///2016 Abstract Details
2016 Abstract Details2019-07-15T10:10:51-05:00

Difficult ventilation management in spina bifida parturient presenting for an urgent cesarian delivery

Abstract Number: T-75
Abstract Type: Case Report/Case Series

Mohamed A Ibrahim MD1 ; Faiza Khan MD2; Jill Mhyre MD3

A 17 year old white nullipara at 37 weeks required urgent cesarean delivery for non-reassuring fetal status. She was not a candidate for neuraxial blockade due to spina bifida, repaired L1 myelomeningocele, scoliosis with thoracolumbar vertebral fusion, paraplegia, hydrocephalus and VP shunt, and short stature (151 cms). Pre-pregnancy MRI revealed a Chiari 2 malformation, thoracic syrinx T7-8 with diastematomyelia, which reconstituted above the conus at L3. Pre-pregnancy pulmonary function testing documented moderate restrictive dysfunction. Airway management was anticipated to be straightforward, given a BMI 21.7kg/m2, Mallampatti 2 examination, and normal teeth, neck extension and mouth opening.

She refused face mask preoxygenation in preparation for general anesthesia, despite midazolam anxiolysis. Modified rapid sequence induction of anesthesia with propofol, rocuronium, cricoid pressure and mask ventilation resulted in grade I laryngoscopy with endobronchial intubation followed by profound oxygen desaturation. Withdrawal of the endotracheal tube to 16 cm, 5 cm PEEP, and lung recruitment maneuvers gradually restored oxygenation. However, surgical abdominal wall compression precipitated subsequent episodes of hypoxemia, particularly during abdominal muscle retraction and fetal extraction. Despite administering 100% oxygen by manual ventilation with lung expansion maneuvers and a head up position, the oxygen saturation remained between 80-90% until after delivery of the 3.2 kg neonate (APGAR scores of 2/3/5 at 1/5/10 minutes).Thenceforth, oxygenation was excellent (≥95% on FiO2≤0.8%), but she required 35 minutes of post-operative sedation and mechanical ventilation to facilitate safe reversal of the neuromuscular blockade and extubation in the operating room. Subsequent recovery was uneventful.

Discussion: In this patient with spinal dysraphism, diastematomyelia, kyphosoliosis, short stature & Arnold chiari malformartion, neuraxial blockade was felt to be both unsafe and unreliable. During general anesthesia for cesarean delivery, ventilation was compromised for three major reasons. First, as an adolescent survivor of a childhood illness, she refused pre-oxygenation despite both verbal and pharmacologic anxiolysis. Second, her scolioisis and short stature resulted in an unusually short distance between her mouth and carina. Third, the combination of kyphoscoliosis, uterine enlargement, and diaphragmatic relaxation during general anesthesia resulted in profound V/Q mismatch; surgical compression of the abdominal wall further compromised ventilation resulting in hypoxemia.

Third trimester pulmonary function testing and pre-anesthetic counselling may have better prepared the patient to cooperate with preoxygenation. Care during endotracheal intubation to insert the cuff balloon just through the vocal cords could help avoid endobronchial intubation. Finally, a head up position and vacuum extraction could improve ventilation during delivery

SOAP 2016