Quality Improvement Projects and Anesthesiology Graduate Medical Education: A Systematic Review.

Quality improvement (QI) projects are essential components of graduate medical education and healthcare organizations to improve patient outcomes. We systematically reviewed the literature on QI projects in anesthesiology graduate medical education programs to assess whether these projects are leading to publications. A literature search was conducted in July 2023, using PubMed, Embase, and the Central Register of Controlled Trials (CENTRAL) for articles describing QI initiatives originating within the United States and applicable to anesthesiology residency training programs. The following data were collected: intervention(s), sample size (number of participants or events), outcome metric(s), result(s), and conclusion(s). One hundred and fifty publications were identified, and 31 articles met the inclusion criteria. A total of 2,259 residents and 72,889 events were included in this review. Educational modalities, such as simulation, training sessions, or online curricula, were the most prevalent interventions in the included studies. Pre-intervention and post-intervention assessments were the most common outcome metrics reported. Our review of the literature demonstrates that few QI projects performed within anesthesiology training programs lead to published manuscripts. Further research should aim at increasing the impact of required QI projects within the sponsoring institution and specialty.

Comparison of differences in cohort (forwards) and case control (backwards) methodological approaches for validation of the Hypotension Prediction Index.

BACKGROUND: The Hypotension Prediction Index (the index) software is a machine learning algorithm that detects physiological changes that may lead to hypotension. The original validation used a case control (backwards) analysis that has been suggested to be biased. We therefore conducted a cohort (forwards) analysis and compared this to the original validation technique. METHODS: We conducted a retrospective analysis of data from previously reported studies. All data were analysed identically with 2 different methodologies and receiver operating characteristic curves (ROC) constructed. Both backwards and forwards analyses were performed to examine differences in area under the ROC for HPI and other haemodynamic variables to predict a MAP < 65mmHg for at least 1 minute 5, 10 and 15 minutes in advance. RESULTS: Two thousand and twenty-two patients were included in the analysis, yielding 4,152,124 measurements taken at 20 second intervals. The area-under-the-curve for the index predicting hypotension analysed by backward and forward methodologies respectively was 0.957 (95% CI, 0.947-0.964) vs 0.923 (95% CI, 0.912-0.933) 5 minutes in advance, 0.933 (95% CI, 0.924-0.942) vs 0.923 (95% CI, 0.911-0.933) 10 minutes in advance , and 0.929 (95% CI, 0.918-0.938) vs. 0.926 (95% CI, 0.914-0.937) 15 minutes in advance. No other variable had an area-under-the-curve > 0.7 except for MAP. Area-under-the-curve using forward analysis for MAP predicting hypotension 5, 10, and 15 minutes in advance was 0.932 (95% CI, 0.920-0.940), 0.929 (95% CI, 0.918-0.938), and 0.932 (95% CI, 0.921-0.940). The R 2 for the variation in the index due to MAP was 0.77. CONCLUSION: Using an updated methodology, we found the utility of the HPI index to predict future hypotensive events is high, with an area under the receiver-operating-characteristics curve similar to that of the original validation method.

The effects of an IV fluid bolus on mitral annular velocity and the assessment of diastolic function: a prospective non-randomized study.

BACKGROUND: Abnormal diastolic function is an independent predictor of adverse postoperative outcomes. Mitral annular tissue Doppler velocity (e') is a key parameter for assessing diastolic function. The purpose of this study was to confirm that an acute increase in preload did not significantly impact the intraoperative measurement of e' and secondarily evaluate the impact of this acute intravascular volume increase on the clinical assessment of diastolic function using a previously described simplified algorithm. METHODS: This was a prospective, non-randomized study in adult patients undergoing elective cardiac surgeries requiring transesophageal echocardiographic monitoring, arterial pressure and Swan-Ganz catheter placements as part of the surgical procedure. Following baseline echocardiographic and hemodynamic measurements, 500 ml of crystalloid solution was infused over 10 min. Hemodynamic and echocardiographic measurements were repeated 5 min after fluid administration. RESULTS: Complete data sets were available from 84 of the 100 patients who were enrolled in this study. There was no significant change in the values of e'. The average baseline was 7.8 ± 2.0 cm/s (95%CI: 7.4, 8.2) and 8.1 ± 2.4 (95%CI: 7.6, 8.6) following the fluid bolus (p = 0.10). All hemodynamic variables associated with increased intravascular volume (central venous pressure, pulmonary arterial pressures and stroke volume variation) changed significantly. The overall distribution of diastolic function grades did not change following fluid administration (p = 0.69). However, there were many individual patient differences. When using this simplified algorithm, functional grading changed in 35 patients. Thirty of these 35 changes were only a single grade shift. 22 patients had worse functional grading after fluid administration while 13 had improved grading. Nine patients with normal diastolic function at baseline demonstrated diastolic dysfunction after fluid administration while 6 patients with baseline dysfunction normalized following the fluid bolus. CONCLUSION: We confirmed that e' is a robust measurement that is reproducible in the intraoperative setting despite variable vascular volume loading conditions, however, the clinical assessment of diastolic function was still altered in 42% of the patients following an intravenous fluid bolus.

The problem with dichotomizing quality improvement measures.

The Anesthesia Quality Institute (AQI) promotes improvements in clinical care outcomes by managing data entered in the National Anesthesia Clinical Outcomes Registry (NACOR). Each case included in NACOR is classified as "performance met" or "performance not met" and expressed as a percentage for a length of time. The clarity associated with this binary classification is associated with limitations on data analysis and presentations that may not be optimal guides to evaluate the quality of care. High compliance benchmarks present another obstacle for evaluating quality. Traditional approaches for interpreting statistical process control (SPC) charts depend on data points above and below a center line, which may not provide adequate characterizations of a QI process with a low failure rate, or few possible data points below the center line. This article demonstrates the limitations associated with the use of binary datasets to evaluate the quality of care at an individual organization with QI measures, describes a method for characterizing binary data with continuous variables and presents a solution to analyze rare QI events using g charts.

The effect of acute ventilation-perfusion mismatch on respiratory heat exchange in a porcine model.

BACKGROUND: Respiratory heat exchange is an important physiological process occurring in the upper and lower respiratory tract and is usually completed when inspired gases reach the alveoli. Animal and human studies demonstrated that heat exchange can be modulated by altering pulmonary ventilation and perfusion. The purpose of this study was to examine the effect of acute ventilation-perfusion (V/Q) mismatch on respiratory heat exchange. In clinical practice, monitoring respiratory heat exchange might offer the possibility of real-time tracking of acute V/Q-mismatch. METHODS: In 11 anesthetized, mechanically ventilated pigs, V/Q-mismatch was established by means of four interventions: single lung ventilation, high cardiac output, occlusion of the left pulmonary artery and repeated whole-lung lavage. V/Q-distributions were determined by the multiple inert gas elimination technique (MIGET). Respiratory heat exchange was measured as respiratory enthalpy using the novel, pre-commercial VQm™ monitor (development stage, Rostrum Medical Innovations, Vancouver, CA). According to MIGET, shunt perfusion of low V/Q compartments increased during single lung ventilation, high cardiac output and whole-lung lavage, whereas dead space and ventilation of high V/Q compartments increased during occlusion of the left pulmonary artery and whole-lung lavage. RESULTS: Bohr dead space increased after pulmonary artery occlusion and whole-lung lavage, venous admixture increased during single lung ventilation and whole-lung lavage, PaO2/FiO2 was decreased during all interventions. MIGET confirmed acute V/Q-mismatch. Respiratory enthalpy did not change significantly despite significant acute V/Q-mismatch. CONCLUSION: Clinically relevant V/Q-mismatch does not impair respiratory heat exchange in the absence of additional thermal stressors and may not have clinical utility in the detection of acute changes.

Simultaneous comparison of depth of sedation performance between SedLine and BIS during general anesthesia using custom passive interface hardware: study protocol for a prospective, non-blinded, non-randomized trial.

BACKGROUND: Intraoperative brain function monitoring with processed electroencephalogram (EEG) indices, such as the bispectral index (BIS) and patient state index (PSI), may improve characterization of the depth of sedation or anesthesia when compared to conventional physiologic monitors, such as heart rate and blood pressure. However, the clinical assessment of anesthetic depth may not always agree with available processed EEG indices. To concurrently compare the performance of BIS and SedLine monitors, we present a data collection system using shared individual generic sensors connected to a custom-built passive interface box. METHODS: This prospective, non-blinded, non-randomized study will enroll 100 adult American Society of Anesthesiologists (ASA) class I-III patients presenting for elective procedures requiring general anesthesia. BIS and SedLine electrodes will be placed preoperatively according to manufacturer recommendations and their respective indices tracked throughout anesthesia induction, maintenance and emergence. The concordance between processed EEG indices and clinical assessments of anesthesia depth will be analyzed with chi-square and kappa statistic. DISCUSSION: Prior studies comparing brain function monitoring devices have applied both sensors on the forehead of study subjects simultaneously. With limited space and common sensor locations between devices, it is not possible to place both commercial sensor arrays according to the manufacturer's recommendations, thus compromising the validity of these comparisons. This trial utilizes a custom interface allowing signals from sensors to be shared between BIS and SedLine monitors to provide an accurate comparison. Our results will also characterize the degree of agreement between processed EEG indices and clinical assessments of anesthetic depth as determined by the anesthesiologists' interpretations of acute changes in blood pressure and heart rate as well as the administration, or change to the continuous delivery, of medications at these timepoints. Patient factors (such as burst suppression state or low power EEG conditions from aging brain), surgical conditions (such as use of electrocautery), artifacts (such as electromyography), and anesthesia medications and doses (such as end-tidal concentration of volatile anesthetic or hypnotic infusion dose) that lead to lack of agreement will be explored as well. TRIAL REGISTRATION: Clinical Trials ( ClinicalTrials.gov ), NCT03865316 . Registered on 4 February 2019 - retrospectively registered. SPONSOR: Masimo Corporation.

Assisted Fluid Management Software Guidance for Intraoperative Fluid Administration.

BACKGROUND: Excessive or inadequate fluid administration causes complications, but despite this, fluid administration during noncardiac surgery is highly variable. Goal-directed management helps optimize the amount and timing of fluid administration; however, implementation is difficult because algorithms are complex. The authors therefore tested the performance of the Acumen Assisted Fluid Management software (Edwards Lifesciences, USA), which is designed to guide optimal intravenous fluid administration during surgery. METHODS: In this multicenter, prospective, single-arm cohort evaluation, the authors enrolled 330 adults scheduled for moderate- to high-risk noncardiac surgery that required arterial catheter insertion and mechanical ventilation. Clinicians chose a fluid strategy based on a desired 10%, 15%, or 20% increase in stroke volume (SV) in response to a fluid bolus. Dedicated fluid management software prompted "test" or "recommended" boluses, and clinicians were free to initiate a "user" bolus of 100 to 500 ml of crystalloid or colloid. Clinicians were free to accept or decline the software prompts. The authors primarily compared the fraction of software-recommended boluses that produced suitable increases in SV to a 30% reference rate. On an exploratory basis, we compared responses to software-recommended and clinician-initiated boluses. RESULTS: Four hundred twenty-four of 479 (89%) software-recommended fluid boluses and 508 of 592 (86%) clinician-initiated fluid boluses were analyzed per protocol. Of those, 66% (95% CI, 62 to 70%) of delivered fluid boluses recommended by the software resulted in desired increases in SV, compared with the 30% reference rate, whereas only 41% (95% CI, 38 to 44%) of clinician-initiated boluses did (P < 0.0001). The mean ± SD increase in SV after boluses recommended by the software was 14.2 ± 13.9% versus 8.3 ± 12.1% (P < 0.0001) for those initiated by clinicians. CONCLUSIONS: Fluid boluses recommended by the software resulted in desired SV increases more often, and with greater absolute SV increase, than clinician-initiated boluses. Automated assessment of fluid responsiveness may help clinicians optimize intraoperative fluid management during noncardiac surgery.

Use of the Hypotension Prediction Index During Cardiac Surgery.

OBJECTIVE: The hypotension prediction index (HPI) is a novel parameter developed by Edwards Lifesciences (Irvine, CA) that is obtained through an algorithm based on arterial pressure waveform characteristics. Past studies have demonstrated its accuracy in predicting hypotensive events in noncardiac surgeries. The authors aimed to evaluate the use of the HPI in cardiac surgeries requiring cardiopulmonary bypass (CPB). DESIGN: Prospective cohort feasibility study. SETTING: Single university medical center. PARTICIPANTS: Sequential adult patients undergoing elective cardiac surgeries requiring CPB between October 1, 2018, and December 31, 2018. INTERVENTIONS: HPI monitor was connected to the patient's arterial pressure transducer. Anesthesiologists and surgeons were blinded to the monitor output. MEASUREMENTS AND MAIN RESULTS: HPI values and hypotensive events were recorded before and after CPB. The primary outcomes were the area under the curve (AUC) of the receiver operating characteristic curve, sensitivity, and specificity of HPI predicting hypotension. The AUC, sensitivity, and specificity for HPI lead time to hypotension five minutes before the event were 0.90 (95% confidence interval [CI]: 0.853-0.949), 84% (95% CI: 77.7-90.5), and 84% (95% CI: 70.9-96.8), respectively. Ten minutes before the event AUC, sensitivity, and specificity for HPI lead time to hypotension were 0.83 (95% CI: 0.750-0.905), 79% (95% CI: 69.8-88.1), and 74% (95% CI: 58.8-89.6), respectively. Fifteen minutes before the hypotensive event AUC, sensitivity, and specificity for HPI lead time to hypotension were 0.83 (95% CI: 0.746-0.911), 79% (95% CI: 68.4-89.0), and 74% (95% CI: 58.8-89.6), respectively. CONCLUSION: HPI predicted hypotensive episodes during cardiac surgeries with a high degree of sensitivity and specificity.

Study of early warning for desaturation provided by Oxygen Reserve Index in obese patients.

Acute hemoglobin desaturation can reflect rapidly decreasing PaO2. Pulse oximetry saturation (SpO2) facilitates hypoxia detection but may not significantly decrease until PaO2 < 80 mmHg. The Oxygen Reserve Index (ORI) is a unitless index that correlates with moderately hyperoxic PaO2. This study evaluated whether ORI provides added arterial desaturation warning in obese patients. This IRB approved, prospective, observational study obtained written informed consent from Obese (body mass index (BMI) kg m-2; 30 < BMI < 40) and Normal BMI (19 < BMI < 25) adult patients scheduled for elective surgery requiring general endotracheal anesthesia. Standard monitors and an ORI sensor were placed. Patient's lungs were pre-oxygenated with 100% FiO2. After ORI plateaued, general anesthesia was induced, and endotracheal intubation accomplished using a videolaryngoscope. Patients remained apneic until SpO2reached 94%. ORI and SpO2 were recorded continuously. Added warning time was defined as the difference between the time to SpO2 94% from ORI alarm start or from SpO2 97%. Data are reported as median; 95% confidence interval. Complete data were collected in 36 Obese and 36 Normal BMI patients. ORI warning time was always longer than SpO2 warning time. Added warning time provided by ORI was 46.5 (36.0-59.0) seconds in Obese and 87.0 (77.0-109.0) seconds in Normal BMI patients, and was shorter in Obese than Normal BMI patients difference 54.0 (38.0-74.0) seconds (p < 0.0001). ORI provided what was felt to be clinically significant added warning time of arterial desaturation compared to SpO2. This added time might allow earlier calls for help, assistance from other providers, or modifications of airway management.Trial registration ClinicalTrials.gov NCT03021551.

Oxygen Reserve Index: Utility as an Early Warning for Desaturation in High-Risk Surgical Patients.

BACKGROUND: Perioperative pulse oximetry hemoglobin saturation (Spo2) measurement is associated with fewer desaturation and hypoxia episodes. However, the sigmoidal nature of oxygen-hemoglobin dissociation limits the accuracy of estimation of the partial pressure of oxygen (Pao2) >80 mm Hg and correspondingly limits the ability to identify when Pao2 >80 mm Hg but falling. We hypothesized that a proxy measurement for oxygen saturation (Oxygen Reserve Index [ORI]) derived from multiwavelength pulse oximetry may allow additional warning time before critical desaturation or hypoxia. To test our hypothesis, we used a Masimo multiwavelength pulse oximeter to compare ORI and Spo2 warning times during apnea in high-risk surgical patients undergoing cardiac surgery. METHODS: This institutional review board-approved prospective study (NCT03021473) enrolled American Society of Anesthesiologists physical status III or IV patients scheduled for elective surgery with planned preinduction arterial catheter placement. In addition to standard monitors, an ORI sensor was placed and patients were monitored with a pulse oximeter displaying the ORI, a nondimensional parameter that ranges from 0 to 1. Patients were then preoxygenated until ORI plateaued. Following induction of anesthesia, mask ventilation with 100% oxygen was performed until neuromuscular blockade was established. Endotracheal intubation was accomplished using videolaryngoscopy to confirm placement. The endotracheal tube was not connected to the breathing circuit, and patients were allowed to be apneic. Ventilation was resumed when Spo2 reached 94%. We defined ORI warning time as the time from when the ORI alarm registered (based on the absolute value and the rate of change) until the Spo2 decreased to 94%. We defined the Spo2 warning time as the time for Spo2 to decrease from 97% to 94%. The added warning time provided by ORI was defined as the difference between ORI warning time and Spo2 warning time. RESULTS: Forty subjects were enrolled. Complete data for analysis were available from 37 patients. The ORI alarm registered before Spo2 decreasing to 97% in all patients. Median (interquartile range [IQR]) ORI warning time was 80.4 seconds (59.7-105.9 seconds). Median (IQR) Spo2 warning time was 29.0 seconds (20.5-41.0 seconds). The added warning time provided by ORI was 48.4 seconds (95% confidence interval [CI], 40.4-62.0 seconds; P < .0001). CONCLUSIONS: In adult high-risk surgical patients, ORI provided clinically relevant added warning time of impending desaturation compared to Spo2. This additional time may allow modification of airway management, earlier calls for help, or assistance from other providers. The potential patient safety impact of such monitoring requires further study.

Percutaneous cannulation for extracorporeal membrane oxygenation (ECMO): A method for pig experimental models.

Pigs are often used for experimental models of cardiogenic shock, cardiac arrest or acute lung injury with veno-arterial (VA) or veno-venous (VV) extracorporeal membrane oxygenation (ECMO) implementation. Percutaneous (as opposed to surgical) cannulation in experimental models has potential advantages, including, less surgical trauma or stressful stimuli and less bleeding complications when compared to open chest cannulation. However, pig anatomy can also be a challenge because of the deep location and angled anatomy of the femoral artery. The Seldinger technique and the use of a percutaneous cannulation kit is feasible in pigs. Summarized here we present (Graphical Abstract):•Percutaneous ECMO cannulation method for non-cardiac surgeon.•Establishment of this simple and rapid methods for pig experimental models.•Predictable complications of this method.

Sedation After Cardiac Surgery: Is One Drug Better Than Another?

The classic high-dose narcotic-based cardiac anesthetic has been modified to facilitate a fast-track, rapid recovery in the intensive care unit (ICU). Postoperative sedation is consequently now an essential component in recovery of the patient undergoing cardiac surgery. It must facilitate the patient's unawareness of the environment as well as reduce the discomfort and anxiety caused by surgery, intubation, mechanical ventilation, suction, and physiotherapy. Benzodiazepines seem well suited for this role, but propofol, opioids, and dexmedetomidine are among other agents commonly used for sedation in the ICU. However, what is an ideal sedative for this application? When compared with benzodiazepine-based sedation regimens, nonbenzodiazepines have been associated with shorter duration of mechanical ventilation and ICU length of stay. Current sedation guidelines recommend avoiding benzodiazepine use in the ICU. However, there are no recommendations on which alternatives should be used. In postcardiac surgery patients, inotropes and vasoactive medications are often required because of the poor cardiac function. This makes sedation after cardiac surgery unique in comparison with the requirements for most other ICU patient populations. We reviewed the current literature to try to determine if 1 sedative regimen might be better than others; in particular, we compare outcomes of propofol and dexmedetomidine in postoperative sedation in the cardiac surgical ICU.

The Utility of 3D Left Atrial Volume and Mitral Flow Velocities as Guides for Acute Volume Resuscitation.

Left ventricular end-diastolic pressure (LVEDP) is the foundation of cardiac function assessment. Because of difficulties and risks associated with its direct measurement, correlates of LVEDP derived by pulmonary artery (PA) catheterization or transesophageal echocardiography (TEE) are commonly adopted. TEE has the advantage of being less invasive; however TEE-based estimation of LVEDP using correlates such as left ventricular end-diastolic volume (LVEDV) has technical difficulties that limit its clinical usefulness. Using intraoperative acute normovolemic hemodilution (ANH) as a controlled hemorrhagic model, we examined various mitral flow parameters and three-dimensional reconstructions of left atrial volume as surrogates of LVEDP. Our results demonstrate that peak E wave velocity and left atrial end-diastolic volume (LAEDV) correlated with known changes in intravascular volume associated with ANH. Although left atrial volumetric analysis was done offline in our study, recent advances in echocardiographic software may allow for continuous display and real-time calculation of LAEDV. Along with the ease and reproducibility of acquiring Doppler images of flow across the mitral valve, these two correlates of LVEDP may justify a more widespread use of TEE to optimize intraoperative fluid management. The clinical applicability of peak E wave velocity and LAEDV still needs to be validated during uncontrolled resuscitation.

Current use of the pulmonary artery catheter in cardiac surgery: a survey study.

OBJECTIVE: Because of its invasive nature, debated effect on patient outcome, and the development of alternative hemodynamic monitoring technologies, the intraoperative use of the pulmonary artery catheter (PAC) has significantly decreased. The authors conducted a survey of the members of the Society of Cardiovascular Anesthesiologists (SCA) to assess current use of the PAC and alternative hemodynamic monitoring technologies in patients undergoing cardiac surgery. DESIGN: A survey study. SETTING: Hospitals in North America, Europe, Asia, Australia, New Zealand, and South America. PARTICIPANTS: SCA members in North America, Europe, Asia, Australia, New Zealand, and South America. INTERVENTIONS: The survey was e-mailed by the SCA to roughly 6,000 of its members. MEASUREMENTS AND MAIN RESULTS: The survey was left open for 30 days. Respondents accessed the survey via a secured web-based database. A total of 854 questionnaires were completed. A total of 705 (82.6%) were from North American members. Four hundred twelve of the respondents (48.1%) worked in a private practice setting, while 350 (40.9%) were from an academic practice. A majority of the respondents (57.9%) were from hospitals that performed more than 400 cardiac surgeries a year, a subset of which (29.6%) did more than 800 cases annually. For cases using cardiopulmonary bypass, 583 (68.2%) of the respondents used a PAC more than 75% of the time, while 30 (3.5%) did not use the PAC at all. Ninety-four percent of respondents used transesophageal echocardiography (TEE) as part of the intraoperative monitoring. When not using a PAC, FloTrac/Vigileo was the alternative cardiac monitoring modality in 15.2% of the responses. Similar trends in monitor preferences were seen in off-pump coronary artery bypass grafting and minimally invasive/robotic heart surgery. CONCLUSIONS: The results of this study suggested that a majority of the respondents still prefer to use the PAC for most cardiac surgeries. Subgroup analysis of the data revealed that geographical location, type of practice, and surgeon support played a significant role in the decision to use a PAC. Although most respondents prefer to use TEE as a complimentary tool, TEE also remains the most popular supplemental/alternative hemodynamic monitoring technology.

Reliability of a new 4th generation FloTrac algorithm to track cardiac output changes in patients receiving phenylephrine.

Phenylephrine is often used to treat intra-operative hypotension. Previous studies have shown that the FloTrac cardiac monitor may overestimate cardiac output (CO) changes following phenylephrine administration. A new algorithm (4th generation) has been developed to improve performance in this setting. We performed a prospective observational study to assess the effects of phenylephrine administration on CO values measured by the 3rd and 4th generation FloTrac algorithms. 54 patients were enrolled in this study. We used the Nexfin, a pulse contour method shown to be insensitive to vasopressor administration, as the reference method. Radial arterial pressures were recorded continuously in patients undergoing surgery. Phenylephrine administration times were documented. Arterial pressure recordings were subsequently analyzed offline using three different pulse contour analysis algorithms: FloTrac 3rd generation (G3), FloTrac 4th generation (G4), and Nexfin (nf). One minute of hemodynamic measurements was analyzed immediately before phenylephrine administration and then repeated when the mean arterial pressure peaked. A total of 157 (4.6 ± 3.2 per patient, range 1-15) paired sets of hemodynamic recordings were analyzed. Phenylephrine induced a significant increase in stroke volume (SV) and CO with the FloTrac G3, but not with FloTrac G4 or Nexfin algorithms. Agreement between FloTrac G3 and Nexfin was: 0.23 ± 1.19 l/min and concordance was 51.1%. In contrast, agreement between FloTrac G4 and Nexfin was: 0.19 ± 0.86 l/min and concordance was 87.2%. In conclusion, the pulse contour method of measuring CO, as implemented in FloTrac 4th generation algorithm, has significantly improved its ability to track the changes in CO induced by phenylephrine.

Perioperative dexmedetomidine improves outcomes of cardiac surgery.

BACKGROUND: Cardiac surgery is associated with a high risk of cardiovascular and other complications that translate into increased mortality and healthcare costs. This retrospective study was designed to determine whether the perioperative use of dexmedetomidine could reduce the incidence of complications and mortality after cardiac surgery. METHODS AND RESULTS: A total of 1134 patients who underwent coronary artery bypass surgery and coronary artery bypass surgery plus valvular or other procedures were included. Of them, 568 received intravenous dexmedetomidine infusion and 566 did not. Data were adjusted with propensity scores, and multivariate logistic regression was used. The primary outcomes measured included mortality and postoperative major adverse cardiocerebral events (stroke, coma, perioperative myocardial infarction, heart block, or cardiac arrest). Secondary outcomes included renal failure, sepsis, delirium, postoperative ventilation hours, length of hospital stay, and 30-day readmission. Dexmedetomidine use significantly reduced postoperative in-hospital (1.23% versus 4.59%; adjusted odds ratio, 0.34; 95% confidence interval, 0.192-0.614; P<0.0001), 30-day (1.76% versus 5.12%; adjusted odds ratio, 0.39; 95% confidence interval, 0.226-0.655; P<0.0001), and 1-year (3.17% versus 7.95%; adjusted odds ratio, 0.47; 95% confidence interval, 0.312-0.701; P=0.0002) mortality. Perioperative dexmedetomidine therapy also reduced the risk of overall complications (47.18% versus 54.06%; adjusted odds ratio, 0.80; 95% confidence interval, 0.68-0.96; P=0.0136) and delirium (5.46% versus 7.42%; adjusted odds ratio, 0.53; 95% confidence interval, 0.37-0.75; P=0.0030). CONCLUSION: Perioperative dexmedetomidine use was associated with a decrease in postoperative mortality up to 1 year and decreased incidence of postoperative complications and delirium in patients undergoing cardiac surgery. CLINICAL TRIAL REGISTRATION: URL: www.clinicaltrials.gov. Unique identifier: NCT01683448.

Stroke volume variation during acute normovolemic hemodilution.

BACKGROUND: The intravascular volume of surgical patients should be optimized to avoid complications associated with both overhydration and underresuscitation. In patients undergoing intraoperative acute normovolemic hemodilution, we investigated whether stroke volume variation (SVV) derived from an arterial pressure-based cardiac output (CO) monitor system (FloTrac/Vigileo, Edwards Lifesciences, Irvine, CA) tracked the changes associated with blood removal and replacement. We further evaluated the correlations between SVV and 3-dimensional (3D) transesophageal echocardiographic (TEE) left ventricular (LV) volume measurements. METHODS: Twenty-five patients had procedures during which acute normovolemic hemodilution was a planned part of the intraoperative management. We defined 7 measurement timepoints: baseline, after the removal of 5%, 10%, and 15% of the estimated blood volume (EBV) and after replacement with an equal volume of 6% hetastarch to -10%, -5%, and baseline EBV. At each timepoint, heart rate and systolic, diastolic, and mean arterial blood pressure were obtained from standard monitors, CO and SVV measurements were obtained from the FloTrac/Vigileo monitor, and TEE images were recorded for subsequent off-line reconstruction and determination of LV end-systolic and end-diastolic volumes. For statistical evaluations, we used a mixed models analysis of variance and Dunnett's test for post hoc comparisons with baseline values. Pearson's correlation was used to examine the relationships between SVV and LV volume. RESULTS: Analysis of variance demonstrated no significant change in heart rate or mean arterial blood pressure over the duration of study. CO decreased from 4.9 +/- 0.3 to 4.5 +/- 0.3 L/min after removal of 15% of the EBV and then increased to a final value of 5.4 +/- 0.3 L/min after replacement of 15% of the EBV. SVV increased from 9.2% +/- 0.9% to 20.3% +/- 2.0% (P < 0.001) after removal of 15% of the EBV and returned to a final value of 7.2% +/- 0.9% after replacement of 15% of the EBV. The indexed LV end-diastolic volume decreased from 42.1 +/- 8.3 to 36.9.3 +/- 8.3 mL/m(2) (P < 0.001) after removal of 15% of the EBV and then returned to a final volume of 45.9 +/- 10.3 mL/m(2) after replacement of 15% of the EBV. The measurements of SVV correlated inversely with the 3D TEE LV volume measurements. CONCLUSIONS: The SVV derived from the FloTrac/Vigileo system changes significantly as blood is removed and replaced during hemodilution. These changes correlate with 3D TEE measurements of LV volume. The utility of SVV in guiding optimization of intravascular volume merits further study.