GERIATRIC ANAESTHESIA Dr GERTRUDE SIYAKA Consultant Anaesthesiologist Steve
- Slides: 24
GERIATRIC ANAESTHESIA Dr. GERTRUDE SIYAKA Consultant Anaesthesiologist Steve Biko Academic Hospital
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
Introduction � Life expectancy in US and Europe now 7480 yrs � 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
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
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
� 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
�Aortic valve sclerosis common �CO decreases linearly after 3 rd 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
�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
�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
� 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 FEV 1 /FVC � Oxygenation: decrease efficiency in alveolar gas exchange resulting in Pa. O 2 and increase alveolar – arterial gradient � Impaired response to hypoxia, hypercarbia and mechanical stress
� 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
� 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
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
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
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
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.
Advantages and disadvantages of RA eye surgery compared to GA ADVANTAGES 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 DISADVANTAGES Control IOP limited Long surgery contraindicated Need pt co-operation Pt coughing , movement not avoided Ventilation not controlled( hypercarbia, hypoxia)
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
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
� 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
� 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
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
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
references �Available on request
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