Geriatric Anesthesia Flashcards

Question

Afib management

Answer 1

Preoperative patient presents with AF Is the rhythm acute change or chronic For chronic AF check rate control and coagulation status and proceed New onset evaluate hemodynamic status and recommend cardiac workup rule out MI protocol and evaluate thrombus formation Must evaluate the urgency of the procedure

Answer 2

1 MET is equal to an oxygen consumption of 3.5ml/kg/min Inability to achieve 4 METS is associated with increased perioperative risk of cardiac complications

Answer 3

SNS tone increased = higher norepinephrine concentration in plasma

Answer 4

Reduced beta receptor sensitivity

Answer 5

PNS tone decreased = anticholinergics may not increase HR as expected

Answer 6

Decreased response to catecholamines = decreased adrenergic receptor density, impaired beta receptor sensitivity, reduced ability to increase HR during hypotension or times of stress

Answer 7

MAC decreases 6% for each decade of life after 40, IV agent dose should be reduced by 30-40%

Answer 8

Reduced activity of Ach, NE, DA and GABA Number of receptors may be reduced Increased sensitivity to anesthesia agents

Answer 9

Decreased Brain mass, but does not reduce mental capacity Reduced number of myelinated nerves and degeneration of nerves that remain

Answer 10

* Chronic neurodegenerative disorder * Most common cause of dementia and forth most common cause of disease related death in patients older than 65 * Amyloid rich senile plaques and neurofibrillary tangles are the hallmark of pathologic findings * Changes in acetylcholine and central nicotinic receptors * Genetic factors-Autosomal dominant mode of transmission * Early onset < 60 non-hereditary * Late onset > 60 hereditary

Answer 11

NO cure Cholinesterase inhibitors Tarcrine, donepezil, rivastigmine and galantamine Poor Prognosis Cholinesterase inhibitors reduce plasma pseudocholinesterase and increase the duration of succinylcholine and mivacurium

Answer 12

A disorder of the extrapyramidal system and is one of the most common neurodegenerative diseases Age is the single most consistent risk factor affecting 3% of the population older than 65 and 50% of the population older than 85 Parkinson’s disease is characterized by progressive depletion of dopaminergic neurons in the substantia nigra of the basal ganglia... **Imbalance between the inhibitory action of dopamine and the excitatory action of acetylcholine **

Answer 13

Classic symptoms rigidity resting tremor and bradykinesia Treatment: L-dopa or dopamine receptor agonist Surgical deep brain stimulation and fetal mesencephalic tissue implantation

Answer 14

Dopaminergic neurons in the basal ganglia are destroyed Increase in cholinergic activity Increased Ach in the basal ganglia increases GABA activity in the thalamus Thalamic inhibition suppresses cortical motor system and motor areas in the brainstem --> over activity of the extrapyramidal system Decreased dopamine and normal acetylcholine = a relative Ach increase --> suppression of corticospinal motor system and overactive extrapyramidal motor system

Answer 15

* Given together the drugs increase the concentration of dopamine in the basal ganglia * Levodopa is the precursor to dopamine, it is metabolized in the blood to DA and can not penetrate the CNS * Carbidopa is the decarboxylase inhibitor that prevents the metabolism in blood so more can enter the CNS * CV side effects: increased inotropy, tachycardia, and orthostatic hypotension * Dyskinesia nausea and vomiting are other side effects

Answer 16

A MAO inhibitor that works by slowing the breakdown of neurotransmitters dopamine norepinephrine and serotonin in the brain

Answer 17

* Patients are at risk for: autonomic instability, orthostatic hypotension arrhythmia and aspiration * Medications should be administered as close to the regular schedule as possible Levodopa has a half life of 6-12 hours consider giving PO dose for longer procedures. * Drugs may exacerbate Parkinson symptoms: phenothiazines (promethazine), butyrophenones (haloperidol and droperidol), and metoclopramide should be avoided * Anticholinergics may be used to treat acute exacerbations * Diphenhydramine has anticholinergic properties * Hypotension should be treated with IVF and direct acting agents * Alfentanil may cause an acute dystonic reaction * Ketamine is controversial due to effects on SNS * No contraindications to NMBD * Monitor for postoperative respiratory failure

Answer 18

May hold levodopa and allow symptoms to worsen which facilitates electrode placement Stereotactic guided burr holes to insert electrodes into the: Sub-thalamic nucleus, Globus palidus, Ventralis intermedius During electrode placement the patient must be awake GABA agonist are avoided Sitting position VAE risk Risk of intracranial hemorrhage keep SBP 140mmHg Seizures can be treated with small doses of propofol or benzodiazepine

Answer 19

* No change in serum creatinine even though GFR decreases with age muscle mass also decreases * Renal blood flow decreases 10% per decade * Renal mass decreases, loss of functioning glomeruli and loss of nephrons cortex >>> medulla * Decreased creatinine clearance The most sensitive indicator of renal function and drug clearance in the elderly

Answer 20

Decreased response to acid load due to the reduced capacity of the renal tubules to secrete ammonium Decreased aldosterone and impaired ability to conserve sodium  risk of dehydration Decreased ADH, and elderly have a reduced response to ADH

Answer 21

No change in hepatocellular function normal enzyme function Decreased hepatic mass less total enzyme produced Decreased hepatic blood flow less drug or toxin delivered to liver per unit time Decreased perioperative hepatic function as a result of decreased blood flow and decreased liver mass

Answer 22

Decreased albumin production  decreased reservoir for acidic drugs Increased alpha 1-acid glycoprotein production  increased reservoir for basic drugs Both are not significant in clinical anesthesia Reduced pseudocholinesterase production --> prolonged duration of succinylcholine and ester local anesthetics men > women

Answer 23

Reduced phase I reactions --> oxidation, reduction and hydrolysis No change in Phase II reactions --> conjugation and acetylation Reduced first pass metabolism due to reduced hepatic mass and liver blood flow

Answer 24

Testing should be directed by the type of surgical procedure , known coexisting conditions or findings on physical exam ECG, baseline hematocrit and hemoglobin Most important for postoperative functional recovery is the patients preoperative functional status Cardiac testing should be reserved for patient who cannot achieve 4 METs with additional risk factors for ischemic heart disease Malnutrition is an independent risk factor for 30 day and 1 year mortality

Answer 25

Increased Sensitivity of nerves to local anesthetics Decrease number of myelinated nerves, diameter of myelinated nerves and conduction velocity Increased sensitivity to intrathecal anesthetics Decreased CSF volume --> greater spread of LA --> reduce dose Increased sensitivity to epidural anesthetics Decreased epidural space volume --> greater spread of LA --> reduce dose Dura is more permeable to LA --> reduce dose

Answer 26

Difficult placement of neuraxial block Anatomic changes: Less space between posterior spinous processes Decreased intervertebral disc height Narrow intervertebral foramen Calcification Because of reduced myocardial sensitivity to catecholamine's there is a higher risk of false negative to epi test dose

Answer 27

Increased circulation time --> reduced CO prolongs the time of drug delivery from the site of administration to the site of action Slower IV Induction, faster inhalation induction Increased Surface area to body mass ratio --> reduced lean body mass Increased total body fat --> Increased Vd of lipophilic drugs and a larger reservoir may prolong their elimination

Answer 28

Decreased lean body mass --> less muscle mass Decreases in: - basal metabolic rate - total body water - blood volume and plasma volume Smaller Vd for hydrophilic drugs higher than expected plasma concentration for a given dose

Answer 29

Reduced anesthetic requirement MAC is decreased by 6% for every decade after the age of 40 Recovery from inhaled anesthetic is delayed due to increased fat content and decreased pulmonary gas exchange

Answer 30

Elderly require less drug to produce unconsciousness (Decrease bolus and infusion by 50%)

Answer 31

Dose required to produce sedation decreases with increasing age minimize dose (Avoid; decrease dose by 75%)

Answer 32

The dose needed to produce pharmacological effect decreases with age. (Decrease bolus by 50%) Enhanced sensitivity to opioids mostly due to pharmacodynamics changes

Answer 33

Slightly slower onset of action due to decreased muscle blood flow Dose requirement for most water soluble non-depolarizing agents is reduced since total body water is decreased Prolonged elimination half life of drugs that are eliminated by hepatic or renal excretion Elimination of cisatracurium is unaffected, onset is delayed

Answer 34

Aging is associated with progressive loss of functional reserve, the extent and onset of these changes vary between individuals CV-less elastic large arteries, increased afterload, concentric hypertrophy of the left ventricle, increased myocardial O2 demand, diastolic dysfunction-impaired passive filling, atrial distention and fibrosis-AF, down regulation of beta adrenergic receptors

Answer 35

Respiratory: restrictive pulmonary changes-thoracic stiffness, increased work of breathing and decreased maximum minute ventilation closing capacity surpassed FRC by 65, decreased ventilatory response to hypoxia and hypercarbia

Answer 36

CNS: cerebral atrophy decreased blood flow, decreased synthesis of neurotransmitters

Answer 37

Renal: decreased GFR, renal blood flow, and renal mass

Answer 38

Hepatic: decreased liver mass, blood flow and hepatic reserve, decreased protein synthesis including albumin

Answer 39

Serious post op complication POCD increases postoperative mortality