Monitoring During Adult Cardiac Surgery
Jessica Tashjian MD 1, James Ramsay MD 2
1 Assistant Professor of Anesthesiology, University of California, San Francisco
2 Professor of Anesthesiology, University of California, San Francisco
Introduction
Monitoring during cardiac surgical procedures should be “patient specific” depending on the underlying cardiovascular disease, patient comorbidities, predicted surgical issues (complexity, duration, blood loss, anticipated problems), and anticipated early postoperative course. In reality, there can be little doubt that cardiovascular anesthesiologists and surgeons often prefer to know as much as possible about cardiovascular function during surgery, as the consequences of untreated poor cardiac function can be fatal. Skill, familiarity and context (busy surgical service vs smaller caseload), surgical experience, and preference based on past clinical experiences also weigh into monitoring decisions. More monitoring may be perceived as necessary and appropriate on the one hand, or both unnecessary and harmful (leading to unnecessary treatment) on the other. Decades ago when two cardiac anesthesiologists from Houston and Atlanta were discussing the pulmonary artery catheter, one remarked, ‘what is considered essential in Atlanta is considered a nuisance in Houston.’
As with all anesthetics, basic monitoring includes standard monitors as defined by the American Society of Anesthesiology [1]. These include intermittent non-invasive blood pressure measurements, continuous EKG monitoring, temperature, continuous pulse oximetry, end-tidal capnography, and FiO2 monitoring. Most cardiac operating rooms are equipped with monitors capable of multiple ECG lead monitoring; most commonly a 5 lead system is used with one precordial (V5) and one limb lead (I or II) being continuously displayed. Some manufacturers offer twelve lead modules. Filtering modes that distort ST segments should be disabled for cardiac procedures. More than one site of pulse oximetry monitoring (i.e., two pulse oximeters on different extremities or one on the ear) may be employed due to the not infrequent loss of signal due to hemodynamic compromise or administration of vasoconstrictors. More complex monitoring (invasive arterial pressure, central pressures, cardiac output, transesophageal echocardiography) is the main subject of this chapter.
Invasive Arterial Pressure
Beat-to-beat arterial blood pressure monitoring with an arterial catheter is required for cardiac surgery. In addition to closely monitoring the blood pressure during surgical manipulations and guiding the administration of vasoactive drugs, monitoring of arterial blood gases and acid-base status is an important component of intraoperative management. Cardiopulmonary bypass (CPB) usually results in significant narrowing or even loss of the pulse pressure. Placement of an aortic crossclamp during CPB always results in the loss of cardiac-generated pulsatility and renders the noninvasive method (automated blood pressure cuff) nonfunctional. Invasive arterial access is often obtained prior to induction of anesthesia as the hemodynamic effects of anesthetic induction agents and the initiation of positive pressure ventilation can be profound in the patient with cardiac disease. The most common site for invasive arterial access is the radial artery; however, brachial, axillary, or femoral arterial access may be required depending on the surgical procedure and patient anatomy. Radial catheters are typically 20 or 22 gauge and 2-4 cm in length; use of more central sites where the distance from skin to artery is greater requires longer (but not necessarily larger gauge) catheters to prevent dislodgement.
Palpation of the pulse has traditionally guided arterial catheter placement; however, the use of real-time ultrasound is increasing for all vascular cannulations. Use of ultrasound for arterial access permits clear visualization of the artery and catheter entry into the vessel, and may decrease the number of attempts needed for successful placement (Figure 1) [2,3]. In the United States, the Center for Disease Control and Prevention (CDC-P) recommends use of sterile technique for arterial cannulation including sterile prep, mask, hat, sterile gloves for the radial artery and a full body drape for central sites (i.e. femoral artery) [4].
As a result of cardiopulmonary bypass, a gradient between central and peripheral (e.g., radial) pressures can develop. Several authors have studied this phenomenon, which usually lasts approximately an hour after termination of CPB and has been attributed to both peripheral vasodilatation and peripheral vasoconstriction [5,6,7]. Surgeons can estimate the central blood pressure by direct palpation of the aorta or by insertion of a small-bore needle in the aorta (the cardioplegia needle is easily available) in order to verify how accurately the radial site reflects central blood pressure, critical information to aid in decision making as one prepares to wean the patient from the cardiopulmonary bypass machine.
The arterial waveform can be used to non-invasively calculate stroke volume and cardiac output (CO). There are several devices on the market using different analytic techniques, however their correlation to the clinical standard (thermodilution catheter CO, see below) has been somewhat variable in the cardiac surgery setting and they are not widely used in North America for cardiac procedures [8].
Risks of invasive arterial access include hematoma, infection, thrombosis, pseudoaneurysm formation, nerve injury, and distal extremity ischemia. While non-invasive blood pressure cuffs will not be functional during periods of decreased pulsatility (as described above), it is prudent to have one in place in the event the invasive line malfunctions after CPB.
Monitoring during cardiac surgical procedures should be “patient specific” depending on the underlying cardiovascular disease, patient comorbidities, predicted surgical issues (complexity, duration, blood loss, anticipated problems), and anticipated early postoperative course. In reality, there can be little doubt that cardiovascular anesthesiologists and surgeons often prefer to know as much as possible about cardiovascular function during surgery, as the consequences of untreated poor cardiac function can be fatal. Skill, familiarity and context (busy surgical service vs smaller caseload), surgical experience, and preference based on past clinical experiences also weigh into monitoring decisions. More monitoring may be perceived as necessary and appropriate on the one hand, or both unnecessary and harmful (leading to unnecessary treatment) on the other. Decades ago when two cardiac anesthesiologists from Houston and Atlanta were discussing the pulmonary artery catheter, one remarked, ‘what is considered essential in Atlanta is considered a nuisance in Houston.’
As with all anesthetics, basic monitoring includes standard monitors as defined by the American Society of Anesthesiology [1]. These include intermittent non-invasive blood pressure measurements, continuous EKG monitoring, temperature, continuous pulse oximetry, end-tidal capnography, and FiO2 monitoring. Most cardiac operating rooms are equipped with monitors capable of multiple ECG lead monitoring; most commonly a 5 lead system is used with one precordial (V5) and one limb lead (I or II) being continuously displayed. Some manufacturers offer twelve lead modules. Filtering modes that distort ST segments should be disabled for cardiac procedures. More than one site of pulse oximetry monitoring (i.e., two pulse oximeters on different extremities or one on the ear) may be employed due to the not infrequent loss of signal due to hemodynamic compromise or administration of vasoconstrictors. More complex monitoring (invasive arterial pressure, central pressures, cardiac output, transesophageal echocardiography) is the main subject of this chapter.
Invasive Arterial Pressure
Beat-to-beat arterial blood pressure monitoring with an arterial catheter is required for cardiac surgery. In addition to closely monitoring the blood pressure during surgical manipulations and guiding the administration of vasoactive drugs, monitoring of arterial blood gases and acid-base status is an important component of intraoperative management. Cardiopulmonary bypass (CPB) usually results in significant narrowing or even loss of the pulse pressure. Placement of an aortic crossclamp during CPB always results in the loss of cardiac-generated pulsatility and renders the noninvasive method (automated blood pressure cuff) nonfunctional. Invasive arterial access is often obtained prior to induction of anesthesia as the hemodynamic effects of anesthetic induction agents and the initiation of positive pressure ventilation can be profound in the patient with cardiac disease. The most common site for invasive arterial access is the radial artery; however, brachial, axillary, or femoral arterial access may be required depending on the surgical procedure and patient anatomy. Radial catheters are typically 20 or 22 gauge and 2-4 cm in length; use of more central sites where the distance from skin to artery is greater requires longer (but not necessarily larger gauge) catheters to prevent dislodgement.
Palpation of the pulse has traditionally guided arterial catheter placement; however, the use of real-time ultrasound is increasing for all vascular cannulations. Use of ultrasound for arterial access permits clear visualization of the artery and catheter entry into the vessel, and may decrease the number of attempts needed for successful placement (Figure 1) [2,3]. In the United States, the Center for Disease Control and Prevention (CDC-P) recommends use of sterile technique for arterial cannulation including sterile prep, mask, hat, sterile gloves for the radial artery and a full body drape for central sites (i.e. femoral artery) [4].
As a result of cardiopulmonary bypass, a gradient between central and peripheral (e.g., radial) pressures can develop. Several authors have studied this phenomenon, which usually lasts approximately an hour after termination of CPB and has been attributed to both peripheral vasodilatation and peripheral vasoconstriction [5,6,7]. Surgeons can estimate the central blood pressure by direct palpation of the aorta or by insertion of a small-bore needle in the aorta (the cardioplegia needle is easily available) in order to verify how accurately the radial site reflects central blood pressure, critical information to aid in decision making as one prepares to wean the patient from the cardiopulmonary bypass machine.
The arterial waveform can be used to non-invasively calculate stroke volume and cardiac output (CO). There are several devices on the market using different analytic techniques, however their correlation to the clinical standard (thermodilution catheter CO, see below) has been somewhat variable in the cardiac surgery setting and they are not widely used in North America for cardiac procedures [8].
Risks of invasive arterial access include hematoma, infection, thrombosis, pseudoaneurysm formation, nerve injury, and distal extremity ischemia. While non-invasive blood pressure cuffs will not be functional during periods of decreased pulsatility (as described above), it is prudent to have one in place in the event the invasive line malfunctions after CPB.
Central venous catheter
Central venous access is required during cardiac surgery for the safe administration of vasoactive and inotropic medications, as well as administration of fluids and blood products, and if peripheral access is difficult or inadequate. A central line makes it possible to sample central venous blood for measurement of oxygen saturation (SCVO2), [an approximation of mixed venous saturation (SVO2), which can only be obtained from the pulmonary artery], which is reflective of the balance between whole-body oxygen supply and demand. A central line may also be used to transduce and monitor the central venous pressure (CVP).
While CVP monitoring has been shown in critically ill populations to correlate poorly with blood volume and to be a poor predictor of left ventricular fluid responsiveness, most cardiac anesthesiologists find trending of CVP values, especially at the extremes, in conjunction with direct visualization of the heart provides some information regarding fluid status [9,10]. In addition the CVP can be a valuable indirect reflection of right heart function, help avoid over-distension of the right ventricle, and the waveform can be used to suggest changes in rhythm, ventricular compliance, and pericardial effects. Timing of central line placement is patient and practitioner dependent; in many patients with adequate peripheral access, anesthesia can be safely induced prior to cannulation for central access. Other patients may require central line placement with sedation prior to induction of anesthesia. Common sites for central venous access include the internal jugular (IJ), subclavian, and femoral veins.
Most anesthesiologists prefer the right IJ site as it provides the most direct and shortest route into the heart and is easily visualized with ultrasound. The left subclavian vein also provides a direct route to the right atrium without a turn; both the left IJ and right subclavian sites require the catheter to make a significant turn in the course of reaching the junction of the superior vena cava and right atrium. If the subclavian vein is accessed too medially, the catheter may be compressed between the first rib and clavicle during sternal retraction. Discussion with the surgeon may help guide the site chosen, as surgery may be close to the subclavian area (e.g., axillary artery access for the “aortic” CPB line during aortic procedures), and left sided IJ or subclavian lines may be at risk in re-operative procedures (via sternotomy) where the innominate vein may be injured and need to be over-sewn.
Maximum sterile precautions (including hat, mask, gown, gloves and large sterile drape) are recommended by the CDC for central venous access, and use of real-time ultrasound to guide the vascular access has become the community standard in North America for the IJ site.4 While use of ultrasound is not as easy for the subclavian site and often requires a more lateral approach than would otherwise be chosen, its use is increasing [11]. Risks of invasive central venous access include hematoma, infection, thrombosis, venous injury, inadvertent arterial cannulation, and air embolism. For internal jugular and subclavian venous insertion sites, pneumothorax and chylothorax are additional potential complications.
Pulmonary arterial catheter (PAC)
A PAC can be placed through a central venous introducer sheath in order to invasively measure pulmonary artery pressure (PAP), pulmonary artery occlusion pressure (PAOP), and CO. As indicated above, the blood drawn from the pulmonary artery, known as the mixed venous oxygen saturation (SVO2) provides a measure of the whole body balance between oxygen supply and demand. Pulmonary artery catheterization may be most useful in patients with known pulmonary hypertension as it provides real time measures of PAP, CVP, and CO to help guide hemodynamic management of the right heart in these difficult patients.
While some centers continue to use PACs in all patients undergoing cardiac procedures, many do not. Studies of the use of the PAC outside of the setting of cardiac surgery have not shown its use to provide benefit; indeed many studies have shown harm, attributed to several possible causes including aggressive treatment of “numbers” that do not need treatment, and misinterpretation of complex waveforms [12,13]. While one would hope that cardiac anesthesiologists and surgeons would be true experts at interpretation of numbers and waveforms obtained with the PAC, there is no evidence to support this contention nor is there scientific evidence to support its use as providing benefit to cardiac surgery patients. Its routine use is institution or practitioner dependent and based more on habit and individual experiences rather than on proven benefit. That being said, transplant surgeons generally request placement of a PAC to help guide management of right ventricular function after the placement of ventricular assist devices (VADs) and after heart transplantation. In the highest risk surgical patients with poor cardiac function, pulmonary hypertension, and those requiring complex procedures, central pressures and CO are viewed by both anesthesiologists and surgeons as useful parameters for hemodynamic management of both right and left ventricular function. While transesophageal echocardiography (TEE) has become the intraoperative cardiac monitor of choice by most (see below), this modality is not continuously available for monitoring in the postoperative period, whereas the PAC is.
Cardiac output is measured with a PAC via thermodilution. A 10 ml bolus of saline at room temperature is injected into a proximal port on the catheter and a thermistor at the tip of the catheter tracks the temperature change of the blood resulting from this injection (Figure 2). A computer integrates the temperature change, and this integral is used in the modified Stewart-Hamilton equation to derive flow (CO). Broadly speaking, a slow or prolonged temperature change means fluid is moving slowly and thus the CO is low; conversely, a rapid temperature changes means CO is high. Note that the PAC measures right ventricular CO. In most cases, this is equivalent to left ventricular CO, but in the case of intracardiac shunt or right-sided valvular regurgitation, this assumption is not valid.
Pulmonary artery occlusion pressure is measured when the balloon at the tip of the PAC is inflated; in the past it was thought balloon inflation caused the catheter tip to float distally into the pulmonary artery to obtain the “wedge” pressure but this is incorrect. The occlusion pressure is assumed to measure the pressure in the pulmonary capillary bed, which is in continuity with the left atrium and can be extrapolated to predict left-ventricular end diastolic pressure (LVEDP) assuming no pulmonary vascular disease and no mitral stenosis. Traditionally, LVEDP has been used as an indicator of left heart function, volume status, and hence fluid responsiveness. Just as with the CVP, however, studies have shown that the PAOP correlates poorly with fluid status and is a poor predictor of fluid responsiveness [9].
Specialized versions of pulmonary artery catheters include technology to provide continual CO measurements using an automated heat source (wire coil around the catheter) rather than a cold injectate signal, and continuous SVO2 using fiberoptic light bundles. In addition, some PACs are made with imbedded pacing electrodes, or with ports specifically designed to accommodate placement of pacing wires (i.e., through the catheter; Figure 2). Risks of placement of PACs include all the risks of central venous access such as local trauma, infection, thrombosis, and air embolism with the added risks of pulmonary artery injury/rupture from balloon inflation, tricuspid and pulmonic valve injury, and arrhythmias. Due to the multiple injection sites and the use of a “sleeve” around the catheter and site where it enters the introducer, there is likely an increased risk of infection (vs a CVC) if the catheter is in place more than 3 days.
Transesophageal echocardiography
Transesophageal echocardiography (TEE) has become the preferred monitor for intraoperative management of cardiac surgical patients. This modality provides continuous, real-time visualization of intra- and extra-cardiac structures, implanted wires and devices, biventricular global and regional cardiac function, valvular disease and function, and intra-cardiac volume. Cardiac imaging with TEE is visible to both the anesthesiologist and the surgeon. Using Doppler-derived velocities, both right- and left-sided stroke volume and cardiac output, as well as PA pressures and right and left-sided filling pressures can be calculated.
Practice Guidelines from the American Society of Anesthesiologists (ASA) and Society of Cardiovascular Anesthesiologists (SCA) state: "For adult patients without contraindications, TEE should be used in all open heart (e.g., valvular procedures) and thoracic aortic surgical procedures and should be considered in coronary artery bypass graft surgeries to: (1) confirm and refine the preoperative diagnosis, (2) detect new or unsuspected pathology, (3) adjust the anesthetic and surgical plan accordingly, and (4) assess the results of surgical intervention" [14]. Real-time three-dimensional TEE has become a reality in the clinical setting, providing remarkable images of the heart which can be manipulated at the time of imaging or later to further define anatomy.
The American Society of Echocardiography currently recommends incorporating 3D TEE into routine clinical practice for assessment of left ventricular size and function, mitral valve anatomy, and guidance of transcatheter valvular interventions [15].
Although TEE has become standard of care for the majority of cardiac surgical procedures, with the benefit of real time imaging being self-evident, little data exist which quantifies any benefit with regard to outcome. Its contribution as a necessary diagnostic tool has therefore gone mostly unchallenged. Contraindications to TEE include esophagectomy, significant esophageal stricture, prior esophageal surgery, tracheoesophageal fistula, and esophageal trauma [14]. If a patient has a relative contraindication and the TEE is thought to provide significant benefit, one can have an upper endoscopy performed to determine if a TEE is a reasonable option. Risks of placement include sore throat, dental damage, oropharyngeal injury and perforation, and esophageal injury and perforation.
Near infrared cerebral reflectance spectroscopy (NIRS)
Maintenance of adequate cerebral perfusion is of utmost importance, particularly during non-pulsatile cardiopulmonary bypass. Near infrared reflectance spectroscopy attempts to quantify cerebral perfusion through measurement of bifrontal cerebral oxygen saturation. This is accomplished by means of two adhesive pads that are applied to the forehead. The pads emit near-infrared light, which is able to penetrate the skull and is differentially absorbed by oxygenated and deoxygenated hemoglobin. The amount of light returning at a particular wavelength is analyzed using the modified Lambert-Beer equation to give an approximate ratio of oxygenated to deoxygenated hemoglobin. As opposed to pulse oximetry that displays saturation only during arterial pulsation (and hence monitors arterial saturation), cerebral oximetry does not require pulsatility and is intended to reflect cerebral tissue rather than arterial oxygenation.
Definitions of cerebral desaturation as detected by NIRS differ by study protocol. Some providers use absolute thresholds to define desaturation, while others use a percent change from baseline saturation [15]. Treatment of cerebral desaturation is treatment for brain hypoperfusion (and likely whole body hypoperfusion). Treatment of brain hypoperfusion consists of increasing cardiac output, blood pressure, and arterial oxygen content. With aortic cannulation for CPB, this monitor may detect unilateral desaturation associated with aortic cannula malplacement, which requires cannula adjustment. While on CPB, treating brain hypoperfusion can be achieved by increasing pump flow, administration of vasopressors, transfusion of red blood cells, and increasing arterial pCO2 to encourage cerebral vasodilation. While case reports indicate that NIRS is able to detect acute changes in oxygenation in one or both cerebral hemispheres (such as might occur with aortic cannula malposition), evidence is still scarce that its routine use affects neurological outcomes after cardiac surgery [16]. Large prospective, randomized, controlled trials in this area are under development [17].
Temperature
Invasive monitoring of core temperature in two locations is required for procedures employing CPB to guide cooling and rewarming of the body for cardiac and other organ function. Nasopharyngeal temperature monitoring more accurately depicts brain temperature and is frequently closer to the temperature of the blood returned from the CPB circuit given its proximity to the arterial return cannula. Recent published guidelines recommend limiting arterial return from the CPB circuit to <37°C to avoid cerebral hyperthermia [18]. The brain is a high blood flow organ and during acute changes in blood temperature (i.e., during active cooling or warming via the CPB circuit) does not reflect total body temperature; bladder (or rectal) temperature is also measured to better reflect less well perfused parts of the body. During warming, the nasopharyngeal temperature is used to guide the temperature of the arterial return from CPB, and bladder (or rectal) temperature is thought to more accurately reflect core body temperature. These temperatures are allowed to equilibrate prior to weaning from bypass in order to optimize warming throughout the core. Due to a lack of evidence there is no formal recommendation for an optimal temperature to achieve prior to weaning from bypass; however, it is common practice to warm patients to at least 36°C (via bladder or rectal site) prior to separation [18].
Bispectral Index
The Bispectral Index (BIS) is an attempt to quantify level of consciousness in a way that is easily useable by clinicians. It does this through use of an algorithm to convert a single channel frontal EEG to a number representing consciousness on a scale from 0 to 100 (0 is an isoelectric EEG; 100 represents an awake patient). Patients undergoing cardiac surgery have been shown to be at high risk for intraoperative awareness and might be expected to derive greater advantage from BIS use; however, use of BIS to decrease intraoperative awareness is highly contested [19,20,21]. Smaller studies have explored using BIS-guided estimates of depth of anesthesia to guide anesthetic delivery and shorten recovery time with promising results [22].
Monitoring patients undergoing cardiac surgery is complex, invasive, and variable depending on patient comorbidities, surgical complexity, practitioner preferences, and institutional practices. Advances in transesophageal echocardiography have revolutionized the standard approach to perioperative monitoring and are central to providing care in the cardiac operating room. Future studies will hopefully better delineate which approaches to monitoring have the potential to improve patient outcomes for these high-risk surgeries.
References
1. STANDARDS FOR BASIC ANESTHETIC MONITORING. Committee of Origin: Standards and Practice Parameters (Approved by the ASA House of Delegates on October 21, 1986, and last amended on October 20, 2010 with an effective date of July 1, 2011).
2. Gu WJ, Tie HT, Liu JC, et al. Efficacy of ultrasound-guided radial artery catheterization: a systematic review and meta-analysis of randomized controlled trials. Crit Care. 2014 May 8;18(3):R93.
3. Ueda K, Bayman EO, Johnson C, et al. A randomized controlled trial of radial artery cannulation guided by Doppler vs. palpation vs. ultrasound. Anesthesia. 2015 Sep; 70(9):1039-44.
4. O’Grady NP, Alexander M, Burns LA, et al, Healthcare Infection Control Practices Advisory Committee (HICPAC). Guidelines for the Prevention of Intravascular Catheter-Related Infections. CDC. 2011.
5. Fuda G, Denault A, Deschamps A, et al. Risk Factors Involved in Central-to-Radial Arterial Pressure Gradient During Cardiac Surgery. Anesth Analg. 2015 Nov 23. Epub.
6. Sun J, Ding Z, Qian Y, et al. Central-radial artery pressure gradient after cardiopulmonary bypass is associated with cardiac function and may affect therapeutic direction. PLoS One. 2013 Jul 22;8(7):e68890.
7. Manecke GR, Parimucha M, Stratmann G, et al. Deep hypothermic circulatory arrest and the femoral-to-radial arterial pressure gradient. J Cardiothorac Vasc Anesth. 2004 Apr; 18(2):175-9.
8. Saugel B, Cecconi M, Wagner JY, et al. Noninvasive continuous cardiac output monitoring in perioperative and intensive care medicine. Br J Anaesth. 2015 Apr; 114(4):562-75.
9. Marik PE, Baram M, Vahid B. Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares. Chest. 2008 Jul; 134(1):172-8.
10. Kumar A, Anel R, Bunnell E, et al. Pulmonary artery occlusion pressure and central venous pressure fail to predict ventricular filling volume, cardiac performance, or the response to volume infusion in normal subjects. Crit Care Med. 2004 Mar; 32(3):691-9.
11. Lalu MM, Fayad A, Ahmed O, et al, Canadian Perioperative Anesthesia Clinical Trials Group. Ultrasound-Guided Subclavian Vein Catheterization: A Systematic Review and Meta-Analysis. Crit Care Med. 2015 Jul; 43(7):1498-507.
12. Rajaram SS, Desai NK, Kalra A, et al. Pulmonary artery catheters for adult patients in intensive care. Cochrane Database Syst Rev. 2013 Feb 28;2.
13. Sandham JD, Hull RD, Brant RF, et al, Canadian Critical Care Clinical TrialsGroup. A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. N Engl J Med. 2003 Jan 2; 348(1):5-14.
14. American Society of Anesthesiologists and Society of Cardiovascular Anesthesiologists Task Force on Tranesophageal Echocardiography. Practice guidelines for perioperative tranesophageal echocardiography. An updated report by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists Task Force on Tranesophageal Echocardiography. Anesthesiology. 2010 May;112(5):1084-96.
15. Lang RM, Badano LP, Tsang W, et al, American Society of Echocardiography, European Association of Echocardiography. EAE/ASE Recommendations for Image Acquisition and Display Using Three-Dimensional Echocardiography. J Am Soc Echocardiogr 2012; 25:3-46.
16. Zheng F, Sheinberg R, Yee MS, et al. Cerebral near-infrared spectroscopy monitoring and neurologic outcomes in adult cardiac surgery patients: a systematic review. Anesth Analg. 2013 Mar; 116 (3): 663-76.
17. Deschamps A, Hall R, Grocott H, et al, Canadian Perioperative Anesthesia Clinical Trials Group. Cerebral Oximetry Monitoring to Maintain Normal Cerebral Oxygen Saturation during High-risk Cardiac Surgery: A Randomized Controlled Feasibility Trial. Anesthesiology. 2016 Apr; 124(4): 826-36.
18. Engelman R, Baker RA, Likosky DS, et al. The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines for Cardiopulmonary Bypass – Temperature Management during Cardiopulmonary Bypass. J Extra Corpor Technol. 2015; 47(3):145-54.
19. Ghoneim MM, Block R, Haffarnan M, et al. Awareness during anesthesia: risk factors, causes and sequelae: a review of reported cases in the literature. Anesth Analg. 2009 Feb; 108(2): 527-35.
20. Avidan MS, Jacobsohn E, Glick D, et al, BAG-RECALL Research Group. Prevention of intraoperative awareness in a high-risk surgical population. NEJM. 2011 Aug; 365(7): 591-600.
21. Punjasawadwong Y, Phongchiewboon A, Bunchungmongkol N. Bispectral index for improving anesthetic delivery and postoperative recovery. Cochrane Database Syst Rev. 2014 Jun 17; 6.
22. Vance JL, Shanks AM, Woodrum DT. Intraoperative bispectral index monitoring and time to extubation after cardiac surgery: secondary analysis of a randomized controlled trial. BMC Anesthesiol. 2014 Sep 18;14.
1. STANDARDS FOR BASIC ANESTHETIC MONITORING. Committee of Origin: Standards and Practice Parameters (Approved by the ASA House of Delegates on October 21, 1986, and last amended on October 20, 2010 with an effective date of July 1, 2011).
2. Gu WJ, Tie HT, Liu JC, et al. Efficacy of ultrasound-guided radial artery catheterization: a systematic review and meta-analysis of randomized controlled trials. Crit Care. 2014 May 8;18(3):R93.
3. Ueda K, Bayman EO, Johnson C, et al. A randomized controlled trial of radial artery cannulation guided by Doppler vs. palpation vs. ultrasound. Anesthesia. 2015 Sep; 70(9):1039-44.
4. O’Grady NP, Alexander M, Burns LA, et al, Healthcare Infection Control Practices Advisory Committee (HICPAC). Guidelines for the Prevention of Intravascular Catheter-Related Infections. CDC. 2011.
5. Fuda G, Denault A, Deschamps A, et al. Risk Factors Involved in Central-to-Radial Arterial Pressure Gradient During Cardiac Surgery. Anesth Analg. 2015 Nov 23. Epub.
6. Sun J, Ding Z, Qian Y, et al. Central-radial artery pressure gradient after cardiopulmonary bypass is associated with cardiac function and may affect therapeutic direction. PLoS One. 2013 Jul 22;8(7):e68890.
7. Manecke GR, Parimucha M, Stratmann G, et al. Deep hypothermic circulatory arrest and the femoral-to-radial arterial pressure gradient. J Cardiothorac Vasc Anesth. 2004 Apr; 18(2):175-9.
8. Saugel B, Cecconi M, Wagner JY, et al. Noninvasive continuous cardiac output monitoring in perioperative and intensive care medicine. Br J Anaesth. 2015 Apr; 114(4):562-75.
9. Marik PE, Baram M, Vahid B. Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares. Chest. 2008 Jul; 134(1):172-8.
10. Kumar A, Anel R, Bunnell E, et al. Pulmonary artery occlusion pressure and central venous pressure fail to predict ventricular filling volume, cardiac performance, or the response to volume infusion in normal subjects. Crit Care Med. 2004 Mar; 32(3):691-9.
11. Lalu MM, Fayad A, Ahmed O, et al, Canadian Perioperative Anesthesia Clinical Trials Group. Ultrasound-Guided Subclavian Vein Catheterization: A Systematic Review and Meta-Analysis. Crit Care Med. 2015 Jul; 43(7):1498-507.
12. Rajaram SS, Desai NK, Kalra A, et al. Pulmonary artery catheters for adult patients in intensive care. Cochrane Database Syst Rev. 2013 Feb 28;2.
13. Sandham JD, Hull RD, Brant RF, et al, Canadian Critical Care Clinical TrialsGroup. A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. N Engl J Med. 2003 Jan 2; 348(1):5-14.
14. American Society of Anesthesiologists and Society of Cardiovascular Anesthesiologists Task Force on Tranesophageal Echocardiography. Practice guidelines for perioperative tranesophageal echocardiography. An updated report by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists Task Force on Tranesophageal Echocardiography. Anesthesiology. 2010 May;112(5):1084-96.
15. Lang RM, Badano LP, Tsang W, et al, American Society of Echocardiography, European Association of Echocardiography. EAE/ASE Recommendations for Image Acquisition and Display Using Three-Dimensional Echocardiography. J Am Soc Echocardiogr 2012; 25:3-46.
16. Zheng F, Sheinberg R, Yee MS, et al. Cerebral near-infrared spectroscopy monitoring and neurologic outcomes in adult cardiac surgery patients: a systematic review. Anesth Analg. 2013 Mar; 116 (3): 663-76.
17. Deschamps A, Hall R, Grocott H, et al, Canadian Perioperative Anesthesia Clinical Trials Group. Cerebral Oximetry Monitoring to Maintain Normal Cerebral Oxygen Saturation during High-risk Cardiac Surgery: A Randomized Controlled Feasibility Trial. Anesthesiology. 2016 Apr; 124(4): 826-36.
18. Engelman R, Baker RA, Likosky DS, et al. The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines for Cardiopulmonary Bypass – Temperature Management during Cardiopulmonary Bypass. J Extra Corpor Technol. 2015; 47(3):145-54.
19. Ghoneim MM, Block R, Haffarnan M, et al. Awareness during anesthesia: risk factors, causes and sequelae: a review of reported cases in the literature. Anesth Analg. 2009 Feb; 108(2): 527-35.
20. Avidan MS, Jacobsohn E, Glick D, et al, BAG-RECALL Research Group. Prevention of intraoperative awareness in a high-risk surgical population. NEJM. 2011 Aug; 365(7): 591-600.
21. Punjasawadwong Y, Phongchiewboon A, Bunchungmongkol N. Bispectral index for improving anesthetic delivery and postoperative recovery. Cochrane Database Syst Rev. 2014 Jun 17; 6.
22. Vance JL, Shanks AM, Woodrum DT. Intraoperative bispectral index monitoring and time to extubation after cardiac surgery: secondary analysis of a randomized controlled trial. BMC Anesthesiol. 2014 Sep 18;14.