SHOULD GENERAL ANAESTHESIA REMAIN THE MAINSTAY OF MODERN ANAESTHESIA?
Ellis Gillespie Lecture
A W Harrop-Griffiths
St Mary's Hospital, London, United Kingdom
The number of surgical procedures performed under general anaesthesia (GA) massively exceeds the number performed under regional anaesthesia (RA) on a global basis, even when GA’s universal applicability and RA’s more limited anatomical and surgical scope are taken into account. This could be for one or more of a number of reasons, including: historical precedence, cultural differences, technical difficulty, established education programmes and, perhaps most notably, a failure by RA enthusiasts to prove the success, safety and efficacy of RA beyond reasonable doubt. Even leading proponents of RA confess to bouts of scepticism in spite of a growing, although admittedly not yet overwhelming, body of evidence supporting the safety and beneficial effects of RA [1]. The publication in 2000 in a leading journal of a meta-analysis purporting to show that the use of neuraxial blocks is associated with a 30% decrease in mortality was greeted with joy by the RA community but by justifiable scepticism by others [2]. Even when the potentially most easily-proven beneficial effect of RA is analysed (that on mortality after neuraxial versus general anaesthesia for patients undergoing surgery for fractured neck of femur), internationally revered bodies such as the Cochrane Collaboration cannot quite bring themselves to confirm the superiority of RA [3]. However, against this evidence-based meta-analytical disbelief must be balanced the simple fact that the number of studies showing positive benefits of RA clearly outweigh the number claiming to demonstrate its adverse effects. Although this consideration is beyond the event horizon of the Oxford Centre for Evidence-Based Medicine’s description of Levels of Evidence, it is arguably significant.
If RA cannot yet prove its worth in terms of crude mortality, can it reasonably claim victory in other areas? A recent review sets some of the complications of anaesthesia of both forms into context and allows a comparison of GA and RA [4]. Regional anaesthesia is associated with significantly lower incidences of the following when compared with GA: awareness, anaphylaxis, eye injury, oral and dental injury, postoperative nausea and vomiting, early postoperative pain, need for admission after day-care surgery, postoperative cognitive dysfunction, etc, etc. Regional anaesthesia is even arguably cheaper, as the patients’ passage through Post-Anaesthesia Care Units can be brief or even non-existent. However, against these benefits must be set the accepted complications of RA. Even members of the lay public are aware of the possibility of nerve damage [5], and this anxiety is shared by RA enthusiasts and opponents alike. The available literature suggest that the incidence of long-term nerve damage after peripheral nerve block is in the order of 1 : 5,000 [6,7]. General anaesthesia is not free from this complication, with rates as high as 1 : 300 having been quoted [4]. However, even this high rate cannot match the accepted incidences of nerve damage associated with some forms of surgery, e.g. 1.3% in knee arthroplasty and up to 5% in major shoulder surgery [8].
Recent evidence suggests that even expert hands conducting procedures with “best practice” approaches can cause peripheral nerve damage as a perhaps unavoidable consequence of the use of RA. When using a nerve stimulator for nerve location, the once-hallowed “hallmarks” of intrafascicular injection (low current threshold, lack of twitch abolition, pain on injection and difficulty in injecting) are now being increasingly questioned. A recent case report details the proven injection of local anaesthetic into a sciatic nerve with a current threshold of 0.56 mA, twitch abolition and easy injection (and catheterisation) [9]. However, the move from the use of nerve stimulators to ultrasound for nerve location may decrease, but not abolish, the incidence of some of the complications of RA [10]. Nerve damage aside, RA is associated with other complications that are absent or lower in GA practice. These include inadvertent intravascular injection of local anaesthetic drugs, vessel damage, pneumothorax, itching, headache and urinary retention. Spinal anaesthesia is associated with a surprisingly high incidence (1 : 1,500) of cardiac arrest, sometimes even occurring in young, fit patients. In terms of overall risk profile, RA compares very favourably with GA overall for healthy patients, and may offer considerable advantage in terms of risk/benefit analysis for patients with significant comorbidities.
In spite of the move towards a more accurate (and perhaps more favourable) assessment in the literature of the benefits and risks of RA when compared with GA, there are still many anaesthetists who declare that they do not practise RA because of its dangers. However, in taking this stance, they risk denying the choice between GA and RA to the one person who should rightly make this decision: the patient. Increasingly, countries’ legal systems are moving away from the concept of the “reasonable doctor” typified by the UK’s historic “Bolam Principle” and are travelling towards the concept of the “reasonable patient”, implying that a doctor should do that which a reasonable patient would wish him/her to do, not that which a respectable body of medical opinion would judge to be correct. Inherent to this principle is the notion of informed consent. Providing accurate and balanced information to a patient is an integral part of the consent process, and medical regulatory bodies demand that patients are told of all treatment options and, for each option, are given explanations of the likely benefits and the probabilities of success, along with discussion of any serious or frequently occurring risks. Patients are seldom told by non-RA practising anaesthetists of the option of RA, and yet it remains an option that arguably should be offered to the patient. Although I am not aware of a legal action for a complication of GA that would not have occurred if the patient was offered and underwent RA, it may well not be long before such an action occurs. “I cannot do blocks” should not be an excuse for not offering RA to a patient – physicians treating patients with cancer may offer them the choice of surgery or radiotherapy while not being competent in the technical performance of either.
There is an inevitability about the continuance of GA’s position as the “mainstay” of anaesthesia in the short to medium term. It is simple to perform, acceptably safe and applicable to all surgical procedures. However, if the large-scale studies that could prove RA’s superiority in many fields of anaesthesia and surgery are performed and if their results both confirm RA enthusiasts’ prejudices and convince the sceptics, RA may increase in popularity from minority interest to realistic option for many (perhaps most?) operations. It could even become the “mainstay of modern anaesthesia” in my lifetime.
Time of Presentation
Saturday 13 May 2006 - 0830-1000
References
1. Regional Anesthesia & Pain Medicine 2002; 27: 503-8
2. British Medical Journal 2000; 321: 1-12
3. http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD000521/pdf_fs.html
4. Anaesthesia 2003; 58: 962-84
5. Regional Anesthesia & Pain Medicine 2004; 29: 96-101
6. Anesthesiology 1997; 87: 479-86
7. Anesthesiology 2002; 97:1274–80
8. Journal of Arthroplasty 2001; 16: 1048-54
9. Anesthesiology 2004; 101: 1027-30
10. British Journal of Anaesthesia 2005; 94: 7-17
