Maternal patent ductus arteriosus with bidirectional shunt: Obstetric anaesthesia and its challenges.

Abstract

Sir, During pregnancy and peripartum period, the physiological changes are poorly tolerated by a patient with bidirectional shunt and severe pulmonary hypertension.[1] We describe a case of 27-year-old primigravida at 32 weeks of gestation who presented with respiratory distress, pre-eclampsia and platelet count of 64 × 109/L. She was a known case of uncorrected congenital PDA with severe pulmonary hypertension and Eisenmenger syndrome. With an interdisciplinary approach, high-risk consent was taken for the emergency caesarean section because of worsening maternal condition, after explaining the high incidence of maternal morbidity and mortality to the family. Pre-operatively, she had tachycardia, hypertension and tachypnoea with an oxygen saturation of 82% on room air, which improved to 89%–92% with oxygen supplementation. Arterial blood gas also showed hypoxaemia and metabolic acidosis, with pH 7.40, PaCO2 22, PaO2 42.00, bicarbonate 16.10, base excess – 5.1 and SaO2 80.70%. In the operating room, right radial artery and right internal jugular vein were cannulated for blood pressure and central venous pressure monitoring, respectively. General anaesthesia with rapid sequence induction and cricoid pressure was instituted using fentanyl, etomidate and succinylcholine. Spinal anaesthesia was not given because of the low platelet count. Soon after induction of anaesthesia, the patient developed supraventricular tachyarrhythmia, followed spontaneously by bradycardia and reverted to normal sinus rhythm in few seconds. This may have been due to sympathetic response to laryngoscopy and intubation, although a higher dose of fentanyl was given at induction to avoid this. A live baby boy was delivered, with Apgar score of 7 at 1 min and 8 at 5 min. During the maintenance phase, she was initially given 100% O2 to maintain oxygen saturation, which was tapered down to 50% and supplemented with 50% air during the procedure. According to the echocardiogram findings, she had severe pulmonary hypertension. She was given milrinone (inodilator) and glyceryl trinitrate infusions, titrated according to response from 0.3–0.6 μg/kg/min, and 0.5–8 μg/kg/min, respectively. At the end of surgery, the trachea was extubated after fulfilling the criteria. During transfer from the operating room, she suddenly developed primary postpartum haemorrhage with a blood loss of approximately 1.5 L, for which immediately 1 unit packed cell was transfused. The surgeon requested general anaesthesia to perform balloon tamponade, which was provided with facemask and sevoflurane 2%–3%. The patient was shifted to cardiac care unit, where she deteriorated from the 2nd post-operative day and inspite of the best possible care provided, patient died on the 4th post-operative day. She experienced sudden cardiac arrest, cardiopulmonary resuscitation was performed but she never revived. The cause of death could not be ascertained. The most probable diagnosis was pneumonia as she had a fever, increasing total leucocyte count, tachypnoea, increased oxygen requirement and pulmonary infiltrate on chest X-ray. She may have aspirated during inhalational anaesthesia by facemask that was given for balloon tamponade, or she may have had a community-acquired infections, leading to severe sepsis and acute respiratory distress syndrome. This could have further worsened the pulmonary hypertension resulting in pulmonary hypertensive crisis and cardiac arrest. Another possible cause could be massive pulmonary embolism resulting in sudden death which is also a common cause of mortality in such patients.[2] The pregnancy induced hypercoagulable state further increases the risk of thromboembolic events in patients with Eisenmenger syndrome, and hence prophylactic anticoagulation is recommended. Unfortunately, our patient never received anticoagulation at any stage, though she was considered high risk for thromboembolic episodes. Haemodynamic disturbance with major fluid shifts occurring after delivery can also be considered as cause of death in such patients. Vigilance is mandated in fluid management as postpartum autotransfusion may expose these patients to fluid overload and heart failure.[3] Pregnancy is contraindicated in women with Eisenmenger syndrome,[4] It is a significant cause of mortality, typically from heart failure or thromboembolic events.[5] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.