Background: Serious complications of central neuraxial block (CNB) are rare. Limited information on their incidence and impact impedes clinical decision-making and patient consent. The Royal College of Anaesthetists Third National Audit Project was designed to inform this situation.
Methods: A 2 week national census estimated the number of CNB procedures performed annually in the UK National Health Service. All major complications of CNBs performed over 1 yr (vertebral canal abscess or haematoma, meningitis, nerve injury, spinal cord ischaemia, fatal cardiovascular collapse, and wrong route errors) were reported. Each case was reviewed by an expert panel to assess causation, severity, and outcome. 'Permanent' injury was defined as symptoms persisting for more than 6 months. Efforts were made to validate denominator (procedures performed) and numerator (complications) data through national databases.
Results: The census phase produced a denominator of 707,455 CNB. Eighty-four major complications were reported, of which 52 met the inclusion criteria at the time they were reported. Data were interpreted 'pessimistically' and 'optimistically'. 'Pessimistically' there were 30 permanent injuries and 'optimistically' 14. The incidence of permanent injury due to CNB (expressed per 100,000 cases) was 'pessimistically' 4.2 (95% confidence interval 2.9-6.1) and 'optimistically' 2.0 (1.1-3.3). 'Pessimistically' there were 13 deaths or paraplegias, 'optimistically' five. The incidence of paraplegia or death was 'pessimistically' 1.8 per 100,000 (1.0-3.1) and 'optimistically' 0.7 (0-1.6). Two-thirds of initially disabling injuries resolved fully.
Conclusions: The data are reassuring and suggest that CNB has a low incidence of major complications, many of which resolve within 6 months.