Incidence, risk factors, management and outcomes of high neuraxial block in obstetric anaesthetic practice: a prospective national observational study using the UK Obstetric Surveillance System

SummaryIntroductionHigh neuraxial block has been identified as a leading cause of maternal cardiac arrest in the UK. There is a need to investigate the potential risk factors and causes of high neuraxial block in obstetrics to reduce its occurrence.MethodsWe investigated the incidence, risk factors, management and outcomes of high neuraxial block presenting in maternity care in the UK using the UK Obstetric Surveillance System. High neuraxial block was defined as spinal and/or epidural anaesthesia/analgesia that required ventilatory support and/or cardiopulmonary resuscitation.ResultsThere were 89 reports of high neuraxial block reported between 2017 and 2019. The estimated overall incidence was 14.7/100,000 (95%CI 11.8–18.0) neuraxial blocks, with the incidence of high neuraxial block of 19.6/100,000 (95%CI 14.9–25.3) after spinal anaesthesia and 7.0/100,000 (95%CI 4.6–10.1) after epidural analgesia or anaesthesia. The most common anaesthetic intervention that preceded a high neuraxial block was a single‐shot spinal following labour epidural analgesia (43/89 of all cases), of which 37% (16/43) occurred after an unsuccessful epidural top‐up to convert epidural analgesia to anaesthesia. Inadvertent dural puncture occurred in 15/89 cases. There were six cases of cardiac arrest. There were no maternal or neonatal deaths. Seven patients were reported to have been psychologically distressed and/or had awareness during tracheal intubation because of the high neuraxial block and its management.ConclusionWhilst high neuraxial block is rare in UK obstetric practice and generally managed well, directed attention to key aspects of clinical practice may ameliorate the risk. These include strategies to minimise acute supine hypotension with induction of spinal anaesthesia; prudent intrathecal local anaesthetic dosing; and careful case selection for converting epidural analgesia to anaesthesia for caesarean birth.