concentrated LA solutions.77
toward the convexity of the curve. The experienced clinician can
track the resistance of both the interspinous ligament and the Combined spinal“epidural analgesia is also an option in
ligamentum flavum to maintain a true course into the epidural patients in whom the spinal spaces can be reached. The efficacy
space. Structural curves of 308 or less and minor functional and complication profiles of the combined technique are similar
to those of epidural analgesia.78 Intrathecal opioids represent
curves, such as those commonly seen in the term pregnant
female, rarely result in much rotatory deviation of the vertebrae. another option for labor analgesia. Although some reports sug-
Little accommodation in technique is required for successful gest that there is less hemodynamic compromise than with
LAs,79,80,81,82,83 others state that the incidence and magnitude of
needle or catheter placement.
hypotension is similar.84 The use of intrathecal opioids for labor
Major spinal surgery in the past is believed by some to repre-
sent a relative contraindication to regional anesthesia. This opin- analgesia has been linked with fetal heart-rate abnormalities,
ion is not shared by me. Regional anesthesia and analgesia may although it is uncertain whether these occur more commonly
than would be observed after epidural analgesia.85,86,87
be offered to patients who have experienced previous spinal
instrumentations. The incidence of successful block is reduced Continuous subarachnoid infusions of sufentanil or meperidine
and complications are more frequent, especially in patients for effective labor analgesia have been described in both normal
populations and in parturients with severe cardiac disease.88,89,90
who have had extensive surgeries involving the lumbar
spine.61,65,68,72,73 Complications include unsuccessful insertions, In the event that the opioid alone provides inadequate pain relief
multiple attempts before successful insertion, false loss of resist- (i.e. perineal pain during second stage), small, hemodynamically
ance, dural puncture, failed block, or inadequate analgesia. innocuous doses of dilute LA solutions are usually adequate
supplements.88
Problems are more frequent in patients with fusions extending
to the lower lumbar and lumbosacral interspaces than in those
with fusions ending in the upper lumbar spine.73 When discuss- Labor analgesia in parturients with cardiopulmonary
compromise
ing regional anesthesia with parturients who have previously
undergone extensive spinal surgery, consideration should be The utilization of small, incremental doses of dilute LA (bupiva-
given to the following. caine 0.0625“0.1%, ropivacaine 0.08“0.125%) to initiate epidural
1. Twenty percent of patients™ spines are fused to L4 and L5 blockade followed by a continuous infusion, should be well tol-
levels, leaving few lumbar interspaces uninvolved. 61,74 erated by most parturients.62 The introduction of lipid-soluble



139
2 Musculoskeletal disorders


opioids (fentanyl 2“4 mg/ml) into the infusing solution reduces preoperative maternal condition, with survivors demonstrating
both the mass of LA required and the potential for significant good RV function. There is evidence that LEA is as safe as general
cardiac decompensation with the initiation of regional analgesia. anesthesia (GA) in parturients with pulmonary hypertension.
It is a prudent strategy to enhance the safety of regional anesthe- Both combined spinal“epidural anesthesia and continuous
spinal anesthesia have also been reported with survival.98,99 If
sia in this subpopulation and is highly recommended. Intrathecal
administration of lipid-soluble opioids may also be an acceptable regional anesthesia is used, a technique that permits cautious
strategy to provide labor analgesia in these parturients, although and incremental titration to achieve the required level of block
hypotension may result from the administration of intrathecal is advocated.
sufentanil alone.84 In patients in whom the lumbar spinal spaces General anesthesia may be indicated because of maternal pre-
cannot be safely reached, consideration may be given to the ference, or maternal cardiopulmonary decompensation, or
performance of a caudal block. because of technical difficulties related to regional block. A thor-
ough evaluation of the maternal airway is indicated, because a
number of conditions associated with scoliosis, including severe
Anesthesia for operative delivery in parturients
scoliosis itself, are associated with difficult laryngoscopy and
with scoliosis
intubation. Many patients with scoliosis resulting from neuro-
Cesarean delivery may be indicated for maternal or fetal welfare muscular diseases have preexisting airway obstruction and may
or for obstetric reasons. Parturients with severe scoliosis often are have sleep apnea. Because GA also causes relaxation of pharyngo-
small and frail. During surgery, the rib hump and bony promi- laryngeal elements, patients may be at particular risk for airway
complications postoperatively.100 Postoperatively, elements of
nences should be padded, with care taken to minimize heat loss.
The patient™s small size may occasionally necessitate pediatric- laryngeal incompetence and impaired swallowing may further
sized equipment, such as BP cuffs. Either general or regional decrease the integrity of the airway defense mechanisms.
anesthesia may be provided and there is no evidence that would In normal patients, the FRC falls at induction of anesthesia,
support a specific choice in this patient population. If regional which is attributable to cephalad shift of the diaphragm, ribcage
anesthesia is chosen, a slow and incremental extension of an dysfunction or instability, and increased intrathoracic blood
epidural or a subarachnoid block provides ideal conditions for volume. Abdominal surgery produces persistent postoperative
operative delivery and postoperative analgesia. Because LA dose decreases in FRC that are progressive, becoming evident hours
after the end of surgery.101,102 The decreases in FRC are related to
requirements are variable, an epidural or a subarachnoid catheter
is preferable to a single-shot subarachnoid injection. Particular diaphragmatic dysfunction and may persist for up to one week.
attention should be paid to the dose of LA, because the patient™s Atelectasis and V/Q abnormalities, which impair gas exchange
small size renders usual volumes toxic. In patients with severe and result in hypoxemia in normal subjects, may occur. In sco-
curves, there is speculation that subarachnoid hyperbaric LA liotic parturients with underlying pulmonary pathology, these
solution may pool in dependent portions of the spine, resulting effects are augmented and may result in significant postoperative
in an inadequate block.91 Supplementing the block with isobaric morbidity. Other causes of postoperative hypoxemia that are of
formulations of LA may improve the quality of the block; supple- particular importance to patients with scoliosis are included in
mentation is facilitated with an indwelling subarachnoid Table 7.3.
catheter. Anesthesia, tracheal intubation, and surgery result in mucocili-
ary dysfunction and abnormal or retrograde mucous flow.103
Multiple reports exist about LEA in parturients with severe sco-
liosis, including those with cardiopulmonary compromise and Reduced competence of the larynx increases the potential for
corrective instrumentation. Performance of regional block in postextubation aspiration in patients already at risk because of
these patients is technically demanding and may be complicated both the pregnancy and underlying airway disorders. Coughing
by failed or inadequate block. Block quality may be enhanced by and bucking at the end of surgery may transiently and signifi-
supplemental epidural injection of chloroprocaine when dose lim- cantly reduce FRC, resulting in further V/Q mismatch and hypox-
emia.104 Tracheal extubation after C/S in the parturient with
its of the other agents have been reached, or by subarachnoid
injection of small doses of LA.92 Reports have been published gestational hypertension may result in significant increases in
both systemic arterial and pulmonary artery pressures.105 These
about extensive spinal blocks associated with profound hemody-
namic instability when full-dose subarachnoid injection is made in
the setting of preexistent, albeit inadequate, epidural blockade in
parturients.93,94,95,96 If time permits, allowing the epidural block to Table 7.3 Factors contributing to postoperative hypoxemia
regress before performing spinal block is recommended.97 in scoliotic parturients
Alternatively, reducing the dose of LA agent injected into the
Increased V/Q mismatch
subarachnoid space is recommended if partial epidural block
Increased alveolar-to-arterial O2 gradient
is present.96
Inhibition of hypoxic pulmonary vasoconstriction
The rate of mortality related to C/S in patients with pulmonary
Decreased CO
hypertension is considerable.38,39,62,63,71 The high mortality rate
Underlying preexistent pulmonary disease
is probably due in part to the presurgical status of the mother
Restriction of chest-wall movement
and reflects her poor condition. Prognosis is related to the



140
Chapter 7


pressure rises take on added significance in the setting of preex- pulmonary vascular reactivity and a mismatch between declining
myocardial contractility and altered preload.39
isting pulmonary hypertension. Criteria for postoperative extuba-
tion must include assessment of preoperative respiratory
function. An assessment of respiratory muscle strength and abil-
Other disorders of the vertebral column
ity to support the airway should be made in all patients, but it is
particularly important in patients with preexisting compromise. Lumbar disc prolapse
Potential hazards of GA in parturients with pulmonary hyperten-
Back pain is a common complaint in the parturient.110 Its occur-
sion include the increased pulmonary artery pressures during
rence during gestation seems most closely correlated with the
laryngoscopy and intubation; adverse effects of positive-pressure
presence of back symptoms in the prepregnant state. However,
ventilation on venous return; and negative inotropism of some
new onset back pain is also common during gestation; it is likely
anesthetic agents. These adverse effects can be largely attenuated
related to both changes induced by relaxin and estrogen and the
by an opioid-supplemented induction and maintenance techni-
biomechanical stresses imposed on the axial skeleton.
que.64 An obvious potential exists for neonatal respiratory depres-
Lumbosacral disc bulges and herniations commonly occur in
sion with this technique, but that is easily managed by the
women of childbearing ages, occurring in slightly more than
neonatologist. Nitrous oxide should be avoided because it
half the women in this age group, whether pregnant or not.111
increases PVR. The patient may require high-surveillance care
Despite the prevalence of back symptoms during pregnancy and
for up to a week following delivery because major cardiopulmon-
the common occurrence of disc prolapse in women of childbear-
ary complications are common during this period.
ing ages, prolapse is uncommon during pregnancy, estimated to
occur in 1 in 10 000 pregnancies.112 The relative rarity of sympto-
Management of acute maternal cardiac matic disc prolapse during pregnancy may be due to the reluct-
decompensation ance of pregnant women to engage in strenuous physical
activities which might predispose to prolapse. Three authors
Most pregnancies in mothers with severe pulmonary hyperten-
have reported a total of 12 women with disc prolapse during
sion do not reach term, but reports suggest that neonatal survival
gestation who presented with significant neurological symp-

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