◊ 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.
◊ Reviewed by M. Vercauteren, MD, PhD
Professor, Dept. of Anesthesia, Antwerp University Hospital, Edegem Antwerpen, Belgium
Rather than providing a ‘best guess’ the authors have tried to give both pessimistic and optimistic calculations with respect to major complications and permanent harm following CNBs. Although the calculated incidences seem reassuring in general, careful attention should be given to some less reassuring findings such as the wrong route injections (still 9 cases with one fatality) and the relatively high incidence of major complications following CSE techniques (only 5.9% of all CNBs but with 2 out of the 6 deaths), i.e. higher than for epidurals or spinals. The authors were unable to provide an explanation for the increased risk associated with CSE. In addition, the incidence of major problems after epidural and CSE was twice that of spinals and caudals.
Having performed the CSE analgesia and anaesthesia technique for more than 20 years, our own experience does not correspond with the suggestion that it may result in the highest incidence of permanent harm. It may be questioned why CSE should be at higher risk than an epidural or single dose spinal. A partial explanation might be that CSE techniques always require a catheter advancing in the epidural space whereas caudals, spinals and caudals/epidurals for chronic pain do not.
Compared to other, mostly retrospective studies, the present incidences correspond well with the Swedish figures (with higher incidences for non-obstetric epidurals) while in the Finnish survey the incidences of major complications were comparable between epidural and spinal. Although the Scandinavian surveys mainly focused on neurological complications, found at one case per 20.000-30.000, the present audit, containing a broader spectrum of possible complications found a pessimistic incidence as low as 2.2 per 100.000. This is surely still far below the incidences reported in the French surveys. It is unclear to me why the prospective surveys of Auroy et al (1,2) have been ignored by Cook et al. These surveys covered a 5- and a 10-month period of hospitals all over France including more than 100.000 (>700 responders) and 150.000 (487 responders) central and peripheral nerve blocks, respectively. In these surveys, spinal anaesthesia was given to approximately 40.000 patients in each study (period). Cardiac arrest with spinal anaesthesia was calculated to occur in 2.7-6.4 per 10.000 and death in 1 per 7.000-10.000 patients. Neurological complications were found in 6-16 per 10.000 cases in both surveys but included cauda equina and transient neurological symptoms (TNS), mostly following the use of hyperbaric lidocaine. In the majority of patients, TNS complaints resolved within the first days. Such transient problems were excluded in the present audit which focused on permanent harm, paraplegia, and death.
The figures of the first survey of Auroy et al have put spinal anaesthesia in such a bad light that its iusage significantly dropped during the second survey performed 5 years later. Due to the high incidence of side effects of any kind, actually many French colleagues consider spinal anaesthesia as the most dangerous technique performed by anaesthesiologists.
A final conclusion may be that it is extremely difficult to compare one survey with another because study periods, definitions, outcome parameters and criteria may differ considerably. However, this does not diminish the value of the present prospective audit which has been achieved with extremely great care, expertise and sense for criticism.
◊ References
- Auroy Y, Narchi P, Messiah A, Litt L, Rouvier B, Samii K.
Serious complications related to regional anesthesia: results of a prospective survey in France. Anesthesiology. 1997 ; 87: 479-86.
- Auroy Y, Benhamou D, Bargues L, Ecoffey C, Falissard B, Mercier FJ, Bouaziz H, Samii K.
Major complications of regional anesthesia in France: The SOS Regional Anesthesia Hotline Service. Anesthesiology 2002 ; 97: 1274-80
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