Introduction

Historically it has been difficult to obtain genuinely informed consent from patients to whom we are offering central neuraxial block because the incidence of serious complications was not known; figures quoted have varied from as high as 1 in 1000 to 1 in 100 000. NAP3 was designed to inform this consent process by answering three key questions:

The project

First an assessment of the number of CNBs performed annually in the UK National Health Service (NHS) was made (for denominator information). Then the major complications of CNBs performed over 12 months were audited (for numerator information).

CNBs were classified as epidurals, spinals, combined spinal epidurals (CSE) and caudals. They included those performed perioperatively for both adults and children, all CNBs on the labour ward and, in the chronic pain setting, whether they were administered by an anaesthetist or non-anaesthetist. Major complications were classified as permanent injury, death or paraplegia.

The project sought to review all patients with a potentially life-changing complication for 6 months in order to assess outcome as well as incidence. As well as neurological complications it also looked at harm resulting from wrong route error or cardiovascular collapse. However, the report does not provide any information on the incidence of minor complications or major complications without permanent harm.

The results at a glance

In the UK NHS, over 700 000 CNBs are performed per year: 46% spinals and 41% epidurals, with 45% for obstetric indications and 44% perioperative.

There were 84 major complications reported with 52 meeting all the inclusion criteria. The data were interpreted both ‘pessimistically’, giving 30 permanent injuries, and ‘optimistically’, giving 14. Therefore, the figures which we can now confidently quote to our patients are:

In the 30 patients with permanent harm, 60% occurred after epidural block, 23% after spinal and 13% after CSE. Given the relative numbers of each performed, the incidence of complications of CSE was at least twice those of spinals and epidurals.

These incidences are lower than those of similar (but smaller) historic studies and therefore reassuring to clinicians and patients. Also reassuring is the finding that two-thirds of patients with complications initially judged to be severe made a full recovery. Patients for whom prognosis was poor were those with vertebral canal haematoma and spinal cord ischaemia.

Most complications leading to harm occurred in the perioperative setting as opposed to the obstetric or pain settings and with the majority occurring after epidurals. Perioperative epidurals represent approximately 1 in 7 of all CNBs but accounted for more than half of all the complications leading to harm. In contrast, wrong route errors were more common in obstetric practice than other clinical areas.

Incidences for the different patient populations are shown in Table 34.1.

Avoidable harm

Several cases reported to the NAP3 study suggest that failure to identify and understand the relevance of inappropriately weak legs after CNB led to avoidable harm. Contributing factors to delays in diagnosis and intervention were: failure to monitor, poor understanding of abnormal findings (by nurses and doctors), poor interdepartmental referral processes, scanning equipment being unavailable out of hours and a lack of availability of beds in tertiary referral centres for patients requiring specialized emergency surgery.

In response to the NAP3 findings some hospitals have developed algorithms for the management of leg weakness with epidural analgesia. An example of these can be found in Appendix 3 of the full NAP3 report^[1].

NAP3 application

Following the NAP3 project an application (app) has been developed for use with smartphones. Its main feature is a calculator into which the user inputs three variables:

The app then displays the calculated incidence of complications both ‘pessimistically’ and ‘optimistically’, enabling the practitioner to have an informed discussion with the patient about the risks and benefits of the proposed procedure.

The full NAP3 report is freely available online^[1].

Introduction

NAP4 was a collaboration between the Royal College of Anaesthetists (RCoA) and the Difficult Airway Society. The audit was designed to answer the following questions:

The project

First an assessment was made of the number of general anaesthetics (GAs) performed and the airway devices used annually in the UK NHS (for denominator information). Then the major complications of GAs performed over 12 months was audited (for numerator information).

Major complications were classified as death, brain damage, the need for an emergency surgical airway, unanticipated ICU admission or prolongation of ICU stay.

Data on complications was collected from all areas of the hospital in which GAs are performed including operating theatres, ICUs and EDs.

The results at a glance

The results showed that a minority of hospitals accounted for disproportionately high percentages of reported cases. Because of this anomaly, further statistical analysis was conducted which suggested that as few as 25% of relevant incidents may have been reported. These rates of complications must therefore be seen as an indication of the lower limit of incidence.