Perioperative Considerations in Care of the Elderly

2. Perioperative Considerations in Care of the Elderly Fred Weitz MD Emory University Dept. of Anesthesiology

3. Realities for the Practicing Anesthesiologist • More than 35 million people in U.S. are > 65 • They account for almost half of hospital care days • 25-35% surgical cases Most anesthesiologists are geriatric anesthesiologists!

4. All Geriatric Patients are not Created Equal!

6. People age at different rates:Organ Function

7. Organ Functional Reserve:Safety Margin of Organ Capacity

8. Considerations: • Cardiovascular function • Respiratory function • Airway Management • Pharmacokinetics • Body temperature regulation • Postoperative Mental function

9. CV Changes with Aging • Connective tissue changes • Loss of elasticity • Loss of SA node cells, slowed conduction • Myocyte death without replacement • Decreased response to beta-receptor stimulation

10. Aging Does Not Diminish: • Intrinsic quality of muscle • Heart does not weaken with age alone • Peripheral vasoconstriction • Enhanced sympathetic nervous system activity at rest • More prone to hypotension with loss of sympathetic tone

11. Arterial Stiffening • Reflected pressure from “stiffened arteries” increases pressure in aortic root during late systole • Leads to ventricular hypertrophy, impaired diastolic filling

12. Decreased Venous Compliance • Veins, like arteries, stiffen with age • Stiff veins are less able to “buffer” changes in blood volume • Volume shifts cause exaggerated changes in cardiac filling pressure

13. Myocyte Death • Cardiac muscle cells die over time • Remaining cells do not divide in adequate numbers in adulthood • Remaining cells hypertrophy to compensate • Another cause of ventricular hypertrophy

14. Ventricular Contraction • Slows with Aging • Ventricle may not be fully relaxed during beginning of diastolic filling phase • Result: Early diastolic filling is impaired

16. Elderly End-Diastolic Pressure Young End-DiastolicVolume Dependence on High Filling Pressure Frank-Starling Curve

17. Consequences of Delayed Relaxation • Late diastolic filling depends on high left atrial pressure and atrial kick • Tachycardia and atrial fibrillation not well tolerated • Narrow range between inadequate filling pressure and fluid overload • Diastolic dysfunction may be the most common cause of heart failure in > 75 y/o

18. Can the Elderly Heart Increase Output?

19. Aging and Contractility:Response to Exercise 7 0 Young 6 5 Ejection Fraction (%) Elderly 6 0 5 5 At Rest Maximal Exercise Stratton et al., Circ 1994;89:1648

20. Decreased Beta-Receptor Responsiveness • Diminished increase in heart rate with stress • Reduced maximum heart rate • Increase their stroke volume • From increase in end diastolic volume

21. Response to Anesthesia • Anesthetics can: • Remove sympathetic tone • Dramatic when baseline tone is very high • Directly depress heart, vascular smooth muscle • Diminish baroreceptor reflexes

22. Add to That … • Changes in sympathetic tone from • waxing and waning surgical stimulus • variable depth of anesthesia • Changes in patient’s volume status • Results in LABILE BLOOD PRESSURE !

23. Summary: Volume Dependence of the Elderly Heart • Elderly heart depends on late filling that in turn depends on left atrial pressure • Elderly heart is also stiff, so the left atrial pressure must be high in order to fill the LV • prone to diastolic dysfunction • poor venous buffering of blood volume makes maintenance of left atrial pressure difficult

24. Summary: Decreased Response to Beta-Receptor Stimulation • Lessened ability to increase in heart rate • Lessened ability to increase ejection fraction

26. Aging and Respiratory Function

27. Lung Volumes:Decreased VC and Increased RV

28. Pulmonary Changes • Decreased thoracic elasticity • Decreased strength and endurance of respiratory muscles

29. Decreased Efficiency of Gas Exchange • Breakdown of elastin connections between connective tissue and alveolar tissue • Results in poor tethering of lung tissue to airways and other lung tissue • Airways are NOT held open • Increases: • Shunting • Dead space

30. Increased Shunt

31. Explains Effect of Age on paO2

32. Pre-oxygenation • Takes longer in elderly than in healthy young patients!

33. Airway Management:Diminished Afferentation • Stimulus threshold for vocal cord closure is increased • Increased risk of aspiration!

34. Airway Management:Changes with Aging Arthritic Changes: • Decreased cervical spine and neck mobility • Smaller mouth opening • Smaller glottic opening • Smaller endotracheal tube Fragile teeth

35. Remember… • Airway management may be more difficult • Prone to airway collapse (risk of pneumonia) • Higher work of breathing (risk of hypercarbia) • Lower blood oxygen levels(greater need for supplemental oxygen) • After leaving PACU, hypoxia more likely • from residual drug/CNS effects

36. Geriatric population is at significantly increased risk of respiratory failure in the postoperative setting!

38. Pharmacology in the Elderly Patient

39. Increased Bolus Drug Effect • Decreased protein binding • Higher free, unbound plasma drug levels • Decreased volume of distribution • Slower redistribution of drug • ALL of these INCREASE target organ levels! • Examples: Thiopental, Propofol

40. Increased Brain Sensitivity • Elderly brain is more sensitive to a given CNS level of a drug • Mechanism ??

41. Slowed Drug Metabolism: • Clearance decreases as • Liver blood flow decreases • Liver mass decreases • Kidney function decreases • Volume of distribution increases with • Increased body fat • Decreased albumin levels

42. Bolus Drug Strategy for the Elderly: • GO LOW ! • GO SLOW ! • You can always give more!

43. Temperature Regulation • Elderly prone to both hypo-, hyperthermia • Lower body metabolism • Decreased ability to change skin blood flow (less able to hold or get rid of heat) • Hypothermia • Shivering increases metabolic demand • Increased risk of myocardial ischemia

45. The Elderly Brain

46. CNS Structural Changes • Brain mass decreases with corresponding decreased cerebral blood flow • Decreased receptors • Acetylcholine • Cholinergic neurons in the basal forebrain regulate normal memory • Dopamine • Norepinephrine

47. Postoperative Cognitive Disorders • Delirium • Mild neurocognitive disorder - POCD • Dementia (rare) • Multiple cognitive deficits • Impairment in activities of daily living

48. Postoperative Delirium • Most common form of perioperative CNS dysfunction • Acute confusion, decreased alertness, misperception • Patient may show agitation or withdrawal • Twice as common in the elderly • 10-15% of elderly surgical patients • 30-50% if undergoing cardiac or orthopedic surgery • Seen after general, regional and MAC anesthetics • Results in prolonged hospital stay and protracted postoperative care

49. Postoperative Delirium:Predisposing Factors • Drug withdrawal • Use of benzodiazepines, tricyclic antidepressants • Alcohol abuse • Drug interactions • Anticholinergics, etc. • Pre-existing depression or dementia • Metabolic disturbances

50. Can Postoperative Delirium be Prevented? • Marcantonio (2001) - Reduced postoperative delirium by 1/3 in hip fracture patients • Minimized benzodiazepines, anticholinergics, antihistamines, meperidine • Maintained BP greater than 2/3 of baseline • Maintained O2 saturation > 90% • Maintained Hct > 30% • Mobilized patients ASAP • Provided appropriate environmental stimulation