Download Anaesthesia for frail and elderly

Anaesthesia in the elderly
Dr. D. de Wet
Introduction
• With advances in medicine and technology the population is changing and
life expectancy increasing
• In South Africa the percentage of people over 65 years increased from 9.6%
in 1996 to 10.6% in 2011
• It is predicted that in Europe people over 65 years will increase to 30% in the
next 40 years
• This indicates that our patient population will also consist of older
individuals of which many will require surgery
Introduction
• Age itself is not a disease process
• Serves as a chance for age related diseases to develop eg. HPT,COPD, Heart
failure etc.
• In giving anaesthesia to the elderly we need to keep in mind normal changes
of physiology and accompanying co-morbidities
Topics covered
• Age related anatomical and physiological changes
o Diastolic dysfunction
• Age related pharmacological changes
• Pre-operative assessment
• Intra-operative considerations
• Post-operative considerations
• Frailty
Age-related anatomical and
physiological changes
Cardiovascular System
• It is important to distinguish between normal changes in physiology with
increased age and pathology
•
Cardiovascular disease is more prevalent in the elderly including
atherosclerosis, hypertension, cardiac failure, valve lesions
Cardiovascular System
• Myocardial hypertrophy
• Myocardial stiffening
• Reduced LV relaxation
• Reduced B-receptor responsiveness
• Conduction system abnormalities
• Stiff arteries
Diastolic dysfunction
• Several changes in cardiac structure and function occur with normal aging
that contribute to DD
• Stiffer and less compliant ventricle affects diastolic relaxation
• Pulse wave velocity is the speed at which the pressure wave generated by
the contracting heart travels to the periphery and is responsible for a
palpable pulse
• Stiffer vessels – faster pulse wave
Diastolic dysfunction
• Young people - Reflected wave returns to the heart during diastole
• Elderly - Reflected wave returns to the heart in late systole, increasing the
SBP and PP
• Most elderly patients have a normal EF, but a third will have DD
Diastolic dysfunction
• LV filling in - young patients - Early diastole
- the elderly - LA contraction more important
• Difference between DD and diastolic HF - DD is a physiological state where
abnormal relaxation is compensated for by LA contraction so that preload
remains adequate
Diastolic dysfunction
• Patients with DD may be asymptomatic at rest - periods of activity will
show SOB, fatigue and exertional dyspnoea
• Important to do thorough pre-op assessment
• During anaesthesia these CV changes predispose the elderly to greater
hemodynamic instability
• Monitoring volume status is critical - A-line to monitor BP is a good idea
Diastolic dysfunction
• Induction may be prolonged due to slow circulation time - titrate
- enough time
• Maintain SBP within 10% of baseline
• DBP must be maintained, as low DBP lead to myocardial ischaemia
• Simultaneous infusions of low dose nitroglycerin and PEP can help
• Administered alone however, these agents may worsen cardiac function
• HR should be maintained at low normal range (60-70)
Diastolic dysfunction
•
Rule of 70
•
•
Patients with DD can acutely deteriorate after initially appearing stable
Common post-op complications
o Patients > 70
o DBP > 70
o PP < 70
o HR = 70
o Hypoxia
o Pulmonary oedema
o AF
Respiratory system
• Aging decreases the elasticity in lung tissue, allowing overdistention of
alveoli and collapse of small airways
• Residual volume and FRC increase – Both physiological and anatomical
dead space increase
• Some airways close during normal tidal breathing resulting in ventilationperfusion mismatch
• Increased chest wall rigidity and decreased muscle strength leads to:
o Decreased cough
o Decreased maximal breathing capacity
Respiratory system
• Blunted response to hypoxia
• Aspiration pneumonia – decrease in protective laryngeal reflexes
Metabolic and endocrine function
• Peak weight at age 60 – most people then begin to lose weight as a
consequence of decreased muscle mass
• Heat production decrease and heat loss increase – more prone to perioperative hypothermia
• DM affects +/- 15% of patients >70 y/o
• Decreased response to ß-adrenergic agents
Renal function
• Renal blood flow and kidney mass decrease – increases the risk of perioperative ARF
• Renal function is reduced in even healthy older patients
• Creatinine level is unchanged (decreased muscle mass) ,
Urea increases
• Predisposed to both dehydration and fluid overload
• As renal function decreases so does the ability to excrete drugs
Gastro-intestinal function
• Liver mass and hepatic blood flow decline with aging – hepatic function
declines in proportion to the decrease in liver mass
• Thus, the rate of biotransformation and albumin production decrease
• The elderly also have slower gastric emptying and a deterioration in parietal
cell function
Nervous system
• Brain mass decreases with age
• Neuronal loss most prominent in the cortex of the frontal lobes
• Cerebral blood flow decreases in proportion to neuronal losses
• Decrease in sensory modalities such as touch, temperature sensation,
proprioception, hearing and vision
Nervous system
• High incidence of POCD and delirium in elderly patients
• Some studies suggest that POCD can be detected in +/- 15% of patients over
60 y/o up to 3 months after major surgery
• Etiology of POCD : drug effects, pain, hypothermia, metabolic disturbances
• Question still remains if GA agents can cause neurotoxicity of the aged brain
Musculoskeletal function
• Muscle mass is reduced
• Skin atrophies with age – susceptible to trauma from removal of tape, ECG
stickers, pressure sores
• Arthritic joints may interfere with positioning or regional anaesthesia
• Degenerative cervical spine disease can limit neck extension – difficult
intubation
• Especially if the patient has no teeth
Age-related Pharmacological
changes
Age-related pharmacological changes
• Age produces both pharmacokinetic and pharmacodynamics changes
• Decrease in muscle mass and increase in body fat results in decreased total
body water
• Increased volume of distribution for lipid-soluble drugs reduce their plasma
concentration
• Reduced volume of distribution for water-soluble drugs lead to greater
plasma concentrations
• Prolonged duration of action of many drugs, because of previously
mentioned decline in hepatic and renal function
Age-related pharmacological changes
• Elimination of drugs also affected by altered plasma protein binding:
-Albumin (binds acidic drugs) Decrease
-α1-acidic glycoprotein (binds basic drugs) Increase
• Reduced anaesthetic requirements
Inhalational Agents
• MAC is reduced by 4% per decade after 40 y/o
• Onset of action:- faster if CO depressed
- delayed if there is V/P abnormalities
• Recovery may be prolonged because of – increased volume of distribution
and decreased pulmonary gas exchange
IV Agents
• In general – lower dose requirements for propofol, opiods and benzo’s
• Propofol is a useful agent in the elderly because of rapid elimination, but is
more likely to cause apnoea and hypotension. Elderly patients require
nearly 50% lower blood levels of Propofol than younger patients
• Geriatric patients have an enhanced sensitivity to fentanyl and alfentanyl
than younger patients (Also require half the dose)
Muscle Relaxants
• Response to sux and other neuro-muscular blockers is unaltered by aging
• A prolongation in the onset of NM blockade in elderly patients is seen due to
a decreased CO and slow muscle blood flow
• Recovery from non-depolarising MR that depend on renal/hepatic excretion
is prolonged
• Hoffman-elimination is not significantly effected by age
Pre-operative assessment
Pre-operative assessment
• Studies show mortality/morbidity rates for fit, healthy geriatric patients are
not significantly higher than younger patients
• 65% Incidence of correctable deficiencies in blood volume, electrolyte
imbalance or oxygen delivery in emergency setting
• Therefor a detailed pre-op evaluation and correction of those deficiencies is
needed in all patients presenting for surgery
The decision to operate
• This decision should be made at consultant level of surgical and anaesthetic
disciplines
• Ideally in conjuction with MDT, family and MOST importantly the patient
• Procedure should improve quality and quantity of life
• No place for heroic, but futile surgery
History
• Prior to taking history – Mini Mental
• Collateral history very important, including old notes
• In addition to standard PMHx and systemic enquiry, also ask:
o Background to admission
o Co-morbids
o Medications
o Level of social support, AODL, exercise tolerance
Examination
• Vitals
• Fluid status
• Full systemic exam
• Walk the stairs with the pt to evaluate exercise tolerance
Investigations
• FBC, U&E, Vx
• ECG
• Otherwise investigate as clinically indicated
Intra-operative considerations
Intra-operative considerations
• Multiple studies have come to the same conclusion: No difference in
outcome can be attributed to the use of any specific agent
• More important to individualise what is compatible with each patient
• Attention to detail
Intra-operative considerations
Some specific issues:
• Pre-warm patients
• Adequate IV access
• Measures to prevent hypoxia: - Longer pre-oxygenation
- Higher FiO2
- PEEP
• With IV induction – doses can be reduced if given slowly
• Use of short acting agents
• Keep vasopressors at hand
Intra-operative considerations
• Airway maintenance more difficult because of: Osteoporotic mandibles,
loose teeth, tempero-mandibular joint stiffness, cervical spondylosis,
arthritis of atlanto-occipital joint
• Regional vs General - 17 trials
• Advantages of RA:
o Reduces Thrombo-embolic events
o Reduces confusion
o Reduces post-op respiratory problems
o Reduces endocrine stress response
Intra-operative considerations
• Maintenance of normothermia needs careful attention
Hypothermia impairs coagulation, immune function and wound healing
Shivering in recovery increases O2 demand and can lead to myocardial
ischaemia
• Fluid management
Based on pre-op hydration, losses, urine output, P , BP
• Positioning
Increased frequency of neuropraxia
Pressure sores
Post-operative considerations
Post-operative considerations
• DVT prophylaxis - Not only Clexane
- Good hydration, early mobilisation, thrombo-embolic
stockings
• Nutrition - Aids healing and recovery
• Glucose monitoring
• Fluid management - prescribe
• Oxygen therapy – prescribe
o Ventilatory muscles fatigue
o Reduced CNS response to hypoxia
o Protective cough reflex reduce with age
Post-operative considerations
• Pain - Myth that pain perception reduses with age and that they cannot
tolerate opiods
- Regional blocks
• Cognition
Frailty
Definition
• Phenotype that identifies people with reduced physiological reserve in
multiple organ systems, who, as a result have increased vulnerability to
physiological stressors
• Not all elderly are frail, Not all frail are elderly
Why is frailty important?
• Identify patients with a limited ability to cope with physiological stressors
associated with the peri-operative period
• Allows treatment decisions to be altered to benefit the patient
• Stronger predictor of mortality than chronological age
Risk factors
• Physiological
o Age
o Reduced body mass
• Co-morbidities
o CV disease
o Stroke, DM, Cancer, COPD
• Psychological factors
o Females
o Lower socio-economic background
o Depression
• Disability
Assessment of frailty
• 3 or more of 5 criteria (Fried et al.) :
1.
2.
3.
4.
5.
Unintentional weight loss - 4,5kg or more in 12 months
Exhaustion - objectively
Weak hand grip strength
Slow walking speed - “get up and go” test
Low physical activity
Take home messages
• Age itself is not a disease
• Many normal physiological changes that influence our anaesthetic
• Co-morbidities more likely in older patients – thorough pre-op exam to
determine any underlying undiagnosed disease
• No ideal agent for the elderly – titrate and go slow
• Frailty - important concept - strong predictor of morbidity
• Treat the elderly with care, dignity and respect
Thank you
Referances
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Dodds C, Foo I. Peri-operative care of elderly patients – an urgent need for
change. Age Anaesthesia Assosiation. (1-9)
Alcock M. Frailty and the perioperative period. Anaesthesia Tutorial of the Week
236. www.totw.anaesthesiologists.org
Partridge JSL, Harari D, Dhesi JK. Frailty in the older surgical patient: a review.
Age and Ageing 2012, 41 (142-147)
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