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 changeso 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 70o Patients > 70

o DBP > 70

o PP < 70

o HR = 70

• Patients with DD can acutely deteriorate after initially appearing stable

• Common post-op complications 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 ventilation-perfusion 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 peri-operative 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 peri-operative 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

oMedications

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 considerationsSome 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

• Physiologicalo Age

o Reduced body mass

• Co-morbiditieso CV disease

o Stroke, DM, Cancer, COPD

• Psychological factorso Females

o Lower socio-economic background

o Depression

• Disability

Assessment of frailty

• 3 or more of 5 criteria (Fried et al.) :1. Unintentional weight loss - 4,5kg or more in 12 months

2. Exhaustion - objectively

3. Weak hand grip strength

4. Slow walking speed - “get up and go” test

5. 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

1. Hollister N. Anaesthesia in the Elderly. World Anaesthesia Tutorial of the Week. www.AnaesthesiaUK.com/WorldAnaesthesia

2. Hubbard RE, Story DA. Patient frailty: the elephant in the operating room. Anaesthesia 2014, 69 (26-34)

3. Dodds C, Foo I. Peri-operative care of elderly patients – an urgent need for change. Age Anaesthesia Assosiation. (1-9)

4. Alcock M. Frailty and the perioperative period. Anaesthesia Tutorial of the Week 236. www.totw.anaesthesiologists.org

5. Partridge JSL, Harari D, Dhesi JK. Frailty in the older surgical patient: a review. Age and Ageing 2012, 41 (142-147)

6. Sanders D, Dudley M, Groban L. Diastolic Dysfunction, Cardiovascular aging, and the Anaesthesiologist. Anesthesiology Clin 27, 2009 (497-517)

7. Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s Clinical Anesthesiology. 5th ed. Lange. 2013