by dr. mohd fadzli bin zahari moderator: dr. tuan norizan bt. tuan mahmud

GERIATRIC ANESTHESIA

By Dr. Mohd Fadzli Bin ZahariModerator: Dr. Tuan Norizan Bt. Tuan Mahmud

Overview Anatomy & physiology of ageing

◦ Respiratory◦ CVS◦ Renal system◦ Central Nervous System◦ Hepatic System◦ Endocrine◦ Musculoskeletal system◦ Skin

Outline

Age & Anesthetic Risk Preoperative Assessment Intraoperative Management

◦ General VS Regional Anesthesia◦ Temperature

Pharmacology Post Operative Management Anesthesia Management Of Patient With

Dementia

Outline

OVERVIEW

The elderly population is increasing in size as people are living longer due to advances in medical science and improvements in standards of living.

In the western world people over 65 years of age represent approximately 15% of the population and almost half of these individuals will present to hospital for a surgical procedure.

Overview

Elderly patients have higher rates of hospital morbidity and mortality compared to younger patients.

This increased risk is related to the normal physiological processes of ageing and increased prevalence of coexisting systemic disease.

Overview

As a person ages, their anatomy and physiology undergo many changes that become more apparent with increasing chronological age.

Ageing is a progressive physiological process that is characterized by degeneration of organ systems and tissues with consequent loss of functional reserve of these systems.

Overview

Loss of these functional reserves impairs an individual’s ability to cope with physiological challenges such as anaesthesia and surgery.

Individuals of the same chronological age may differ significantly in the rate and severity of functional decline.

Patients who maintain greater than average functional capacity are considered ‘physiologically young’ and those whose function declines at an earlier age appear to be ‘physiologically old’.

Overview

ANATOMY & PHYSIOLOGY OF AGEING

Lung and chest wall compliance decreases with advancing age.

Total lung capacity (TLC), Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1) and Vital Capacity are all reduced as people age.

Residual Volume (RV) increases and Functional Residual Capacity (FRC) remains unchanged.

Anatomy & Physiology of Ageing( respiratory system )

Anatomy & Physiology of Ageing ( respiratory system )

Anatomy & Physiology of Ageing ( respiratory system )

These changes occur as a result of reduction in elastic support of the airways and leads to increased collapsibility of alveoli and terminal conducting airways.

By the age of 65 years closing capacity typically encroaches into tidal volume during normal tidal ventilation. This results in ventilation perfusion mismatch and reduced arterial oxygen tension. estimated PaO2=13.3 - (age/30) kPa or PaO2=100 - (age/4) mmHg

Anatomy & Physiology of Ageing ( respiratory system )

Atelectasis, pulmonary emboli and pneumonia are common post-operative complications in the elderly.

Loss of elastic tissue around the oropharynx can lead to collapse of the upper airway. Sleep or sedative states may result in partial or complete obstruction of the airway.

Patients are often edentulous making bag-mask ventilation difficult.

Anatomy & Physiology of Ageing ( respiratory system )

Osteoarthritic changes may limit cervical spine flexibility and can make tracheal intubation more difficult. Care must be taken to avoid stressing the cervical spine as fragile ligaments and bones may be injured when subjected to mechanical forces.

Anatomy & Physiology of Ageing ( respiratory system )

Large and medium sized vessels become less elastic and therefore become less compliant with age.

This results in raised systemic vascular resistance and hypertension -> LV hypertrophy

Cardiac output falls by 3% per decade which is due to reduced stroke volume and ventricular contractility.

Anatomy & Physiology of Ageing( CVS )

The reduction in cardiac output with age increases the arm-brain circulation time for drugs.

Cardiac conducting cells decrease in number making heart block, ectopic beats, arrhythmias and atrial fibrillation more prevalent.

Anatomy & Physiology of Ageing ( CVS )

Catecholamine β adrenergic receptors in the myocardium are down regulated in the elderly resulting in a decreased responsiveness to catecholamines and sympathomimetic agents.

The non-compliant vascular systems may result in reduced efficacy of vasoconstricting drugs such as ephedrine and metaraminol.

Anatomy & Physiology of Ageing ( CVS )

There is global impairment of autonomic homeostasis and impaired carotid baroreceptor response such that the heart rate cannot always respond to maintain arterial blood pressure.

Postural hypotension is common in the elderly population and may be exacerbated by diuretics, antihypertensive drugs and hypovolaemia.

Anatomy & Physiology of Ageing ( CVS )

Ischaemic heart disease is common in older patients, especially in smokers and diabetics. Since activity may be limited by poor mobility and other co-morbid features, symptoms such as angina or exertional dyspnoea may not be detectable.

It is important that even without objective evidence of coronary heart disease all elderly patients should be considered at increased cardiovascular risk.

Anatomy & Physiology of Ageing ( CVS )

Structural heart lesions such as valvular heart disease are common either by RHD or valve calcification.

Intravenous and inhalational agents depress cardiac and vascular smooth muscle contractility and may impair the baroreceptor response to hypotension.

Anatomy & Physiology of Ageing ( CVS )

Neuroaxial regional anaesthesia techniques may result in significant hypotension but elderly patient tolerate spinal anesthesia well as the non-elastic vascular tree is not as susceptible to vasodilatation caused by sympathetic blockade compared to younger patients.

Anatomy & Physiology of Ageing ( CVS )

Glomerular filtration rate is thought to decrease by 1% per year over the age of 20 years due to a progressive loss of renal cortical glomeruli.

A reduction in renal perfusion secondary to reduced cardiac output and atheromatous vascular disease leads to a decline in renal function.

Anatomy & Physiology of Ageing ( Renal System)

Addition to reduction of renal function by DM & nephrotoxic drugs ( NSAID’s & ACEi ).

Prostatism in males can lead to obstructive nephropathy and dehydration is common in the elderly especially during illness.

Laboratory results may be deceivingly normal in the elderly since muscle bulk decreases with age resulting in reduced creatinine production.

Anatomy & Physiology of Ageing ( Renal System)

Creatinine clearance is a more useful test of renal function and can be calculated from a 24-hour urine collection

Cockroft-Gault formula to estimate creatinine clearance:Creatinine Clearance (ml/min) = (140-age) x Weight (Kg) x

Constant

Serum Creatinine (μmol/L)

Constant for males = 1.23, Constant for females = 1.04

Anatomy & Physiology of Ageing ( Renal System)

Renal impairment can lead to:◦ reduced ability to excrete or conserve fluids◦ electrolyte imbalance◦ reduction in the clearance of renally excreted

drugs

Anatomy & Physiology of Ageing ( Renal System)

Cerebrovascular disease is common in the elderly secondary to diffuse atherosclerosis and hypertension.

Neuronal density is reduced by 30% by the age of 80 years.

Cognitive impairment can lead to difficulties in communication, patient compliance and consent to surgical and anaesthetic procedures.

Anatomy & Physiology of Ageing ( Central Nervous System )

hospitalisation, anaesthesia and surgery can lead to deterioration in cognitive function which is thought to be multfactorial in origin.

Visual and hearing impairment are very common in elderly people and can also lead to difficulties in communication.

Autonomic neuropathy may lead to impaired baroreceptor response and haemodynamic instability.

Anatomy & Physiology of Ageing ( Central Nervous System )

Delayed gastric emptying and increased risk of gastric aspiration.

Anatomy & Physiology of Ageing ( Central Nervous System )

The ageing liver preserves its function relatively well. This maybe due to its capacity to regenerate.

Anatomically there is marked reduction in liver size by 60 years of age due to the decline of splanchnic blood flow.

Physiological changes primarily affects the plasma protein binding & drug metabolism.

Anatomy & Physiology of Ageing ( Hepatic System)

Common liver disease encountered in elderly:◦ Alcoholism◦ Cirrhosis ( alcoholic or viral hepatitis )◦ Biliary tract disease ( gallstone & malignancies )

Anatomy & Physiology of Ageing ( Hepatic system )

The basal metabolic rate falls by 1% per year after the age of 30.

Fall in metabolic activity and reduced muscle mass may cause impaired thermoregulatory control.

Anatomy & Physiology Of Ageing ( Endocrine & Metabolism)

Approximately 25% of patients over 85 years have Non-Insulin Dependent Diabetes Mellitus (NIDDM).

Diabetes leads to renal impairment, cardiovascular disease, neuropathy and retinopathy.

Elderly patients also have an increase in thyroid disorders, osteoporosis and nutritional disorders.

Anatomy & Physiology Of Ageing ( Endocrine & Metabolism)

Arthritis is extremely common and leads to pain and reduced mobility in affected individuals.

Bones and joints may be deformed, making regional anesthesia techniques difficult or even impossible.

Osteoporosis occurs especially in females, immobile patients and those with a history of steroid use.

Anatomy & Physiology Of Ageing ( Musculoskeletal System )

Much care must be taken when moving and positioning patients so as to avoid exacerbating joint pain or causing fractures or dislocations.

Prominent bony areas are susceptible to skin breakdown and pressure sores.

Anatomy & Physiology Of Ageing ( Musculoskeletal System )

Elderly patients tend to have thin skin and fragile subcutaneous blood vessels and therefore patients tend to bruise easily.

Achieving and securing venous access can be difficult and problems of extravasations of fluid or drugs can occur if infused under pressure.

Care should be taken on transferring patients to avoid skin abrasions.

Anatomy & Physiology Of Ageing ( Skin )

AGE & ANESTHETICRISK

Perioperative outcome described as mortality that is death within 30 days of the surgical procedure and/or morbidity which involves anesthetic or surgical complications that occur also within 30 days.

Factors influence outcome:◦ Emergency surgery◦ Atypical clinical presentation ( atypical angina or

silent ischemia ) at the time of surgical intervention

◦ Presence of CAD◦ Type of surgery◦ The ageing process itself lead to a person with

higher probability requiring operative procedure

Methods of risk assessment & stratification◦ ASA classification◦ Lee cardiac risk index◦ Goldman & Detsky cardiac risk index◦ Postoperative pneumonia index◦ Delirium risk predictors◦ POSSUM◦ SAS

ASA classification◦ Preoperative assessment of overall co morbidity

and physical status.◦ Focus primarily on physical status and discourage

the use of operative risk because of excessive number of variables to be considered.

◦ One of the most reliable and accurate predictors of surgical mortality

Lee cardiac risk◦ Also known as revised cardiac risk index◦ Complication rate ranging from 0.4% to 11%◦ Predictive of cardiovascular mortality but

suboptimal for surgical procedure◦ "Major cardiac event" includes myocardial

infarction, pulmonary edema, ventricular fibrillation, primary cardiac arrest, and complete heart block

Risk stratification by specific age◦ Recently was classified into chronological decade

due to physiological changes reported by chronological decade.

◦ Classified as: Sexagenarians ( 60 – 69 ) Septagenarians ( 70 – 79 ) Octogenarians ( 80 – 89 ) Nonagenarians ( 90 – 99 ) Centenarians ( > 100 )

PREOPERATIVE ASSESSMENT

Objective is to optimize patient care in preparation for surgery.

Preoperative history and physical examination including laboratories findings comprise the basic information used to make decisions regarding surgical risk in the elderly.

Another most important issue overlooked in elderly patient is maintaining their independence & current level of functional ability post operatively.

Preoperative Assessment( General Consideration )

Inadequate preparation and evaluation is unfortunately commonplace in a time-pressured environment ( emergency cases )

Preoperative assessment ideally would benefit from cross specialty advice from a multidisciplinary team (MDT)

Preoperative Assessment( General Consideration )

A decision whether to operate ideally should be made at a consultant level, in conjunction with the MDT, family and most importantly the patient.

The procedure to be undertaken should improve the quality, or quantity of a patient’s life.

“There is no place for heroic, yet futile surgery!“

Preoperative Assessment( General Consideration )

Surrogate decision-making ◦ Living wills and advanced directives are

documents of competent patient wishes. They must be respected.

◦ When such formal information is unavailable, it might be necessary to turn to relatives, making the assumption the family’s decision is in the patient’s best interests and that they share a common cultural background.

Preoperative Assessment( General Consideration )

Prior to taking a history, a mini mental state score / mini cog algorithm is very useful.◦ primarily to assess reliability of information◦ secondarily it might prove very useful in the

postoperative period Collateral history may be important via

relatives, care taker, nurses. Old notes are a very useful source of information, especially old anesthetic charts.

Preoperative Assessment( History Taking )

Preoperative Assessment( History Taking )

Preoperative Assessment( History Taking )

Preoperative Assessment( History Taking )

Specific point to be highlighted:◦ Presenting history ( eg. ascertain that history of

fall is purely mechanical or proceeded by syncopal attack )

◦ Co-existing medical problems & medications. Pay particular attention to steroids, beta-blockers, ACE inhibitors, diuretics, insulin or hypoglycaemic agents and anticoagulants.

◦ Gastro-oesophageal reflux disease (GORD) and dentition.

Preoperative Assessment( History Taking )

Specific point to be highlighted ( cont ):◦ A detailed social appraisal to assess the level of

home support may allow day surgery or earlier involvement of social services prior to discharge.

◦ Assess premorbid functional ability including activities of daily living and exercise tolerance as a means of risk stratification ( refer SAS )

◦ Frailty criteria assessment

Preoperative Assessment( History Taking )

Full exposure whilst ensuring warmth, comfort and dignity allows a full complete clinical examination.

Documentation of blood pressure allows appropriate intraoperative management of hypotension to maintain organ auto regulation perioperatively.

Fluid balance, weight and nutrition are all important in the assessment.

Preoperative Assessment( Examination )

Bowel prep or fractures may need fluid pre operatively.

Unrecognized pathology might be found, and be highly relevant, such as the systolic murmur of aortic stenosis.

If possible, walk the ward or stairs with the patient to assess “real-time” exercise tolerance.

Preoperative Assessment( Examination )

ECG CXR Full blood count ( FBC ) Blood urea, serum electrolytes & creatinine ( BUSEC ) Blood sugar ( RBS / FBS )

Preoperative Assessment( Investigation )

INTRAOPERATIVE MANAGEMENT

The theoretic reasons behind the concept that regional anesthesia safer are:◦ Provides more stable cardiovascular

hemodynamic◦ Superior pain relieves intraoperative &

postoperative with a superior recovery profile & satisfaction

◦ RA placed preoperatively may provide preemptive analgesia

Regional VS General Anesthesia

The theoretic reasons behind the concept that regional anesthesia safer are ( cont ):◦ Avoid endotracheal intubation & mechanical

ventilation leading to less respiratory complication

◦ Reduced opioid-related complications such as those related with GI system

◦ Superior pain relief may reduce unplanned hospital admission for ambulatory patients thus reduce costs.

Regional VS General Anesthesia

Age related impairment of basic homeostatic function.

3 general component of thermoregulatory system:◦ Afferent input◦ Central processing ( ant hypothalamus )◦ Efferent response control heat loss & production

Temperature

Efferent responses:◦ First behavioral response◦ If inadequate vasodilation & sweating are

triggered to release heat OR vasoconstriction & shivering to conserve heat

Temperature

Effect of anesthesia to thermoregulatory system

General anesthesia◦ Inhibit all thermoregulatory responses◦ 1 C drop post induction & cont to drop after 2-3h

of GA until core T down to 34C without body responses to hypothermia

Regional anesthesia◦ Major conduction blockade ( afferent & efferent )

Temperature

Temperature

Monitoring◦ 2 thermal compartment:

Core ( relatively constant internal T ) Periphery

◦ Accuracy of T site monitoring Most accurate

Pulmonary artery Distal 1/3 esophagus Tympanic membrane Nasopharynx Oropharynx

Temperature

Benefits of hypothermia◦ Neurologic protection◦ Renal protection

Temperature

Adverse effects of hypothermia◦ Postoperative shivering increases metabolism &

O2 demand◦ Blunts ventilatory response to CO2◦ Hypoxic pulmonary vasoconstriction◦ Tissue hypoxia by increase oxygen affinity of

hemoglobin. 7.5% increment every 1C

Temperature

Adverse effect hypothermia ( cont )◦ Increase in norepinephrine production lead to

vasoconstriction & increased BP◦ “cold – induced” MI. Randomized trial showed

reduction to 55% cardiac morbidity with pt normothermia perioperatively.

◦ Coagulopathy via: Platlet dysfunction Impaired coagulation cascade Activation of fibrinolysis

Temperature

Adverse effect hypothermia ( cont )◦ Slow wound healing due to impaired collaged

deposition◦ Increased risk ( 3x ) for infection due to impaired

macrophage function.◦ Altered pharmacokinetics & pharmacodynamics

Temperature

Methods of controlling body temperature◦ Ambient operating room temperature◦ Warming the inspired gas◦ Warming the IV fluids ( high volume & flow rates )◦ Passive insulation ( reduce 30% of heat loss )◦ Active patient warming by using forced air

warming

Temperature

Temperature

PHARMACOLOGY

Reduced cardiac output results in delayed onset of intravenous anesthesia.

Reduced total body water and increased adipose tissue leads to an altered volume of distribution of some drugs.

Plasma proteins are reduced resulting in decreased protein binding and increased free drug availability.

Pharmacology

Minimum alveolar concentration (MAC) decreases by approximately 6% per decade for all inhaled anaesthetics.estimated MAC(age) = a x 10bx

x = Age – 40 years

b = − 0.00269 a = MAC at age 40 years ( halothane 0.75%, isoflurane1.17%, enflurane1.63%, sevoflurane1.8%, desflurane 6.6%)

Pharmacology

Elderly patients have an increased sensitivity to CNS depressant drugs and so drug doses need to be modified accordingly.

Reduced hepatic and renal function leading to slower metabolism and elimination of drugs.

Polypharmacy

Pharmacology

POST OPERATIVE MANAGEMENT

DVT prophylaxis◦ Good hydration◦ Early mobilization◦ TED stocking◦ Heparin / calf compression devices

Good nutrition aids healing and recovery. Blood sugar monitoring. Elderly tend to

have hypo/hyperglycemia.

Proper fluid management avoiding acute renal failure.

Adequate pain control. Pain assessment & treatment.

+/- oxygen therapy:◦ Respiratory muscle fatigue◦ Reduced CNS response to O2 & CO2 with further

suppression with opioids◦ Protective reflexes, coughing and swallowing

reduce with age & increase risk for aspiration pneumonitis

Early mobilization, physiotherapy and occupational therapy facilitate post op recovery.

Treatment of Acute delirium & POCD

DEMENTIA

Slowly progressing loss of mental abilities which exceeds the normal age – related decline of brain efficiency

Causes such as:◦ Alzheimer’s disease◦ Multifocal infarct ( vascular dementia )◦ Associated dementia◦ Frontal dementia◦ Reversible dementia

Problem arises since preoperative assessment◦ Lack of insight◦ Lack of understanding◦ Lack of cooperation

Consent & history taking cannot be obtained from the patient instead relatives / guardian are included in the physician – patient relationship

Geriatric anesthesia, Frederick Sieber http://www.aagbi.org/education/educational-

resources/tutorial-week/my-events/tutorial/search-results◦ 32-Anaesthesia-in-the-elderly◦ 33-Anatomy-and-physiology-of-ageing

Referrence