Como Evaluar Situciones De Emergencia

08RC1 ‘My block doesn’t work’ - analysis of possible reasons, avoidance and emergency strategies
Barry Nicholls
Consultant in Anaesthesia and Pain Management, Taunton & Somerset NHS Foundation Trust, Musgrove Park Hospital, Taunton, Somerset, UK

Saturday, 11 June 2011

13:00 - 13:45

Room: G102-103

‘It is not a failure to fail, it is a failure to not have a plan in case you fail.’Operator
No clinician or technique can sustain a 100% success rate due to the many variables that exist between the patient, clinician and the environment. Success in regional anaesthesia is itself a variable, do you measure operative anaesthesia, operative analgesia or just postoperative analgesia? In clinical terms most anaesthetists would accept success of a regional technique as ‘that whichavoids the need for general anaesthesia’. Whatever your end-point is, regional anaesthesia has an inherent failure rate; what’s important is whether your failure rate is acceptable and what strategies you should employ to minimise failure and how to deal with it. Regional anaesthesia is a practical skill that has to be learnt and as such has a definite learning curve; the main determining factors ofthis learning curve are the clinician himself, the teaching available and the number of cases that they are exposed to. A common failure is the exposure to multiple techniques, which confuses the trainee who then fails to become competent in any one technique. To learn a procedure, adequate exposure to sufficient numbers is important and the learning curve for techniques can to an extent beexpressed as minimum numbers need reach a certain level or consistency. Early work done by Kopacz et al showed that a 90% success rate for spinal or epidural was not reached till 45 and 60 procedures were performed, respectively, although significant improvement compared with baseline was shown at 20 and 25, respectively [1]. This can also be shown with other techniques, and the numbers needed varyconsiderably with each technique. Scheupfer et al showed that in children, a 91% success rate for penile blocks can be achieved after ten procedures, and this will increase to 96% after 20, but will not significantly change further with increasing numbers [2]. However, for lumbar plexus blocks (children) the institutional learning curve to achieve only a 70% success was 55 procedures [3]. These learningcurves will vary between individuals and institutions and a better way of tracking individual learning curves is the use of cumulative summation analysis (CUSUM) [4)]. Even with all these methods, we need to know what is an acceptable failure rate and is this different for trainees or specialists. Grau et al surveyed German-speaking anaesthetists and found success rates for residents performingsupraclavicular blocks (SPB) of 69.7% and for spinal anaesthesia (SAB) of 85.5%, compared with rates in specialists of 79.2% and 91.0%, respectively [5]. Failure is inevitable even in the best-trained hands and may be as high as 20% for certain techniques. Although the promise of improved success rates with the use of ultrasound has not materialised [6], the benefits of ultrasound may well beimproved patient comfort, a better side-effect profile and a shorter and steeper learning curve, with reduced numbers performed to achieve acceptable failure rates [7, 8]. Regional anaesthesia is just applied anatomy and as such a comprehensive knowledge of the anatomy is essential. Anatomical variation is common and the path and area of innervation of peripheral nerves may be variable. It is importantto know the innervation of the structures being operated on and the proposed surgical approach and incision.

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Patient
Patient factors may well affect success, and choice of patient and the choice of technique are important, as anxious patients do not make ideal candidates for regional anaesthesia. Co-morbidities such as obesity, arthritides and diabetes will affect positioning,...