Anesthesia and the Cardiac Patient

1. Anesthesia and the Cardiac Patient Wayne E. Ellis, Ph.D., CRNA

3. Preoperative Preparation Angina Medications to control it Blood pressure controlled Diastolic < 95 torr Congestive heart failure treated Diuretics Afterload reduction Bedrest if indicated Control diabetes

4. Preoperative Medications Sedation Prevent tachycardia Hypertension Prepared for hypoxia Supplemental oxygen Calcium channel blockers not protective of perioperative ischemia Antihypertensives continue on day of surgery Stop Diuretics

5. Antianginal medications Beta-blockers Calcium Channel Blockers Nitrates Nitropaste morning of surgery WE Ellis

6. Beta Blockers Negative inotropic effects Withdrawal following stoppage of beta blocker Unstable angina Myocardial infarction

7. Monitoring EKG Blood Pressure Temperature Pulse oximetry End tidal CO2

8. Arterial Catheter Beat to beat blood pressure monitoring ABGs Early detection of hypotension

9. Laboratory studies HGB & HCT Electrolytes Liver function studies Creatine clearance Osmolality

10. PA catheter Assessment of LV Function Early detection of ischemia “v” waves Increased PCWP More accuracy than CVP Intravascular volume problems Especially in patients with severe lung disease

11. Transesophageal Echocardiography Demonstrates regional wall motion abnormalities Suggestive of ischemia Most accurate measure of left ventricular volume

12. Non-invasive Continuous Cardiac Output Monitors Transesophageal Doppler Thoracic impedance Limited Accuracy is controversial No information about systemic vascular resistance Measure CVP

13. Improved outcomes Aggressive monitoring & treatment Vasoactive drugs Reduced intraoperative ischemia MI < 6 months has better survival rate Occurrence reduced from 30-5% Multi-institution study over last 10 years 5000 patients Continued for 3 days post-operatively

14. Decision to use Invasive Monitoring Patients with severe inoperable CAD Chronic stable angina undergoing significant abdominal or thoracic surgery Large blood loss History of remote MI with stable angina Not necessary to use invasive monitors

15. Anesthetic Management Regional vs general Anesthetic management skills more important than technique Safest technique is the one the practitioner does best

16. General anesthesia Avoids sympathectomy Risks with intubation Sympathetic stimulation Hypoxia Increased catecholamines Loss of subjective monitor Chest pain Ischemia

17. General Anesthesia required Narcotics Effective control of catecholamines Respiratory depression Prolonged ventilation

18. Inductions Agents Avoid Ketamine Hypertension Tachycardia Use in trauma Etomidate Painful to inject More CV stability Barbiturate Direct depressant Extended duration of activity Smaller doses 1-2 mg/kg Add benzodiazepines and narcotic

19. Benzodiazepines Quell anxiety Hemodynamic stability Extended duration of action Potential for hypoxia Lidocaine Esmolol

20. Muscle Relaxants Avoid pancuronium Tachycardia ST segment changes consistent with ischemia Doxacurium Duration similar to pancuronium No cardiovascular effects

21. Avoid Histamine releasing drugs Curare Atracurium Mivacurium <15 mcg/kg Hypotension Tachycardia

22. Inhalation Agents Potential for coronary steal Alters coronary autoregulation Alters regional blood flow Little influence on outcome

23. Nitrous Oxide Constricts coronary arteries Aggravates myocardial ischemia High FiO2 recommended Maintain saturation at 95-100%

24. Regional Anesthesia Monitor patient more accurately Control sympathetic responses Fluids Esmolol

25. Intraoperative predictors Choice of anesthetic Site of surgery Duration of Anesthesia Emergency Surgery

26. Intraoperative predictors Choice of Anesthetic No difference in infarction rate GETA vs. Regional No significant hypotension No significant tachycardia TURP Regional decreased risk post MI Reinfarction rate SAB < 1% GETA 2-8%

27. Intraoperative predictors Choice of Anesthetic Patient with CHF will benefit from regional technique Sympathectomy Decreased preload Coronary Steal Potent inhalation agents vs. narcotics

28. Intraoperative predictors Site of Surgery Thoracic and upper abdominal 2-3 X’s risk of extremity procedures Duration of Anesthetic > 3 hours > risk of morbidity & mortality Emergency Surgery 2 - 5 X’s greater risk than nonemergent surgery

29. Cardioactive drugs Nitroglycerin Lower LVEDP Vasodilator Poor ventricular function

30. Esmolol Control heart rate and blood pressure Induction Emergence

31. Labetalol Mixed alpha and beta Control hypertension Heart rate management

32. Lidocaine Blunt effects of intubation 1.5 mg/kg 4-6 minutes prior to intubation

33. Clonidine Less hypertension Decreased anesthesia requirements

34. Nifedipine Controlling hypertension Manage coronary artery spasm

35. Postoperative Management Maintain analgesia Balance supply and demand Supplemental oxygen Continue monitoring into postoperative period Early transfusion

36. Coronary Artery Disease Major Goal Balance Supply and Demand Primary Determinants of Myocardial Oxygen Demand Wall tension and Contractility

37. Coronary Artery Disease Factors modifying coronary blood flow diastolic time perfusion pressure coronary vascular tone intraluminal obstruction

38. Coronary Artery Disease Myocardial O2 Extraction infrequently the cause of ischemia intraoperatively Arterial O2 Content Correction of anemia High FiO2

39. Hemodynamic Goals for the Patient with CAD P - keep the heart small, decrease wall tension, increase perfusion pressure A - maintain, hypertension better than hypotension C - depression is beneficial when LV function is adequate R - slow, slow, slow

40. Hemodynamic Goals for the patient with CAD Rhythm - usually sinus MVO2 - control of demand frequently not enough, monitor for and treat “supply ischemia CPB - elevated ventricular filling pressure usually not needed after CABG

41. Valvular Heart Disease Aortic Stenosis IHSS Aortic Insufficiency Mitral Stenosis Mitral regurgitation

42. Aortic Stenosis Characterized by: Obstruction to LV outflow Intraventricular systolic pressure and wall tension increase Concentric hypertrophy Decreased LV compliance Reliance on atrial contribution

43. Hemodynamic Goals for the Patient with AS P - full, adequate intravascular volume to fill noncompliant ventricle A - already elevated but relatively fixed, coronary perfusion pressure must be maintained C - usually not a problem, inotropes may be helpful preinduction in end-stage AS with hypotension

44. Hemodynamic Goals for the Patient with AS R - not too slow (decrease CO), not too fast (ischemia) Rhythm - Sinus!! Cardioversion if hemodynamic instability from SV dysrhythmias MVO2 - Ischemia is an ever present risk, Avoid tachycardia and hypotension

45. Idiopathic Hypertrophic Subaortic Stenosis Characterized by: Myocardial hypertrophy 20 -30 % have subvalvular obstruction Outflow tract of LV is narrowed Increases in contractility, heart rate or decreases in preload or afterload increase the risk of ischemia

46. Hemodynamic Goals for the Patient with IHSS P - Full, full, full; volume is treatment for hypotension A - Up, up, up; vasoconstrictor follows fluid for hypotension C - Depression is ok R - not too slow, not too fast

47. Hemodynamic Goals for the Patient with IHSS Rhy - Sinus, sinus, sinus; consider pacing PA cath to control atrial mechanism MVO2 - Usual precautions apply CPB - Avoid inotropes post-CPB, the myocardial disease is still present, try vasoconstrictors first

48. Aortic Insufficiency Characterized by: Chronic volume overload Ventricular dilatation Eccentric hypertrophy Forward stroke volume higher than normal causing increased systolic pressure Regurgitation across the valve causes diastolic pressure to be lower than normal

49. Hemodynamic Goals for the Patient with AI P - normal to slightly increased A - Reduction beneficial with anesthetics or vasodilators,increases augment regurgitant flow C - usually adequate R - Modest tachycardia reduces ventricular volume, raises aortic diastolic pressure

50. Hemodynamic Goals for the Patient with AI Rhythm - usually sinus, not a problem MVO2 - Not usually a problem CPB - observe for ventricular distention (decreased HR, increased ventricular filling pressure) when going onto bypass