FRCA Notes

Anaesthesia for the Elderly Patient

The curriculum is concise on tihs matter: 'Recalls/describes the peri-operative care of the elderly'.

The topic was a CRQ in 2020 (62% pass rate), with feedback focussing on poor understanding of physiology and pharmacological changes and their affect on anaesthesia.

Resources

  • An increasing number of elderly patients are undergoing surgery
  • Elderly patients are not homogenous and therefore age cannot be used as a sole indicator of peri-operative risk
  • However, elderly patients are often complex due to the combination of:
    • Age-related physiological decline
    • Medical comorbidities
    • Cognitive impairment
    • Frailty
    • Polypharmacy
Peri-operative issues associated with increasing age
↑ post-operative morbidity
↑ post-operative mortality
90-day mortality after EmLap 4x higher in those >60yrs
↑ length of stay
30% increase in LOS if >65yrs

Respiratory system

  • ↓ chest wall compliance and lung compliance
  • ↓ lung volumes: TLC, FVC, FEV1, PEFR
  • Closing volume > FRC, leading to V/Q mismatch
  • COPD is more common due to smoking, leading to impaired gas exchange across the alveolar capillary membrane
  • Blunted responses to hypoxia and hypercarbia due to ↓ chemoreceptor function

Cardiovascular system

  • A number of cardiovascular comorbidities are more common, including hypertension, ischaemic heart disease, valvular pathology and heart failure
  • More likely to have implanted cardiac devices such as pacemakers

  • There is a generalised decrease in the elasticity/increase in stiffness of the vasculature due to collagen and fibrous deposition
    • Diastolic cardiac dysfunction ensues
    • ↑ SVR due to reduced vascular compliance
  • Down-regulated myocardial catecholamine receptors leading to a ↓ myocardial responsiveness to catecholamines & sympathomimetics
  • ↓ SV, maximum HR and ventricular compliance, leading to a reduced cardiac output
  • Conduction defects are more common due to fat and fibrotic infiltration of the cardiac conducting system
  • Progressive calcification of valves e.g. aortic stenosis
  • There is an ↓ baroreceptor response to raised SVR

Central nervous system

  • General decline in performance
  • Cognitive impairment, be it from Alzheimer's disease or other forms of dementia, is common
    • 17% of those >80yrs are affected by cognitive decline
  • Increased incidence of:
    • Visual impairments e.g. cataracts, ARMD, glaucoma
    • Hearing impairments e.g. sensorineural hearing loss

  • Potential for autonomic neuropathy due to age-related autonomic dysfunction
    • There is generally increased sympathetic but decreased parasympathetic nervous system activity
    • There are attenuated baroreceptor responses
    • There may be delayed gastric emptying

  • Delirium is more common
  • Decreased CBF and CMRO2
  • Reduced levels of both neurotransmitters and their receptors

Renal system

  • Higher prevalence of both dehydration and fluid overload
  • Higher prevalence of electrolyte imbalance esp. sodium and potassium, which is often polyfactorial
  • There is age-related decline in GFR, with impaired ability to conserve sodium
    • Up to 50% loss of nephrons by 75yrs
    • Reduced cardiac output further compromises renal tubular flow
  • Reduced drug clearance
  • Benign prostatic disease is common (60% of those >90yrs) and can cause obstructive renal impairment

Metabolic homeostasis

  • Diabetes and thyroid disease are more common
  • Reduced BMR
  • Reduced tolerance of hypothermia

Musculoskeletal sysmte

  • Presence of pathology such as OA, RA and osteoporosis
  • Sarcopaenia
  • Thin skin increases risk of bruising and pressure-related injuries
  • Reduction in fat volume increases susceptibility to hypothermia
  • Reduced TBW and muscle mass affects pharmacokinetics
  • Poor dentition

Pharmacokinetics

  • More likely to have multiple co-morbidities:
    • Diseases processes may alter pharmacokinetics
    • Polypharmacy increases risk of drug interactions

  • Absorption: reduced gastric emptying (clinically insignificant) due to age-related autonomic changes

  • Distribution
    • Reduced muscle mass by proportion
      • Affects volume of distribution
      • Increases sensitivity to remifentanil that is metabolised by muscle esterases
    • Decreased albumin level
    • Decreased total body water

  • Metabolism
    • Reduced hepatic blood flow
    • Reduced activity of hepatic enzymes
    • Therefore reduced 1st pass metabolism of drugs = increased bioavailable fraction

  • Excretion
    • Reduced creatinine clearance with age

Perioperative care of the elderly patient


  • General principles of perioperative care:
    • MDT working improves outcomes
    • Decision to operate/anaesthetise should be made at consultant level, in conjunction with the patient, family and MDT
    • Senior personnel should be available to anaesthetise/operate on the patient
    • Suitable post-operative care should be arranged inc. HDU/ICU

History

  • May be difficult or limited due to deafness, aphasia or cognitive impairment
  • Collateral history may be required from family members or caregivers

  • Identify background reason for admission e.g. why patient fell if #NOF
  • Identify comorbidities

  • Drug history - polypharmacy increases risk of drug interactions
  • Nutritional assessment ± replacement
  • Functional assessments
    • Pre-morbid exercise tolerance
    • ADLs
    • Social circumstances
    • Assessments by PT and OT

Investigations

  • Examination be difficult due to poor cooperation, understanding, difficult getting (un)dressed, poor mobility
  • Targeted examination of relevant systems
  • Cognitive assessment e.g. MMSE
  • Baseline BP important as patients prone to intra-operative hypotension
  • Often require at least FBC, U&E's, blood glucose and an ECG ± further targeted investigations

Optimisation

  • Clinics dedicated to pre-operative assessment of the older patient (POPS) improve outcomes
  • Consider prehabilitation where relevant
  • Polypharmacy reduction
  • Input from surgical, geriatric medicine, PT/OT, pharmacy and other relevant subspeciality teams

  • No demonstrable difference in outcome between general and regional techniques, but rather best outcomes from adopting technique best suited to individual patients

Monitoring and access

  • Low threshold for arterial line, especially if:
    • Existing CV disease
    • Large blood loss or fluid shifts expected

  • Depth of anaesthesia monitoring may allow better titration of anaesthetic agents, reducing sequelae from excess anaesthetic

Airway and ventilation

  • GORD more common therefore higher aspiration risk
  • May have more difficult airway management owing to:
    • Posterior column issues such as arthritis, spondylosis, general stiffness
    • General poor positioning due to musculoskeletal disease
    • Edentulous patients being more difficult to facemask ventilate without adjuncts

  • FRC reduces with age and other factors such as kyphoscoliosis
  • Closing capacity encroaches on FRC when supine by 40yrs, standing by 70yrs
  • Therefore hypoxia may be more common and robust pre-oxygenation should be undertaken

Drugs

  • Increased sensitivity to induction agents, inhalational agents (reduced MAC), opioids and benzodiazepines
  • Arm-brain circulation time is increased so speed of administration of induction agents should be reduced
  • Autonomic responses are blunted and hypotension may be more prominent

Care bundle

  • Thin skin ± less fat and muscle mass so more prone to bruising, pressure sores and neurapraxia
  • Meticulous approach to positioning and padding required

  • Prone to hypothermia so increased requirement for temperature monitoring and warming devices

  • More difficult fluid management strategy as more prone to both overload and hypovolaemia

Analgesia

  • Inadequate analgesia contributes to delirium, CV complications and failure to mobilise
  • Assessment of pain may be more difficult due to cognitive impairment - non-verbal cues should be used

  • A multi-modal opioid-sparing approach is best, using LA techniques such as infiltration by surgeons ± wound catheters ± other regional techniques where possible
  • NSAIDs relatively contra-indicated due to risk of renal impairment and GI bleeding
  • Opioids should be used cautiously at minimum effective doses, bearing in mind increased incidence of renal failure and therefore side-effects

Re-enablement

  • MDT approach inc. early mobilisation, PT and OT
  • Enhanced recovery programmes
  • Input from dedicated elderly care physicians
  • Appropriate physiological management in the peri-operative period

Complications