Anesthesia for Geriatrics.pdf

Anesthesia for Geriatrics 1935-6.1% of population >65 2010-13% of population >65 (40 Mil) 2030- >20% of population (71 Mil) 2050- 90 mil 28 %surgical cases (2.7 X more) For optimal anesthetic management: o Understanding normal changes of A&P in aging population o Understanding of pharmacologic chang...

Anesthesia for Geriatrics 1935-6.1% of population >65 2010-13% of population >65 (40 Mil) 2030- >20% of population (71 Mil) 2050- 90 mil 28 %surgical cases (2.7 X more) For optimal anesthetic management: o Understanding normal changes of A&P in aging population o Understanding of pharmacologic changes Geriatric Anesthesia Considerations What are three primary factors associated with perioperative risks in older adults? o Reduced reserve capacity and functional decline o Comorbidities (atypical disease presentation) o Untoward reactions to medications Aging Process Gradual and cumulative process of damage and deterioration Variety of processes attack DNA, proteins and lipids Primary culprits--free radicals o by products of oxidative metabolism How does body composition change? Lean body mass—decreases Skeletal muscle—decreases Total body water—decreases Tissue elasticity—decreases Body fat—increases o affects Vd, protein binding Plasma albumin levels—decreases Basal metabolism—decreases Body Composition Loss of lean body mass and skeletal muscle Decrease in total body water (↓ Muscle mass) Loss of tissue elasticity Increase in body fat (more in women) o Any effect to Vd? ▪ Increased Vd of lipophilic drugs (prolongs elimination) ▪ Decreased Vd of hydrophilic drugs o Any effect on anesthetic agent? ▪ Decreased CO leads to slower IV induction and faster inhalation induction Decrease in plasma albumin levels o Any anesthetic concerns? ▪ Decreased reservoir for acidic drugs Thin, fragile skin Stiff joints o Any anesthetic concerns? ▪ Airway management ▪ Limited neck ROM Basal metabolism decreases with age Metabolic Equivalents (METs) 1 MET = O2 consumption of 3.5 ml O2/kg/min 1 MET → poor functional capacity o Self-care o Working at a computer o Walking 2 blocks slowly 4 METs → good functional capacity o Climbing flight of stairs without stopping o Walking up a hill (> 1-2 blocks) o Light housework o Raking leaves; gardening 10 METs → outstanding functional capacity o Strenuous sports (running, swimming, basketball) Organ Functional Reserve: Safety Margin of Organ Capacity Functional reserve: difference between maximal and basal reserves o decreased as a result of aging Organ Systems Affected: Cardiovascular Respiratory Renal Hepatic, GI Endocrine Thermoregulatory Nervous (CNS, PNS) CV Changes Calcification of heart valve ↓ Arterial elasticity o Arterial compliance decreases o Loss of elastin & collagen o Increased SVR and afterload → increases BP Elevated afterload Elevated SVR (SBP) Elevated pulse pressure o pulse pressure = SBP – DBP o normal: 40-50 LVH Systolic function → no change Diastolic function → decreased HR, SV, CO → decreased o SA node atrophy o loss of atrial kick → a-fib Circulation time → increased (prolonged) o Due to decreased CO Slower onset of IV drugs Faster onset of inhalation agents CV changes and Frank-Starling Relationship: o Leads to diastolic dysfunction o Culprit in most cases of CHF o Ventricular filling-more critical with age o Decreased response to beta receptor stimulation → dependence on EDV o EDV needed to generate contractile strength ▪ more difficult to generate forceful contraction Frank-Starling Curve SV – CO LVEDP – PCWP & RAP/CVP Aging and Contractility: Response to Exercise CV Changes: ↓ adrenergic responsiveness ↓ resting and maximal HR ↓ baroreceptor reflex o Diminished in increased HR with stress Fibrosis of conduction system o Increased incidence of dysthymias o Loss of SA node tissue CV Patho and Aging: Atherosclerosis—thickening/plaque in arteries CAD Essential HTN: o 50-75% ↑ in atrial stiffness o 25% ↑ SVR CHF Cardiac dysrhythmias Aortic stenosis Anesthetic considerations: o o o o o o Concurrent drug regimens can impair autonomic reflex function Beta Blockers: Need to continue? YES Consider other medications? D/c NTG ▪ blood thinners Consider positioning → slow baroreceptor response, slow position changes, orthostasis During anesthesia can: ▪ Changes in sympathetic tone from ▪ Waxing and waning surgical stimulus ▪ Variable depth of anesthesia ▪ Changes in patient’s volume status Results in: ▪ CV/BP instability ▪ Exaggerated SNS activity & hypertension during induction SUMMARY OF CV CHANGES: Volume Dependence of the Elderly Heart o Elderly heart depends on delayed filling that in turn depends on left atrial pressure o Elderly heart is also stiff, so the left atrial pressure must be high in order to fill the LV o Prone to diastolic dysfunction o Poor venous buffering of blood volume makes maintenance of left atrial pressure difficult Less ability to respond to: ♥ hypovolemia ♥ hypotension ♥ hypoxia Remember: delayed circulation → slower onset of IV drugs! Respiratory Changes increased pulmonary collagen decreased pulmonary elasticity decreased alveolar surface area increased deadspace ventilation V/Q mismatch o increased alveolar–arterial difference for oxygen o decreased PaO2 What happens to chest wall compliance? o decreases o chest is stiffer What factors cause these changes in the elderly? o increased AP diameter o increased intercostal muscle mass o joint calcification o loss of intervertebral disc height o flatter diaphragm What happens to lung compliance? o increases → easier to increase the lung but decreased elasticity (harder to relax/exhale) o chest wall compliance decreases Lung Volumes & Capacities Increase in: o Residual volume o Closing capacity o Functional residual capacity Decreased in: o Vital capacity o Total lung capacity ▪ questionable; some say decreased, some say no change How does minute ventilation change in the elderly? o increases d/t increased dead space o increases to maintain normal PaCO2 o FRC increases, dead space increases Why? o increased dead space Respiratory Changes: Loss of muscle tone in airway o Predisposes to what? Upper airway obstruction ▪ obstruction and failure Sleep disordered breathing Increase: shunting, dead space o Predisposes elderly to postop hypoxia Less effective coughing and swallowing o Risk of: aspiration, PNA Respiratory Patho & Aging emphysema chronic bronchitis PNA lung cancer TB Respiratory Anesthetic Considerations Edentulous patient o Challenge? BMV Arthritis of the TMJ or cervical spine o Challenge? Position, airway Perioperative hypoxia o What are few actions you can do to prevent it? ▪ preoxygenate ▪ higher FiO2 ▪ more PEEP ▪ pulmonary recruitment/toileting Postop anesthesia considerations: o Discuss post operative pulmonary related anesthetic considerations in elderly patients ▪ Responds less vigorously to hypoxia and hypercarbia ▪ Increased risk of resp failure ▪ Decreased reflexes ▪ Post-op pain mgmt. – multimodal approach vs. narcotics Renal Changes Renal function o RBF and GFR decreased Renal mass decreased Tubular function decreased o Impaired Na/fluid handling o Impaired K excretion o Decreased drug excretion o Decreased renin-aldosterone responsiveness By age 80, 50% of nephrons are lost. Renal Patho & Aging Diabetic nephropathy Hypertensive nephropathy Prostatic obstruction CHF Anesthetic considerations: o Risk of post-op acute renal failure o What are two main factors? ▪ decreased renal blood flow and GFR ▪ loss of mass and loss of functioning glomeruli ▪ nephrotoxic drugs (Toradol, antibiotics like tobramycin & Amikacin) o What are your concerns with elderly pts w/renal impairment? ▪ risk of fluid overload (CHF) ▪ electrolyte imbalances → arrhythmias ▪ accumulation of metabolites and drugs excreted by kidneys prolonged effects of drugs d/t decreased elimination Endocrine Changes Surgery and anesthesia result in increased glucose increased insulin resistance with age increased insulin requirements during the surgery decreased renin decreased aldosterone increased K+ (careful with KCl containing fluids) decreased hypertensive response Hepatic Changes Liver size → decreased Hepatic blood flow → decreased Age-related redistribution of perfusion → decreased Albumin production → decreased Hepatocellular synthetic activity → decreased o Meets demands for coagulation factors o Activity is significantly reduced o Easily overwhelmed w/maximal stress (surgery) o Clearance mechanism reduced Decreased colloid osmotic pressure Thermoregulation Basal metabolism → decreased o decreased heat production Autonomic peripheral vasoconstriction → decreased Shivering → increased o increases O2 consumption o increases myocardial workload & O2 demand ▪ increases risk of ischemia Surgical wound infection → increased Coagulopathy → increased blood loss GI Changes decreased esophageal/intestinal motility decreased GE sphincter tone Anesthetic considerations: o increased risk for pulmonary aspiration with GETA o take appropriate precautions: ▪ maintain NPO ▪ RSI & cricoid pressure o Reglan? ▪ extrapyramidal syndromes common in elderly patients ▪ increases GI motility ▪ antidopaminergic ▪ do not give if Parkinson dz o Two causes of death r/t aspiration ▪ Acidic burning of the lungs ▪ Obstruction o The longer the patient is NPO ▪ The greater acidic the gastric contents ▪ Give Bicitra (neutralize) CNS Changes CNS Function o Brain mass? decreased o Cerebral blood flow? decreased o Synthesis of neurotransmitters? decreased o Neurotransmitter receptors? decreased o Sensitivity to anesthetic agents? increased o POCD increased o POD increased Postoperative Cognitive Dysfunction (POCD) Deterioration of intellectual function o Presenting as impaired memory or concentration Not detected until days or weeks after surgery Duration of several weeks to permanent Diagnosis is only warranted if: o Corroborated with neuropsychological testing and evidence of greater memory loss than one would expect due to normal aging Risk factors: o Nagelhout box 54-6 ▪ aging ▪ drugs ▪ ASA status ▪ genetic dispositions ▪ type of surgery ▪ length of surgery Anesthetic considerations: o Prevention of POCD (Nagelhout Box 49-2) ▪ Keep anesthesia and sx as short/minimally invasive as possible ▪ Use short-acting and rapidly metabolized drugs ▪ Prefer inhaled over IV anesthetics in at-risk pts ▪ Neuroprotective drugs currently under investigation: Piracetam (nootropic) “mind-turning drugs” Ketamine Pexelizumab Remacemide Postoperative Delirium (POD) Most common form of perioperative CNS dysfunction Twice as common in the elderly o 10-15% of elderly surgical patients o 30-50% if undergoing cardiac or orthopedic surgery Considered as CNS dysfunction induced by surgical stress Acute confusion, decreased alertness, misperception Patient may show agitation or withdrawal Results in prolonged hospital stay and protracted postoperative care Pathophysiology: o Excess of dopamine o Several metabolic pathways under hypoxic conditions lead to: ▪ Increased production of dopamine ▪ Reduced degradation of dopamine o Cerebral accumulation results in delirium o Antipsychotics (dopamine D2 receptor) antagonists, could theoretically prevent POD o Neuroinflammatory process where proinflammatory cytokines cause central synaptic dysfunction and neuronal damage o This inflammatory state can be triggered by cardiac procedures on cardiopulmonary bypass o May respond to potent anti-inflammatory drugs ▪ Corticosteroids o Cholinesterase Inhibitors ▪ Under a variety of conditions Brain hypoxia, CVA, infections, surgical trauma Reduced synthesis and release of central acetylcholine o Clinically to confusion and delirium ▪ Prevalence of delirium is higher in patients with an increased serum anticholinergic activity level Incidence of POD: o The incidence of POD varies greatly ▪ Type of surgery Hip, cardiac, vascular surgery ▪ Pre-op cognitive function of patient Baseline function o Higher with males o Patients > 60 yrs of age Risk factors: o Perioperative? o General anesthesia? Do you need it? Brain hypoperfusion o Hemodynamic instability? MAP w/n 20% of baseline o Type of surgeries? CV, vascular, ortho; high stress o Post-operative? Pain control Anesthetic considerations: o Preop: ▪ Vd? increased (benzos) age > 70 caution use of Versed, may need to decrease dose to 1 mg o half-life is prolonged in the elderly ▪ anesthetic techniques? spinal/epidural; regional when possible MAC ▪ cognition impairing drugs? ▪ MAID: machine, airway, IV, drugs o Perioperative: ▪ Drug try to avoid? anticholinergics, Reglan cholinergic neurons regular normal memory ▪ Inhalational agents? Reduced concentration ▪ ▪ o Postop? ▪ ▪ ▪ ▪ Volume of distribution: increased fat, reduce dosing, prolongs emergence and recovery anesthetics will have increased Vd reduce doses of propofol and etomidate Maintain hemodynamic stability keep MAP within 20% of baseline Avoid narcotics Infections Sleep deprivation Use Ofirmev Assessment and Diagnosis Confusion Assessment Method (CAM) o Developed by Dr. Sharon K. Inouye, MD, remains a very popular and widely used tool for delirium assessment. Later developed into the CAM-ICU tool for delirium assessment specifically for the intensive care population. Case Study An 86 yr old male pt with early onset dementia is scheduled for a coronary artery bypass graft. The client has been NPO for 12 hours. This is a general anesthetic case and you are concerned about the possibility of POD. To properly guard against this occurrence and costly outcome, your peri-operative anesthetic plan should include: o avoid anticholinergics if possible o reduce the dose of inhalation agents o avoid narcotics if possible o Alfenta/Sufenta used commonly → quicker off Geriatric Syndromes Osteoporosis Osteoarthritis, RA Parkinson’s Disease Dementia Osteoporosis Microarchitectural deterioration of bone o ↓ bone density o ↑ bone fragility o Susceptibility to fractures May be asymptomatic until a fracture occurs Loss of height/increasing kyphosis-secondary to vertebral fractures Women with fractures -50% spend time in a nursing home Peak incidence is 70 years old Associated risk factors: o o o o o -Estrogen deficiency -Increased alcohol consumption, smoker -Cancer -Calcium deficiency -Long term steroid therapy Osteoarthritis Non-pharmacologic intervention(cornerstone) Patient education, PT and OT Decrease in joint stress Acetaminophen and NSAIDs Muscle relaxants-spasms Intra-articular glucocorticoid injections Narcotics and arthroplasty Cervical OA: o Difficult intubation ▪ -Decreased mobility airway ▪ -TMJ arthritis ▪ -Cervical spine-mobility and stability ▪ -Decrease glottic opening o Consider flexion/extension x-rays if concern o Easy to fracture Parkinson’s Disease Characterized by progressive depletion dopaminergic neurons of substantia nigra from basal ganglia Age is most consistent factor o 3% of population older than 65 o 50% of people older than 85 Clinical signs when approximately 80% of dopaminergic activity is lost Imbalance between the inhibitory action of dopamine and excitatory action of acetylcholine Imbalance leads to classic triad Triad: rigidity, resting tremor, bradykinesia Anesthesia considerations: o Aspiration prophylaxis o Monitoring of respiratory function o Administer drugs as close to schedule as possible o Drugs should to avoid: phenothiazines, butyrophenones (droperidol), metoclopramide o Diphenhydramine can be effective to counter drug-induced extra-pyramidal effects o ANS dysfunction-hemodynamic monitoring as needed What is deep brain stimulation? neurostimulator What type of anesthesia approach is preferred? o MAC, local o very small amount of propofol You gave your patient with Parkinson Disease 150 mcg of fentanyl intraoperatively. o What side effect should you monitor for? Why? ▪ stiffness ▪ chest wall rigidity ▪ muscle rigidity Normal physiology: o Muscle coordination depends on a feedback loop between the motor cortex, basal ganglia, cerebellum, and thalamus. o motor cortex sends instructions to cerebellum o basal ganglia and cerebellum send information back to the cortex via the thalamus o Feedback loop depends on concentrations of dopamine (DA) and acetylcholine (ACh). Pathophysiology: o Neurodegenerative disorder marked by a characteristic loss of dopamine fibers in the basal ganglia o depleting dopamine → decreased inhibition of neurons that control the extrapyramidal motor system → leads to unopposed stimulation of ACh o Increasing age – single most important risk factor for development o Dopaminergic neurons in the basal ganglia are destroyed. o This favors a relative increase in cholinergic activity. o Increased ACh in the basal ganglia increases GABA activity in the thalamus. o GABA is INHIBITORY, so increased GABA suppresses the thalamus. o When the thalamus is suppressed, the cortical motor system and motor areas of the brain are also suppressed. o This ultimately results in overactivity of the extrapyramidal system. Role of DA: o What is the extrapyramidal system? ▪ The extrapyramidal system is part of the motor system. It is responsible for involuntary movement. ▪ Controls involuntary movements of the arms when walking. Case Study Mrs. P is a 64 kg, 74 yr. old female. She is planned to undergo an open reduction and internal fixation of her humerus after a fall this morning. She has a diagnosis of Parkinson Disease and was not able to take her morning dose of Levodopa due to her fall. Patient states her symptoms are moderately controlled with her medication, but she does suffer from mild tremors, occasional episodes of confusion, dyspnea on exertion, and dysphagia. HR 78, BP 123/86, RR 16, SpO2 98% on RA, temp 98.0. What are the recommendations for the perioperative period concerning medications? Dementia Early hallmark → intellectual decline Sudden changes in cognitive function may occur Abrupt changes in mental status-necessitates search for further problems Decreased longevity with cognitive decline Summary of anesthesia for geriatric patients: Reduced drug binding to albumin: o Circulating level of serum protein o Qualitative changes in circulating protein o Co-administered drugs that interfere with ability of anesthetic drugs to bind to sites o Disease states Volume of distribution: o Affected by altered plasma protein binding o Albumin binds to acidic drugs (barbs, benzos, & opioids) Levels decrease with age o Alpha 1-acid glycoprotein binds to basic drugs (LA and sufentanil) ▪ Typically decreases or unchanged with age (??) Induction drugs: o Thiopental: ↓ dose required after age 60 o Etomidate: ↓ dose (age-related decline in Vd not alteration in brain activity) ▪ Causes HTN and tachycardia in all age groups o Propofol: benefits in elderly r/t short beta- elimination ½ life. ▪ Decrease dose & titrate slowly-propofol leads to hypotension Muscle relaxants & reversals: o SUX: Slower onset (40%) o NDMRs depending on renal excretion are prolonged (Pancuronium?) o Atracuruim is unaffected by age o NDMRs doses are changed little by the process of aging itself o How about Neostigmine? ▪ increased dose Regional vs. Spinal o No technique has shown to be superior for the elderly o Selection of technique: ▪ Pt’s clinical condition ▪ Surgical requirements ▪ Skill/experience of the anesthetist ▪ Some evidence supports that older pts have better prognosis of the surgery is done under local rather than GETA or regional Local anesthetics: o Suggestion of decrease in requirements LA o Decrease in quantity of myelinated fibers in dorsal and ventral roots of spinal cord o Decrease in original neuronal population, number of axons in the peripheral nerves o Increased permeability of extraneural tissues (why you decrease the dose) LA in epidural anesthesia: o Narrowing of intervertebral spaces and osteophytic growth suggests that LA less likely to spread outward and more likely to spread upward in the spinal canal o Increased permeability produces more rapid onset o Reduced clearance and prolonged elimination ½ life leads to toxic conc. with lower doses Preop assessment to prevent drug-related problems: o Previous anesthetic hx o Medications (prescribed and OTC) o Adverse drug reactions o Potential for drug interaction with current meds o Pertinent medical problems o Provide information/education r/t pain management, anesthetic agents, surgical medications