High Neuraxial Block in Pregnancy

Reporting a case of High Neuraxial Block

Because of the differing anaesthetic interventions associated with this condition there a several versions of the data collection form. To establish which form is required, when you report a case of High Neuraxial Block you will receive an email asking you to select the most accurate description of the anaesthetic intervention prior to the development of the condition. It is important you respond to this email promptly so that we can send you the correct data collection form for completion.

The email will contain the following question:

What was the very last anaesthetic intervention that directly resulted in the high neuraxial block?

  • De novo epidural first dose
  • Top up of epidural/Top up of epidural component of CSE
  • Top up of epidural/ Top up of epidural component of CSE after resited epidural catheter
  • Single shot spinal/Spinal component of CSE
  • Single shot spinal/ Spinal component of CSE after epidural catheter
  • Top up of an intentionally threaded epidural catheter into the intrathecal space (i.e. intrathecal catheter)

Key Points

  • High (complete or total) neuraxial block is a known complication of epidural or neuraxial anaesthesia.
  • Incidence estimates vary widely.
  • The recent UKOSS Cardiac Arrest in Pregnancy study identified anaesthetic causes, including high neuraxial block, as the leading cause of maternal cardiac arrest in the UK.
  • This study aims to identify the risk factors for the development of high neuraxial block associated with obstetric anaesthesia in the UK.

Surveillance Period

1st September 2017 – 31st August 2019

Background

High (complete or total) neuraxial block is a known complication of central neuraxial blockade (epidural or spinal anaesthesia). The terms high, total or complete are used interchangeably to describe a sensorimotor block above that which is required for the surgery and which is associated with significant cardiovascular /respiratory compromise, sometimes culminating in cardiorespiratory arrest. The incidence of high neuraxial block associated with obstetric anaesthesia is not known. Estimates vary between 1:2,971 [1] and 1:16,200 [2] anaesthetics. More recently a retrospective study in the USA suggested an incidence of high neuraxial block of 1:4336 anaesthetics [3]. However the majority of the studies that include high neuraxial as a complication of central neuraxial block, come from the era before the widespread use of low dose techniques in obstetric anaesthesia (‘mobile epidurals’). Importantly, the recent UKOSS Cardiac Arrest in Pregnancy study identified anaesthetic causes, including high neuraxial, as the leading cause of maternal cardiac arrest in the UK [4]. While the outcomes for cardiac arrest in this setting were good, it behoves obstetric anaesthesia to identify the potential risk factors and causes of high neuraxial block in obstetrics to reduce this complication. This study will provide the most accurate description of the incidence of high neuraxial block in obstetric patients to date, with implications for improved safety.

Objective

To use the UK Obstetric Surveillance System (UKOSS) to determine the incidence of high neuraxial block amongst pregnant women in the UK and examine the management of the condition as well as maternal and neonatal outcomes.

Research Questions

  • What is the current incidence of high neuraxial block associated with obstetric anaesthesia in the UK?
  • What are the factors associated with the development of high neuraxial block associated with obstetric anaesthesia?
  • How is high neuraxial block associated with obstetric anaesthesia managed?
  • What are the outcomes for the mother and baby in a woman who develops a high neuraxial block associated with obstetric anaesthesia?

Case Definition

Any pregnant or postpartum woman who develops a high block in association with spinal and or epidural anaesthesia /analgesia that requires ventilatory support* and /or cardiopulmonary resuscitation**.

*Ventilatory support includes the additional use of ‘bag/mask’ ventilation, or ventilation assisted by the use of a supraglottic airway device or endotracheal tube.

**Cardiopulmonary resuscitation includes the use of basic and advanced life support.

Funding

This study is funded by a grant from the Obstetric Anaesthetists Association (OAA).

Ethics Committee Approval

This project has been approved by the North London REC1. (ref 10/H0717/20).

Lead Investigator

Gary Stocks, Imperial College Hospitals; Nuala Lucas, Northwick Park Hospital; Marian Knight, NPEU; Paul Sharpe, University Hospitals of Leicester NHS Trust

References

[1] Scott DB, Tunstall ME. Serious complications associated with epidural/spinal blockade in obstetrics: A two-year prospective study. Int J Obstet Anesth 1995;4:133–9.
[2] Jenkins JG. Some immediate serious complications of obstetric epidural analgesia and anaesthesia: A prospective study of 145,550 epidurals. Int J Obstet Anesth 2005;14:37-42.
[3] D’Angelo R, Smiley RM, Riley ET, Segal S. Serious complications related to obstetric anesthesia: the serious complication repository project of the Society for Obstetric Anesthesia and Perinatology. Anesthesiology. 2014;120:1505-5.
[4] Beckett VA, Knight M, Sharpe P. The CAPS Study: incidence, management and outcomes of cardiac arrest in pregnancy in the UK: a prospective, descriptive study. BJOG. 2017. Epub 2017 Feb 24 [Epub ahead of print].