Outcome after anaesthesia and surgery in the geriatric patient

Abstract

Summary Outcome after anaesthesia and surgery in the elderly patient is subject to great variation. Elderly patients often bring multiple preoperative morbidity with them to the surgical suite. Age cannot be used as a predictor of outcome. The type and number of preoperative disease states seems to be the most highly predictive factor for outcome. The most important of these diseases include previous myocardial infarction, ischaemic heart disease, cardiac failure, pulmonary disease, impaired renal failure, diabetes mellitus and dementia. The more concomitant diseases, the higher the risk. Elective surgery has a lower risk than emergency surgery. The elderly are also more likely to present with advanced surgical disease. Care must be taken to balance the need for stabilization of preoperative conditions and the possibility that the time taken to do this could allow the patient's surgical problem to become critical, and hence cause an emergency situation. Intraoperative causes of poor outcome include: (a) hypotension, which has been shown to cause increased morbidity in almost every organ system; (b) hypertension in hypertensives, which has been shown to have adverse effects on the cardiovascular and renal systems; (c) duration of anaesthesia, since over 300 min of inhalational anaesthesia has been shown to correlate with increased pulmonary morbidity; and (d) volume depletion, which has been shown to have negative effects on kidney function. Cardiovascular complications arise from factors including previous myocardial infarction, preoperative hypertension, cardiac failure, high score on the Goldman Cardiac Risk Scale, class III or greater ASA grade, emergency surgery, vascular and orthopaedic surgery, and intrathoracic or intraperitoneal surgical site. Respiratory complications may be predicted by the site of surgery, preoperative protein depletion and pulmonary function testing. Other predictive methods based on functional capacity (the ability to meet preset exercise parameters) may also be important predictors. Central nervous system morbidity is an important complication in the elderly patient. The occurrence of postoperative delirium can have significant sequelae, including prolonged hospital stay and increased morbidity. Preoperative dementia, anticholinergic medication and intraoperative hypotension are the factors most strongly associated with the development of postoperative delirium. The development of mental status changes post-operatively may also be indicative of other illnesses and must be investigated. Preoperative evaluation, consisting of a thorough history and physical examination, proper ancillary testing, evaluation of physiological reserve, and review and management of medications is of critical importance in the elderly patient. Prevention of intraoperative and postoperative morbidity can be significantly enhanced with a proper preoperative work-up. Choice of anaesthetic technique must be made on an individual basis. Spinal and epidural methods have been shown to cause intraoperative hypotension, but have been shown to lead to fewer pulmonary complications. Inhalational agents, while causing more pulmonary morbidity, have not been shown to increase mortality in this age group. No matter which technique is used, prevention of hypotension should be of primary importance. Anaesthesia and surgery in the elderly patient has changed drastically in the last 100 years. As the number of surgical procedures on elderly patients increases, so does the understanding of the complex processes of ageing. The anaesthesiologist must not base his or her evaluation solely on age, but on the number of and interaction between the diseases and the age-related changes in each individual.