Anaesthesia in Elderly - Azizul Salehudin.pptx

Anaesthesia in Geriatric Population

1. ANAESTHESIA IN ELDERLY PATIENTS PRESENTER: DR AZIZUL SALEHUDIN SUPERVISOR: DR PHANG SL

2. OVERVIEW Introduction Objectives Definition Classification Factors of Aging Changes Aging Related Physiological Changes Cardiovasular Respiratory Nervous Musculoskeletal Renal Hepatobiliary Hematology Pharmacokinetics and Pharmacodynamics Strategies Pre-op Intra-op Post-op Conclusion References

3. INTRODUCTION Perioperative complication increased 3 times higher in patient > 70 years old (more in emergency op) In advanced aged patients, the decision for surgery must be made collectively by surgeon, anaesthetist, supportive teams and family members A careful pre-operative assessment is imperative to achieve a good outcome

4. OBJECTIVES To understand impact of physiological changes of ageing in anaesthetic care To anticipate the possible anaesthetic complications in geriatric populations To provide the optimal anaesthetic and perioperative care for elderly patients

5. DEFINITION Gerontology is the broadest term applied to studies of aging Geriatrics - medical subspecialty that focuses upon care of the elderly patients

6. DEFINITION Chronological Age: Age according to birth date Physiological Age: Estimated ageaccording to body organs state Ageing is a progressive physiological process that is characterised by degenerative changes in both structure and function of organ and tissues with consequent loss of functional reserve of various systems, more importantly with a decrease in ability to respond to stress and overcome complication. Successful ageing -“low probability of disease and disease-related disability, high cognitive and physical functional capacity, and active engagement with life”.

7. CLASSIFICATION

8. Decline in functional reserve Slower healing process FACTORS THAT INFLUENCED THE AGING CHANGES

9. FUNCTIONAL RESERVE The difference between maximal activity and basal level of function – Organ system functional reserve Physiologically Young – Elderly patients who maintain greater than average functional capacities. Physiologically Old – Elderly patients whose organ function declines at an earlier age than usual or at a more rapid rate.

10. AGING RELATED PHYSIOLOGICAL CHANGES

11. AGING OF CARDIOVASCULAR SYSTEM Modest decrease in resting cardiac index in elderly, attributable to lower metabolic requirements with age related atrophy of muscle and loss of lean tissue mass.   Exercise tolerance - maximum attainable HR, SV and CO are typically reduced 1 MET self-care, walking around the house 4 METs household chores, climbing stairs or walking up a hill 4-10 METs brisk walking, running short distances, heavy household work, engaging in sports such as golf, softball or dancing >10 METs swimming, football, basketball, skiing

12. 2. Decreased cardiac output (by 1% per year) and stroke volume Unable to increase CO by increasing HR- due to “ hyposympathetic state” SV mostly dependent on venous return 3. Decreased beta adrenergic receptor responsiveness • Reduced response to stimulation at cardiac and end organ level • Decreased heart rate, reduced SAN function • Decreased baroreceptor sensitivity 4. Conduction abnormality, sick sinus syndrome

13. 5. Diastolic Dysfunction - physiologic or preclinical state in which abnormal relaxation and  LV stiffness is compensated by  LA pressure to maintain LV preload. Structural changes Stiffer and less complaint ventricles Loss of ‘atrial kick’ 6. Age related arteriosclerosis – chronic elevated afterload, LVH 7. Increased activity of sympathetic nervous system Increase in the amount of norepinephrine release. Increase in SVR (0.5% increase/ yr ). Slightly increased Alpha receptor response. 8. Decreased response to atropine

14. Anaesthetic Implications (CVS) In neuraxial block Greater degree of stability over GA . Eliminates surgical stimulation induced increased sympathetic tone Can cause severe hypotension when compared to GA Hypotension -> fluid resuscitation and α agonist - to restores BP and CO to basal levels drug of choice -> α agonist - Metaraminol ( Aramine )

15. Anaesthetic Implications (CVS) 2. In General Anaesthesia Diminished cardiac reserve - exaggerated fall in BP during induction. β blockers promotes hemodynamic stability particularly at the time of intubation. Anticholinergic mixed with α/β agonist are indicated in bradycardia compromising cardiac output.

16. AGING OF RESPIRATORY SYSTEM Chest wall compliance, the elastic recoil of the lungs and respiratory muscle strength all decreased. Structural changes Upper airway-  protective reflexes,  mucociliary function Lungs -  tissue elasticity, loss of recoiling effect of lung. -Loss of alveolar septa -  diffusing capacity ,  physiological dead space. - interstitial connective tissue causes duct ectasia -  anatomical dead space. Stiff chest wall -  work of breathing, shortness of breath

17. Ventilatory mechanics Lungs - emphysematous and compliant RV of lung increases at the expense of IRV and ERV- causing VC is significantly compromised Mismatch between stiff chest wall and respiratory muscle weakness- After 60yrs, FVC  by 14- 30ml/ yr and FEV 1  by 23-32ml/ yr . FRC increases (Closing capacity reaches FRC in upright position at 66 yrs and supine position at 44yrs)  A ir trapping due to loss of elastic forces-  closing capacity ,  RV

18. 3. Control of Ventilation and Gas Exchange Ventilatory response to hypercapnia  by 40% and hypoxia  by 50% due to declining chemoreceptor function Respiratory drive  Misdistribution of ventilation- V/Q mismatch- dead space V>Q Pulmonary venous admixture- Q> V P A O 2 and P a O 2  with age P A O 2 = (100- age/4) mm of Hg Mean arterial oxygen tension at room air reduces from 95mm of Hg at 20 years to 70mm of Hg at 80 years. More prone to sleep apnoea

19. Anaesthetic Implications (Respiratory) Difficult mask ventilation - loss of facial contour, buccal fat, dentition Cervical arthritis- restrict neck movements, more prone to vertebra-basilar artery insufficiency Distorted alveoli impairs gas exchange - blood O 2 content falls by 10-15% while CO 2 levels remain unchanged Less compliant chest wall - greater risk of peri-op hypoxemia ABG is more reliable in assessing respiratory functions

20. Anaesthetic Implications (Respiratory) Premedication- increases risk of aspiration Aspiration prophylaxis- sodium citrate, ranitidine, metoclopramide V/Q scan for elderly patients undergoing pulmonary surgery Increase in MV to achieve normal PaCO2 due to gas exchange abnormality , which is more in recumbent position and in respiratory disease. Early respiratory mobilization and sitting position in post operative period improves respiratory mechanics and oxygenation.

21. AGING OF NERVOUS SYSTEM 1. Brain anatomy Neuronal shrinkage and loss.  production of neurotransmitters- noradrenaline, serotonin, acetylcholine and dopamine Grey matter – atrophy (grey>white), brain weight reduces 2-3g per year after 60 years. Hemispheric volume reduces by 2% -3.5% per decade after the age of 20. Enlarged ventricles,  CSF, sulcal widening and  space between surface of brain and skull. Function- decline in cognition, motor, sensory and behavioural function. Decrease in memory, vision, hearing and vibratory sense in lower extremity is common.

22. 2. Cerebral circulation Cerebral autoregulation and CO 2 responsiveness – well preserved.  mass - specific (ml/100g/min) global and regional blood flow. Progressive  total (ml/min) hemispheric blood flow. 3. Neurophysiology -  neuronal activity,  brain-spinal cord neurotransmitter activity. Decreased plasticity, impaired recovery from neuronal injury 4. Autonomic system-  sympathetic and  parasympathetic flow. Common problems - hypothermia, heat stroke, orthostatic hypotension, syncope 5. Common pathologies - cerebral atherosclerosis, Parkinson’s disease, Alzheimer’s disease, delirium, depression, dementia

23. Anaesthetic Implications (CNS / PNS) Increased pain threshold and potency of inhalational agents. Increased sensitivity to anaesthetic drugs Decrease in anaesthetic requirement Delayed recovery from anaesthesia Incidence of post-op delirium and in 15-50% POCD (post-op cognitive dysfunction) Decreased requirement of LA for spinal and epidural anaesthesia Tracheal Extubation only when wide awake.

24. In Neuromuscular Junction Decline in number and density of motor neuron Increase in the number and variety of cholinergic receptors at the NMJ and surrounding areas offsets the age related decline in the number of motor endplates Hence, despite loss of skeletal muscle mass, dose requirements of NM blocking drugs are not reduced.

25. Thermoregulation Elderly- reduced metabolic rate, reduced subcutaneous fat Delayed and less vigorous compensatory mechanisms- cutaneous vasoconstriction, shivering etc. Effects of hypothermia CNS depression, depression of ventilator drive - postop somnolence and hypoxia Prolonged drug action Accelerates protein catabolism

26. Vigorous compensatory mechanisms for hypothermia- increases oxygen demand beyond respiratory and cardiac capacity of the patient. Hence, can precipitate myocardial ischemia. Leftward shift of oxygen dissociation curve (ODC) Slower wound healing and surgical recovery, impairs coagulation, immune dysfunction. Prevention Use of warming blankets Warm solutions, fluid warmers Regulating OT temperature accordingly

27. AGING OF RENAL SYSTEM Renal tissue atrophy – decrease of glomeruli and nephrons by 40% GFR (45% by 80yrs) ;  Creatinine clearance – decline of 0.75ml/min/ yr Maintain urine output >0.5ml/kg/hr – 20% of total post- op death due to post-op AKI Decline in active tubular secretion and reabsorption of drugs Elimination half-life of anaesthetic drugs prolonged in elderly Estimation of Cr. Clearance - Cockroft & Gault formula to assess excretion of drug (140-age in yrs )* ( wt in kg) ----------------------------------- 72* S. Cr (mg/ dL )

28. Fluid and electrolyte disturbances  R esponse to ADH,  absorption of filtered glucose  Na + and water homeostasis, functional hypoaldosteronism - impaired Na + conservation and  K + excretion Response to fluid loading and dehydration impaired. Loss of water of >2kg is significant In water depletion, rapid replacement might result in cerebral edema . Hence, half deficit infused over 24hrs and rest half over next 24-48hrs Volume overload can occur due to functional impairment of diluting segment of nephrons Decreased acid excretion.

29. AGING IN HEPATOBILIARY SYSTEM  Hepatic tissue- 40-50% of total hepatic tissue involute by the age of 80.  Hepatic blood flow ( falls by 1% per yr to about 40% beyond 60yrs)  Hepatic microsomal function (quantitative, quality of hepatocellular enzymatic function retained)  Pseudocholinesterase level  A bility to handle a glucose load – insulin resistance or impairment of insulin function.  Glycogen storage may lead to hypoglycemia  Synthesis of clotting factor Quantitative loss of hepatic tissue affects clearance of anaesthetic drugs. Further prolongation of action of anaesthetic drugs if primary or secondary metabolite take the renal route for elimination.

30. AGING IN HEMATOLOGY Anaemia due to iron deficiency Decline in erythropoietin functional reserve  coagulation and haemostasis  WBC function - p redisposition to infection (streptococcal pneumonia, meningitis, septicaemia) and autoimmune phenomena.

31. AGING IN MUSCULOSKELETAL Loss of skeletal mass (lean body mass) Percentage of body fat  Osteoporosis- microarchitectural deterioration of bone and decreased bone density Osteoarthritis- Cervical osteoarthritis may interfere with visualization of glottic opening. Progressive reduction in height - gradual increasing kyphosis secondary to vertebral compression fractures Calcified ligaments – difficult neuraxial

32. BODY COMPOSITION Loss of lean body mass Accelerated loss of subcutaneous and intramuscular fat, although percentage of fat compared to LBW is increased Loss of vital organ-lean tissue mass (liver, spleen) Decreased intracellular water- more prone to dehydration Blood volume is maintained

33. PHARMACOKINETICS AND PHARMACODYNAMICS Pharmacokinetics: The relationship between drug dose and plasma concentration . It deals with what body does to the drug and it includes drug absorption, tissue distribution, metabolism and elimination. Pharmacodynamics: The relationship between concentration and clinical effect . It explains what a drug does to the body. T½ of any drug depends on two factors. V d = volume of distribution CI = clearance T½ = (0.693 x V d )/CI

34. Pharmacokinetics Implications Plasma concentration and V d of a drug are inversely related. Decline in TBW – smaller V d for hydrophilic drugs,  plasma concentration With age percentage of total body fat  Lipophilic drugs, V d  ; accumulation, prolongation of drug effects Impaired hepatic metabolism and renal elimination-  clearance Increase in the arm-brain circulatory time

35. Pharmacokinetics Implications Most induction agents (hydrophilic) are distributed in a smaller initial compartment, resulting in increased exposure of receptors and potentially augmented impact. Drug - binding proteins- albumin  , alpha-1 glycoprotein  with age. Qualitative changes in these proteins alters drug-binding and result in  free fraction in circulation, which affects clearance, V d and apparent potency.

36. Pharmacodynamics Implications Physiological state-  cardiac output in elderly Prolongs circulation time to drug effect when drug given IV Polypharmacy - risk of drug interactions Factors predisposing elderly patients to adverse drug events Multiple comorbidities Polypharmacy Drug-drug interactions Age related reduction in metabolism and elimination Increased sensitivity of CNS to side effects of the medications

37. BEERS CRITERIA INAPPRORIATE/ ALWAYS AVOID Flurazepam Pentazocine Meperdine RISKY- avoid if possible Long acting BZD- Diazepam Limit doses of intermediate acting BZD- Lorazepam INEFFECTIVE or a better alternative exists Diphenhydramine Chlorphenaramine Ketorolac Clopidogrel

38. COMMON GERIATRIC-RELATED DISEASES CVS: HTN, IHD, CHF, aortic stenosis, AF, heart block, PVD Respi : COPD, lung fibrosis CNS: TIA, CVA, senile dementia, Alzheimer, Parkinson Endocrine: DM, hypothyroidism Renal: CKD

39. STRATEGIES

40. Pre-op Assessment and Preparation Pre-operative evaluation aims at Pre op optimization Prediction / Anticipation of complication Application of risk reduction strategies RISK FACTORS FOR POST-OP MORTALITY IN ELDERLY SURGICAL PATIENTS ASA physical status III or IV Surgical procedure Major and/or emergency Coexisting disease Cardiac, pulmonary, DM, liver, renal dysfunction Functional status 1-4 METs Nutritional status Poor, albumin <35%, anaemia Place of residence Alone Ambulatory patients Confined to bed

41. CONSENT The patient’s mental acuity, cognitive status must be considered and documented Elderly may not be fully aware of the gravity of the intervention, hence a family member must be explained the possible outcomes in detail. Potentially reversible causes of confusion may be caused by dementia, sepsis, dehydration, over hydration, electrolyte/metabolic abnormalities, hypoxia or constipation Patient, family members or legal guardian should be explained about the surgical intervention and possibilities of likely complications. Documented living wills and advanced directives must be respected.

42. History and Nutritional status History of current illness Complete medical and surgical history Details of regular medications FBC- anaemia, S. albumin <3.2g/ dL , S. Cholesterol <160mg/ dL – shown to be risk markers for adverse post-op outcome Assess hydration, nutrition Vitals – pulse rate, BP Systemic examination Stature ; kyphosis, sclerotic spine Air way examination - loss of buccal fat, edentulous, dentures Mental status - Preop dementia is a predictor of poor surgical outcome Physical examination

43. Preoperative Investigations FBC RP, serum electrolytes Blood glucose, cholesterol LFT, albumin levels and coagulation profile ECG - for all patients >40yrs Chest X-ray, PFT in COPD patients Cardiology reference must be considered and subsequent echocardiography is required.

44. Systemic Evaluation CARDIOVASCULAR SYSTEM Hypertension- Antihypertensives to continue. DBP>110 requires control before surgery CHF – high morbidity and mortality CAD without CHF- less mortality, comparable to general population CHF with arrhythmias - evaluate and control before elective surgery

45. Arrhythmias 1. Incidence of AF very high - evaluate and rule out atrial clot 2. Peri-op therapy and anticoagulation to be considered 3. II and III Heart blocks - pre-op pacing required Diastolic dysfunction- control heart rate, hypertension, maintain sinus rhythm Coronary stents Angioplasty without stenting 2 weeks ( preferably 4-6 weeks) Bare metal stent placement Atleast 6 weeks; preferably 12 weeks Coronary artery bypass grafting Atleast 6 weeks; preferably 12 weeks Drug eluting stent placement Atleast 12 months

46. Diabetes mellitus Hyperglycemia (with or without diabetes) in patients with myocardial ischemia – increased morbidity and mortality American diabetic association recommends : To keep pre-prandial blood glucose at 4.4 – 7.8 mmol/L HbA1c<7% Intra-op tight sugar control with insulin infusion to maintain 4.4 – 8.3 mmo /L OHAs to be discontinued the night before and on the day of surgery Patient to be started on insulin regime after discontinuing OHAs

47. Pulmonary Disease Peri-op opioid dose for elderly much less than younger patients Short and intermediate acting neuromuscular blocking agents preferred and antagonists to reverse routinely used Steps to avoid post-op pulmonary complications (PPCs) Adequate analgesia Early mobilization Supplemental O 2 for at least 12hrs post-op as indicated by pulse oximetry Active COPD or bronchial asthma – vigorous pre-op management and optimization prior to surgery Smokers- hyperactive airway, bronchospasm, atelectasis, increased cardiopulmonary complications. Long period of abstinence (8-10wks) reduce peri-op complications

48. SELECTION OF ANAESTHESIA Depends on the patient’s clinical condition, proposed surgical procedure Skill and experience of the anaesthesiologist. Aims: safe and smooth anaesthesia with good cardiovascular control and quick emergence with minimal post-op cognitive dysfunction or complication. Stable vital parameters and the patient regain protective physiologic function as rapidly as possible.

49. GA vs RA ? A Cochrane review of hip surgery in elderly looked at 2567 pts comparing GA to RA. Conclusion: RA might reduce mortality at 1 month but the long-term mortality was unchanged. No ideal anaesthesia mode. Must consider case by case.

50. REGIONAL ANAESTHESIA Local nerve blocks preferred if patient is cooperative Lower subarachnoid block for lower abdominal and perineal surgeries Advantages Lower incidence of PDPH due to closure of intervertebral foramina, which inhibit the leakage of CSF. Decreased stress response to surgical stimulation and blood loss Decreased incidence of thromboembolism Good post operative analgesia, early ambulation and discharge Ensures better recognition of ischaemic attack and better assessment of mental status. Less risk of aspiration

51. Disadvantages Difficulty in controlling the level of block Increased sensitivity to local anaesthetic Limited power of adaptation to vasomotor changes. Wide fluctuation in hemodynamic status. Difficulty in technique due to calcified ligaments and ankylosis of joints. Increased incidence of persistent numbness, nerve palsies, neuralgia

52. GENERAL ANAESTHESIA MONITORING Basic monitors - Pulse oximetry, NIBP, ECG, ETCO 2 , urine output monitoring, temperature monitoring Major procedures- CVP, IABP, TOE, ABG analysis PREOXYGENATION Elderly are more prone to cardiac event from desaturation Maximum oxygenation – 8 deep breaths of 100% oxygen within 60s with oxygen flow of10L/min PREMEDICATION Anticholinergic- Inj. Glycopyrrolate Anxiolytics- drugs with minimal and short lived sedative effects must be used. Short acting BZDs with dose titration. Aspiration prophylaxis, preferably RSI to be followed for all patients

53. Hypertensive response to intubation should be reduced especially in hypertensive patients with Lidocaine 1.5mg/kg Esmolol 0.3mg/kg IV. Alfentanil 5µgm/kg IV. INDUCTION Commonly used - Propofol, thiopentone (5-7mg/kg), etomidate (0.3mg/kg) Graded induction practised Peak effects of drugs administered is delayed: Midazolam- 5min, Fentanyl- 6-8min, Propofol- 10min Drug dose calculated according to IBW; Propofol 1-1.5mg/kg, and 0.5-1mg/kg if opioids supplemented. Slow onset of anaesthesia due to sluggish circulation. Dose titration- delayed elimination due to retarded metabolism

54. Airway maintenance may be more difficult/hazardous because of: Osteoporotic mandibles Loose teeth Temporo-mandibular joint stiffness Lax oropharyngeal muscle tone and edentulous jaws Cervical spondylosis Arthritis of atlanto -occipital joint Cervical osteoarthritis may interfere with visualization of glottic opening

55. Maintenance of Anaesthesia After induction controlled ventilation with muscle relaxants, N 2 0, O 2 , adequate analgesia Cuffed tube in patient – to avoid aspiration Short or intermediate acting NMBs, dose calculated according to IBW Atracurium and Cisatracurium are more preferred over Vecuronium and Rocuronium  L evel of plasma cholinesterase - prolong the effect of Sch. Vecuronium dose reduced by 30%. Atracurium dose not affected.

56. Maintenance of Anaesthesia Two fold prolongation in onset of NM block in elderly patients due decreased cardiac output, slow muscle blood flow. Monitoring depth of neuromuscular blockade is useful Inhalational agents - MAC of all inhalational agents reduced by 4-5% per decade after 40yrs of age Sevoflurane and desflurane excreted unchanged by lungs It is better to maintain sub MAC concentrations of potent inhalationals with b-blockers to control hypertension rather than use supra MAC Combined epidural and GA reduce MAC by as much as 50%

57. Extubation Criteria Adequate oxygenation SpO 2 >92; PaO 2 >60 Adequate ventilation TV>5ml/kg, RR> 7bpm, ETCO 2 <50, PaCO 2 <60 Hemodynamically stable Full reversal; TOF>0.9, sustained 5s hand grasp Neurologically intact – follows commands, intact cough reflex ABG - pH>7.25 Normal S. Electrolyte, normovolemic , normothermic Other factors - aspiration risk, airway edema

58. Causes of Delayed Recovery From Anaesthesia Prolonged action of anaesthetic drugs: sedative, opioids, muscle relaxant. Hypoxia or carbon dioxide retention Hypothermia Diabetic ketoacidosis or hypoglycemia Anaemia or myxoedema Intra operative hypotension. Cerebral hypoxia.

59. POST-OP CONSIDERATIONS DVT prophylaxis - risk of pulmonary thromboembolism Nutrition - aids healing and recovery Blood sugar monitoring Fluid management - Acute renal failure account for 20% of post-op deaths Pain Oxygen therapy - greatest incidence of myocardial ischaemia is on day 2 or 3 postoperatively Rehabilitation - Early mobilisation Cognition - Postoperative Cognitive Dysfunction (POCD) in 26% of patients at one week and 10% at 3 months after surgery

60. POSTOPERATIVE COMPLICATIONS Post op cardiovascular complication Myocardial infarction Congestive heart failure Cardiac arrest Arrhythmias Hypotension Post op respiratory complication Ventilatory depression Hypoxemia Carbon dioxide retention Aspiration Pneumonia Atelectasis.

61. CNS related complications Post-op delirium Typically presents after 24-72 hrs post operatively Prevention- controlling intraoperative use of sedation and adequate post-op pain relief. Post-op cognitive dysfunction- post-op memory or thinking impairment that has been corroborated by neuropsychological testing. multifactorial in origin Incidence - fairly equal in regional and general anaesthesia. Avoided by maintaining adequate oxygenation and stable hemodynamic status intra-op and judicious titration of anaesthetics. POCD may last upto 5-6 months from surgery.

62. POST OP ANALGESIA Adequate post-op analgesia Reduces incidence of cardiorespiratory complication. Reduces thromboembolic complications. Reduces duration of hospital stay. Commonly used are NSAID Opioid Patient controlled analgesia Epidural opioids, Nerve blocks

63. CONCLUSION Ageing is multifactorial process resulting in decreased capacity for adaptation and producing a gradual decrease in functional reserve. A good understanding of the physiological changes that occurs in these patients, pharmacokinetics and pharmacodynamic help in planning of an optimal anaesthetic technique for each elderly patient. The effects of ageing on the body are numerous, but the most important point is to differentiate physiological from pathological and attain prompt optimization prior to surgery. To attain best possible outcome in geriatrics is to have a multidisciplinary approach with involvement of the surgeons, physicians, cardiologists and anaesthesiologists to anticipate, identify and treat the patient accordingly.

64. REFERENCES World Anaesthesia Tutorial of the Week: Anaesthesia in the Elderly, Dr Nigel Hollister Anesthetic Considerations in the Geriatric Population, Britton Staheli & Bryan Rondeau (2023) Chapter 31: Anaesthesia and the Elderly, C.Y. Lee