General anaesthesia in elderly patients with cardiovascular disorders: choice of anaesthetic agent

Abstract

Our population is aging; currently 15% of the Western population are aged >65 years, and represent 25% of those undergoing surgery. The proportion of the population aged >or=65 years is rapidly growing, and an increasing number are affected with cardiovascular disease. The older person is a high-risk patient. This is because of their altered physiology and associated co-morbidities, as well as the pharmacokinetic and pharmacodynamic changes that may alter drug responses. There is considerable variability seen in the physical and physiological states of individual patients within the older population. This has an important impact on choosing a safe anaesthetic technique for each individual, which in turn can influence the morbidity and mortality in this population. The physiological changes in the aging cardiovascular system affect the arterial and venous vasculature, myocardium and autonomic nervous system, making the older person more prone to cardiovascular instability. In addition to the physiological changes, the cardiovascular status of the older person tends to be compromised by associated pathological conditions that are more common with increasing age. Pharmacokinetic and pharmacodynamic changes must be taken into account when deciding about drug dosing in this age group. Aspects of dose reduction, titration of drugs, dosing intervals and the pharmacodynamic effects of each class of drug are explained in detail in the text. The major challenge in anaesthesia for the older person with cardiovascular disease is maintenance of haemodynamic stability, particularly in the face of reduced physiological reserve and capability to respond to periods of instability. An appropriate anaesthetic technique must be selected to minimize haemodynamic changes and maintain near normal physiological status. The other key objective is to minimize the incidence of adverse outcomes, such as perioperative myocardial ischaemia/infarction, arrhythmias, heart failure, postoperative cognitive dysfunction and stroke. No single anaesthetic regimen or agent can be advocated. Knowledge of the pharmacokinetic and pharmacodynamic principles of anaesthetic agents and their altered response in elderly patients is essential when selecting an anaesthetic agent. This article provides a practical guide to the selection and use of general anaesthetic agents in older patients with cardiovascular disorders, highlighting the differences among various agents.