Anaesthetic techniques for carotid surgery

Abstract

In the GALA trial (Dec 20, p 2132),1GALA Trial Collaborative GroupGeneral anaesthesia versus local anaesthesia for carotid surgery (GALA): a multicentre, randomised controlled trial.Lancet. 2008; 372: 2132-2142Summary Full Text Full Text PDF PubMed Scopus (450) Google Scholar all types of regional anaesthesia were grouped as one: “local anaesthesia”. Yet clinical and anatomical studies confirm important differences between simple subcutaneous infiltration, formal “superficial” cervical plexus block, and a deep block. The last two are clinically equally effective,2Pandit JJ Satya-Krishna R Gration P Superficial or deep cervical plexus block for carotid endarterectomy: a systematic review of complications.Br J Anaesth. 2007; 99: 159-169Crossref PubMed Scopus (145) Google Scholar anatomical investigations showing that the so-called deep cervical fascia might not exist as a distinct or impermeable entity as previously supposed.3Pandit JJ Dorje P Satya-Krishna R Investing layer of the cervical fascia of the neck may not exist.Anesthesiology. 2006; 104: 1344Crossref PubMed Scopus (9) Google Scholar Solutions freely enter the deep space:4Pandit JJ Dutta D Morris JF Spread of injectate with superficial cervical plexus block in humans: an anatomical study.Br J Anaesth. 2003; 91: 733-755Crossref PubMed Scopus (85) Google Scholar local anaesthetic placed relatively superficially in the neck will reach the same anatomical sites as that placed more deeply. However, the deep block results in a consistently higher rate of direct harm owing to the penetrating needle damaging or entering important vessels or even the cerebrospinal fluid.2Pandit JJ Satya-Krishna R Gration P Superficial or deep cervical plexus block for carotid endarterectomy: a systematic review of complications.Br J Anaesth. 2007; 99: 159-169Crossref PubMed Scopus (145) Google Scholar We found this direct complication rate to be 0·25% (vs 0% for superficial cervical plexus block), and, further, a higher conversion rate to general anaesthesia of more than 2% (vs 0·4%).2Pandit JJ Satya-Krishna R Gration P Superficial or deep cervical plexus block for carotid endarterectomy: a systematic review of complications.Br J Anaesth. 2007; 99: 159-169Crossref PubMed Scopus (145) Google Scholar GALA finds an even higher rate of more than 4%.1GALA Trial Collaborative GroupGeneral anaesthesia versus local anaesthesia for carotid surgery (GALA): a multicentre, randomised controlled trial.Lancet. 2008; 372: 2132-2142Summary Full Text Full Text PDF PubMed Scopus (450) Google Scholar If these instances were confined to deep block, it suggests a perhaps prohibitive complication rate for this method. The GALA trial results failed to show differences between anaesthetic techniques in terms of cerebral or cardiac outcomes. However, by careful subgroup analysis, GALA might at least help establish which is the safer (and therefore more suitable) regional technique. With efficacy equal, the safety profile will help determine the anaesthetic choice. I declare that I have no conflict of interest. Anaesthetic techniques for carotid surgery – Authors' replyJaideep Pandit suggests that careful subgroup analysis of GALA might help establish which regional anaesthetic technique is safer, but GALA will not reliably answer this question. The trial was designed as a pragmatic trial of a policy of general anaesthesia versus a policy of local anaesthesia, and we allowed individual centres to provide these techniques and surgery in the way they currently practised. Thus any subsidiary analysis of individual local anaesthetic techniques will be non-randomised (and, moreover, selected by the anaesthetist after the randomised treatment was allocated), and will have to be interpreted very carefully indeed. Full-Text PDF