characterized by gradual loss of skeletal muscle and increase in body fat composition • Decline in basal metabolism • Reduction in total body water • Small decrease in plasma albumin levels • Small increase in alpha1-acid glycoproteins • Minimal effect on drug protein binding
for most of the 20-40% decrease in liver blood flow • Modest reduction in phase I drug metabolism and bile secretion • Renal cortical mass decreases by 20-25% with age • Loss of up to half of the glomeruli by age 80 • Decrease in GFR of approx 1mL/min/yr after age 40 leads to reduced excretion of drugs • Does not retain or eliminate free water as rapidly as young kidneys
interact with anesthetic management to a significant degree • Aging associated with decreased insulin secretion in response to glucose load and increased insulin resistance • Central Nervous System Aging • Brain mass begins to decrease slowly beginning approx. at age 50 and declines more rapidly later • An 80 year old brain has typically lost 10% of its weight • Neurotransmitter (Dopamine, serotonin, GABA, Ach) functions suffer • Leads to increase sensitivity to anesthetic drugs • 6% decrease in MAC per decade • Age is a major risk factor for postoperative delirium and/or cognitive decline
effects in older patients • Pharmacodynamic- target organ is more sensitive • Pharmacokinetic- given dose of drug produces higher blood levels • The most prominent pharmacokinetic effect of aging is a decrease in drug metabolism, due to both decrease in clearance and increase in Vd • Increase in Vd secondary to increase in fat content • The most commonly used muscle relaxants have modestly slowed metabolism with aging, so an increased duration of effect should be expected, especially with repetitive dosing • Increased risk of residual blockade
by aging • Major changes • Decreased response to beta-receptor stimulation • Stiffening of myocardium, arteries and veins • Leads to systemic HTN • Changes in the autonomic nervous system with increased sympathetic activity at rest and decreased parasympathetic activity • Although there is decreased to alpha-receptors with age, the swings in sympathetic activation during surgery can still produce significant changes in vascular resistance during anesthesia→ lability in BP, decrease in BP when anesthesia removes sympathetic tone • Decreased efficacy of the baroreceptor reflex • Conduction system changes • Defective ischemic preconditioning
decreased stiffness of the lung parenchyma (due to loss of elastin with age) • Increased work of breathing • Decreased lung tissue stiffness increases V/Q mismatch • Thorax becomes more barrel-shaped and leads to flattening of the diaphragm • Increased closing capacity • The need for greater lung inflation to prevent small airway collapse • Closing capacity exceeds FRC by mid 60s • These changes in addition to modest reduction in alveolar surface area with age contribute to modest decline in resting PaO2 with age
the ventilatory response to hypercapnea and an even greater decrease in the response to hypoxia • Generalized loss of muscle tone with age applies to hypopharyngeal and genioglossal muscles and predisposes the elderly to upper air obstruction • Less effective coughing and impaired swallowing
(initial) and shivering • Impaired in the elderly • Decreased heat production due to decrease in metabolism • Inhalational and some intravenous agents alter regulatory thresholds in all populations, but aging further impairs thresholds • Risks of hypothermia include myocardial ischemia, surgical wound infection, coagulopathy, impaired drug metabolism
benefits should include probable degree of functional recovery and speed of recovery • If health care directives prohibit life sustaining or resuscitative procedures, the patient/proxy and anesthesiologist must come to a understanding of what will or will not be performed in case of emergencies • Review of medications and possible drug interactions • Opportunities for optimization
needed compared to younger patients • May attempt to reduce the amount of propofol with use of adjuncts, such as opioids, or combination of small dose of propofol with etomidate • However, must be careful not to underdose as there can be a excessive hypertensive response to intubation • Decrease in both systemic vascular resistance and cardiac output • Largest contributor is decrease in SVR • Must be cautious with fluid administration as fluid shifts (esp. in the postoperative period) can push an elderly heart into diastolic heart failure. • If using positive pressure ventilation, goal should be to have the lung volume exceed closing capacity to prevent atelectasis • Preferred approach is modest TV plus PEEP • Older patients are at double to the risk of residual neuromuscular blockade and adverse respiratory events
• Sometimes difficult in the elderly because they underreport their pain, may be cognitively impaired • Failure to achieve associated with sleep deprivation, respiratory impairment, ileus, suboptimal mobilization, insulin resistance, tachycardia, hypertension • Consider epidural analgesia when possible • Avoid meperidine (risk factor for delirum), expect in small doses for shivering • Euvolemic fluid balance • Look for signs of fluid overload (rales, dyspnea, tachypnea, orthopnea) particularly around POD#2 • Timely diuretic administration may prevent further complications
because of comorbidities • Anesthetic management may influence long term outcomes • Studies show an association between intraoperative hypotension and 1-month adverse outcomes (cardiac events, kidney dysfunction, CVA) • Complications of the cardiovascular and pulmonary systems are associated with the greatest perioperative mortality • Pulmonary complications (PNA, prolonged intubation or reintubation etc) have higher incidence than MI or cardiac arrest (higher mortality rates) • CNS complications include stroke, postoperative delirium and postoperative cognitive decline (role of GA in cognitive decline is controversial) • Annual stroke incident in non-surgical eldery=0.1%; increased to 0.5% in surgical elderly population
surgery in older patients is approximately 10% • Highest risk is emergent hip surgery (incidence approx. 35%) • Risk factors: age, baseline low cognitive function, depression, overall frailty, • Consider using a BIS to reduce anesthetic exposure and risk of postoperative delirium • Unfortunately, use of regional/neuraxial vs. General does not seem to decrease the incidence of delirium • Treatment includes identifying reversible causes (opioids, benzos); Haloperidol in doses no greater than 1.5mg • Studies ongoing on benefits of subanesthetic doses of intraoperative ketamine to decrease incident of post-op delirium
Avoid hypotension and hypoxia • Pain control with multimodal therapy to reduce opioid consumption • However, poor pain control may be just as bad as too much opioid • Unclear relationship between anesthesia and cognitive decline
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