A comparison of two anaesthetic techniques for daycase arthroscopy

Abstract

Patients admitted for daycase surgery pose particular problems for the anaesthetist. In common with all paticnts who await surgery. they suffer from a variety of dcgrees uf fear and anxiety. The administration of appropriate prcrnedicalion would hclp to allay such anxiety and also reduce the doscs of anaesthetic agents required both to induce and maintain anaesthesia. The short-acting anxiolytic agent temazepam has been shown to allay anxiety and to reduce anaesthetic requirement and postoperative morbidity without prolonging recovery time.' ,z Howcvcr. there are logistical difficulties associated with the organisation of oral premedication for patients who may be admitted to a busy day-surgery ward only a short time before the induction of anaesthesia. It has become common practice in our hospital for such patients to be given small doses of midazolam and alfentanil prior lo induction of anaesthesia. in the hope that this pretreatment might reduce the dose o f induction agent necessary and thus provide a shorter and more pleasant recovery. Such an outcome would have potential advantages in that postopcrativc morbidity might be reduced, and a more rapid turnover of paticnts might result. with more efficient use of beds. We therefore conducted a study to examine the quality of anaesthesia and rccovery in paticnts who were scheduled to undergo daycase arthroscopy. and who were either pretreated with a combination of mida~olam and alfentanil or received alfentanil alone. Patients and methodsOnc hundrcd patients between thc ages of 15 and 63 years who were admitted to the day unit for arthroscopic cxamination and in some cases arthroscopic surgery of the knee. took part in the study which was approved hy the local ethical committee. All the patients were fit apart from their orthopaedic condition and all gave informed consent.The paticnts werc allocated randomly to onc of two groups; a midazolam group (Group M ) and a saline group (Group S ) . A 23-gauge cannula was inserted into an antecuhjtal fossa vein when the patient arrived in the anaesthetic room, and 500 pg of alfentanil was administered either with midarolam 5 mg (Group M) or I ml o f sodium chloride 0.9% (Group S ) . The midazolam and saline were prepared in unmarked coded ampoules and the anaesthetist was not aware which solution was bcing given. Exactly 2 minutes after this injection, the patients received a dose of methohexitone 1 % given at a rate of I ml per 3 seconds until the eyelash reflex was obtunded. The dose of meth-~ Pringle, MD. MRCS, LRCP, DCH, FFARCS, Consultant,