Factors That Influence Postoperative Vomiting*

WE AVE ~r.T. famlhar with the observation that when two pahents undergo the same operalaon, one may vomit repeatedly, while the other may not even be nauseated Much interest has centred around the reasons underlying these differences, since many anaesthetists and surgeons are reluctant to gwe powerful ant:-emehe drugs unnecessarily to pataents who may not have vom:ted without them : If we could forecast accurately wh:ch of our pahents would vomit postoperahvely, and how severe the symptoms would be, then the unlus~fied risk Of routine anh-emetlc drugs could be avoided z However desirable :t m:ght be to the statist:clan or med:cal theorist, it is unhkely that such accuracy m predlctaon will ever be achieved, fortunately for all of us, people are dtfferent What we can do, following the lead of life insurance compames, is to pick out certain groups of patients m whom the mclc~ence of :nausea and vomiting postoperahvely :s hkely to be higher than that of the general population, and by careful assessment, to dec:de which of the pahents m t~hese h:gh-nsk groups are most hkely to be troubled by symptoms These patients may then lustlfiably be gaven a prophylact:c mlectmn of an antx-emehc drug The anatomy ~ and physiology 4 ofvomiting and the pharmacology of many of the ant:-emet:c drugs have been ably rewewed by others 4 5 ,~ The purpose of this paper is to rev:ew, the factors reported to influence the mc:dence and seventy of postoperat:ve nausea and vommng, and to present observahons, made durmg the course of a comparahve survey of four anh.emet:c drugs, concernmg the influence of these factors The effects of these drugs, methods of observation, and cnterm used have been reported elsewhere ~ It shoald be stressed that the method selected a standard premedlcatlon (meper!dme 50-100 mg and atropine 0 2-~ 6 mg ) and ten representahve surgical operatmr~s, dlugs and anaesthetics were allocated to pahents to achieve an even d~strlbutmn of valuables between groups Th:s method resulted m the selectmn of a h~gher than average ratao of female to male pahents m order to prowde a greater challenge to the anh-emetic drugs The observatmns reported here deal with 17] 3 pat:ents m this survey who received the standard premedlcataon, and only one m]echon of an ant:-emetic drug durmg the postoperahve period For convemence of presentahon, the factors reported to influence the mc:denc e of postoperahve vommng are consldered under the following headings (1) those varying with the patient, (2) those m couneclaon with the anaesthetic, (3) those concerned with the operatmn, and (4) those related to the postoperatave permd