بسم الله الرحمن الرحيم

Anesthesia for the Geriatrics By Ahmed El-Shaer MSc, MD anesthesia, MSc Pain Management

Objectives 1- Define the geriatric population 2- enumerate the anesthetic problems for a Ger. Pt. 3- mention the different methods for avoiding these problems 4- Categorize patients according to risk 5- Mention the ethical considerations for dealing with the old aged pts

The elderly (≥65 yr) population is the fastest growing part of the population in many parts of the developed world. Perioperative morbidity becomes more frequent in the elderly with steep increases after the age of 75.

Aging is a universal and progressive physiological phenomenon clinically characterized by degenerative changes in both the structure and the functional capacity of organs and tissues. Aging increases the probability of a person to undergo surgery.

Physiology and pathophysiology of aging

Age alters both pharmacokinetic and pharmacodynamic aspects of anesthetic management. The functional capacity of organs declines and co-existing diseases further contribute to this decline.

Geriatric patient means:  decreased beta-adrenergic responsiveness increased incidence of conduction abnormalities, bradyarrythmias & HTN.  Fibrotic infiltration of cardiac conduction pathways conduction delay & atrial and ventricular ectopics.  increased reliance on Frank-Starling mechanism for cardiac output. Cardiovascular

It is important to consider fluid administration carefully: non compliant older heart (diastolic dysfunction) + decreased vascular compliance small changes in venous return will large changes in ventricular preload and cardiac output elderly patient compensates poorly for hypovolemia & exaggerated transfusion.

Cardiovascular effects of aging

Respiratory COPD, pneumonia, sleep apnea very common. Closing volume increases with age FEV1 declines 8-10% per decade due to reduced pulmonary compliance. PaO2 progressively with age d.t. – V/Q mismatch – anatomical shunt.

Respiratory effects of aging

Thus, it is recommended that elderly patients are transferred to PACU with oxygen via nasal cannula. Postoperative respiratory complications are most common in geriatric patients. The most significant clinical predictor of adverse pulmonary outcome is the site of surgery, with thoracic and upper abdominal surgery having the highest pulmonary complication rate.

Renal function Renal BF and nephron mass with age increased risk of acute renal failure in the postoperative period. Serum creat. remains stable due to a reduction in muscle mass(!). Impairment of sodium handling, conc. ability and diluting capacity predisposes elderly pts to dehydration and fluid overload.

Nervous system As the nervous system is the target for virtually every anesthetic drug, age related changes in nervous system function have essential implications for anesthetic management.

Nervous system Aging results in decreased nervous tissue mass neuronal density concentration of neurotransmitters norepinephrine and dopamine receptors.

Nervous system That’s Why: Dosage requirements for local and general anesthetics are reduced. Administration of a given volume of epidural anesthetic results in – more cephalic spread, – though a shorter duration of sensory and motor block.

Nervous system Elderly patients: take more time to recover from GA especially if they were disoriented preoperatively. experience varying degrees of delirium. sensitive to centrally acting anticholinergic agents. The % of delirium is less with regional anesthesia, provided there is no additional sedation.

Pharmacology

The circulating level of albumin (binding protein for acidic drugs) decreases with age. While the level of α-1 acid glycoprotein (binding protein for basic drugs) increases.

The decrease in total body water leads to a reduction in the central compartment and increased serum concentrations after a bolus administration of a drug. On the other hand, the increase in body fat results in a greater volume of distribution, thus prolonging drug action. Drug metabolism could probably be altered by the aging effect on hepatic or renal function.

TO SUM-UP The elderly are more sensitive to anesthetic agents and generally require smaller doses for the same clinical effect, and drug action is usually prolonged.

anesthetic agents in the elderly

Inhalation drugs: Minimum alveolar anesthetic conc. (MAC) decreases approximately 6% for every decade. Due TO – altered activity of neuronal ion channels associated with cholinergic, nicotinic and GABA receptors. – Alterations in ion channels, synaptic activity and receptor sensitivity.

Opioids: The elderly require less doses for pain relief. Morphine clearance is decreased. Sufentanil, alfentanil, and fentanyl are twice as potent in the elderly, d.t. increased brain sensitivity. Remifentanil is more potent in geriatric pts. For All: infusion rates should be titrated.

Neuromuscular blockers: The duration of drug action may be prolonged if their metabolism depends on renal or hepatic excretion. Cisatracurium undergoes Hofmann degradation,so, unaffected by age.

Peripheral nerve blocks: The duration of analgesia may be prolonged with age depending on the baricity of the bupivacaine solution. When using 0.75% ropivacaine for nerve blocks, age is a major factor in determining the duration of motor and sensory block. When GA carries great risk for the pt, regional anesthesia could provide an excellent solution.

Preoperative evaluation

it is very important to determine the patient’s status and physiologic reserve in the pre- anesthetic evaluation. The risk from anesthesia is more related with the presence of co-existing disease than with the age of the patient. If the condition can be optimized before surgery this should be done without delay, as long delays increase morbidity rates.

DM and CV diseases are very common. Pulmonary complications are one of the leading causes of postoperative morbidity, so, pulmonary optimization is essential. History, physical examination, Lab. and diagnostic studies are of great importance.

Some more issues that must be always in mind in a geriatric patient is the significant possibility of depression, malnutrition, immobility and dehydration.

It is important to determine the cognitive status of an elderly patient. Cognitive deficits are associated with poor outcomes and higher perioperative morbidity. It is controversial whether general anesthesia accelerates the progression of senile dementia.

lower doses of premeds. Opioid premed is valuable only if there is severe preoperative pain. Anticholinergics are not required since salivary gland atrophy is usually present. H 2 antagonists are useful to reduce the risk of aspiration. Metoclopramide could be used to promote gastric emptying, although risk of extrapyramidal effects is higher.

Intraoperative care and anesthetic management

Advanced age is not a contradiction for either GA or RA. Some aspects of RA may benefit the pt.: – It prevents postoperative inhibition of fibrinolysis decreases the incidence of DVT after total hip arthroplasty. – The hemodynamic effects of RA may reduce blood loss in pelvic and lower extremity operations. – More important, the patient maintains his airway and pulmonary function.

Advanced age and general anesthesia are associated with hypothermia, so; Maintenance of normothermia is important as hypothermia to myocardial ischemia & hypoxemia in the early postop. period. In case of general anesthesia, it is of major importance to titrate drug doses and it would be wise to use short acting drugs.

The use of peripheral blocks promises favorable outcomes without compromising airway or hemodynamics. However, peripheral blocks have shown to last longer d.t. some anatomic changes in geriatric patients.

Postoperative care

Pulmonary problems are of major importance in the postoperative period. Shorter hospitalization is badly needed. Minimal-invasion surgery and regional over general anesthesia when possible, could probably lead to a more favorable outcome for geriatric patients Postop. Pain!!

Common causes of postoperative morbidity: Atelectasis Heart failure Pneumonia Delirium Neurological disease Acute bronchitis Myocardial infraction

Postoperative delirium

Postoperative delirium is common in the elderly in the postoperative period. It can result in increased morbidity, delayed functional recovery, and prolonged hospital stay. In surgical patients, factors such as age, alcohol abuse, low baseline cognition, severe metabolic derangement, hypoxia, hypotension, postop. Pain and type of surgery appear to contribute to postoperative delirium.

Anesthetics, esp. anticholinergics and benzodiazepines, increase the risk for delirium. Despite the above recommendations, postoperative delirium in the elderly is poorly understood. Research is needed to define the effects of hypoxemia on cerebral function and whether oxygen therapy has any benefits.

The geriatric-anesthesiologic intervention program: pre- and postop. geriatric assessment, early surgery, thrombosis prophylaxis, oxygen therapy, prevention and treatment of perioperative decrease in BP, and vigorous ttt of any postoperative complic.

In Conclusion

Elderly patients are uniquely vulnerable and particularly sensitive to the stress of trauma, hospitalization, surgery and anesthesia. Accordingly, minimizing perioperative risk in geriatric patients requires: – meticulous preoperative assessment of organ function and reserve, – meticulous intraoperative management of coexisting disorders, – Careful drug selection & dosage titration, – Careful fluid therapy, – RA better than GA – Proper psychological preparation & management – and alert postop. pain control.