J. A. W. Wildsmith

Suspected Anaphylactic Reactions Associated with Anaesthesia

Summary (1) The AAGBI has published guidance on management of anaphylaxis during anaesthesia in 1990, 1995 and 2003. This 2008 update was necessary to disseminate new information. (2) Death or permanent disability from anaphylaxis in anaesthesia may be avoidable if the reaction is recognised early and managed optimally. (3) Recognition of anaphylaxis during anaesthesia is usually delayed because key features such as hypotension and bronchospasm more commonly have a different cause. (4) Initial management of anaphylaxis should follow the ABC approach. Adrenaline (epinephrine) is the most effective drug in anaphylaxis and should be given as early as possible. (5) If anaphylaxis is suspected during anaesthesia, it is the anaesthetist’s responsibility to ensure the patient is referred for investigation. (6) Serum mast cell tryptase levels may help the retrospective diagnosis of anaphylaxis: appropriate blood samples should be sent for analysis. (7) Specialist (allergist) knowledge is needed to interpret investigations for anaesthetic anaphylaxis, including sensitivity and specificity of each test used. Specialist (anaesthetist) knowledge is needed to recognise possible non-allergic causes for the ‘reaction’. Optimal investigation of suspected reactions is therefore more likely with the collaboration of both specialties. (8) Details of specialist centres for the investigation of suspected anaphylaxis during anaesthesia may be found on the AAGBI website http://www.aagbi.org. (9) Cases of anaphylaxis occurring during anaesthesia should be reported to the Medicines Control Agency and the AAGBI National Anaesthetic Anaphylaxis Database. Reports are more valuable if the diagnosis is recorded following specialist investigation of the reaction. (10) This guidance recommends that all Departments of Anaesthesia should identify a Consultant Anaesthetist who is Clinical Lead for anaesthetic anaphylaxis.

Predictors of emotional outcomes of intensive care

Negative emotional outcomes (anxiety, depression and post‐traumatic stress) have been identified in patients discharged from intensive care. The aims of this prospective, longitudinal study were to assess levels of and changes in emotional outcome after intensive care, and to explore how these relate to objective and subjective indicators of the intensive care experience. Emotional outcome was assessed using the Hospital Anxiety and Depression and Impact of Event Scales. Anxiety (p = 0.046) and depression (p = 0.001) were reduced subsequently, but not avoidance (p = 0.340) or intrusion (p = 0.419). Most objective (age, gender, length of ICU and hospital stay) and subjective indicators (as measured by the Intensive Care Experience Questionnaire) of the intensive care experience were related to negative emotional outcome. Subjective interpretation of the intensive care experience emerged as a consistent predictor of adverse emotional outcome, in both the short‐ and the long‐term.

Failed spinal anaesthesia: mechanisms, management, and prevention

Although spinal (subarachnoid or intrathecal) anaesthesia is generally regarded as one of the most reliable types of regional block methods, the possibility of failure has long been recognized. Dealing with a spinal anaesthetic which is in some way inadequate can be very difficult; so, the technique must be performed in a way which minimizes the risk of regional block. Thus, practitioners must be aware of all the possible mechanisms of failure so that, where possible, these mechanisms can be avoided. This review has considered the mechanisms in a sequential way: problems with lumbar puncture; errors in the preparation and injection of solutions; inadequate spreading of drugs through cerebrospinal fluid; failure of drug action on nervous tissue; and difficulties more related to patient management than the actual block. Techniques for minimizing the possibility of failure are discussed, all of them requiring, in essence, close attention to detail. Options for managing an inadequate block include repeating the injection, manipulation of the patients posture to encourage wider spread of the injected solution, supplementation with local anaesthetic infiltration by the surgeon, use of systemic sedation or analgesic drugs, and recourse to general anaesthesia. Follow-up procedures must include full documentation of what happened, the provision of an explanation to the patient and, if indicated by events, detailed investigation.

Principles and practice of regional anaesthesia

1. History of Regional Anaesthesia - JAW Wildsmith 2. Features of Regional Anaesthesia - NB Scott and AR Absalom 3. Pain Pathways - L Colvin and JH McClure 4. Local Anaesthetic Action - GR Strichartz and JAW Wildsmith 5. Systemic Kinetics of Local Anaesthetics - GT Tucker 6. Clinical Pharmacology of Local Anaesthetics - JAW Wildsmith 7. Pre-operative Assessment for Regional Anaesthesia - MR Checketts and JAW Wildsmith 8. Management of Regional Anaesthesia - JE Charlton 9. Anatomy and Physiology of the Vertebral Canal - WA Chambers and M Brockway 10. Spinal Anaesthesia - AP Rubin 11. Epidural Anaesthesia and Analgesia - EN Armitage 12. Caudal Block - LVH Doyle and E Martin 13. Regional Anaesthesia of the Trunk - A Lee 14. Upper Limb Blocks - HBJ Fischer 15. Lower Limb Blocks - D Coventry and WA Macrae 16. Head and Neck Blocks - N Smart and S Hickey 17. Ophthalmic Blocks - AP Rubin 18. Obstetric Anaesthesia and Analgesia - JH McClure 19. Paediatric Anaesthesia and Analgesia - A Lloyd-Thomas 20. Acute Pain Management - D Connolly and McLeod 21. Autonomic Blocks in Pain Management - DM Justins 22. Regional Blocks for Day Care Surgery - HBJ Fischer 23. Regional Anaesthesia and Analgesia in the Elderly - B Veering

Cerebral oximetry: a useful monitor during carotid artery surgery

Cerebral oximetry was evaluated as a monitor of oxygenation during carotid endarterectomy in 22patients. The oximeter was a reliable continuous monitor, identifying changes in cerebral oxygenation during episodes of hypotension and after arterial occlusion. Changes in oxygenation correlated well with the surgical assessment of backbleeding after arterial clamping, but less well with other methods which are used to make a decision on insertion of an arterial shunt. There was no correlation between internal carotid artery stump pressure and change in cerebral oxygenation after application of the arterial cross clamp. However, cerebral oxygenation correlated weakly with the change in middle cerebral artery velocity as measured by transcranial Doppler ultrasonography (r = 0.49, p < 0.02).

Costing anaesthetic practice. An economic comparison of regional and general anaesthesia for varicose vein and inguinal hernia surgery.

A computerised database of operating theatre activity was used to estimate the costs of regional and general anaesthesia for varicose vein and inguinal hernia surgery. Data retrieved for each procedure included the anaesthetic technique and drugs used, and the duration of anaesthesia, surgery and recovery. The costs of anaesthetic drugs and disposables, salary costs of the anaesthetic personnel and maintenance costs for anaesthetic equipment were considered. Drugs and disposables accounted for ≈ 25% of the total cost of an anaesthetic. Anaesthetic times were 5 min longer for regional anaesthesia, but recovery times were 10 min shorter following regional anaesthesia for varicose vein surgery. Staff costs were dependent on the length of time each staff member spent with the patient. Although the number of cases was small, provision of a field block and sedation for inguinal hernia repair was considerably cheaper than other anaesthetic techniques.

A national census of central neuraxial block in the UK: results of the snapshot phase of the Third National Audit Project of the Royal College of Anaesthetists.

The first stage of the Royal College of Anaesthetists Third National Audit Project to assess the incidence of major complications of central neuraxial block in the UK was a 2‐week national census of block use. A reporting system was established in the 309 National Health Service hospitals believed to undertake surgical work and data were received from 304, a response rate of 98.7%. Over 90% of these were judged by the reporters to be ‘accurate’. The total number of procedures reported as being performed in the 2‐week period was 27 533: extrapolation using a multiplier of 25 suggests that nearly 700 000 major blocks are performed annually (315 000 spinals, 287 000 cervical, thoracic or lumbar epidurals, 42 000 combined spinal‐epidurals and 56 000 caudal epidurals). After the second stage of the project, which will record complications from the same hospitals over a 12‐month period, these data will be used as denominators to calculate the incidences of complications.

Alleged allergy to local anaesthetic drugs

Objective: To identify the true nature of an acute reaction in 25 patients initially diagnosed as allergic to local anaesthetic drugs.Setting: University General and Dental Hospitals.Interventions: Detailed review of each patients previous exposure to local anaesthetic drugs and of the history of the acute event was followed up with challenge testing by intradermal injection.Results: One patient was subsequently found to be genuinely allergic to a local anaesthetic drug of the amide type. A wide range of conditions had actually precipitated the other adverse reactions, but all could be classified under three major headings: an immunological condition to a different antigen; a manifestation of anxiety; or an iatrogenic problem.Conclusion: Local anaesthetic allergy is rare, but does occur. All reactions to local anaesthetic drugs must be assessed carefully and specialist referral may be appropriate

Thigh rotation and the anterior approach to the sciatic nerve: a magnetic resonance imaging study.

Background and Objectives: The anterior approach to the sciatic nerve block may be associated with a high failure rate because the nerve lies posterior to the lesser trochanter of the femur at the level of needle insertion. However, previous work using cadavers demonstrated that internal rotation of the leg renders the nerve more accessible to the anterior approach. Methods: Ten volunteers consented to undergo magnetic resonance imaging. Markers were placed on the surface where a needle would have been inserted for an anterior approach to the sciatic nerve. Three scans were then performed: the first with both legs in the neutral position, the second with maximal bilateral internal rotation at the hip, and the third with maximal bilateral external rotation at the hip. Results: Examination of the scans by a consultant radiologist showed that, as the thigh is rotated, the number of scans showing an unobstructed needle passage from the skin marker to the sciatic nerve rate increased from 5% in external rotation to 85% in internal rotation. The number of times the needle path passed through femoral neurovascular bundle also fell from 55% in external rotation to 15% in internal rotation. Conclusions: The results confirm that, as the thigh is moved from an externally to an internally rotated position, the sciatic nerve becomes more accessible by the anterior approach at the level of the lesser trochanter, and the risk of femoral artery or nerve puncture is reduced but not eliminated.

Comparison of extradural and intravenous diamorphine as a supplement to extradural bupivacaine

The influence of route of administration (extradural as compared with intravenous) of diamorphine 0.5 mg/hour as a supplement to extradural bupivacaine (0.125% at 15 ml/hour) was investigated in two groups of 20 patients who underwent major abdominal gynaecological surgery. Significantly more patients in the intravenous group withdrew because of inadequate analgesia (p < 0.05). Those in the extradural group were significantly more drowsy throughout the study (p < 0.01), but no major side effects were encountered.