Incremental epidural anaesthesia for emergency caesarean section in a patient with ostium secundum atrial septal defect and severe pulmonary stenosis with right to left shunt.

Sir,

We read with interest the article by Saravana Babu et al.[1] on incremental epidural anaesthesia for emergency caesarean section in a patient with ostium secundum atrial septal defect and severe pulmonary stenosis with right to left shunt. The authors mentioned that this case was an emergency caesarean section in view of cephalopelvic disproportion (CPD) in labour. In CPD, once the baby's head engages into the pelvis, any delay in getting baby out of uterus results in traumatic brain injury of the baby. The authors proceeded with sequential epidural anaesthesia, which usually takes a very long time to achieve a reasonable anaesthetic band up to T4 level required for caesarean section. If this case had been an elective caesarean section, titrated epidural or very low-dose combined spinal–epidural anaesthesia could have been a better choice,[2] but if there is any evidence of foetal distress or chances of traumatic brain injury in CPD, general anaesthesia (GA) should be preferred. The authors mentioned that GA poses clear risk related to pulmonary vascular resistance and magnitude of shunt, but controlled ventilation with avoidance of hypoxia, hypercarbia and hyperinflation of lungs will not increase pulmonary vascular resistance.[3] In addition, the authors had supplemented epidural anaesthesia with ketamine and midazolam; however, it would carry the risk of respiratory depression in spontaneously breathing patient leading to hypoxia and hypercarbia (room air saturation of this patient was 90%–95%). Although hypotension during GA induction can decrease systemic vascular resistance (SVR) and increase the shunt magnitude, this can be prevented by the use of cardio-stable drugs for induction of anaesthesia such as ketamine or etomidate with judicious use of vasopressors (e.g., phenylephrine), or opioid during induction in a well-equipped hospital.[4] Invasive beat-to-beat arterial blood pressure monitoring would have been a better method to detect any decrease in SVR.

Hence, although the authors were fortunate in this case, GA is safer in view of emergency nature of the surgery.