Open Heart -CABG-2011 with audio

Anesthesia for Cardiac Surgery: 

Anesthesia for Cardiac Surgery Catherine Hagerman, CRNA,MSNA ANE:624 Advanced Principles III University of New England School of Nurse Anesthesia

Cardiac Surgery Statistics: 

Cardiac Surgery Statistics CABG Valve replacement Heart Transplants 427,000 90,000 2,125

Ischemic Heart Disease: 

Ischemic Heart Disease Myocardial Infarction 8,500,000 Angina Pectoris 10,200,000 Coronary heart disease caused about 425,420 deaths in 2006 and is the single leading cause of death in USA. According to AHA

Ischemic Heart Disease: 

Ischemic Heart Disease Reflects the presence of atherosclerosis in the coronary arteries. Angina pectoris, acute myocardial infarction and sudden death are often the first manifestations of ischemic heart disease. Cardiac arrhythmias are probably the major cause of sudden death.

Risk Factors for Ischemic Heart Disease: 

Risk Factors for Ischemic Heart Disease Hypercholesterolemia Smoking Hypertension Hyperglycemia Type A Behavior Pattern Hemostatic factors Hereditary factors

Medical Treatment of Ischemic Heart Disease: 

Medical Treatment of Ischemic Heart Disease Lifestyle modification Antiplatelet drugs (ASA, Plavix) Antithrombin drugs Beta blockade Calcium channel blockers Organic Nitrates (Isosorbide, NTG)

Triple-Vessel Coronary Artery Disease: 

Triple-Vessel Coronary Artery Disease Usually involves the following vessels: Right coronary artery (RCA) Left anterior descending artery (LAD) Left circumflex artery (CX)

Surgical Treatment of CAD: 

Surgical Treatment of CAD Percutaneous transluminal angioplasty (PTCA) and stent-assisted percutaneous coronary intervention (PCI) have become mainstays of revascularization. Non-invasive techniques which widen the lumen to facilitate revascularization of tissue. 400,000 to 800,000 cases from 1997-2006. Coronary-subclavian steal syndrome is a complication of left internal mammary artery grafting

Surgical Treatment of CAD: 

Surgical Treatment of CAD Coronary Artery Bypass Grafting (CABG) revascularizes ischemia areas to control symptoms of CAD. Arteries or veins (saphenous vein, internal mammary artery) are grafted from the aorta to the CA to bypass atherosclerotic narrowings to improve blood supply to the myocardium.

PTCA vs CABG: 

PTCA vs CABG Among patients with multi-vessel disease, PCI with coronary stent placement was associated with higher rates of death and repeat revascularization compared with CABG surgery through 5 years of follow-up.

Indications for CABG: 

Indications for CABG Unstable angina pectoris Repeated episodes of myocardial ischemia after myocardial infarction. Prinzmetal angina with CAD High-grade left main coronary artery obstruction, triple-vessel or double-vessel obstruction or proximal LAD. AMI, cardiogenic shock. Stable angina that interferes with lifestyle.

Preoperative Considerations: 

Preoperative Considerations Assess the severity of CAD and concomitant diseases. Continue cardiac meds to the time of surgery, except Digoxin. Discontinue and/or reverse anticoagulation. For those who need anticoagulation, a continuous heparin drip can be continued up to surgery.

Digoxin: 

Digoxin To prevent digitalis intoxication after CPB, digitalis preparations are usually discontinued one-half life (1.5-1.7 days for digoxin; 5-7 days for digitoxin) before surgery. Acid-base and electrolyte abnormalities after CPB increased risk of digitalis intoxication, especially in context of K+ and Ca2+.

Essential Preoperative Tests: 

Essential Preoperative Tests Complete blood count PT/PTT/INR Metabolic panel EKG, Chest X-ray Evaluation of coronary anatomy and physiologic reserve (LVEDP, EF) Blood type and crossmatch

Preoperative Considerations: 

Preoperative Considerations Administer sedative premedication for anxiolysis, amnesia and sedation, thereby reducing myocardial oxygen demand and myocardial ischemia. Tailor premedication to patient’s size, severity of cardiac pathology, and functional status. Prepare for full cardiopulmonary bypass (CPB). Set up room as per standard CABG institutional protocol: lines, monitors, anesthetic agents, cardiac drugs.

Room Setup: 

Room Setup Vasoactive drugs on infusion pumps Monitor lines primed, leveled, calibrated TEE probe and monitor Pacemakers: check function Additional pressure lines/transducers, EKG leads available (IABP) Head rest, padding for pressure points.

Vasoactive/Adjunct Infusions: 

Vasoactive/Adjunct Infusions Nitroglycerine Epinephrine Levophed Neosynephrine Regular insulin infusion for diabetics Antifibrinolytics (amicar) Cardizem

Additional Medications: 

Additional Medications Dopamine Dobutamine Lidocaine Amiodarone Vasopressin Heparin Protamine

Table Top Medications: 

Table Top Medications Induction drugs Narcotics Muscle relaxants Emergency drugs Epinephrine Calcium chloride Betablockers (especially for off pump)

Monitors: 

Monitors Routine (EKG, NIBP, SpO2, ETCO2,) A-line: Most commonly in right radial to prevent pulse obliteration by chest wall retraction during harvesting of left internal mammary artery (LIMA). Must confirm whether radial artery grafts are being used prior to placement .

Monitors: 

Monitors Temperature : Need both esophageal and rectal temperatures, which will be useful during cooling and rewarming. Esophageal temp reflects core body temperature. Rectal temperature reflects peripheral body temperature. Thermistor of the PA catheter is the most accurate indicator of core body temperature.

Monitors: 

Monitors Central access required for both monitoring and delivery of vasoactive drugs. PA catheters not necessary in low-risk patients with good ventricular function. PA cath indicated for those with recent MI, unstable angina, CHF, VSD, MR, reoperation, combined valve cases.

Monitors: 

Monitors Foley catheter to measure urinary output. Bladder temperature monitoring is used in some institutions, and reflects the body temperature between esophageal and rectal temperature.

TEE: 

TEE Transesophageal echocardiography (TEE) is used to visualize cardiac anatomy and function. Assesses ventricular filling and ejection. Detects myocardial ischemia from wall motion abnormalities (hypokinesia, akinesia, dyskinesia). Detects air embolism, valvular regurg.

Other Monitors: 

Other Monitors Laboratory monitors: I-Stat, ABG, ACT often in room to provide ongoing analysis. BIS monitors used in some centers. Cerebral oximeter, particularly for patients at high risk for negative postoperative neurological outcomes.

Preoperative Line Placement: 

Preoperative Line Placement Usually one or two large-bore peripheral IVs are inserted preinduction with local anesthesia infiltration. Arterial and central venous catheters/ PA catheter may be inserted preinduction or post-induction depending on institutional practice and patient condition.

CABG Procedure: 

CABG Procedure Incision to initiation of CPB : Supine position Midline mediastinal incision Harvesting of saphenous grafts by assistant with simultaneous exposure of the heart. Cannulation of aorta and vena cava .

CABG Procedure: 

CABG Procedure Revascularization on CPB : CPB initiated, body cooling begins. Heart stopped with cardioplegia. Anastomoses between aorta and coronary arteries made with grafts. At the onset of cardiopulmonary bypass in cardiac surgery, hemodilution from the CPB priming solution typically decreases the patient’s hematocrit to 25%.

CABG Procedure: 

CABG Procedure Centrifugal pumps are pressure sensitive and require monitoring. Venous drainage from the vena cava into the CPB machine is determined by the: Height of the reservoir in relation to the patient. Venous cannula diameter. Resistance of the venous drainage tubing .

CABG Procedure: 

CABG Procedure Weaning from CPB : Body re-warming begins. Heart defibrillated. Pacing wires inserted in epicardium. Heart takes over pumping from CPB. Hemostasis secured.

CABG Procedure: 

CABG Procedure Closure : Mediastinal and pleural chest tubes inserted. Pericardium closed. Sternum closed with wire. Skin closure.

Antifibrolytics: 

Antifibrolytics Used to reduce incidence bleeding after bypass. Given prior to initiation of bypass, often after induction. First-time patients are treated with aminocaproic acid (Amicar) or transexamic acid. Aprotinin (Trasylol) given in past for redo cases, renal failure, patients on ASA and Jehovah’s witnesses.

Aprotinin: TRASYLOL: 

Aprotinin: TRASYLOL Recently removed from market due to issues with renal toxicity and ischemic events (MI and stroke). Blood conservation using antifibrinolytics NEJM May 14, 2008. Available still as investigative drug under a special treatment protocol.

Aprotinin: TRASYLOL: 

Aprotinin: TRASYLOL A serine inhibitor extracted from bovine lung effective in reducing blood loss in cardiac surgery. Acts as an antifibrinolytic and platelet preserver. Expensive ($1,000/dose).

Aprotinin: TRASYLOL: 

Aprotinin: TRASYLOL Test dose = 1 mL = 1.4 mg = 10,000 KIU Loading dose of 100 mL IV and pump prime dose of 100 mL before skin incision. Infusion through case 25 mL/hr. Adverse reactions include thrombosis, shock, PE, CVA, acute kidney failure.

Aminocaproic Acid: AMICAR: 

Aminocaproic Acid: AMICAR Hemostatic agent given as a loading dose then by continuous infusion prior to CPB. Loading dose is 100-150 mg/kg and infusion rate is 10-15 mg/kg/hr. Adverse reactions include left ventricular thrombus and arterial thrombi.

Anesthetic Technique: 

Anesthetic Technique Usually a balanced technique provides hemodynamic stability and easy reversibility postoperatively. Overall goal is to maintain balance between myocardial oxygen demand and supply during perioperative period. Critical factor in choosing technique is degree of ventricular function.

Determinants of Myocardial Oxygen Balance: 

Determinants of Myocardial Oxygen Balance Decreased supply : tachycardia, hypotension, preload, hypoxemia. Increased demand : tachycardia, preload, afterload or contractility

Anesthetic Technique: 

Anesthetic Technique For balanced anesthetic, isoflurane and fentanyl are common choices. High-dose narcotic techniques can be used for patients with poor ventricular function (fentanyl 50 to 100 mcg/kg or sufentanil 10 to 20 mcg/kg) but do not consistently prevent hypertensive response to periods of increased surgical stimulation. Neuromuscular blockade Consider a regional technique or neuraxial technique for pain control.

Induction: 

Induction Choice, dose and speed of administration depend primarily on the patient’s cardiovascular reserve and desired CV profile. Common induction drugs include propofol, etomidate, thiopental, midazolam, fentanyl. Neuromuscular blockade.

Anesthesia Management: Preincision: 

Anesthesia Management: Preincision Low anesthetic requirement during prepping and draping so careful attention must be paid to the BP. May need to lower anesthetic or give vasoconstrictor to treat BP. Use caution with vasopressors in patients with poor ventricular performance.

Preincision: 

Preincision Establish post-induction cardiac output, hemodynamic parameters. Insert OGT TEE insertion Administer antifibrinolytics Prebypass, post induction ABG, lytes, Hct, ACT

Periods of Stimulation: 

Periods of Stimulation Skin incision of the leg Skin incision of the chest Sternotomy Sternal retraction Opening of the pericardium

Anesthesia Management: Incision to Bypass: 

Anesthesia Management: Incision to Bypass Brief periods of intense stimulation seen with incision and with sternotomy. Maintenance of anesthesia titrated with inhalation agents (Isoflurane 0.5-2.0%), propofol and additional narcotics. Lungs must be deflated as sternotomy accomplished with saw to prevent injury to parenchyma.

Anesthesia Management: Incision to Bypass: 

Anesthesia Management: Incision to Bypass Risk of bleeding, especially with repeat procedures, occurs with sternotomy as cardiac chamber could be entered. Must be ready to respond to hemorrhage at any point. Cannulation of large vessels prior to initiation of CPB also a moment of increase risk for bleeding.

Anesthesia Management: Incision to Bypass: 

Anesthesia Management: Incision to Bypass Heparin 300U/kg is administered prior to initiation of bypass in order to prevent thrombosis and embolization. Average half-life of heparin is 100 minutes in a normothermic patient. There is an increase in the half-life of heparin proportional to the degree of hypothermia. In patients with antithrombin III deficiencies, to achieve adequate anticoagulation requires the administration of fresh frozen plasma .

Anesthesia Management: Incision to Bypass: 

Anesthesia Management: Incision to Bypass Heparin therapy assessed with activated clotting/coagulation time test (ACT) Normal range of ACT is < 130 seconds. Hypothermia and hemodilution with CPB affect ACT. Hypothermia greatest. ACT goal for CPB is 400-450 seconds. It is imperative that the ACT is at least 350 seconds before CPB is initiated.

Anesthetic Management: Bypass: 

Anesthetic Management: Bypass Goals for bypass included adequacy of venous drainage from heart, unobstructed arterial return, sufficient gas exchange and the provision of adequate anesthetics and muscle relaxants.

Anesthetic Management: Bypass: 

Anesthetic Management: Bypass Lungs are generally not ventilated during bypass so volatile agent on the anesthesia machine are turned off. Anesthesia is maintained by inhalation agent and a vaporizer on CPB machine and by IV medications given by infusion including midazolam, paralytic and fentanyl. Hemodynamics are managed by perfusionist during bypass.

Anesthetic Management: Bypass: 

Anesthetic Management: Bypass BP is measure by mean during CPB. MAP can drop to 30-40 mmHg with initiation of CPB due to hemodilution by CPB prime which dilutes catecholamines and by rapid cooling to 28 o C. Flow rates in CPB are 50-60 mL/kg/min with MAP in 50-60 mmHg range. Some prefer MAP 60-80 mmHg especially with carotid vascular disease or CRI.

Anesthetic Management: Bypass: 

Anesthetic Management: Bypass With systemic hypothermia used in cardiac surgery for myocardial and neurologic protection, an 8% reduction in the metabolic rate is observed for each degree centigrade reduction in temperature.

Anesthetic Management: Weaning from Bypass: 

Anesthetic Management: Weaning from Bypass Rewarming begins at a rate no greater than 1 o C per 3-5 minutes (maintain a gradient of 10 o C between patient and perfusate) to prevent gaseous emboli forming in the blood. Core temperature should be greater than 36 o C before terminating CPB. Rectal temp must be 33 o C.

Anesthetic Management: Weaning from Bypass: 

Anesthetic Management: Weaning from Bypass Ventilation is reinstituted and volatile anesthetics can be used to prevent recall in a smooth bypass run. As surgeon removes residual air from the ventricles, lungs are vigorous inflated to remove air from the pulmonary veins and aid in filling the cardiac chambers. TEE is useful in verifying effectiveness of de-airing process.

Anesthetic Management: Weaning from Bypass: 

Anesthetic Management: Weaning from Bypass Heart is debrillated internally by the surgeon if needed. Systemic flow is reestablished by pacing if necessary, optimizing preload with fluid, reducing afterload and/or increasing contractility with medications. Cardiac function is constantly evaluated from hemodynamic data and direct inspection of the heart.

Anesthetic Management: Weaning from Bypass: 

Anesthetic Management: Weaning from Bypass Pharmacological agents must be ready on infusion pumps prior to termination of CPB. These include: Calcium chloride Vasodilators (NTG, SNP) Inotropes (dopamine, dobutamine, epinephrine, milrinone) Vasoconstrictors (phenylephrine, norepinephrine) Institution protocols or anesthetist specific.

Anesthetic Management: Weaning from Bypass: 

Anesthetic Management: Weaning from Bypass Acceptable range of pressures: SBP > 80 mmHg. Ideal SBP 100-120 mmHG CI > 2.0 PAD < 20 mmHg, CVP < 15 mmHg. Failure of the heart to function properly may require IABP, VAD or return to CPB to determine etiology.

Anesthetic Management: Weaning from Bypass: 

Anesthetic Management: Weaning from Bypass When weaning a patient from cardiopulmonary bypass, if a high cardiac output is noted along with low arterial blood pressures packed red blood cells may be required.

Anesthetic Management: Weaning from Bypass: 

Anesthetic Management: Weaning from Bypass

Ventricular Dysfunction after CPB: 

Ventricular Dysfunction after CPB Ischemia Inadequate myocardial protection, introperative infarction, reperfusion injury, coronary spasm, coronary embolism (air, thrombus, calcium), kinked or clotted graft. Uncorrected defects CPB-related factors Excessive cardioplegia, cardiac distention .

Protamine: 

Protamine Used to reverse heparin after CPB discontinued. Premature use of protamine is catastrophic. LABEL WELL! Protamine inactivates heparin by binding to it to form an inert salt. Test dose of 1 mg is given over 10 minutes.

Protamine: 

Protamine Risk factors for adverse cardiovascular responses include: Mitral valve disease, Pulmonary HTN, diabetes with previous exposure to NPH, vasectomy 10 mg protamine reverses approximately 1000U heparin. Protamine is given at infusion rates < 5 mg/min to minimize adverse reactions and hypotension.

Protamine: 

Protamine Reactions from protamine include histamine-releasing actions, hypotension, true anaphylaxis, reactions in which the release of thromboxane leads to pulmonary vasoconstriction or bronchoconstriction. Heparinase I is replacement in high risk patients.

Emergence: 

Emergence Fast track patients with uncomplicated surgery can be extubated in the OR. Others need to be sedated and paralyzed for transfer to ICU. Continuous hemodynamic monitoring required.

Postoperative Complications: 

Postoperative Complications Myocardial ischemia/infarction Ventricular dysfunction Respiratory failure Cardiac tamponade Pneumothorax/Hemothorax Acute graft closure Postoperative neurologic dysfunction

The end………: 

The end………