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Clinical Anaesthesia File Afiaesthetic manage- ment of a parturient with severe muscular dystrophy, lumbar lordosis and a difficult airway

Case presented by Purpose: This case describes the management of a 19-yr-old Michael P. Pash MD FRCPC wheelchair bound primigravida with severe muscular dystro- phy who presented for Caesarean section after spontaneous rupture of membranes. Anaesthesia was influenced by several Case discussed by features of her systemic disease which were impediments to John BalatOn MD FRCPC both neuraxial and . Chris Eagle MD FRCPC FANZCA Clinical features: Other than for a prenatal record and the Department of Anaesthesia history obtainable from the patient, little additional medical Foothills Hospital information was available. Physical examination showed dif- University of Calgary fuse muscular weakness and an anatomically abnormal air- way. Examination of the spine showed slight 10-15 ~ thoraco- lumbar scoliosis and >45 ~ lumbar lordosis. Fetal assessment was normal. Echocardiography revealed mildly decreased left ventricular function and was consistent with pulmonary hyper- tension. After discussion with the patient and her obstetrician, elective Caesarean delivery was deemed the best management. Neuroaxial anaesthesia was at an increased risk offailure due to the profound lumbar lordosis. A plan for awake intubation and general anaesthesia was described to the patient in case regional anaesthesia could not be initiated. A fibreoptic bron- choscope and difficult intubation kit were made available. General anaesthesia was expected to have increased risk of postoperative pulmonary complications, hence epldural anaesthesia was attempted. After difficult catheter insertion, a sensory block was titrated to a T4 level. This was well tolerat- Key words ed by both mother and fetus. A healthy baby was delivered ANAESTHESIA" obstetrical; with Apgar scores of 9 and 9. Postoperatively the mother was ANAESTHETIC TECHNIQUES: epidural; transferred to the intensive care unit. After 72 hr, the patients ANALGESIA: postoperative, respiratory status allowed transfer to the ward. MUSCLE: limb-girdle muscular dysrophy. Conclusion: This case illustrates the use of epidural anaesthe- Address correspondence to: Dr. Chris Eagle, Department of sia in the successful management of a severely compromised Anaesthesia, Foothills Hospital, Calgary, Alberta, T2N 2T9. patient with limb-girdle muscular dystrophy undergoing elec- Accepted for publication 13th May, 1996. tive Caesarean section.

CAN J ANAESTH 1996 / 43:9 / pp959--63 960 CANADIAN JOURNAL OF ANAESTHESIA

Objectif: Ddcrire la prise en charge d'une primipare de 19 admissions to hospital during the past three three ans cloude ?t la chaise roulante par une dystrophie musculaire years and no regular follow-up by any medical spe- grave, hospitalis6e pour une cdsarienne aprks une rupture cialists. She had had one or two bouts of pneumonia spontande des membranes. L'anesthdsie a dtd influencde par each year for the last few years which required only plusieurs propres ~ cette maladie syst~mique g~nant ?t aussi ambulatory treatment. She had stopped at bien l' anesthtsie rdgionale centrale que l'anesthdsie gdndrale. eight weeks gestation. She denied having fever, chills, Caract~ristiques cliniques: Peu de renseignements ~taient cough, sputum, or any dyspnoea. The patient did not disponibles ~ part le dossier prdnatal et l'histoire obtenue de take any medications and had no allergies. Fetal la patiente. L'examen physique r#vdlait une faiblesse muscu- movements were normal. laire diffuse et voies adriennes anormales. L' examen du rachis montrait une l~gbre scoliose thoracolombaire et une lordose ddpassant 45 ~ L'dvaluation foetale dtait normale. L'dlectro- This patient presents two issues of concern for her cardiographie indiquait une diminution ldgbre de la fonction anaesthetic management, muscular dystrophy and preg- ventriculaire gauche et dtait compatible avec un hypertension nancy. She gives a history of severe weakness and fre- pulmonaire. Aprks discussion avec le patiente et son ob- quent respiratory infection, suggesting either impair- stdtricien, un accouchement par cdsarienne programmde dtait ment of normal clearance mechanisms and/or weakness d~cid~. Une anesthdsie rdgionale centrale risquait d'dchouer fi involving the bulbar muscles with resulting recurrent cause de l'importance lordose lombaire. Pour pallier & un pulmonary aspiration. Duchenne muscular dystrophy is dchec de l' anesthdsie rdgionale, un plan comportant une intu- most commonly an 'X' linked recessive disorder but has bation vigile et une anesthdsie gdndrale dtait expliqud gt la been reported in female patients.~ In any event, the case patiente. Un bronchoscope gl fibres optiques et une trousse will need to be managed without knowledge of the exact pour intubation difficile dtaient maintenus en disponibilitd. type of muscular dystrophy. Comme l'anesthdsie gdndrale augmentait le risque de compli- The anaesthetic considerations for the muscular dys- cations pulmonaires, une anesthdsie dpidurale dtait entreprise. trophies are similar in many respects. All patients with Apr~s l'insertion laborieuse d'une cathdter dpidural, le niveau muscular dystrophy show sensitivity to medications de bloc sensitif dtait progressivement installd & T4, ce que la including opioids and sedatives and the non-depolariz- m~re comme le foetus ont bien toldrd. Un enfant en bonne ing muscle relaxants. ! Patients have been described as santd avec des scores d'Apgar de 9 et 9 ~tait mis au monde. existing in a state of "partial curarization. ''! The adverse Aprds l'intervention, la mdre dtait transfdrde aux soins inten- events reported following administration of succinyl- sirs. Aprds 72 heures, la condition respiratoire de la patiente choline vary considerably. For example, some patients permettait le transport gt sa chambre. with Duchenne muscular dystrophy have suffered Conclusion: Cette observation illustre l'utilisation de hyperkalaemic responses with rhabdomyolysis and car- l'anesthdsie dpidurale pour la prise en charge d'une patiente diac arrest. 2 The risk of with the gravement atteinte de dystrophie musculaire des ceintures use of succinylcholine and inhalational anaesthetics is soumise gt une cdsarienne programmde. probably increased both in patients with Duchenne mus- cular dystrophy and limb-girdle muscular dystrophy but this relationship is difficult to quantify. Avoidance A 19-yr-old primigravida patient at 37 wk gestation of succinylcholine and the inhalational anaesthetics arrived by air ambulance after spontaneous rupture appears to be the most prudent approach) of membranes 12 hr previously. Her prenatal care Pregnancy presents a number of considerations for comprised four visits to her obstetrician. A history of anaesthetic management which are beyond the scope of "severe Duchenne Muscular Dystrophy" was record- this discussion. In this case, spontaneous rupture of ed on the antepartum record. She described a history membranes places the patient at an increased risk for of muscle weakness beginning at the age of three sepsis which would then be a relative contraindication years and progressing to confinement in a wheel- to regional anaesthesia. 4 chair by age 10 yr. The patient was now totally dependent on nursing care. A complete functional assessment was last done three years earlier in Physical examination revealed a gravid 59 kg woman another institution, but the results of these tests were near term in no acute distress. Her was not available. Past surgical history included ventric- 110 bpm, blood 100/60 mmHg, respiratory ular sept.al defect repair at 18 mo and tonsillectomy rate 20 per minute. She was afebrile. Physical exami- at 13 yr. The associated anaesthetics were described nation confirmed the presence of profound muscular by the patient as uneventful. There had been no weakness, which was more severe proximally. Air- Pash.: CLINICAL ANAESTHESIA FILE 961 way examination revealed a small mouth, large ment and congestive he.art failure may occur. Typical tongue, reduced neck extension, and a thyromental ECG changes are sinus tachycardia and a right bundle distance of two fingers. The airway was assessed as branch block. Diaphragmatic muscle may also be Mallampatti Grade IH. Air entry was decreased involved. 1 Similarly, Duchennes .muscular dystrophy is symmetrically, but no adventitious sounds were characterized by frequent cardiac, and electrocardio- audible. Some use of the accessory muscles of respi- graphic abnormalities, respiratory weakness, and kypho- ration was apparent. Examination of the cardiovas- scoliosis. Although the exact type of muscular dystro- cular system revealed normal neck veins and mini- phy presented here was not initially clear, the important mal edema. A left parasternal lift was present with a consideration is recognition of the commonly shared loud, palpable P2. No murmurs or extra heart features of the muscular dystrophies. sounds were audible. The non-stress test showed a There is little or no information in the literature con- reactive fetal heart tracing with a baseline fetal heart cerning the effects of the muscular dystrophies on uter- rate of 130 bpm. ine muscle function. Potentially, uterine smooth muscle function could be affected, as are cardiac and gastric smooth muscle. This might lead to an abnormal pattern Physical examination revealed a high probability of dif- of labour and possibly increasing the risk of postpartum ficult direct . and severe respiratory muscle haemorrhage secondary to uterine atony. These are only involvement. Clinically this patient likely has pul- hypothetioal concems. monary hypertension with adequate compensation since Given this patients condition, a "stat" Caesarean sec- there .is minimal evidence of right heart failure. To tion for fetal distress would be hazardous. At this point, assess the severity of the pulmonary and cardiovascular the obstetrician should be informed of these issues and a disease further, arterial blood , spirometry, chest x- decision made concerning operative delivery. There are ray, and transthoracic echocardiography should be two management paths to be considered. The first is requested. In addition, the pulmonary, cardiology, inten- general anaesthesia following awake fibreoptic intuba- sive care, and neonatology services should be consulted lion. If this is chosen, then neuromuscular blocking to allow them to prepare for postoperative care. drugs and opioids should be used in the smallest The CBC was normal. Arterial blood gases taken with amounts possible tofacilitate the surgery and postopera- the patient breathing room air showed: pH 7.33, PCO2 tive analgesia. 1 The second option is either spinal or 45 mmHg, PO2 68 mmHg, and saturation 92%. Spi- epidural anaesthesia. Epidural anaesthesia has the rometry was performed with the patient supported in the advantage of allowing careful titration of block height, sitting position and good effort was documented by the recognizing'that identification of the epidural space may technician. The FEVf. 0 was 0.25 L (7% predicted) and be technically challenging. In addition, fluid preloading FVC 0.61 L (15% predicted). The ECG showed sinus should be done slowly because of the patients pul- tachycardia with a right bundle branch block and right monary hypertension and decreased left ventricular axis deviation. Transthoracic echocardiography showed function. Central venous or pulmonary, artery pressure normal valvular function, a prominent pulmonary artery, may be helpful in guiding fluid replacement. a' small ventricular septal defect with persistent left to Finally, the epidural catheter could be used to adminis- right shunt, and moderate reduction in left ventricular ter narcotics/dilute local anaesthetic for post- contractility. Right and left ventricular, wall thicknesses operative pain relief. Although epidural anaesthesia has were at the upper limits of normal. The chest x-ray certain advantages, it does not eliminate the possibility showed basilar atelectasis and borderline cardiomegaly of intraoperative ventilatory failure due either to fluid but was otherwise unremarkable. The thoracic spine on shifts or additional weakening of the respiratory mus- chest x-ray was essentially normal. cles. The results of these investigations conf'n-m severe res- piratory involvement. A PCO2 of 45 mmHg is a distinct- Actual course ly abnormal finding in pregnancy since the PCO2 would be expected to be approximately 32 mmHg. 4 This pa- The patient was taken to the operating room 24 hr tient is in incipient respiratory failure. after the membranes ruptured. She was not in active This case has features compatible with several of the labour and the fetal heart tracing had remained muscular dystrophies. For example, limb-girdle muscu- active. The attending anaesthetist decided to proceed lar dystrophy is an autosomal recessive disorder usually, with an epidural anaesthetic. If this had been unsuc- but not exclusively, of intermediate severity with onset cessful, then an awake intubation was planned fol- in the first to the third decades of life. Cardiac involve- lowed by induction of general anaesthesia. The 962 CANADIAN JOURNAL OF ANAESTHESIA patient consented to this plan and was aware that she Discussion would be managed postoperatively in the intensive This case describes a patient with severe muscular dys- care unit. With the flushed and txophy and an anatomically difficult airway who pre- a fibreoptic bronchoscope, difficult intubation cart, sented for Caesarean section. 5 After careful assessment, and transtracheal jet in close proximity, the patient the attending anaesthetist opted for lumbar epidural was brought to the operating room. Routine moni- anaesthesia, a choice complicated by the patients severe tors were applied, by nasal prongs continued lumbar lordosis. Two concerns about the care provided at 2 L-min -~, and an was placed in the were administration of a fluid load in the presence of left radial artery. A large bore iv catheter was insert- pulmonary hypertension without central pressure moni- ed for crystalloid infusion. Ampicillin and gentam- toring and use of an untitrated dose of epidural mor- icin were given for prophylaxis against bacterial phine. Although the degree of pulmonary hypertension endocarditis. Initially the epidural was attempted was not documented in this case, the echocardiograph without success with the patient in the lateral posi- showed a prominent pulmonary artery, a small VSD, tion. She was then assisted to the sitting position and right and left ventricular wall thicknesses at the which produced a minor decrease in the amount of upper limits of normal. Nevertheless, the physical exam- lumbar lordosis. Cannulation of the epidural space ination did suggest considerable pulmonary hyperten- was then successful. Using a total of 15 ml lidocaine sion. Apparently, the pulmonary hypertension was ade- 2% and 1:200,000 epinephrine in divided doses, the quately compensated and the fluid load was well tolerat~ block was gradually titrated to the forth thoracic ed, a fortunate outcome. dermatome. During this titration approximately 1.0 One can speculate that epidural morphine contributed L of crystalloid was infused without perceived diffi- to the ventilatory insufficiency seen postoperatively. culty. The epidural block was well tolerated by both This patient showed inadequate ventilation preopera- mother and fetus. No was given. Blood loss tively on the basis of an elevated PCO2. Using patient was estimated at 500 ml. A vigorous 2850 g baby girl controlled epidural analgesia to titrate a dilute local was delivered with Apgar scores of 9 and 9. Cord pH anaesthetic mixture, PCEA, rather than giving a fixed was normal at 7.29. At the end of the procedure 3 mg dose of opioid may have been a better option. This how- preservative free morphine was injected through the ever is only speculation since the local anaesthetic itelf epidural catheter for postoperative pain manage- can promote muscle weakness. It should also be remem- ment and the epidural catheter was left in situ. bered that even a successful regional anaesthetic is no Intraoperative blood gases were omitted but should guarantee that respiratory failure will not ensue intra- or have been done to assess any worsening of this postoperatively. The decision to intubate this patient's patients respiratory status. The patient was then trachea would be a clinical one, based on a variety of transferred to the intensive care unit for observation. measures such as respiratory rate, dyspnoea, blood The baby was treated for transient tachypnoea of the gases, haemodynamics, level of consciousness, etc. newborn which resolved spontaneously over the next The muscular dystrophies are a heterogeneous group few hours. For the next three days the patients respi- of diseases whose genetic basis is subject to active ratory function was worse than it had been preoper- investigation. This patient was given the diagnosis of atively. The PCO2, measured at 45 mmHg preopera- Duchenne muscular dystrophy because two male second tively, was consistently in the 50-60 mmHg range cousins were diagnosed with that disorder. In order for postoperatively. The patient had no complaint of Duchenne muscular dystrophy, an X-linked recessive dyspnoea and minimal postoperative pain. Respira- disorder, to present in a female the "non affected" X tory function gradually improved over the next three chromosomes must be deactivated (the Lyon days with oxygen by nasal prongs, vigorous chest Hypothesis). It is theoretically possible for patients with physiotherapy, and incentive spirometry. Intubation Turner's syndrome who have only one functioning X and positive pressure ventilation were not required. chromosome to inherit muscular dystrophy, but these She was transferred to a hospital ward on the third individuals would not be fertile. An alternative diagno- postoperative day and followed by the obstetrician sis is severe, early onset limb-girdle muscular dystro- and pulmonologist. The need for home oxygen thera- phy. Finally, spinal muscular atrophies, another diverse py and home ventilation were to be assessed on an group of disorders, could present with this degree of outpatient basis. Sleep studies were also to be ar- muscle weakness but without the cardiac manifestations. ranged to rule out sleep apnea. The patient was sub- Later in the course of this patients hospital stay it was sequently lost to follow up. determined that the most likely diagnosis was in fact a severe form of limb-girdle muscular dystrophy. Muscle Pash.: CLINICAL ANAESTHESIA FILE 963 biopsy should not be forgotten as a useful diagnostic tool. This patient underwent muscle biopsy at age 12 yr, but the results were reported as ambiguous and not help- ful in delineating the diagnosis. If a had been required for this patient, then the basic approach would have been to per- form an awake intubation, to provide a trigger free anaesthetic, and to use opioids and neuromuscular blocking drugs judiciously because of the patients incip- ient respiratory failure. Careful weaning from mechani- cal ventilation in an intensive care unit setting is a safe course of action postoperatively. In summary, anaesthesia for patients with severe muscular dystrophy can be accomplished through a careful review of the patients respiratory status, antici- pation of cardiac dysfunction, and careful selection of anaesthetic agents based on the potentially increased risk of malignant hyperthermia and their residual effects on respiratory function. Since perioperative care can be complex in these patients, a well organized multidisci- plinary approach may be advantageous.

References 1 Stoelting RK, DierdorfS. and Co-Existing Disease, 3rd ed. New York: Churchill Livingston, 1993. 2 Katz J, BenumofJL, Kadis LB. Anesthesia and Uncommon Diseases, 3rd ed. Philidelphia: W.B. Saunders Company, 1990. 3 Miller RD. Anesthesia, 3rd ed. New York: Churchill Livingston, 1990. 4 Barash PG, Cullen BF, Stoelting RK. Clinical Anesthesia, 2nd ed. Philidelphia: J. B. Lippincott Company, 1992. 5 EkbliM U, Kanto J. Pregnancy outcome in an extremely small woman with muscular dystrophy and respiratory insufficiency. Acta Anaesthesiol Scand 1993; 37; 228-30.