Co-medications, pre-medication and common diseases in the elderly

1. Co-medications, pre-medication and common diseases in the elderly R3 Guo, Shu-lin 92.07.04

2. Pre-operation Visit Evaluation • Cardio-pulmonary function • The American Heart Association and the American College of Cardiology guideline for cardiovascular evaluation for non-cardiac surgery— A&A 2002;94:1052-64

5. Co-medication • Klugger (1991)— Anaesthsia 1991;46:456-9 • Incidence of concomitant medication was high and rose steadily with the increase in age • 44% of all patients were given at least one drug • On average, patients took 2.1 drugs, especially in CV field • About 50% of patients scheduled for surgery, the regular medication was not given on the day of surgery

6. Co-medication • Kennedy(2000)— Br J of Clin Pharma 2000; 49:353-62 • The withdrawal of a regular cardiovascular drug for greater than 24 hrs was associated with 14% incidence of cardiac complication • The complication rate showed a correlation with time without medication • If the time was over 48hrs, the rate of complication increased to 27%

8. Co-medication • It is generally accepted that at least three half-times and ideally five T1/2 • Increasing age is associated with changes in Vd, bio-availability, and limitations in renal clearance and hepatic function • Medications associated with acute withdrawal effects should be continued throughout the perioperative period

9. Cardiovascular drugs • Calcium-channel blockers • Beta-adrenoreceptor blockers • Angiotensin-converting enzyme (ACE) inhibitors • Angiotensin receptor II antagonists • Digoxin • Anti-arrhythmic therapy • Diuretics

10. Calcium-channel blockers • Short-acting calcium-channel blockers • Cause sympathetic activation and increase the risks of MI or heart failure • Avoid in perioperative period (ex: Verapamil) • Long-acting calcium-channel blockers • No reports on severe complications in the perioperative period • Continued on the morning of surgery and throughout the perioperative period (ex: Novasc)

11. Beta-adrenoreceptor blockers • Mangano (1996)— NEJM 1996;335:1713-20 • Patients with CAD or high risks showed lower mortality with during the perioperative period • Even 2 years after discharge, the mortality in β-blocker vs. placebo groups is 10% vs. 21% • Wallace (1998)— Anesthesiology 1998;88:7-17 • Atenolol given prior to or during the induction of anesthesia and continued for several days after surgery cause a significant in the incidence of perioperative MI (5-10mg iv, 50 or 100mg po q12hr)

13. Angiotensin-converting enzyme inhibitors • ACEI can cause a significant reduction in the body’s ability to compensate for hypotensive episodes • The hypotension can be reversed by the volume support or moderate doses of vasoconstrictors • Withholding ACEI on the morning of surgery

14. Angiotensin receptor II antagonist • Brabant(1999)– A&A 1999;89: 1388-92 • Compared to the incidence and severity of hypotension during induction of anesthesia • Angiotensin receptor blocker is the most frequent to cause hypotension • Adequate treatment of these often quite severe hypotensive episodes could not be achieved by ephedrine but required 1mg boluses of terlipressin • Angiotensin receptor antagonist should not be given on the day of surgery

15. Digoxin • Digoxin • A narrow therapeutic ratio, is further reduced by hypokalemia • Withhold digoxin on the morning of surgery, and reduce the chance for toxicity • Continuation of digoxin therapy through the day of surgery and justify their approach by indicating that it provides cardiac stability

16. Other cardiovascular drugs • Anti-arrhythmic therapy • Not withhold these drugs if they are given for a serious condition • Diuretics • Diuretics therapy should be stopped on the day of surgery • To avoid further volume loss in an already volume-depleted elderly patients

17. Insulin • During the course of anesthesia and surgery, it is the severe hyperglycemia state that is associated with adverse outcome • Type I (IDDM) • Receive insulin during perioperative period • 5-10g of glucose per hour and insulin giving depends on blood sugar • Keep blood sugar within 110-180 to minimise the risk of accident hypoglycemia

19. Insulin • Type II (NIDDM) • OHA should not be given on the day of surgery • A long half-life should be withhold for 48 hrs • Biguanides (metformin) acts by inhibiting hepatic gluconeogenesis and causes a significant impairment of lactate metabolism • Withhold metformin for at least 24 hrs prior to surgery

20. Insulin • Minor procedures • With good control (HbAIc<8), short duration can be performed without glucose support • [Glu]250~300 Insulin 4-6U • [Glu]>300 Insulin 6-8U • Major procedures • Should receive an insulin-based regime (5-10g/hr glu, insulin from 1 U/hr) • Check blood sugar every 1-2 hrs

21. Psychotropic medications • Tricyclic antidepressants • Monoamine oxidase inhibitors • Lithium

22. Tricyclic antidepressants • Inhibit the re-uptake of biogenic amines (NE and 5-HT) • Chronic use will cause a reduction in the endogenous NE pool • Anti-cholinergic effects: sedation, urinary retention, hyperthermia, cardiac arrhythmia, and delirium • Continuation of these agents through the perioperative period

23. Monoamine oxidase inhibitors • Not to block the re-uptake, but inhibit their metabolism • Chronic use will result in reduced neurotransmitters and an accumulation of the false neurotransmitters • Side-effect is orthostatic hypotension • Adverse interaction of MAOI is with opioid, especially meperidine

24. Monoamine oxidase inhibitors • The use of meperidine in the patients with chronic use of MOAI causes excitatory reaction due to inhibition of 5-HT re-uptake • Recent expert opinion recommends continuation of the treatment with MAOI, but with consideration of certain drug interactions

25. Lithium • Li produces an antagonism to ADH • This causes polyuria and hypovolemia • In the presence of Li, non-depolarising NM blocker might be prolonged • High Li cause sedation, muscle weakness, hypotension, wide QRS complex, seizure and coma • Cessation of Li 24 hrs before minor surgery and 2-3 days in major procedures

26. Anti-parkinson medication • The withdrawal of levodopa therapy may cause an exacerbation of symptoms of Parkinson’s disease and possibly a neuroleptic syndrome • Levodopa is with a short elimination half-time and a short acting time • Levodopa should be given in the morning of surgery and continued throughout the perioperative period.

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