Anesthesia for cardiac surgery: General principles

INTRODUCTION — 

Anesthetic management for different types of cardiac surgical procedures such as coronary artery bypass grafting (CABG), cardiac valve repair or replacement, surgery involving the ascending aorta, heart transplantation, and procedures for surgical repair of congenital heart defects has many shared principles. This topic will discuss general principles for anesthetic management of adults undergoing cardiac surgery with cardiopulmonary bypass (CPB). Similar techniques are employed for patients undergoing cardiac surgery without the aid of CPB (eg, off-pump CABG).

Anesthetic management issues for specific types of cardiac surgical procedures are discussed in separate topics:

●(See "Anesthesia for coronary artery bypass grafting surgery" and "Anesthesia for coronary artery bypass grafting surgery", section on 'Off-pump coronary artery bypass surgery'.)

●(See "Anesthesia for noncardiac surgery in patients with aortic or mitral valve disease".)

●(See "Anesthesia for cardiac valve surgery".)

●(See "Anesthesia for aortic surgery with hypothermia and elective circulatory arrest in adult patients".)

●(See "Anesthesia for heart transplantation".)

●(See "Anesthesia for surgical repair of congenital heart defects in adults: General management" and "Anesthesia for surgical repair of congenital heart defects in adults: Management of specific lesions and reoperation".)

For cardiac surgical procedures requiring CPB, key steps are noted in the table (table 1), and intraoperative management during and after CPB is discussed in individual topics:

●(See "Anticoagulation and blood management strategies during cardiac surgery with cardiopulmonary bypass".)

●(See "Initiation of cardiopulmonary bypass".)

●(See "Management of cardiopulmonary bypass".)

●(See "Weaning from cardiopulmonary bypass".)

●(See "Achieving hemostasis after cardiac surgery with cardiopulmonary bypass".)

●(See "Intraoperative problems after cardiopulmonary bypass".)

Multidisciplinary approaches including standardized preoperative, intraoperative and postoperative care protocols to enhance recovery after cardiac surgery (ERACS) are discussed separately. (See "Overview of enhanced recovery after cardiothoracic surgery".)

PREANESTHETIC CONSULTATION — 

Preanesthetic consultation involves assessing cardiac and overall health risks to identify conditions that could cause problems during and after cardiac surgery. The anesthesiologist works with the cardiologist and cardiac surgeon to optimize medical conditions, develops an anesthetic care plan, educates the patient and family regarding anesthetic care, and alleviates patient anxiety. These topics are discussed in detail separately. (See "Overview of preoperative evaluation and management for cardiac surgery in adults".)

PREMEDICATION — 

Some cardiac surgical patients benefit from premedication with small incremental doses of a short-acting intravenous (IV) benzodiazepine anxiolytic (eg, midazolam 1 to 2 mg) and/or opioid (eg, fentanyl 50 mcg), administered under the anesthesiologist's observation, particularly during placement of intravascular catheters. (See 'Intravascular cardiac monitors' below.)

Protocols for enhanced recovery after cardiac surgery typically emphasize minimal sedative medications before or during surgery. (See "Overview of enhanced recovery after cardiothoracic surgery".)

MONITORING — 

Cardiac surgery is conducted using standard American Society of Anesthesiologists (ASA) monitors (table 2) [1], as well as intra-arterial and central venous access. We also monitor urine output, degree of neuromuscular blockade (using quantitative neuromuscular monitoring), and temperature.

Furthermore, for most cardiac surgical cases, we use transesophageal echocardiography (TEE), processed electroencephalography (EEG), and point-of-care (POC) testing of laboratory values. Additional monitoring with a pulmonary artery catheter (PAC) to monitor pulmonary artery pressure (PAP), cardiac output/index, and mixed venous oximetry, or a cerebral oximetry monitor may be employed in selected patients.

Noninvasive standard monitors

●Standard noninvasive monitors – Prior to induction, we place standard noninvasive continuous monitors, including pulse oximetry (SaO₂), electrocardiogram (ECG), and noninvasive blood pressure (BP) as a backup monitor for intra-arterial BP. After endotracheal intubation, end-tidal carbon dioxide as well as airway pressure and volume measurements are continuously monitored.

Both ECG leads II and V₅ are employed, with computerized ST-segment trending to facilitate optimal detection of myocardial ischemia, as in other patients with ischemic heart disease (see "Anesthesia for noncardiac surgery in patients with ischemic heart disease", section on 'Monitoring for myocardial ischemia'). In high-risk patients for whom pacing, defibrillation, or cardioversion may be necessary, defibrillator/pacing pads should be placed prior to anesthetic induction (figure 1).

A quantitative neuromuscular blockade monitor is positioned along the course of the ulnar nerve to intermittently elicit contraction of the adductor pollicis muscle [2]. This ensures that appropriate muscle relaxation is maintained throughout the case. (See "Monitoring neuromuscular blockade".)

Other standard monitors

●Bladder catheter – A bladder catheter with an integrated thermistor is inserted after induction to measure urine output and bladder temperature.

●Temperature monitors – Temperature is monitored at several sites (see "Management of cardiopulmonary bypass", section on 'Temperature'):

•A nasopharyngeal temperature probe is typically employed, particularly as a monitor of brain temperatures during cardiopulmonary bypass (CPB). However, the oxygenator arterial outlet temperature is the most reliable surrogate for cerebral temperature during cooling and rewarming [3-6].

•A bladder catheter with an integrated thermistor is used to monitor "core temperature"; a rectal temperature probe may be substituted if no urine output is expected (eg, in a patient with end-stage kidney disease). During the cooling and rewarming phases of CPB, bladder (or rectal) temperatures typically lag behind oxygenator, nasopharyngeal, and blood temperatures; thus, bladder temperature poorly reflects temperatures in the highly-perfused organs (eg, brain) [3,6]. It is nonetheless reflective of the temperature of a considerable amount of body mass that eventually needs to be rewarmed prior to weaning from bypass to reduce postbypass temperature “after drop.”

•If a PAC is inserted, pulmonary artery blood temperature is also monitored before and after CPB [7].

●Point-of-care laboratory testing – Routine intraoperative laboratory point-of-care (POC) testing includes intermittent blood gas analysis, hemoglobin, electrolytes, calcium, glucose, activated whole blood clotting time (ACT), and in some institutions, other coagulation assays [8]. (See "Clinical use of coagulation tests".)

Intravascular cardiac monitors — Cardiac surgery requires continuous monitoring of the cardiovascular system because:

●Critical cardiovascular disease (eg, coronary artery obstruction or cardiac valve lesions) necessitates close hemodynamic monitoring to avoid and rapidly correct myocardial ischemia or dysfunction.

●Sudden and/or severe hemodynamic changes may occur due to mechanical manipulations during the surgical procedure itself.

●Effects of anesthetic and pharmacologic manipulations of the cardiovascular system must be assessed rapidly.

The following cardiovascular monitors are typically employed:

●Intra-arterial catheter – An intra-arterial catheter is inserted before anesthetic induction for continuous monitoring of BP and to facilitate intermittent blood sampling for specific POC tests during the operation. (See "Intra-arterial catheterization for invasive monitoring: Indications, insertion techniques, and interpretation".)

The radial artery is the most common cannulation site due to its superficial course, consistent accessibility, and redundant blood supply of the hand via the ulnar artery. If the cardiac surgical plan includes radial artery harvest, the contralateral radial artery or ulnar artery is also suitable. Despite concerns for hand ischemia or ulnar nerve injury (due to its proximity to the artery), complications associated with ulnar artery cannulation rarely occur [9-12]. Other alternative sites may be selected in some patients, including brachial, axillary, and femoral arteries. These more proximal monitoring sites have the advantage of providing better estimates of central aortic pressure, particularly following CPB, and complications are rare [13,14]. (See "Intra-arterial catheterization for invasive monitoring: Indications, insertion techniques, and interpretation", section on 'Complications'.)

If an intraaortic balloon pump (IABP) is in place, intra-arterial BP may be monitored at the tip of the balloon catheter in the descending thoracic aorta to avoid any delay to starting surgery. Insertion of a peripheral intra-arterial catheter can then be accomplished as soon as possible after induction of anesthesia.

If surgery on the aortic arch or repair of aortic dissection is planned, it may be necessary to obtain a second upper extremity intra-arterial catheter after induction. (See "Anesthesia for aortic surgery with hypothermia and elective circulatory arrest in adult patients".)

●Central venous catheter – A large-bore central venous catheter (CVC) is useful given the frequent need for infusion of vasoactive medications and the potential for high-volume administration of fluids or blood products. Typically, we cannulate the internal jugular vein using ultrasound guidance for vein localization (movie 1 and movie 2) [15,16].

We insert an introducer sheath such as a multi-lumen access catheter or sheath introducer that functions as a large-caliber CVC and/or as a means to place a PAC, even if insertion of a PAC is not initially planned. Thus, if the patient becomes hemodynamically unstable in the postbypass or postoperative period, the introducer sheath facilitates later insertion of a PAC without interruption of vasoactive infusions. We typically insert the large-bore CVC shortly after induction of general anesthesia if there is adequate peripheral intravenous (IV) access for use during induction. Insertion after induction avoids patient discomfort due to pain and Trendelenburg positioning, which might also result in hypertension, tachycardia, dyspnea, and myocardial ischemia in an awake patient. However, in a patient with difficult peripheral IV access or risk factors for critical hemodynamic instability during induction, we may insert the introducer sheath and/or PAC before induction of general anesthesia [17].

●Pulmonary artery catheter – In selected patients, a PAC may be inserted to provide dynamic information regarding pulmonary artery pressure (PAP), cardiac output, and mixed venous oxygen saturation (SVO₂) [17-21].

We insert a PAC in patients with acute hemodynamic instability, preferably before induction of anesthesia or surgical incision [17]. Also, PAC monitoring is often employed in patients with moderate to severe pulmonary artery hypertension, reduced left ventricular (LV) ejection fraction (<40 percent), severe coexisting pulmonary or kidney disease, planned coronary artery bypass grafting (CABG) surgery in combination with valve repair or replacement (due to longer CPB and aortic cross-clamp times that may result in increased potential for postbypass myocardial dysfunction), and in patients undergoing heart and/or lung transplantation. One prospective study noted that low cardiac index is common in cardiac surgical patients during the prebypass and postbypass periods, despite normotensive arterial BP [22]. However, routine use of a PAC is avoided in many centers because evidence for mortality benefit is lacking in cardiac surgical and other patient populations, and there are several potential risks [23-29]. (See "Pulmonary artery catheterization: Indications, contraindications, and complications in adults", section on 'Complications'.)

Selection of the type of PAC to be inserted is based on institution-specific availability and preferences. We prefer a continuous cardiac output catheter with continuous mixed venous oximetry (SvO₂) capabilities to facilitate management in the intensive care unit in the highest risk patients who have a greater likelihood of continued hemodynamic instability following surgery. (See "Pulmonary artery catheterization: Indications, contraindications, and complications in adults", section on 'Physiologic measurements' and "Evaluation of and initial approach to the adult patient with undifferentiated hypotension and shock", section on 'Pulmonary artery catheterization'.)

Brain monitors

●Electroencephalography – We routinely employ a raw and/or processed electroencephalography (EEG) device (eg, a bispectral index [BIS] monitor) [30,31]. Although such monitoring may help assess depth of anesthesia, EEG indices have not been shown to reliably reduce the incidence of intraoperative awareness [32] (see "Accidental awareness during general anesthesia", section on 'Brain monitoring'). Whether the use of processed EEG to target depth of anesthesia is associated with important neurocognitive outcomes such as reduced postoperative delirium and long-term cognitive impairment has been investigated. However, a retrospective analysis of the Society of Thoracic Surgeons database did not support the use of processed EEG to prevent postoperative neurocognitive disorders including postoperative delirium, encephalopathy, or stroke after cardiac surgery [33].

One substudy of a larger randomized trial noted a reduction in postoperative delirium and cognitive impairment for patients with BIS targeted levels at 50 (light anaesthesia) compared with BIS readings at 35 (deep anaesthesia) [34,35]. However, a large randomized trial did not find differences in postoperative delirium based on use of intraoperative EEG [36].

In selected cases in which deep hypothermia and circulatory arrest (DHCA) is employed during the cardiac surgical procedure, EEG is used to establish a neurophysiologic endpoint (ie, electrocortical silence) for the cerebral effects of cooling. (See "Anesthesia for aortic surgery with hypothermia and elective circulatory arrest in adult patients", section on 'Electroencephalography'.)

Some centers use EEG to supplement near-infrared spectroscopy (NIRS) monitoring to detect cerebral hypoperfusion [37].

●Cerebral oximetry – NIRS cerebral oximetry monitoring and maintenance of regional cerebral oxygen saturation (rSO₂) within 20 percent of baseline may be employed to detect regional cerebral malperfusion events and intraoperative catastrophe [31]. This monitoring may be particularly useful in selected patients with risk factors for neurologic complications such as significant cerebrovascular disease, and during selected procedures such as cardiac surgery with a concomitant procedure involving the ascending aorta or arch [38]. The algorithm describes management of significant decreases in rSO₂ during CPB (algorithm 1).

One large retrospective multicenter cohort study noted that adult cardiac surgical patients monitored with intraoperative cerebral oximetry had lower rates of major organ morbidity and mortality compared with unmonitored patients [39]. However, other meta-analyses of randomized trials have not found sufficient evidence to recommend routine use of cerebral oximetry to reduce mortality or organ-specific morbidity [40]. (See "Management of cardiopulmonary bypass", section on 'Neuromonitoring modalities' and "Anesthesia for aortic surgery with hypothermia and elective circulatory arrest in adult patients", section on 'Cerebral oximetry'.)

Prebypass transesophageal echocardiography — Practice guidelines of the American Society of Anesthesiologists (ASA) and Society of Cardiovascular Anesthesiologists suggest an initial comprehensive prebypass transesophageal echocardiography (TEE) examination [41-43]. This initial examination is performed to guide PAC insertion and final position, confirm and refine preoperative diagnoses, and detect new or unsuspected cardiovascular pathology that may alter anesthetic or surgical plans. The initial TEE examination is followed by continuous monitoring of ventricular function and volume.

Intraoperative TEE has particularly important clinical benefits in patients undergoing cardiac valve repair or replacement or proximal aortic surgery [44,45]. A matched cohort study of 872,936 patients undergoing open cardiac valve surgery and/or proximal aortic surgery from the Society of Thoracic Surgeons (STS) database found that intraoperative TEE was associated with lower 30-day mortality (3.81 versus 5.27 percent; odds ratio [OR] 0.69, 95% CI 0.67-0.72) compared with not using TEE [44]. Composite outcomes were also lower in patients who received intraoperative TEE, including stroke or 30-day mortality (5.56 versus 7.01 percent; OR 0.77, 95% CI 0.74-0.79), and reoperation or 30-day mortality (7.18 versus 8.87 percent; OR 0.78, 95% CI 0.76-0.80). Results were similar for within hospital, within surgeon matched analyses.

For patients undergoing CABG surgery, a retrospective cohort study that included 114,871 patients noted that intraoperative use of TEE was associated with lower 30-day mortality (3.7 versus 4.9 percent) and combined incidence of stroke and mortality (4.5 versus 5.5 percent) compared with no use of TEE [46].

Even if TEE is not used electively, rapid deployment may be needed to diagnose causes of acute, persistent, and life-threatening hemodynamic instability (ie, "rescue" TEE). (See "Intraoperative rescue transesophageal echocardiography (TEE)".)

Components of the initial TEE examination — After initial probe insertion, TEE examination enables confirmation of the preoperative diagnoses and refinement of the operative plan [47]. A comprehensive TEE examination includes:

●Assessment of global ventricular function [43]. The initial assessment of global (and regional) biventricular function allows comparisons during subsequent continuous TEE monitoring.

•Global LV systolic function is assessed and ejection fraction is evaluated using a qualitative grading system (eg, mild, moderate, or severe global LV hypokinesia and systolic LV dysfunction) or estimated LV ejection fraction. Patients with significant LV or right ventricular (RV) systolic dysfunction may require intraoperative inotropic support (movie 3 and movie 4). There is also some evidence for the use strain-based indices of LV dysfunction to predict adverse postbypass and postoperative outcomes [48-50]. (See "Intraoperative transesophageal echocardiography for noncardiac surgery", section on 'Global LV systolic function' and "Transesophageal echocardiography in the evaluation of the left ventricle", section on 'Systolic function'.)

Also, the presence of spontaneous echo contrast in the left atrium (LA) or aorta indicates low cardiac output.

•Global LV diastolic function is assessed using a quantitative grading system (grade 1, impaired relaxation; grade 2, pseudonormal; grade 3 restrictive filling) (image 1). Patients with significant diastolic dysfunction may benefit from atrioventricular pacing to optimize cardiac output. Diastolic dysfunction has been shown to be associated with major adverse cardiac events, in-hospital mortality, and prolonged mechanical ventilation after cardiac surgery [51-54]. However, the prebypass evaluation of LV diastolic function is most important for prognostic reasons rather than specific therapeutic interventions. Also, agreement is often poor between diastolic function assessed with preoperative transthoracic echocardiography (TTE) in the awake patient compared with prebypass intraoperative diastolic function assessed with TEE [55]. Details regarding comprehensive assessment of diastolic function are discussed elsewhere. (See "Echocardiographic evaluation of left ventricular diastolic function in adults".)

•Estimates of cardiac output can be made using the LV outflow tract or aortic valve area combined with Doppler-based methods [56]. Such estimates may be particularly useful when thermodilution measurements of cardiac output are not available in the absence of a PAC. Details regarding calculation of hemodynamic parameters are discussed elsewhere. (See "Hemodynamics derived from transesophageal echocardiography", section on 'Cardiac output'.)

●Assessment of LV regional wall motion abnormalities (RWMAs), characterized as hypokinesis, akinesis, or dyskinesis (movie 5). These may be chronic (preexisting) or may be new changes, indicative of myocardial ischemia. RWMAs indicate specific territories of myocardium perfused by each of the major coronary arteries supplying the LV (figure 2 and figure 3) [57]. In each of the 16 segments (17 minus the apical cap) of the LV wall, function may be graded as:

•Normal

•Hypokinetic (ie, reduced and delayed contraction)

•Akinetic (ie, absence of inward motion and thickening)

•Dyskinetic (ie, systolic thinning and outward systolic endocardial motion)

Although rigorous quantitative grading of each myocardial segment is not typically performed during cardiac operations, a qualitative assessment of regional ventricular function is noted and recorded. Further details regarding TEE assessment of regional LV systolic function are available elsewhere. (See "Intraoperative transesophageal echocardiography for noncardiac surgery", section on 'Regional LV systolic function' and "Transesophageal echocardiography in the evaluation of the left ventricle", section on 'Evaluation of regional wall motion'.)

●Assessment of structure and function of all cardiac valves [41,43,58]. Notably, intraoperative assessment of the severity of cardiac valve stenosis and/or regurgitation may differ from preoperative assessments due to hemodynamic changes that occur with induction of general anesthesia [59,60]. For example, reduced systemic BP decreases severity of aortic regurgitation (AR) and/or mitral regurgitation (MR), while reduced cardiac output (CO) decreases the gradients across stenotic valves.

Identification of aortic regurgitation (AR) is particularly important (movie 6 and image 2 and image 3 and image 4). Significant (ie, more than mild) AR since this will limit delivery of adequate antegrade cardioplegia solution into the coronary artery ostia after cross-clamping the ascending aorta, since much of the cardioplegia solution will regurgitate back through the incompetent aortic valve into the LV. Consequences include failure to achieve cardioplegia as well as distention of the LV. Management of significant AR during CPB typically includes use of alternative methods for delivery of cardioplegia (eg, retrograde cardioplegia), as well as insertion of an LV vent to maintain LV decompression. In addition, significant AR is a relative contraindication to the placement of an intraaortic balloon pump (IABP) because the degree of regurgitation may be increased by diastolic balloon inflation during counterpulsation. (See "Intraaortic balloon pump counterpulsation", section on 'Contraindications'.)

●Assessment of the LV for mural thrombus in patients who have an akinetic or dyskinetic myocardial segment, most commonly involving the ventricular apex (image 5 and movie 7 and movie 8). (See "Left ventricular thrombus after acute myocardial infarction".)

●Assessment of RV function. Myocardial ischemia or exacerbation of pulmonary hypertension may cause severe RV dysfunction (movie 9). Some clinicians obtain strain measurements of RV dysfunction [61]. Details regarding a comprehensive assessment of the right heart are discussed elsewhere. (See "Echocardiographic assessment of the right heart".)

●Evaluation of the thoracic aorta for atheromatous disease, calcification, or dilatation prior to aortic cannulation, and cross-clamping (image 6). Some centers also perform epiaortic scanning prior to aortic cannulation and cross-clamping (image 6), either selectively or routinely, as a supplemental and possibly superior technique for identifying disease in the ascending aorta. Further discussion can be found in a separate topic. (See "Initiation of cardiopulmonary bypass", section on 'Aortic cannulation'.)

●Identification of a patent foramen ovale that will be repaired during planned open cardiotomy. The interatrial septum is interrogated for presence of a patent foramen ovale (PFO) or atrial septal defect [62]. This is accomplished using two-dimensional (2D) imaging, as well as color-flow Doppler imaging. If there is equivocal evidence of a PFO, confirmation by injection of IV agitated saline contrast (known as a "bubble study") is a maneuver used to detect right to left atrial shunting through a PFO (movie 10). Transient atrial pressure reversal achieved with release of a sustained positive pressure breath may enhance sensitivity of this maneuver. Although repair of an incidentally discovered PFO is not warranted unless the surgical plan includes right atriotomy [63], its presence should be documented as useful information in case the patient suffers a future embolic stroke.

●Assessment of the LA and left atrial appendage (LAA) for thrombus, particularly in patients with current or past history of atrial fibrillation (movie 11). The finding of spontaneous echo contrast, indicative of stasis that predisposes to thrombus formation, is used to differentiate thrombi from normal variants such as a multilobed LAA or prominent trabeculations (movie 12 and movie 13). Identification of LA or LAA thrombus may lead to a decision to institute postoperative anticoagulation to reduce the risk of stroke. (See "Echocardiographic evaluation of the atria and appendages", section on 'Transesophageal echocardiography'.)

Continuous monitoring with TEE — Subsequently, throughout the prebypass period, and again during the postbypass period, we continuously monitor ventricular function and volume status. We monitor LV and RV function and filling. Goals include rapid detection and assessment of:

●New RWMAs (eg, hypokinesis, akinesis, or dyskinesis), which are highly suggestive of myocardial ischemia (figure 2 and figure 3) [57]. (See "Anesthesia for coronary artery bypass grafting surgery", section on 'Avoidance and treatment of ischemia'.)

●Assessment of intravascular volume status; development of hypovolemia or hypervolemia (movie 14). (See "Intraoperative transesophageal echocardiography for noncardiac surgery", section on 'Volume status'.)

●Development of low systemic vascular resistance as a cause of arterial hypotension. (See "Intraoperative transesophageal echocardiography for noncardiac surgery", section on 'Systemic vascular resistance'.)

●Factors causing hypotension, including abnormalities in:

•Preload or volume status (ie, hypovolemia or hypervolemic congestive heart failure)

•Afterload or vascular resistance (ie, low systemic vascular resistance)

•Contractility or ventricular function (ie, poor LV or RV function)

•Valvular structure and function (ie, structural abnormalities or poor function)

•Other less common causes of hypotension, such as aortic dissection or cardiac tamponade

INDUCTION OF GENERAL ANESTHESIA

Induction techniques — The goals of general anesthetic induction are to induce and maintain unconsciousness, attenuate the hemodynamic responses to endotracheal intubation and surgical stimulation, and prevent or treat hemodynamic changes that lead to myocardial oxygen imbalance and ischemia. Specific hemodynamic and physiologic goals for different types of cardiac disease (eg, coronary artery disease, cardiac valve lesions) are discussed in individual topics.

Regardless of the induction technique employed, hypotension may occur post-induction when a volatile anesthetic agent is administered to increase anesthetic depth in anticipation of the surgical incision. Hypotension can occur because of the long context-sensitive half time for high doses of an opioid such as fentanyl [64], and synergistic interaction of opioids with volatile agents (see "Maintenance of general anesthesia", section on 'Analgesic component: Opioid agents'). Significant hypotension is avoided by reducing the dose of volatile agent, or treated by administering a vasopressor in small bolus doses (eg, phenylephrine) or as a low-dose infusion (table 3).

Balanced technique — The most common anesthetic induction techniques for cardiac surgical patients includes use of a low dose of a sedative-hypnotic agent combined with a low dose of opioid and volatile anesthetic agent ("balanced technique"). For example, a small dose of propofol (eg, 0.5 to 1.5 mg/kg) may be administered in combination with a moderate dose of fentanyl 2 to 4 mcg/kg and a neuromuscular blocking agent. Since a bolus injection of propofol typically produces dose-dependent hypotension due to venous and arterial dilation as well as decreased myocardial contractility, administration of a vasopressor such as phenylephrine is often necessary. (See "General anesthesia: Intravenous induction agents", section on 'Propofol'.)

Owing to its minimal hemodynamic side effects, etomidate may be selected as the anesthetic induction agent for patients with cardiogenic shock, hemodynamic instability, critical left main coronary disease, severe aortic stenosis, or severe cardiomyopathy. A possible concern with the use of etomidate is that it inhibits the biosynthesis of cortisol, an effect that lasts <24 hours following a single dose. Although this finding may not be clinically significant [65], etomidate is not routinely administered. (See "General anesthesia: Intravenous induction agents", section on 'Etomidate'.)

A neuromuscular blocking agent is also administered during induction. During the few minutes required for adequate relaxation for endotracheal intubation, a volatile inhaled anesthetic is typically titrated to its effect on anesthetic depth. Anesthetic depth should be sufficient to assure unconsciousness and attenuate the sympathetic response to laryngoscopy and intubation. Lidocaine 1 mg/kg intravenous (IV) is often included in the induction sequence to further blunt this sympathetic response. (See "General anesthesia: Intravenous induction agents", section on 'Lidocaine' and "Anesthesia for noncardiac surgery in patients with ischemic heart disease", section on 'Induction'.)

Higher-dose opioid technique — An alternative induction technique that is used less commonly includes administration of a higher dose of a synthetic opioid (eg, fentanyl 10 to 25 mcg/kg) for patients who will remain intubated with controlled ventilation for several postoperative hours. This technique results in minimal direct myocardial depressant effect and only a small decrease in blood pressure (BP). One important adverse side effect of high-dose opioid administration is chest wall rigidity, which may make ventilation difficult [66]. Also, the technique is becoming less common in the United States (in part due to recognition of the increased prevalence of inappropriate opioid use) [67]. (See "Perioperative uses of intravenous opioids in adults: General considerations", section on 'High-dose opioid induction technique'.)

Other techniques — A newer option for anesthetic induction of cardiac surgical patients is administration of a bolus dose of the short-acting benzodiazepine remimazolam 0.2 mg/kg, with reported loss of responsiveness in 48 ± 9 seconds and no significant changes in hemodynamic parameters [68].

Patient positioning — Patients are typically in the supine position during cardiac surgery. The arms may either be tucked at the patient's side, or, less commonly, in an abducted position. A shoulder roll is typically placed under the scapulae to extend the neck. (See "Patient positioning for surgery and anesthesia in adults", section on 'Supine' and "Patient positioning for surgery and anesthesia in adults", section on 'Particular concerns with the supine position'.)

Patients are susceptible to positioning injuries during CABG surgery due to a prolonged duration in an unchanging position [69]. Theoretically, nonpulsatile flow and induced hypothermia during cardiopulmonary bypass (CPB), as well as intermittent hypotension during the prebypass and postbypass periods, may exacerbate nerve, skin, and other positioning injuries. Although there is no definitive evidence for the roles of these potential risk factors, extra precautions are taken to prevent such injuries. For example, the head is initially positioned on a cushioned pillow or "donut" pad, with frequent repositioning to prevent scalp ischemia and resultant occipital alopecia. If arms are tucked, the olecranon groove and fingers should be padded and protected to avoid pressure injuries such as ulnar neuropathy. If arms are abducted, overextension beyond 90 degrees is avoided to prevent excessive tension on the pectoralis major muscle and brachial plexus injury [69]. (See "Patient positioning for surgery and anesthesia in adults", section on 'Nerve injuries associated with supine positioning'.)

After sternotomy, placement of a sternal retractor is necessary for harvesting the internal mammary artery (see "Anesthesia for coronary artery bypass grafting surgery", section on 'Incision, sternotomy, and harvesting of venous and arterial grafts'). Retractor positioning is closely observed since the steel post attaching it to the operating table may compress the upper arm causing radial nerve injury and may also be associated with brachial plexus injury [69-71]. In addition, when the retractor lifts the sternum, the patient's head may be lifted off the supporting head cushion, particularly in an older patient who has cervical spine arthritis. If this occurs, the retractor should be adjusted or the patient's head should be repositioned with additional pillow support.

Antibiotic prophylaxis — Administration of antimicrobial therapy, typically a cephalosporin, should be initiated by the anesthesiologist within 60 minutes before the surgical incision, so that drug levels are optimal at the time of incision (table 4). If vancomycin is selected for a patient with a beta-lactam penicillin allergy or one who is known to be colonized with methicillin-resistant Staphylococcus aureus (MRSA), administration should begin within 120 minutes before the incision because of the prolonged infusion time required. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults", section on 'Cardiac surgery'.)

MAINTENANCE OF GENERAL ANESTHESIA

Maintenance techniques

●Selection of anesthetic agents – During cardiac surgery, general anesthesia is typically maintained with a volatile anesthetic inhalation agent (eg, isoflurane, sevoflurane). Use of a total intravenous anesthetic (TIVA) technique during cardiac surgery or combinations of volatile and intravenous agents are reasonable alternatives to maintain adequate depth of general anesthesia and prevent movement during surgery [72,73].

A 2021 meta-analysis noted that although volatile inhalation anesthetics were associated with shorter durations of intensive care unit stay (16 trials; 2003 participants) and hospital stay (12 trials; 1241 participants), there were no differences in mortality or MI compared with TIVA [74]. An earlier 2020 meta-analysis (42 trials, 8197 participants) comparing maintenance of anesthesia with volatile inhalation anesthetic agents versus TIVA techniques noted that inhalation agents were associated with lower one-year mortality and myocardial infarction (MI) [75]. Methodologic differences may account for the conflicting results in these meta-analyses [76]. Furthermore, in the 2020 meta-analysis [75], the largest included trial had 3430 patients, accounting for nearly 50 percent of total patients in this meta-analysis. This trail noted no difference in one-year mortality with use of TIVA versus volatile anesthetic techniques [77]. A subsequently published large retrospective study that included all Korean patients undergoing cardiac valve surgery between 2010 and 2019 did not find a difference in mortality in the 19,961 patients who received a volatile inhalation anesthetic technique compared with the 10,794 patients who had a TIVA technique [73].

●Anesthetic depth – Anesthetic requirements vary considerably during cardiac surgical procedures; thus, frequent adjustments of anesthetic depth are necessary. For example, in the prebypass period, significant nociceptive stimuli and endogenous catecholamine release may occur during initial incision, and particularly during sternotomy, necessitating adjustments to the depth of general anesthesia to reduce tachycardia and hypertension. Subsequently, during the periods of reduced surgical stimulation that typically follow sternotomy, it is appropriate to reduce anesthetic depth to avoid hypotension. (See "Anesthesia for coronary artery bypass grafting surgery", section on 'Incision, sternotomy, and harvesting of venous and arterial grafts'.)

Notably, hypothermia and rewarming during CPB may considerably change anesthetic requirements [78-80]. Furthermore, some degree of hemodilution occurs with initiation of CPB, even when limited by autologous priming. Hemodilution expands the patient's volume of distribution for anesthetic and other drugs [81]. Thus, drugs such as neuromuscular blocking agents (NMBAs) that are primarily distributed within the intravascular space should be re-dosed when CPB is initiated, particularly if peripheral nerve stimulator monitoring shows a return of neuromuscular function. During CPB, neuromuscular function is monitored with a peripheral nerve stimulator. In contrast, re-dosing may not be necessary for agents with a large volume of distribution (eg, fentanyl and propofol) because of their rapid redistribution into the new larger intravascular volume [81,82].

Prebypass ventilation strategies — We use an intraoperative lung-protective ventilation strategy in the prebypass and postbypass period (with low tidal volume [TV], low driving pressure, and positive end-expiratory pressure [PEEP]) to potentially reduce the incidence of pulmonary complications. These ventilator settings are consistent with recommendations for lung-protective ventilation for all patients undergoing anesthesia and surgery with use of mechanical ventilation. Overdistention of the lungs should be avoided [83]. (See "Mechanical ventilation during anesthesia in adults", section on 'Lung protective ventilation during anesthesia'.)

In a retrospective study that included 4694 patients undergoing cardiac surgery with CPB, 10.9 percent experienced pulmonary complications in the postoperative period (pneumonia, prolonged mechanical ventilation, need for reintubation, and/or poor oxygenation with a ratio of arterial oxygen tension/fraction of inspired oxygen <100 mmHg within 48 postoperative hours while intubated) [84]. Fewer pulmonary complications were noted in patients managed with lung-protective ventilation that included TV <8 mL/kg ideal body weight, modified driving pressure (peak inspiratory pressure - PEEP) <16 cmH₂O, and PEEP ≥5 cmH₂O, compared with patients managed with other ventilation strategies (adjusted odds ratio [OR] 0.56, 95% CI 0.42-0.75). A sensitivity analysis revealed that use of modified driving pressure <16 mmHg, but not PEEP or low TV, was also independently associated with fewer pulmonary complications (adjusted OR 0.51, 95% CI 0.39-0.66) [84]. Although elevated driving pressure may simply be a marker (rather than a cause) of lung injury, we maintain this pressure <16 mmHg as a component of lung-protective ventilation after CPB. A separate retrospective study that included 9359 cardiac surgical patients has noted that lower tidal volume (6.8 ± 1.3 mL/kg) was associated with very modest improvement in postoperative oxygenation, compared with moderate (7.9 ± 0.3) or higher (9.5 ± 0.9) tidal volumes [85].

During the prebypass period, it may be necessary to make frequent adjustments in ventilation to accommodate changing surgical conditions. Notably, during sternotomy ventilation is briefly interrupted to prevent lung injury from the sternal saw. During subsequent internal mammary artery harvest, some surgeons request reduction in the tidal volume (TV) to avoid suboptimal surgical exposure due to interference from the lungs during inspiration. In these instances, respiratory rate is increased to maintain adequate alveolar ventilation.

Prebypass fluid management — Prior to CPB, fluid administration (usually with a balanced crystalloid solution rather than a colloid solution) is typically restricted to the small volumes necessary to administer IV medications because initiation of CPB results in significant hemodilution as the CPB circuit prime (up to 1.5 liters of crystalloid) mixes with the patient's blood volume. However, judicious IV volume expansion, or administration of a vasopressor infusion, may be necessary to maintain hemodynamic stability in response to blood loss or hypovolemia in the prebypass period. Excessive hemodilution is avoided during cardiac surgery with or without CPB due to risks for postoperative weight gain, increased use of blood products, delirium, and longer durations of controlled mechanical ventilation and hospital stay [86,87]. (See "Anticoagulation and blood management strategies during cardiac surgery with cardiopulmonary bypass", section on 'Avoid excessive fluid administration' and "Anesthesia for coronary artery bypass grafting surgery", section on 'Off-pump coronary artery bypass surgery'.)

We use transesophageal echocardiography (TEE), particularly the transgastric midpapillary short-axis view, for qualitative visual assessment of left ventricular (LV) cavity size. Underfilling of the left ventricle caused by acute hypovolemia is recognized in a patient with decreased end-diastolic and end-systolic LV cavity dimensions (movie 14). Also, quantitative measurements of the internal diameter or cross-sectional area of the LV at end-diastole can be made (image 7 and image 8 and table 5) [88,89]. (See "Intraoperative transesophageal echocardiography for noncardiac surgery", section on 'Assessment of left ventricular volume'.)

Measurement or continuous monitoring of cardiac output (CO) and stroke volume (SV) with a pulmonary artery catheter (PAC) is often used to assess volume status or fluid responsiveness. In addition, several devices can be used to assess variations in the arterial pressure waveform occurring during respiration (eg, pulse pressure variation [PPV], stroke volume variation [SVV], systolic BP variation [SPV]) (figure 4 and figure 5) [90]. Normal respiratory variations in these dynamic parameters are <10 percent [91], with greater variations suggesting fluid responsiveness [92] (see "Intraoperative fluid management", section on 'Dynamic parameters to assess volume responsiveness'). Unfortunately, all these methods that are based on respiratory-circulatory interactions depend on unchanging patterns of positive pressure mechanical ventilation, which are frequently not maintained during the various phases of cardiac operations (eg, surgical requests to "breath hold" or alter tidal volume). In addition, their ability to reflect fluid responsiveness may not be accurate once the chest is opened after sternotomy.

We avoid hydroxyethyl starch (HES) colloid solutions due to concerns regarding impairment of hemostasis and acute kidney injury (AKI), as discussed in a separate topic [93-98]. (See "Intraoperative fluid management", section on 'Hydroxyethyl starches'.)

Transfusion of red blood cells is uncommon prior to CPB but may be necessary in response to sudden blood loss, or while preparing for initiation of CPB in patients with severe anemia. (See "Anticoagulation and blood management strategies during cardiac surgery with cardiopulmonary bypass", section on 'Management of anemia'.)

Urine output is measured before CPB, confirming proper placement of the Foley catheter and adequate bladder drainage, and subsequently as a gross indicator of renal perfusion and function. Effects of anesthesia and surgery typically reduce glomerular filtration and tubular function and may reduce urine output in the prebypass period [99]. Urine output is also monitored during CPB as a surrogate for end-organ perfusion, but oliguria (output <0.5 mL/kg per hour should not be interpreted as a reliable indicator for fluid administration [100].

PREPARATIONS FOR CARDIOPULMONARY BYPASS — 

Prior to initiating cardiopulmonary bypass (CPB), several key steps must be completed, as noted in separate topics (table 1) [31].

●Systemic anticoagulation – Systemic anticoagulation is necessary before aortic cannulation and subsequent initiation of CPB. Typically, this is accomplished with an intravenous (IV) dose of heparin 300 to 400 units/kg, with confirmation of adequacy of systemic anticoagulation to prevent clot formation in the CPB circuit. Details regarding heparin administration and monitoring are available in a separate topic. (See "Anticoagulation and blood management strategies during cardiac surgery with cardiopulmonary bypass", section on 'Systemic anticoagulation'.)

●Antifibrinolytic administration – Prophylactic antifibrinolytic therapy using a lysine analog (eg, tranexamic acid [TXA] or epsilon-aminocaproic acid [EACA]) is typically administered shortly after systemic heparinization to decrease microvascular bleeding in the postbypass period. Details are available in a separate topic. (See "Intraoperative use of antifibrinolytic agents", section on 'Use of antifibrinolytic agents in cardiac surgery'.)

●Cannulation of the great vessels – To initiate CPB, aortic and venous cannulation are necessary to divert the patient's blood from the heart and lungs, with rerouting through the extracorporeal circuit. (See "Initiation of cardiopulmonary bypass", section on 'Aortic, venous, and coronary sinus cannulation'.)

MANAGEMENT OF CARDIOPULMONARY BYPASS — 

Initiation of cardiopulmonary bypass (CPB), management during CPB, and weaning from CPB are discussed in separate topics (table 1) [31]:

●(See "Initiation of cardiopulmonary bypass".)

●(See "Management of cardiopulmonary bypass".)

●(See "Weaning from cardiopulmonary bypass".)

MANAGEMENT DURING THE POSTBYPASS PERIOD — 

Key steps for any cardiac surgical procedure in the period immediately after cardiopulmonary bypass (CPB) include venous and arterial decannulation and reversal of anticoagulation with protamine administration (table 1) (see "Achieving hemostasis after cardiac surgery with cardiopulmonary bypass", section on 'Reversal of anticoagulation activity'). Residual pump blood is reinfused, and temporary or backup epicardial pacing wires are inserted.

Management of cardiovascular problems — Cardiovascular problems that result in hemodynamic instability are identified and treated (table 6 and table 3), as discussed separately. (See "Intraoperative problems after cardiopulmonary bypass", section on 'Cardiovascular problems'.)

Since patients undergoing cardiac surgery (particularly aortic valve replacement [AVR]) are at increased risk for postoperative atrioventricular block, epicardial (bipolar or unipolar) pacing wires are routinely attached to the right atrium and right ventricle (RV) to maintain a stable postbypass rhythm. These pacing wires are typically placed prior to weaning from CPB (as single or duplicate sets). We ensure that pacing thresholds are adequate and perform regular checks to determine whether there is an adequate underlying cardiac rhythm (see "Weaning from cardiopulmonary bypass", section on 'Maintenance of optimal pacemaker function'). If the underlying rhythm remains inadequate following bypass, an additional temporary (backup) transvenous right RV lead (generally bipolar or quadripolar) may be inserted prior to chest closure. Another option is placement of a lead sewn to the chest wall (skin lead) in the left subclavicular area to allow unipolar RV pacing between the skin and endocardium, if bipolar pacing is not effective. Patients with persistent conduction abnormalities after the third postoperative day are referred for consideration of permanent pacemaker implantation. (See "Postoperative complications among patients undergoing cardiac surgery", section on 'Dysrhythmias' and "Temporary cardiac pacing", section on 'Pacing techniques' and "Permanent cardiac pacing: Overview of devices and indications".)

Similar cardiovascular problems may be encountered after cardiac surgical repairs accomplished without the aid of CPB (eg, off-pump coronary artery bypass grafting [CABG] surgery). (See "Anesthesia for coronary artery bypass grafting surgery", section on 'Off-pump coronary artery bypass surgery'.)

Postbypass management of fluids and blood products — After weaning from CPB, intravascular volume status is reevaluated with transesophageal echocardiography (TEE) assessments (see 'Postbypass TEE examination' below), with consideration of hemodynamic parameters such as blood pressure, central venous pressure (CVP), pulmonary artery pressure (PAP), cardiac output, and mixed venous oxygen saturation (SvO₂). Serial lactate and/or base deficit values on arterial blood gases can also be useful to guide fluid therapy. Fluid administration may be necessary due to treat hypovolemia, or transfusion of red blood cells may be necessary due to persistent surgical bleeding. Decisions regarding transfusion are individualized, but hemoglobin is typically maintained ≥7.5 g/dL [101-105]. (See "Achieving hemostasis after cardiac surgery with cardiopulmonary bypass", section on 'Transfusion of red blood cells'.)

Management of other systemic problems — Other systemic complications (eg, pulmonary, metabolic, renal) are frequently encountered immediately after weaning from CPB while the patient is still in the operating room. These problems are often predictable based on patient-specific and cardiac surgical procedure-specific factors. However, some patients experience unpredictable, sudden, or severe complications that require immediate intervention and/or urgent reinstitution of CPB. Management of these problems is discussed separately. (See "Intraoperative problems after cardiopulmonary bypass".)

Postbypass TEE examination — During and immediately after weaning from CPB, TEE is used to assess results of all surgical interventions while the patient is still in the operating room [41,43]. The following aspects are emphasized:

●Removal of air after open cardiotomy. Air accumulates in the left heart chambers during aortic or mitral valve repair or replacement. TEE is employed to identify air in the cardiac chambers, with ongoing monitoring to guide its removal via surgical venting.

Air can accumulate in the pulmonary veins, the left atrial appendage, the dome of the left atrium (LA), and the LV apex. Any intracardiac air may embolize to the coronary, cerebral, and other vital organs once the aortic cross-clamp is removed and the heart begins to contract (movie 15 and movie 16 and movie 17 and movie 18). Thus, it is important to remove nearly all air prior to allowing full ventricular ejection during weaning from CPB to avoid or minimize arterial embolization. (See "Intraoperative problems after cardiopulmonary bypass", section on 'Arterial air embolization'.)

The right coronary artery is in a superior or nondependent position when a patient is supine; thus, air preferentially enters the right coronary artery, which may cause ischemia of the RV and inferior wall of the LV, as well as arrhythmias (particularly heart block) (movie 15).

Retained air may be eliminated via a vent/catheter in the aortic root as well as via an LV vent catheter, just prior to and following removal of the aortic cross-clamp. The de-airing process is monitored with TEE (movie 17). In some centers, the patient is placed in the Trendelenburg position during de-airing to decrease the risk of cerebral air embolization.

●Adequacy of any surgical repair (eg, repair or replacement of a cardiac valve, assessing the function of the repaired or replaced valve, including identification of any paravalvular leaks).

●Identify complications such as myocardial ischemia, evidenced by development of new or worsening regional wall motion abnormalities. These assessments are ideally performed when hemodynamic variables are similar to the patient's baseline values obtained after induction of general anesthesia and before initiation of CPB.

●Assessment of global left ventricular (LV) and right ventricular (RV) function.

●LV and RV chamber sizes are assessed to determine intravascular volume status (movie 14). This is important because CVP and PAP measurements are poor predictors of intravascular volume and fluid responsiveness [106]. (See "Intraoperative transesophageal echocardiography for noncardiac surgery", section on 'Volume status'.)

●LV regional wall motion abnormalities (RWMAs) are documented as part of the overall assessment of the adequacy of revascularization in territories of myocardium perfused by each of the major coronary arteries supplying the LV (figure 2 and figure 3). (See "Anesthesia for coronary artery bypass grafting surgery", section on 'Post-revascularization transesophageal echocardiography'.)

Previously ischemic or hibernating myocardium may show improved function in the early postbypass period. However, myocardial stunning is common and consequently, myocardial segments that had abnormal contraction in the prebypass period may remain impaired even after adequate coronary blood flow has been restored.

Significant deterioration of regional wall motion in previously normal myocardial segments may indicate a technical problem with a coronary graft (eg, poor quality of a bypass graft anastomosis, kinking, vasospasm, or embolization of air or microparticulate debris into the graft) (movie 5). Poor graft flow can be confirmed by a Doppler flow probe applied to the graft. ST-segment changes on the electrocardiogram (ECG) or hypotension with low cardiac output may also be noted. Detection of such problems allows surgical correction prior to leaving the operating room. (See "Intraoperative problems after cardiopulmonary bypass", section on 'Surgical or technical problems'.)

In patients who require ventricular pacing after CPB, a distinct septal motion abnormality termed "septal bounce" is often observed; this occurs due to the dyssynchronous pattern of ventricular depolarization that accompanies RV epicardial pacing (movie 19). Septal bounce can be distinguished from a true RWMA because septal thickening persists during ventricular pacing but is absent when the septum is ischemic. If this is difficult to discern visually, a brief pause in ventricular pacing may be helpful.

New or worsening mitral regurgitation (MR) in the postbypass period should prompt a thorough evaluation for LV RWMAs indicating an ischemic cause of the MR.

●Hypotension after cardiac surgical procedures may occasionally be caused by dynamic LV outflow tract obstruction with systolic anterior motion of the mitral leaflets [107].

●If aortic dissection is suspected following decannulation (eg, in a patient with a calcific or diffusely atheromatous ascending aorta, or one who develops postbypass hypotension that is unresponsive to treatment), the aorta (ascending, arch and descending segments) is evaluated to identify this potentially fatal complication (image 9).

Communication with the surgeon regarding complications noted on the TEE examination facilitates decisions to reinstitute CPB for surgical correction, if necessary. After aortic decannulation, the ascending aorta is evaluated to exclude aortic dissection. TEE is also used for continuous monitoring throughout the postbypass period to assess ventricular volume and LV and RV function to aid in diagnosis of hypotension for the remainder of the intraoperative period. The TEE probe is left in place until the patient is ready for transport to the intensive care unit.

Postbypass ventilation — As noted above, we use an intraoperative lung-protective ventilation strategy in the prebypass and postbypass period (with low tidal volume [TV], low driving pressure, and positive end-expiratory pressure [PEEP]) to potentially reduce the incidence of pulmonary complications [84,85]. (See 'Prebypass ventilation strategies' above and "Mechanical ventilation during anesthesia in adults", section on 'Lung protective ventilation during anesthesia'.)

Sternotomy closure — Hemostasis must be achieved prior to closure of the sternotomy wound. Management of bleeding and coagulopathy in the postbypass period can be challenging, as discussed in detail separately. (See "Achieving hemostasis after cardiac surgery with cardiopulmonary bypass", section on 'Achieving hemostasis and management of bleeding'.)

With chest closure, it is common to see minor decreases in arterial blood pressure (BP) with concomitant increases in CVP and/or PAP. This occurs due to cardiac chamber compression as the sternum is reapproximated. TEE is employed to verify that hypotension is not the result of new RWMAs that may result from kinking or occlusion of a newly placed bypass graft.

In rare cases, sternal closure is not possible due to persistent bleeding, hemodynamic instability caused by compression of the right atrium and ventricle, or other technical problems. In these instances, the chest is left “open” with an Esmarch bandage sutured to the open sternal edges to provide coverage to the "open" chest prior to leaving the operating room. (See "Intraoperative problems after cardiopulmonary bypass", section on 'Inability to close the sternum'.)

Transport and handoff in the intensive care unit

Preparation for transport — Optimal patient condition for transport to the intensive care unit (ICU) is ensured as surgery concludes (eg, hemodynamic stability, control of bleeding and coagulopathy, adequate oxygenation and ventilation). A final arterial blood gas is obtained to assess PaO₂ and base deficit, and point-of-care tests are obtained to check hemoglobin (Hgb), potassium, and calcium levels. A final transesophageal echocardiography (TEE) evaluation of ventricular function and volume status is performed, and appropriate adjustments in inotropic, vasodilator, or fluid therapy are made.

If there is clinical evidence for ongoing hemodynamic instability evidenced by refractory hypotension, low measured cardiac index, metabolic acidosis, persistent electrocardiogram (ECG) changes (particularly ST-segment elevation), or significant deterioration in regional or global left ventricular (LV) or right ventricular (RV) function noted with TEE, then we often insert a pulmonary artery catheter (PAC) before the patient leaves the operating room. The continuous hemodynamic data provided by a PAC may be useful for ongoing resuscitation in the ICU since continuous TEE monitoring will no longer be available in the postoperative period. PAC placement under controlled conditions in the operating room is preferred to urgent or emergency placement in an unstable patient after transport to the ICU. Risks during insertion include inducing ventricular fibrillation, particularly in patients with active RV ischemia [108].

Continuous infusion of an intravenous (IV) sedative such as propofol or dexmedetomidine is initiated before discontinuing the volatile inhalation anesthetic. Adequate time for the selected IV agent to reach steady plasma concentrations should be allowed in the final minutes before leaving the operating room so that the patient remains adequately sedated during transport. (See "Monitored anesthesia care in adults", section on 'Propofol' and "Monitored anesthesia care in adults", section on 'Dexmedetomidine'.)

Transport to the intensive care unit — Details regarding transport to the intensive care unit are discussed separately. (See "Transport of surgical patients" and "Transport of surgical patients", section on 'Transport of critically ill patients'.)

In rare cases, direct transport to a cardiac catheterization suite for emergency coronary angiography may be necessary after cardiac surgery (eg, if acute coronary ischemia is suspected or if hemodynamic instability of unclear etiology persists) [109].

Handoff in the intensive care unit — Upon arrival in the ICU, patient information is communicated from the surgical team to the ICU team using a formal process that is termed a "handoff," or "handover." The table outlines one suggested handover protocol (table 7) [110-112]. In all cases, the anesthesiologist should remain with the patient until hemodynamic and overall stability are ensured. (See "Handoffs of surgical patients", section on 'Operating room to intensive care unit'.)

In a 2018 literature review of 21 studies (4568 patients), a structured interdisciplinary handover from the operating room to the ICU after cardiac surgery was associated with prevention of adverse events (seven studies), as well as with improved provider satisfaction (13 studies), handoff completeness (18 studies), and compliance with process measures such as efficiency in transfer of equipment and technology and handoff of critical information, compared with unstructured handoffs [113].

EMERGENCY CARDIAC SURGICAL PROCEDURES — 

Selected patients are unstable upon presentation to the cardiac operating room and have extremely high risk for morbidity or mortality. Examples include acute ascending (type A) aortic dissection, cardiogenic shock or mechanical complications after acute myocardial infarction (MI) such as rupture of the left ventricular free wall or interventricular septum, acute mitral regurgitation (MR), ongoing ischemia after unsuccessful or complicated percutaneous coronary intervention, critical aortic stenosis (AS) with coexisting unstable coronary artery disease, acute severe aortic regurgitation (AR) with pulmonary edema, or presence of large mobile vegetations due to endocarditis [114]). Patients requiring emergency surgery have a high risk for morbidity and mortality [17,115-118], particularly those who experience preincision cardiac arrest [119].

Considerations for emergency or high-risk cases include:

●Patients with actual or potential hemodynamic instability may present to the operating room with an intraaortic balloon pump (IABP) in place, or the surgeon may plan to insert an IABP after induction of general anesthesia or before termination of cardiopulmonary bypass (CPB). Notably, an IABP is contraindicated if the patient has significant aortic regurgitation (AR). (See "Intraaortic balloon pump counterpulsation".)

●Most monitoring should be established before (rather than after) anesthetic induction if possible, including insertion of the intra-arterial catheter and placement of a central venous catheter (CVC).

●External defibrillator pads should be placed on the patient prior to induction, and a functioning pacemaker/defibrillator should be ready at the bedside. If atrial or ventricular fibrillation occur, appropriate and immediate cardioversion or defibrillation is typically necessary unless the surgical team can rapidly insert arterial and venous cannulae to initiate CPB.

●In some cases, prepping and draping in preparation for surgery should be completed while the patient is still awake, with the entire operating room team present and ready to urgently establish CPB if cardiac arrest occurs during anesthetic induction.

●Inotropic and vasopressor infusions should be connected in the CVC ports, ready to infuse.

●Induction of anesthesia is performed with agents that cause minimal change in hemodynamics. Examples include etomidate 0.3 mg/kg or fentanyl 5 to 10 mcg/kg combined with midazolam 0.05 to 0.1 mg/kg. Anesthesia is subsequently maintained during the prebypass period with appropriate doses of volatile inhalation anesthetic.

●Hemodynamic stability is carefully maintained during the prebypass period. Typically, vasoactive drug infusions are required to maintain adequate blood pressure (BP) and cardiac output (table 3). Atrial pacing may be necessary to establish optimum heart rate, or atrioventricular (AV) pacing may be necessary if heart block is present.

●CPB is established as quickly as possible. (See "Initiation of cardiopulmonary bypass".)

●Postbypass problems should be anticipated. (See "Intraoperative problems after cardiopulmonary bypass".)

Preoperative preparations for emergency cardiac surgery are discussed separately. (See "Overview of preoperative evaluation and management for cardiac surgery in adults", section on 'Emergency surgery'.)

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Management of cardiopulmonary bypass".)

SUMMARY AND RECOMMENDATIONS

●Premedication – Some cardiac surgical patients benefit from premedication with small incremental doses of a short-acting intravenous (IV) benzodiazepine (eg, midazolam 1 to 2 mg) and/or opioid (eg, fentanyl 50 mcg), administered under the anesthesiologist's observation. However, titration of smaller doses is warranted in older patients with critical cardiac lesions.

●Monitoring – Cardiac surgery is conducted using standard American Society of Anesthesiologists (ASA) monitors (table 2), as well as intra-arterial and central venous access. We also monitor urine output, degree of neuromuscular blockade (using a peripheral nerve stimulator), and temperature. Furthermore, for most cardiac surgical cases, we use transesophageal echocardiography (TEE), processed electroencephalography (EEG), and point-of-care (POC) testing of laboratory values. Additional monitoring with a pulmonary artery catheter (PAC) or a cerebral oximetry monitor may be employed in selected patients. (See 'Monitoring' above.)

●TEE considerations – Intraoperative TEE is often used during cardiac surgery to confirm and refine preoperative diagnoses, detect new or unsuspected cardiovascular pathology that may alter anesthetic or surgical plans, and guide PAC positioning. We conduct an initial comprehensive prebypass TEE examination, followed by continuous use of the TEE to monitor ventricular function and volume. In the postbypass period, TEE is used to assess results of all surgical interventions while the patient is still in the operating room. Even if TEE is not used electively, rapid deployment may be needed to diagnose causes of acute, persistent, and life-threatening hemodynamic instability (ie, "rescue" TEE). (See 'Prebypass transesophageal echocardiography' above and 'Postbypass TEE examination' above.)

●Induction of anesthesia – The most common anesthetic induction technique includes use of a low dose of a sedative-hypnotic agent combined with a low dose of opioid and volatile anesthetic agent ("balanced technique"). Administration of higher doses of a synthetic opioid is avoided in patients participating in enhanced recovery after cardiac surgery (ERACS) protocols to avoid prolonged respiratory depression and need for mechanical ventilation. (See 'Induction techniques' above and "Overview of enhanced recovery after cardiothoracic surgery".)

●Maintenance of anesthesia – We suggest maintenance of general anesthesia with a volatile anesthetic agent (Grade 2C). Use of a total intravenous anesthetic (TIVA) technique or combinations of volatile and intravenous agents are reasonable alternatives to maintain adequate anesthetic depth and prevent movement during surgery. Neuromuscular function is monitored with a peripheral nerve stimulator during CPB. (See 'Maintenance techniques' above.)

●Lung-protective ventilation – We use a lung-protective ventilation strategy before and after cardiopulmonary bypass (CPB) with low tidal volume [TV], low driving pressure, and positive end-expiratory pressure [PEEP]) to potentially reduce the incidence of pulmonary complications. (See 'Prebypass ventilation strategies' above and 'Postbypass ventilation' above.)

●Fluid management

•Prebypass period - Judicious fluid administration (usually with a balanced crystalloid solution rather than a colloid solution) prior to CPB is typically restricted to small volumes because initiation of CPB results in significant hemodilution as the CPB circuit prime mixes with the patient's blood volume. (See 'Prebypass fluid management' above.)

We avoid hydroxyethyl starch (HES) colloid solutions due to concerns regarding increased risk of bleeding and acute kidney injury (AKI). Evidence is discussed in a separate topic. (See "Intraoperative fluid management", section on 'Hydroxyethyl starches'.)

•Postbypass period - After weaning from CPB and return of reservoir pump blood, intravascular volume status is reevaluated and treated. Decisions regarding transfusion of blood products are individualized, but hemoglobin is typically maintained ≥7.5 g/dL. (See 'Postbypass management of fluids and blood products' above.)

●Management during CPB – Key steps for intraoperative management of CPB are noted in the table (table 1), and are discussed in detail in separate topics:

•(See "Anticoagulation and blood management strategies during cardiac surgery with cardiopulmonary bypass".)

•(See "Initiation of cardiopulmonary bypass".)

•(See "Management of cardiopulmonary bypass".)

•(See "Weaning from cardiopulmonary bypass".)

•(See "Achieving hemostasis after cardiac surgery with cardiopulmonary bypass".)

●Management after CPB – Key steps for the period immediately after CPB are noted in the (table 1). Cardiovascular and other systemic problems in the postbypass period are identified and treated (table 6). (See 'Management during the postbypass period' above and "Intraoperative problems after cardiopulmonary bypass".)

●Emergency or high-risk procedures – Considerations for emergency or high-risk cardiac surgical procedures are discussed above. (See 'Emergency cardiac surgical procedures' above.)