GERIATRIC ANAESTHESIA

1. GERIATRIC ANAESTHESIA Dr. GERTRUDE SIYAKA Consultant Anaesthesiologist Steve Biko Academic Hospital

2. Lecture outline • Introduction • Normal physiological changes associated with ageing • Pharmacokinetics and pharmacodynamics in the elderly • Pre-operative assessment • Day case surgery • Anaesthesia for orthopaedic surgery • Post operative complications • References

3. Introduction • Life expectancy in US and Europe now 74-80yrs • Medical progress most effective in change • Demographical data indicate the elderly most rapidly growing of population • Use of health care services by elderly disproportionately higher than younger patients • Elderly patients now routinely undergo operative procedures

4. Introduction • Ageing a complex multifactorial process • Universal and progressive physiological process marked by declining end organ function, imbalance haemostatic mechanisms, increasing pathologic processes • Theories on numerous and diverse: evolutionary, molecular, cellular and systemic • Include mutation accumulation, programmed cell death, cumulative environmental damage, free radical damage • End result is impaired function and progressive decline

5. Physiological changes of ageing • Age –related changes occur in all organs • 1. Cardiovascular system • Main contributor for adverse outcome in peri-operative period • Heart • LV hypertrophy frequently evolves and related to elevated SVR • Cardiac mass increases- concentric hypertrophy • Interstitial fibrosis in myocardium leads to poor contractility

6. Stiffness myocardium affects diastolic relaxation as well as systolic contraction • Prolonged systolic myocardial contraction then ensues • LV relaxation time delayed at time mitral valve opening • Early diastolic filling declines • Age related increase in LA volume and contribution to diastolic filling shows importance of “atrial kick”. • Ventricular eccentric hypertrophy and loss wall tension may lead to valve closure deficiency and regurgitant valves

7. Aortic valve sclerosis common CO decreases linearly after 3rd decade at 1% per year even in healthy individuals 80 yr old will have approx 50% CO compared to when was age 20 CI decreases at 80% per year

8. Vasculature Arteriosclerosis is the hallmark feature Contributing factors are: hypertension ,hypercholesterolemia, oxidative stress and genetic disposition Arteriosclerosis an irreversible process CEA and AAA repair most frequently performed procedures in elderly

9. Adrenergic sensitivity • Plasma CATS levels after stimuli not been shown to diminish • Blunted B-receptor responsiveness possibly due to down regulation and decreased agonist binding to receptor • Increase in vigil tone • There is 20% loss of HR response during exercise in 75 yr old compared to 25 yr old

10. 2. Respiratory system • Typical barrel chest appearance results in increased work of breathing and reduced compliance • Loss of elastic recoil within the lung and changes in surfactant production leads to limited maximal expiratory flow • Lung volumes: increase in RV, closing capacity, FRC , TLC (minimal). Decrease in VC • Flow :progressive decrease in FEV1 /FVC • Oxygenation: decrease efficiency in alveolar gas exchange resulting in PaO2and increase alveolar –arterial gradient • Impaired response to hypoxia, hypercarbia and mechanical stress

11. 3.Renal Renal mass decreases by 30% by age 80 Renal blood flow and creatinine clearance decrease Poor electrolyte handling and capacity to concentrate or dilute urine Excretion of some anaesthetic agents is impaired

12. 4. Nervous system • Brain weight declines by 10% • Cerebral atrophy common • Cerebral blood supply reduced and vertebrobasilar insufficiency common • Gradual decline in cognitive function, memory and reasoning performance • Confusion common • Altered sleep pattern • Thermoregulation: poor response to hypothermia

13. Pharmacokinetics and pharmacodynamics in the elderly • Pharm’kinetics influenced by in plasma protein binding, lean body mass, changes in circulating blood volume and metabolism and excretion of drugs • Lean body mass reduced • Protein binding sites reduced • Decrease in circulating blood volume-higher than expected initial plasma concentration of drugs • Polypharmacy • Elderly more sensitive to anaesthetic agents

14. Pre-operative evaluation • Get medical history, current functional status and medication • ASA status • Lab investigation as appropriate for anticipated surgery and medical issues: CXR,12 lead ECG, FBC , U/E and CT scan as appropriate • Worry about polypharmacy • Enquire about social circumstances • Continue B blockers, but discontinue ACEIs, Digoxin • Premedicate if appropriate

15. Intra-operative management NO MAGIC BULLETS Effects of initial dose on single patient highly variable Smaller doses compared to younger patients Low threshold for invasive monitoring Position carefully to avoid pressure and nerve injuries Avoid hypothermia

16. Day case surgery • An excellent option for carefully selected pts • Pre-operative evaluation to determine functional reserve , physical status ,and rational pre-operative testing but must be done early enough to allow for interventions • Suitable for minimally invasive surgery (eyes, urology) in maximally co-morbid pts • Any anaesthetic technique :LA ,RA ,GA • Premed as appropriate.

17. Advantages and disadvantages of RAeye surgery compared to GA advantages Disadvantages • RA provides good post –op analgesia • Peri-op MI less frequent • Oculocardiac reflex less frequent • PONV unlikely • Short stay in PACU • Pts eat ,drink earlier • Discharge home earlier • Control IOP limited • Long surgery contraindicated • Need pt co-operation • Pt coughing ,movement not avoided • Ventilation not controlled( hypercarbia, hypoxia)

18. Day case surgery GA may be needed Same drugs used but consideration to dosing the elderly LMA can safely be used but proviso Manage pain adequately Consider prophylaxis for PONV

19. Anaesthesia for orthopaedic surgery • Number of elderly pts in orthopaedic surgery steadily growing (hip fractures, OA, rheumatoid arthritis) • Elderly pts may have significant organ dysfunction; cardiorespiratory, renal and neurological. • They may be malnourished • No single clear anaesthetic technique. RA preferred • Use of cement during surgery known to be associated with intra-operative morbidities

20. Tourniquet use common • Sedation often needed when RA used • DVT prophylaxis necessary for major joint surgery • Antibiotics routinely used but must be given before tourniquet • Blood loss may significant in revision surgery • Neuraxial blockade with opioid provides good analgesia

21. Prolonged use of urinary catheters should be avoided • Goal is early and efficient rehab • Central neuraxial blockade reduces surgical stress by blocking nociceptive inputs • Geriatric pts have decreased functional organ system reserve and are thus tolerate surgical stress poorly • RA recommended the elderly and has advantage over GA

22. Peri-operative complications • Older pt at risk for complications in peri-operative period due to co-morbid diseases and the ageing process • Cardiovascular complications include MI, dysrhythmias esp. AF, and cardiac arrest • Pulmonary complications: atelactasis , pneumonia • Neurological complications: stroke, POD,POCD. • Post operative delirium(POD): acute confusional state • Post operative cognitive dysfunction(POCD): long term impairment in memory, concentration ,language and social integration

23. conclusion Surgery is now performed in older ,sicker elderly patients Ageing is associated with numerous physiological changes Surgery not always benign because of high prevalence of co-morbidities Adjust anaesthetic technique Aim to minimise peri-operative complications

24. references Available on request