Monitored anaesthesia care in the elderly: guidelines and recommendations

As the number of elderly patients undergoing surgery continues to rise, it is important to consider anaesthetic options that minimize physiological stress in these patients. Monitored anaesthesia care (MAC), or sedation and monitoring during surgery, is an attractive option for certain common procedures. However, those administering MAC must consider the normal decline in functional reserve in patients aged >70 years. This includes loss of normal compensation for the stress of hypovolaemia, decreased peripheral vascular resistance, altered mental status and reduced response to hypoxia and hypercarbia associated with the perioperative and sedated state in this population. In addition, vigilance is necessary to identify co-morbid states, which increase in incidence with age and often present atypically. Elderly patients have increased sensitivity to all sedatives and opioids (doubled by age 80 years, quadrupled by age 90 years with benzodiazepines). As a result of changes in body composition, as well as senescence of renal and hepatic function, the time to onset and offset of even short-acting sedatives will be prolonged. There is also extreme variability in the response to sedatives among these patients. Anaesthetic dosing should be in smaller increments in the elderly, boluses reduced by half and infusions reduced by as much as two-thirds. Caution must be exercised through full monitoring of intra-operative and postoperative mental status, oxygenation and perfusion states. Pain is best treated using smaller doses in a multimodal regimen, the aim being to reduce adverse effects while ensuring adequate pain relief. In this way, a huge range of procedures can be safely performed in our aging population with expectations for a full and early return to baseline functional status.