PERIOPERATIVE

MANAGEMENT

OF

PATIENTS ON

CARDIAC DRUGS

INTRODUCTION

Perioperative period is a stressful condition where a number of physiological changes take place which can result in a change in drug requirement.

May be due to altered hepatic or renal function or neuro hormonal changes.

INTRODUCTION

It is estimated that one fourth of all patients undergoing a surgical procedure are taking long-term medications

The issues surrounding the decision to discontinue such medications before surgery and when to reinstitute them are complex

In the preoperative period, it is important to avoid the use of medications that may negatively interacts with anesthetic agents.

INTRODUCTION

Postoperatively,the concern shifts towards avoiding withdrawal symptoms that may develop and possible progression of the underlying disease if the medications are not restarted in a timely fashion

The potential for decreased gastrointestinal motility in the postoperative patient, which may reduce the efficacy of oral medications must be also considered

INTRODUCTION

Antihypertensive medications may cause cardiovascular complications, such as hypotension or myocardial ischemia.

Psychoactive medications may cause prolonged sedation and withdrawal symptoms may develop

Antithrombotic agents may increase the risks of bleeding during surgery

INTRODUCTION

THE ROLE OF THE ANAESTHETIST

IN THE PREOPERATIVE , INTRAOPERATIVE

AND POSTOPERATIVE IS AN IMPORTANT

ONE

BETA BLOCKERS

MECHANISM OF ACTION: Decrease oxygen consumption Improve myocardial metabolism Block the action of catecholamines Decrease sympathetic outflow Shift ODC to right leading to increased oxygen

supply Suppress dysrrhymias LV remodelling

RECOMMENDATION

Perioperative betablocker therapy to be instituted before CABG if LVEF > 30% and preop status allows it.

Pt already on BB should take on morning of surgery and renew it immediate past op

In pt with COPD/reactive airway disease, preferable to use cardio selective agents

ANAESTHETIC IMPLICATIONS

Decrease in HR, decrease in BP and myocardial depressant effects of BB and GA agents appear to be additive

Severe decrease in HR and block may occur with drugs like fentanyl, vecuronium and propofol.

Intubation, incision and extubation occur during periop period result in a surge in endogenous catecholamines.

ANAESTHETIC IMPLICATIONS

ISIS-I study (International study of infarct survival) MIAMI study (Metoprolol in AMI) MAPHY study (Metoprolol Vs Thiazide diuretics

in HT) ASIST study (Atenolol ischaemia study)

-have shown that BB is effective in reducing cardiac complications and could be safely used in the periop period.

CCB - ADVANTAGES

Well tolerated and do not alter exercise tolerance like BB’s

Do not cause fluid retention although ankle edema is a well known side effect.

Control dysrhythmias Prevent coronary artery spasm Anti-HT effect Negative inotropic, chronotropic and dromotropic

CCB – DISADVANTAGES

Low response to inotropes and vasopressors AV node conduction block Peripheral vasodilation after CPB Profound brady cardia and low BP when given in

presence of BB

RECOMMENDATIONS

Preferable to continue CCB upto the time of surgery, including an oral dose on the morning of surgery

ANAESTHETIC IMPLICATIONS

CCB can also enhance the action of muscle relaxants and lowers MAC of inhaled agents

CCB being vasodilators and myocardial depressants are similar to volatile gents – synergistic role

CCB must be administered with caution to patient with impaired LV function or hypovolemia

ACEI/ARA

Renin-AT system plays a significant role in maintaining intraop BP

Inhibitors of this system exaggerate the hypotensive effects of anaesthesia, can cause refractory hypotension and reduced organ perfusion

ANAESTHETIC IMPLICATIONS

Patients treated chronically with ACEI will have significant reduction in MAP,CI,PCWP,SVR and HR in periop period

Increased incidence of low BP at induction requiring vasopressors after induction

RECOMMENDATIONS

Preferable not to continue ACEI/ARA upto day of surgery OMIT on the morning of surgery If continued, it is mandatory to maintain an adequate volume

load and BP with vasopressor, if necessary Discontinue ACEI preop (12 hours preop if captopril (or) 24

hours preop if enalapril) and substitute shorter acting IV anti-HT drugs

ACEI may increase insulin sensitivity and hypoglycemia-concern in DM patients

DIURETICS

Cause significant dyselectrolytemia and fluid imbalance

Should be discontinued preop Efficacy comes down with decrease in GFR

NITRATES

Weightman etal found nitrates to be independent predictors of mortality after CABG surgery

This may be due to tolerance to nitrates which in turn decreases the effectiveness of nitrates causing

decreased vasodilatation of IMA graft, decreased inhibition of platelets, decreased ischaemic preconditioning, decreased sensitivity to vasoconstrictors

NITRATES

Preop discontinuation results in rebound coronary

vasoconstriction and worsening of myocardial

ischaemia

RECOMMENDATIONS

Regarding patients on therapeutic and prophylactic NTG, this agent should be continued until and perhaps beyond induction of anaesthesia, especially in patients who were preop on nitrates for angina

DIGITALIS

INDICATIONS Prevents post operative arrhythmias after lung

surgery Controls ventricular rate in patients with atrial

fibrillation Improves cardiac contractility in patients with

congestive cardiac failure

DISADVANTAGES

Narrow margin of safety Exacerbation of hypokalemic risk –K+

concentration can fluctuate widely during anaesthesia due to fluid shifts,ventilatory acid-base dearrangements and adjuvant treatments

Intraoperative arrhythmia due to digitalis may be difficult to differentiate from those having other sources

DISADVANTAGES

Digitalis toxicity can present with such diverse cardiac arrhythymais on junctional escape rhythm,PVC Ventricular bigeminy or trigeminy,Junctional Tachycardia, PAT with/without, sinus arrest, Mobitz type I and II block or VT

Prophylactic digitalization to prevent arrhythmias after lung surgery has proven ineffective in a number of Randomized controlled studies

RECOMMENDATION

As digitalis has a long blood half-life(36 Hrs),pre-op discontinuation on the day of surgery should not result in a significant decrease in blood levels.

As intravenous preparation is available,the drug can be supplemented if required.

Moreover heart rate can be effectively controlled with b-blockers and cardiac contractility can be increased with inotropes.pre-op discontinuation of digitalis is recommended

AMIODARONE

Antiarrhythmic agent Used to treat recurrent SVT & VT It causes a significant reduction in the incidence of post-op

atrial fibrillation and duration of hospitilization Side effects Pulmonary infiltrates Hypo/Hyperthyroidism

Peripheral neuropathy Deranged LFT Prolonged QT interval

AMIODARONE

Increase quinidine, procainamide, digoxin levels Prolongation of Prothrombin time causing

bleeding in patient on warfarin Amiodarone increase phenytoin levels and

phenytoin enhance the conversion of amiodarone Synergism with BB

RECOMMENDATIONS

As amiodarone has a long T1/2 (29 days), and pharmacologic of effects may persists for over 45 days after its discontinuation, effective preoperatively discontinuation is not feasible

Omit morning dose as IV form is available and is fact acting Risk of discontinuation increases reappearance of life

threatening ventricular arrhythmias Amiodarone has to be started 7 days preop This is both inconvenient and costly

ANTIPLATELET DRUGS

RECOMMENDATIONS

To discontinue, aspirin, clopidogrel & Ticlopidine atleast 5-7 days before surgery to reduce the risk of periop bleeding & reinstitute them when the bleeding risk is diminished.

CONCLUSION

The decision to withhold and restart medications should be based on the

pharmacokinetics and pharmacodynamics of the agent, available clinical data and expert opinion Anaesthetists should exercise diligence in obtaining an

accurate medication history on all preoperative patients and in reviewing the medications in the post operative orders