dr. gertrude siyaka consultant anaesthesiologist steve biko academic hospital
TRANSCRIPT
Dr. GERTRUDE SIYAKAConsultant Anaesthesiologist
Steve Biko Academic Hospital
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
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
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
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 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
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 FEV1 /FVC Oxygenation: decrease efficiency in alveolar
gas exchange resulting in PaO2and 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
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
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
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
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 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)
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
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
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
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
Available on request