Cardiac Assessment in the OR: Troubleshooting when coming off bypass Kimberly D. Milhoan, MD Assistant Clinical Professor, University of Texas Health Science Center, San Antonio, TX 2011 Cardiac Critical Care Course Kathmandu, Nepal October 17, 2011

Anesthetic Order of Events Cardiac Bypass: Cardiac Bypass: Pre-operative evaluation Pre-operative evaluation Sedation outside OR Sedation outside OR Induction in OR Induction in OR Pre-bypass Pre-bypass Initiation of bypass Initiation of bypass Maintenance of bypass Maintenance of bypass Re-warming Re-warming Separation from bypass Separation from bypass Post-bypass Post-bypass (Extubation) (Extubation) Transport to ICU Transport to ICU

Maintenance of Bypass ASD ASD –Temperature maintained –Heart fibrillated Most other lesions Most other lesions –Temperature cooled –If intra-cardiac, aortic cross-clamp placed and cardioplegia given

Re-warming phase Target temperature: 36.5 – 37.5 C Target temperature: 36.5 – 37.5 C –Use “Bair hugger,” warming blanket, humidified circuit and/or Humidivent Consider redose of sedation, muscle relaxant, narcotic Consider redose of sedation, muscle relaxant, narcotic Give H1- and H2-blockers and anti- arrhythmics (magnesium sulfate or lidocaine) Give H1- and H2-blockers and anti- arrhythmics (magnesium sulfate or lidocaine) Start vasoactive drips, e.g. milrinone 50 mcg/kg bolus; mcg/kg/min Start vasoactive drips, e.g. milrinone 50 mcg/kg bolus; mcg/kg/min

Re-warming phase Prior to removal of cross-clamp Prior to removal of cross-clamp –Echocardiographer looks for intracardiac air –Begin ventilation Pulmonary toilet: suction, (albuterol) Pulmonary toilet: suction, (albuterol)

Re-warming phase After removal of cross-clamp After removal of cross-clamp –Spontaneous cardiac activity –If not, check ABG and electrolytes –If ventricular fibrillation, direct cardiac defibrillation; consider more anti-arrhythmics –If ST-segment depression/elevation, look for intracardiac air –If non-sinus rhythm, consider cardiac pacing

Re-warming phase Check ABG and electrolytes Check ABG and electrolytes –Correct base deficit: Vd x base deficit x wt in kg  give half of calculated dose in meq (Vd: 0.4 in infants, 0.3 in children/adolescents, 0.2 in adults) –Correct calcium (approximately 40 mg/kg)--give calcium after cross-clamp removal and patient is warmer than 34 degrees Celsius –Correct potassium (1 meq/kg over 10 minutes if <3.0)

Criteria for Separation from Bypass Patient warm (36 degrees Celsius) Patient warm (36 degrees Celsius) ABG and electrolytes normal ABG and electrolytes normal Hematocrit adequate Hematocrit adequate Sinus rhythm at appropriate rate Sinus rhythm at appropriate rate Effective ventilation Effective ventilation Appropriate vasoactive drips Appropriate vasoactive drips Adequate repair Adequate repair

Separation from Bypass After usually at least 10 minutes of cardiac activity, allow heart to fill and eject (partial bypass) to assess cardiac function, hemodynamics After usually at least 10 minutes of cardiac activity, allow heart to fill and eject (partial bypass) to assess cardiac function, hemodynamics

Separation from Bypass: Troubleshooting Philosophies: Philosophies: –Consider one problem, one solution at a time –Use direct observation of heart/surgical field –Use all monitors –Consider where you are in procedure –Consider returning to previous condition –Consider potential post-operative risks of repair undertaken

Separation from Bypass: Troubleshooting On either partial bypass or after removal from bypass: On either partial bypass or after removal from bypass: –Repair or rhythm issues –Hypovolemia (low BP & low CVP): give volume –LV failure (low BP & normal/high CVP): afterload reduction, inotropes –RV failure (low BP, high CVP): pulmonary vasodilator, assess oxygenation/ventilation and acid/base status –Vasodilation (low BP, normal/low CVP): consider increasing hematocrit

Resources Andropoulos DB, Stayer SA, and Russell IA. Anesthesia for Congenital Heart Disease. Malden: Futura, Andropoulos DB, Stayer SA, and Russell IA. Anesthesia for Congenital Heart Disease. Malden: Futura, Lake CL and Booker PD. Pediatric Cardiac Anesthesia, 4 th edition. Philadelphia: Lippincott, Williams, & Wilkins, Lake CL and Booker PD. Pediatric Cardiac Anesthesia, 4 th edition. Philadelphia: Lippincott, Williams, & Wilkins, Morgan, G. Edward et al. Clinical Anesthesiology, 3 rd ed. New York: Appleton & Lange, Morgan, G. Edward et al. Clinical Anesthesiology, 3 rd ed. New York: Appleton & Lange, 2002.