Managing spinal hypotension during caesarean section: An update

Abstract

Hypotension is common after spinal local anaesthesia for caesarean section. However, the substandard treatment of spinal hypotension and associated complications are responsible for up to two-thirds of deaths that occur in South Africa (SA) for caesarean section under spinal anaesthesia. In some cases, spinal hypotension may be predicted by simple parameters such as age >25 years, preoperative heart rate >90 bpm and preoperative mean arterial pressure <90 mmHg. Heart rate variability and point-of-care echocardiography also predict hypotension with greater accuracy, but are limited by equipment and training issues. Spinal anaesthesia is absolutely contraindicated if the parturient is hypovolaemic. Left lateral tilt is still advised, despite the absence of strong supporting evidence. The dose of spinal bupivacaine should not be reduced in obese patients. Crystalloid co-loading is an adequate fluid strategy in most cases, but is of limited efficacy in the prevention of hypotension. It is imperative that immediately after the patient is placed supine, close attention is paid to communication with her, heart rate changes and pulse volume. Early intervention with phenylephrine is the first-line approach for hypotension if heart rate is preserved under spinal anaesthesia. Phenylephrine infusions (25 - 50 μg/min) are easy to administer, maintain baseline maternal haemodynamics and are applicable to the SA context. The vigilant use of phenylephrine boluses (50 - 100 μg), targeting maternal heart rate as a surrogate for cardiac output, is also effective. Noradrenaline has been used successfully to prevent spinal hypotension, but evidence does not yet suggest practice change. Local and international guidelines have recently been published.