Cardiopulmonary Bypass Separation Research Articles

Instantaneous Right Ventricular to Pulmonary Artery Systolic Pressure Difference in Cardiac Surgery: A Retrospective and Prospective Cohort Study

BackgroundDuring cardiac surgery, right ventricular outflow tract obstruction (RVOTO) is defined as an instantaneous pressure difference ≥ 6 mm Hg between right ventricular systolic pressure (RVSP) and pulmonary artery systolic pressure (PASP), for ≥ 5 minutes. Risk factors for RVOTO remain poorly understood. This cohort study was designed to evaluate the incidence, characteristics, and outcomes of the patients who experienced RVOTO. MethodsInstantaneous pressure difference between RVSP and PASP was measured by means of a pulmonary artery catheter with a right ventricular port during cardiac surgery from a retrospective (n = 295) and a prospective (n = 105) cohort. ResultsFrom the retrospective and prospective cohorts, respectively, incidence of RVOTO was 30.2% and 36.2% before cardiopulmonary bypass (CPB) initiation and 43.7% and 47.6% after CPB separation. Before CPB initiation, patients with RVOTO had higher cardiac output (4.2 ± 1.5 vs 3.8 ± 1.1 L/min; P = 0.033) and received more inhaled epoprostenol (79% vs 61%; P = 0.005) and inotropes (66% vs 51%; P = 0.016) compared with those without RVOTO. After CPB separation, patients with RVOTO had higher heart rate (62 ± 15 vs 58 ± 13 beats/min; P = 0.011), cardiac output (4.1 ± 1.4 vs 3.7 ± 1.1 L/min; P = 0.003), and CPB duration (90 ± 45 vs 77 ± 30 min, P = 0.014), had lower fluid balance (758 ± 1123 vs 1063 ± 1089 mL; P = 0.021), and were more exposed to intratracheal milrinone (12% vs 4%; P = 0.015) compared with those without RVOTO. The time with persistent organ dysfunction (TPOD) at 28 days after surgery was similar among patients who had an RVOTO event, before CPB initiation or after CPB separation, compared with those who did not. ConclusionsRVOTO is common in cardiac surgery. However, it is not associated with longer TPOD.

Continuous Right Ventricular Pressure Monitoring in Cardiac Surgery

Right ventricular (RV) dysfunction in cardiac surgery can lead to RV failure, which is associated with increased morbidity and mortality. Abnormal RV function can be identified using RV pressure monitoring. The primary objective of the study is to determine the proportion of patients with abnormal RV early to end-diastole diastolic pressure gradient (RVDPG) and abnormal RV end-diastolic pressure (RVEDP) before initiation and after cardiopulmonary bypass (CPB) separation. The secondary objective is to evaluate if RVDPG before CPB initiation is associated with difficult and complex separation from CPB, RV dysfunction, and failure at the end of cardiac surgery. Prospective study. Tertiary care cardiac institute. Cardiac surgical patients. Cardiac surgery. Automated electronic quantification of RVDPG and RVEDP were obtained. Hemodynamic measurements were correlated with cardiac and extracardiac parameters from transesophageal echocardiography and postoperative complications. Abnormal RVDPG was present in 80% of the patients (n = 105) at baseline, with a mean RVEDP of 14.2 ± 3.9 mmHg. Patients experienced an RVDPG > 4 mmHg for a median duration of 50.2% of the intraoperative period before CPB initiation and 60.6% after CPB separation. A total of 46 (43.8%) patients had difficult/complex separation from CPB, 18 (38.3%) patients had RV dysfunction, and 8 (17%) had RV failure. Abnormal RVDPG before CPB was not associated with postoperative outcome. Elevated RVDPG and RVEDP are common in cardiac surgery. RVDPG and RVEDP before CPB initiation are not associated with RV dysfunction and failure but can be used to diagnose them.

Clinical relevance of transcranial Doppler in a cardiac surgery setting: embolic load predicts difficult separation from cardiopulmonary bypass

BackgroundDuring cardiac surgery, transcranial Doppler (TCD) represents a non-invasive modality that allows measurement of red blood cell flow velocities in the cerebral arteries. TCD can also be used to detect and monitor embolic material in the cerebral circulation. Detection of microemboli is reported as a high intensity transient signal (HITS). The importance of cerebral microemboli during cardiac surgery has been linked to the increased incidence of postoperative renal failure, right ventricular dysfunction, and hemodynamic instability. The objective of this study is to determine whether the embolic load is associated with hemodynamic instability during cardiopulmonary bypass (CPB) separation and postoperative complications.MethodsA retrospective single-centre cohort study of 354 patients undergoing cardiac surgery between December 2015 and March 2020 was conducted. Patients were divided in tertiles, where 117 patients had a low quantity of embolic material (LEM), 119 patients have a medium quantity of microemboli (MEM) and 118 patients who have a high quantity of embolic material (HEM). The primary endpoint was a difficult CPB separation. Multivariate logistic regression was used to determine the potential association between a difficult CPB separation and the number of embolic materials.ResultsPatients who had a difficult CPB separation had more HITS compared to patients who had a successful CPB separation (p < 0.001). In the multivariate analysis, patients with MEM decreased their odds of having a difficult CPB weaning compared to patients in the HEM group (OR = 0.253, CI 0.111–0.593; p = 0.001). In the postoperative period patients in the HEM group have a higher Time of Persistent Organ Dysfunction (TPOD), a longer stay in the ICU, a longer duration under vasopressor drugs and a higher mortality rate compared to those in the MEM and LEM groups.ConclusionThe result of this study suggests that a high quantity of cerebral embolic material increases the odds of having a difficult CPB separation. Also, it seems to be associated to more complex surgery, a longer CPB time, a higher TPOD and a longer stay in the ICU. Six out of eight patients who died in this cohort were in the HEM group.

Incidence, factors, and prognostic analyses of challenging cardiopulmonary bypass separation in Chinese cardiac surgical populations.

Challenging separation from cardiopulmonary bypass (CPB) has been associated with multiple medical adversities, while its incidence, associated factors, and prognosis among cardiac surgery populations are substantially understudied. Adult cardiac surgical patients in two medical centers were retrospectively analyzed. Separation from CPB was stratified as easy, difficult, or complex, based on the use of pharmacologic assistance agents and mechanical supports. The various in-hospital adverse outcomes (e.g., mortality, common complications) were assessed. The incidence of difficult and complex separation from CPB was 21.9% (1159 cases, 95% CI 20.8% to 23.1%), and 6.1% (320 cases, 95% CI 5.4% to 6.7%), respectively. High age, the presence of pulmonary hypertension or unstable angina, decreased ejection fraction, and emergency surgery were more frequently associated with challenging separation from CPB. Patients who experienced challenging separation from CPB had an elevated risk of adverse outcomes, including in-hospital mortality (complex: odds ratio [OR] 2.85), composite infection events (difficult: OR=1.82; complex: OR=1.88), major adverse cardiac events (difficult: OR=1.40; complex: OR=1.57), pulmonary complications (difficult: OR=1.31; complex: OR=1.20), acute kidney injury (difficult: OR=1.75; complex: OR=2.64), and prolonged postoperative hospital stays. We depicted the incidence of challenging separation from CPB among cardiac surgery population. Additionally, results of influential factors and various adverse outcome analyses emphasize the potential of interventions aimed at preventing difficult or complex separation from CPB and reducing associated adverse outcomes.

Rotational Thromboelastometry–Guided Use of Synthetic Blood Products in Cardiac Transplant Patients: A Retrospective Before-After Study

Viscoelastic hemostatic assays, such as rotational thromboelastometry (ROTEM), are used increasingly in cardiac surgery to guide transfusion decisions. After separation from cardiopulmonary bypass (CPB), achieving hemostasis rapidly is the main goal before chest closure. The authors hypothesized that introducing a ROTEM-guided factor- concentrate transfusion algorithm would reduce the duration from CPB separation to chest closure during cardiac transplantation. A retrospective cohort study of 21 patients before and 28 patients after implementation of the ROTEM-guided transfusion algorithm who underwent cardiac transplantation. This single-center study was conducted at Saint Paul's Hospital, Vancouver, British Columbia, Canada. Using a ROTEM-guided factor-concentrate transfusion algorithm for cardiac transplant recipients. The primary outcome was the duration from CPB separation to chest closure analyzed using Mann-Whitney U tests. The secondary outcomes included the volume of postoperative chest tube drainage, packed red blood cell (pRBC) transfusion requirements within 24 hours of surgery, the incidence of adverse events, and the length of stay before and after introducing a ROTEM-guided factor-concentrate transfusion algorithm. After adjusting for confounders using multivariate linear regression analysis, using a ROTEM-guided factor-concentrate transfusion algorithm resulted in a significant decrease in time from CPB separation to skin closure of 39.4 minutes (-73.1 to 123.5 min, p=0.016). For the secondary outcomes, the use of ROTEM-guided transfusion showed reductions in pRBC transfusion within 24 hours of surgery (-1.3 units, -2.7 to 0.1 units; p=0.077) and chest tube bleeding (-0.44 mL, -0.96 to +0.083 mL; p=0.097); however, neither was statistically significant after adjustment.The median hospital length of stay in the study group was lower by 3 days (13 days v 16) days; p=0.048). The introduction of a ROTEM-guided factor-concentrate transfusion algorithm was associated with a significant reduction in time to chest closure after separation from CPB. Although it reduced the total hospital length of stay, there were no differences in mortality, major complications, or intensive care unit length of stay.

Longitudinal Validation of Right Ventricular Pressure Monitoring for the Assessment of Right Ventricular Systolic Dysfunction in a Large Animal Ischemic Model.

RV pressure monitoring can detect changes in RV systolic performance assess by RV Ees following the development of an acute RV ischemic model. Acute ischemic RV dysfunction was induced by progressive embolization of microsphere in the right coronary artery to mimic RV dysfunction clinically experienced during cardiopulmonary bypass separation caused by air microemboli. RV hemodynamic performance was assessed using RV pressure waveform-derived parameters and RV Ees obtained using a conductance catheter during inferior vena cava occlusions. Acute ischemia resulted in a significant reduction in RV Ees from 0.26 mm Hg/mL (interquartile range, 0.16-0.32 mm Hg/mL) to 0.14 mm Hg/mL (0.11-0.19 mm Hg/mL; p < 0.010), cardiac output from 6.3 L/min (5.7-7 L/min) to 4.5 (3.9-5.2 L/min; p = 0.007), mean systemic arterial pressure from 72 mm Hg (66-74 mm Hg) to 51 mm Hg (46-56 mm Hg; p < 0.001), and mixed venous oxygen saturation from 65% (57-72%) to 41% (35-45%; p < 0.001). Linear mixed-effect model analysis was used to assess the relationship between Ees and RV pressure-derived parameters. The reduction in RV Ees best correlated with a reduction in RV maximum first derivative of pressure during isovolumetric contraction (dP/dtmax) and single-beat RV Ees. Adjusting RV dP/dtmax for heart rate resulted in an improved surrogate of RV Ees. Stepwise decreases in RV Ees during acute ischemic RV dysfunction were accurately tracked by RV dP/dtmax derived from the RV pressure waveform.

Perioperative Doppler ultrasound assessment of portal vein flow pulsatility in high-risk cardiac surgery patients: a multicentre prospective cohort study

BackgroundPortal vein Doppler ultrasound pulsatility measured by transoesophageal echocardiography is a marker of the haemodynamic impact of venous congestion in cardiac surgery. We investigated whether the presence of abnormal portal vein flow pulsatility is associated with a longer duration of invasive life support and postoperative complications in high-risk patients. MethodsIn this multicentre cohort study, pulsed-wave Doppler ultrasound assessments of portal vein flow were performed during anaesthesia before initiation of cardiopulmonary bypass (before CPB) and after separation of cardiopulmonary bypass (after CPB). Abnormal pulsatility was defined as portal pulsatility fraction (PPF) ≥50% (PPF50). The primary outcome was the cumulative time in perioperative organ dysfunction (TPOD) requiring invasive life support during 28 days. Secondary outcomes included major postoperative complications. Results373 patients, 71 (22.0%) had PPF50 before CPB and 77 (24.9%) after CPB. PPF50 was associated with longer duration of TPOD (median [inter-quartile range]; before CPB: 27 h [11–72] vs 19 h [8.5–42], P=0.02; after CPB: 27 h [11–61] vs 20 h [8–42], P=0.006). After adjusting for confounders, PPF50 before CPB showed significant association with TPOD. PPF50 after CPB was associated with a higher rate of major postoperative complications (36.4% vs 20.3%, P=0.006). ConclusionsAbnormal portal vein flow pulsatility before cardiopulmonary bypass was associated with longer duration of life support therapy after cardiac surgery in high-risk patients. Abnormal portal vein flow pulsatility after cardiopulmonary bypass separation was associated with a higher risk of major postoperative complications although this association was not independent of other factors. Clinical trial registrationNCT03656263.

Impact of Processed Electroencephalography in Cardiac Surgery: A Retrospective Analysis

The use of brain function monitoring with processed electroencephalography (pEEG) during cardiac surgery is gaining interest for the optimization of hypnotic agent delivery during the maintenance of anesthesia. The authors sought to determine whether the routine use of pEEG-guided anesthesia is associated with a reduction of hemodynamic instability during cardiopulmonary bypass (CPB) separation and subsequently reduces vasoactive and inotropic requirements in the intensive care unit. This is a retrospective cohort study based on an existing database. A single cardiac surgical center. Three hundred patients undergoing cardiac surgery, under CPB, between December 2013 and March 2020. None. One hundred and fifty patients had pEEG-guided anesthesia, and 150 patients did not have a pEEG-guided anesthesia. Multiple logistic regression demonstrated that pEEG-guided anesthesia was not associated with a successful CPB separation (p=0.12). However, the use of pEEG-guided anesthesia reduced by 57% the odds of being in a higher category for vasoactive inotropic score compared to patients without pEEG (odds ratio=0.43; 95% confidence interval: 0.26-0.73; p=0.002). Duration of mechanical ventilation, fluid balance, and blood losses were also reduced in the pEEG anesthesia-guided group (p < 0.003), but there were no differences in organ dysfunction duration and mortality. During cardiac surgery, pEEG-guided anesthesia allowed a reduction in the use of inotropic or vasoactive agents at arrival in the intensive care unit. However, it did not facilitate weaning from CPB compared to a group where pEEG was unavailable. A pEEG-guided anesthetic management could promote early vasopressor weaning after cardiac surgery.

Predicting the Response of Hydroxocobalamin in Postoperative Vasoplegia in Recipients of Cardiopulmonary Bypass

The primary aim of this study was to identify predictors of response to hydroxocobalamin. A retrospective cohort study. A single large academic medical center within the cardiovascular surgery intensive care unit. Postoperative cardiovascular surgery patients within 96 hours of cardiopulmonary bypass separation between May 7, 2018, and August 1, 2020. None. Of the 66 administrations, 43 administrations yielded hemodynamic improvements (65.2%). Comparing responders to nonresponders, nonresponders had a greater median cardiopulmonary bypass duration (223 v 131 minutes; p < 0.001) and a prolonged median cross-clamp time (153 v 77 minutes; p=0.014). Multivariate modeling demonstrated a reduction in the odds of being a responder by 57% for every 60 minutes of cardiopulmonary bypass duration (odds ratio, 0.43; 95% confidence interval, 0.28-0.68; p < 0.001), but there was no significant difference based on time from intensive care unit admission to hydroxocobalamin administration (odds ratio, 0.95; 95% confidence interval, 0.88-1.03; p=0.20). Shorter total bypass duration and more rapid utilization after bypass of hydroxocobalamin were associated with a higher likelihood of response to refractory vasoplegic shock.

Hydroxocobalamin or Methylene Blue for Vasoplegic Syndrome in Adult Cardiothoracic Surgery

To compare hydroxocobalamin and methylene blue for the treatment of vasopressor-refractory vasoplegic syndrome (VS) after adult cardiac surgery with cardiopulmonary bypass (CPB). A retrospective, propensity-matched, cohort study was performed. The primary endpoints were the percentage change in vasopressor use at 30, 60, and 120 minutes, characterized as both norepinephrine equivalents and vasoactive inotropic score. Eligible patients who received methylene blue were matched 3:1 with patients who received hydroxocobalamin based on sequential organ failure assessment score, preoperative mechanical circulatory support, CPB duration, and use of pre-CPB vasopressors, angiotensin-converting enzyme inhibitors, or beta-blockers. A quaternary care academic medical center. Adult patients who underwent cardiac surgery with CPB from July 2013 to June 2019. Patients were included who received either hydroxocobalamin (5,000 mg) or methylene blue (median 1.2 mg/kg) for VS in the operating room during the index surgery or in the intensive care unit up to 24 hours after CPB separation. Of the 142 included patients, 120 received methylene blue and 22 received hydroxocobalamin. After matching, 66 patients in the methylene blue group were included in the analysis. Baseline demographics, surgical characteristics, and vasoactive medications were similar between groups. There were no significant between-group differences in percentage change in norepinephrine equivalents or vasoactive inotropic score at each timepoint. In adult patients undergoing cardiothoracic surgery using CPB with VS, the ability to reduce vasopressor use was similar with hydroxocobalamin compared with methylene blue.

Combined Use of Rotational Thromboelastometry (Rotem) and Platelet Impedance Aggregometry (Multiplate Analyzer) in Cyanotic and Acyanotic Infants and Children Undergoing Cardiac Surgery With Cardiopulmonary Bypass: Subgroup Analysis of a Randomized Clinical Trial

Few studies have investigated the Multiplate platelet function analyzer in pediatrics. The authors evaluated Multiplate combined with Rotem in terms of guiding platelet transfusion after pediatric cardiac surgery with cardiopulmonary bypass (CPB). The authors further compared coagulation parameters between cyanotic and acyanotic patients. Subgroup analysis of a randomized clinical trial. Tertiary hospital. Patients weighing between seven and 15 kg. None. Rotem and Multiplate tests were performed (1) after anesthesia induction, (2) upon CPB separation, and (3) upon intensive care unit arrival. Among a total of 59 subjects, 9 patients required platelet transfusion. In multivariate linear regression, analysis EXTEM maximum clot firmness upon CPB separation was associated with the volume of transfused platelets (regression coefficient = -0.348 [95% confidence interval -1.006 to -0.028]; p = 0.039). No such association was found for the Multiplate test. Acyanotic and cyanotic heart disease were present in 32 and 27 children, respectively. There were no significant differences between these two groups in terms of platelet count and function. Postoperative blood loss was significantly higher in the cyanotic group compared with the acyanotic arm (p = 0.015; difference [95% confidence interval -2.40 {-4.20 to -0.60}]). There were no differences between groups regarding transfusion of allogeneic blood products. This study showed that Rotem, but not Multiplate results, were associated with platelet transfusion in pediatric cardiac surgery with no intake of platelet inhibitors. The usefulness of combining these tests in platelet transfusion decision-making needs to be evaluated in larger populations.

Topical versus low-dose systemic tranexamic acid in pediatric cardiac surgery: A randomized clinical study.

The current study aimed to compare the benefits of topical and low-dose systemic tranexamic acid administration in pediatric cardiac surgery. A total of 117 children undergoing cardiac surgery for congenital heart disease were assigned into three groups. Patients in the systemic group received 20 mg/kg-1 tranexamic acid through the cardiopulmonary bypass followed by another dose of 20 mg/kg-1 after cardiopulmonary bypass separation. Patients in the topical group were administered with 50 mg/kg-1 tranexamic acid poured into the pericardium, while the control group received no antifibrinolytics. The outcome measures of bleeding and blood products transfusion were recorded over the first 48 h postoperatively. Chest tube drainage was significantly lower in both topical and systemic groups than the control group, but it did not differ between the case groups. Blood products requirement did not show a difference between groups. Neurological or thromboembolic events did not variate among the groups, and no deaths occurred in this study. Topical or systemic tranexamic acid administration reduced postoperative blood loss effectively without adding an extra risk.

Acute Right Ventricular Failure in Cardiac Surgery During Cardiopulmonary Bypass Separation: A Retrospective Case Series of 12 Years’ Experience With Intratracheal Milrinone Administration

To report the authors' 12 years of experience with intratracheal milrinone administration and to assess the efficacy and limitations of intratracheal milrinone bolus administration for the treatment of unexpected acute right ventricular (RV) failure in patients undergoing cardiac surgery. Retrospective analysis. Single-center university hospital. One hundred seventy-six patients (4.6%) undergoing on-pump cardiac surgery. Endotracheal tube administration of milrinone (5-mg bolus) after unexpected acute RV failure during separation from cardiopulmonary bypass (CPB) weaning. RV failure was defined as the simultaneous presence of all of the following criteria: (1) hemodynamic instability or difficult separation from CPB with associated elevated central venous pressure or abnormal RV pressure waveform, (2)>20% reduction of RV fractional area change from baseline evaluated by transesophageal echocardiography, and (3) anatomical visualization of impaired or absent RV wall motion by direct intraoperative visual inspection. Intratracheal milrinone administration was found to improve RV failure in 109 patients (61.9%) whereas RV failure persisted in 67 patients (38.1%). Using a multiple logistic regression model, severely decreased left ventricular ejection fraction (<35% v >50%) (adjusted odds ratio [OR] 3.72; 95% confidence interval [CI] 1.2-11.3; p = 0.012), longer CPB time (adjusted OR 1.014; CI 1.01-1.02; p = 0.001) and elevated postoperative fluid balance (adjusted OR 1.39; CI 1.1-1.8; p = 0.02) were found to be significant predictors of persistent RV failure. Intratracheal instillation of milrinone was associated with clinical improvement of RV failure occurring during separation from CPB in almost two-thirds of patients. Factors limiting its therapeutic efficacy include severe left ventricular dysfunction, increased fluid balance, and long CPB time.

Identifying Variability in Mental Models Within and Between Disciplines Caring for the Cardiac Surgical Patient.

The cardiac operating room is a complex environment requiring efficient and effective communication between multiple disciplines. The objectives of this study were to identify and rank critical time points during the perioperative care of cardiac surgical patients, and to assess variability in responses, as a correlate of a shared mental model, regarding the importance of these time points between and within disciplines. Using Delphi technique methodology, panelists from 3 institutions were tasked with developing a list of critical time points, which were subsequently assigned to pause point (PP) categories. Panelists then rated these PPs on a 100-point visual analog scale. Descriptive statistics were expressed as percentages, medians, and interquartile ranges (IQRs). We defined low response variability between panelists as an IQR ≤ 20, moderate response variability as an IQR > 20 and ≤ 40, and high response variability as an IQR > 40. Panelists identified a total of 12 PPs. The PPs identified by the highest number of panelists were (1) before surgical incision, (2) before aortic cannulation, (3) before cardiopulmonary bypass (CPB) initiation, (4) before CPB separation, and (5) at time of transfer of care from operating room (OR) to intensive care unit (ICU) staff. There was low variability among panelists' ratings of the PP "before surgical incision," moderate response variability for the PPs "before separation from CPB," "before transfer from OR table to bed," and "at time of transfer of care from OR to ICU staff," and high response variability for the remaining 8 PPs. In addition, the perceived importance of each of these PPs varies between disciplines and between institutions. Cardiac surgical providers recognize distinct critical time points during cardiac surgery. However, there is a high degree of variability within and between disciplines as to the importance of these times, suggesting an absence of a shared mental model among disciplines caring for cardiac surgical patients during the perioperative period. A lack of a shared mental model could be one of the factors contributing to preventable errors in cardiac operating rooms.

Reduction in blood transfusion in a cohort of infants having cardiac surgery with cardiopulmonary bypass after instituting a goal-directed transfusion policy.

Current trends in pediatric cardiac surgery and anesthesiology include goal-directed allogeneic blood transfusion, but few studies address the transfusion of platelets and cryoprecipitate. We report a quality improvement initiative to reduce the transfusion of platelets and cryoprecipitate in infants having cardiac surgery with cardiopulmonary bypass (CPB). Data from 50 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB were prospectively collected after the institution of a policy to obtain each patient's platelet and fibrinogen levels during the rewarming phase of CPB. Data from 48 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB prior to the implementation of the policy change were retrospectively collected. Demographics, laboratory values and blood product transfusion data were compared between the groups, using the Chi-square/Fisher's exact test or the T-Test/Wilcoxon Rank-Sum test, as appropriate. The results showed more total blood product exposures in the control group during the time from bypass through the first twenty-four post-operative hours (median of 2 units versus 1 unit in study group, p=0.012). During the time period from CPB separation through the first post-operative day, 67% of patients in the control group received cryoprecipitate compared to 32% in the study group (p=0.0006). There was no difference in platelet exposures between the groups. Checking laboratory results during the rewarming phase of CPB reduced cryoprecipitate transfusion by 50%. This reproducible strategy avoids empiric and potentially unnecessary transfusion in this vulnerable population.

Postoperative Hydrocortisone Infusion Reduces the Prevalence of Low Cardiac Output Syndrome After Neonatal Cardiopulmonary Bypass.

Neonatal cardiac surgery with cardiopulmonary bypass is often complicated by morbidity associated with inflammation and low cardiac output syndrome. Hydrocortisone "stress dosing" is reported to provide hemodynamic benefits in some patients with refractory shock. Development of cardiopulmonary bypass-induced adrenal insufficiency may provide further rationale for postoperative hydrocortisone administration. We sought to determine whether prophylactic, postoperative hydrocortisone infusion could decrease prevalence of low cardiac output syndrome after neonatal cardiac surgery with cardiopulmonary bypass. Double-blind, randomized control trial. Pediatric cardiac ICU and operating room in tertiary care center. Forty neonates undergoing cardiac surgery with cardiopulmonary bypass were randomized (19 hydrocortisone and 21 placebo). Demographics and known risk factors were similar between groups. After cardiopulmonary bypass separation, bolus hydrocortisone (50 mg/m²) or placebo was administered, followed by continuous hydrocortisone infusion (50 mg/m²/d) or placebo tapered over 5 days. Adrenocorticotropic hormone stimulation testing (1 μg) was performed before and after cardiopulmonary bypass, prior to steroid administration. Blood was collected for cytokine analysis before and after cardiopulmonary bypass. Subjects receiving hydrocortisone were less likely to develop low cardiac output syndrome (5/19, 26% vs 12/21, 57%; p = 0.049). Hydrocortisone group had more negative net fluid balance at 48 hours (-114 vs -64 mL/kg; p = 0.01) and greater urine output at 0-24 hours (2.7 vs 1.2 mL/kg/hr; p = 0.03). Hydrocortisone group weaned off catecholamines and vasopressin sooner than placebo, with a difference in inotrope-free subjects apparent after 48 hours (p = 0.033). Five placebo subjects (24%) compared with no hydrocortisone subjects required rescue steroids (p = 0.02). Thirteen (32.5%) had adrenal insufficiency after cardiopulmonary bypass. Patients with adrenal insufficiency randomized to receive hydrocortisone had lower prevalence of low cardiac output syndrome compared with patients with adrenal insufficiency randomized to placebo (1/6 vs 6/7, respectively; p = 0.02). Hydrocortisone significantly reduced proinflammatory cytokines. Ventilator-free days, hospital length of stay, and kidney injury were similar. Prophylactic, postoperative hydrocortisone reduces low cardiac output syndrome, improves fluid balance and urine output, and attenuates inflammation after neonatal cardiopulmonary bypass surgery. Further studies are necessary to show if these benefits lead to improvements in more important clinical outcomes.

Clinical Decision Support for Perioperative Information Management Systems

Clinical decision support (CDS) systems are being used to optimize the increasingly complex care that our health care system delivers. These systems have become increasingly important in the delivery of perioperative care for patients undergoing cardiac, thoracic, and vascular procedures. The adoption of perioperative information management systems (PIMS) has allowed these technologies to enter the operating room and support the clinical work flow of anesthesiologists and operational processes. Constructing effective CDS systems necessitates an understanding of operative work flow and technical considerations as well as achieving integration with existing information systems. In this review, we describe published examples of CDS for PIMS, including support for cardiopulmonary bypass separation physiological alarms, β-blocker guideline adherence, enhanced revenue capture for arterial line placement, and detection of hemodynamic monitoring gaps. Although these and other areas are amenable to CDS systems, the challenges of latency and data reliability represent fundamental limitations on the potential application of these tools to specific types of clinical issues. Ultimately, we expect that CDS will remain an important tool in our efforts to optimize the quality of care delivered.

High-frequency oscillatory ventilation after cardiac surgery: a treatment for all ages

In a recent issue of Critical Care, Bojan and colleagues [1] reported their experience with early initiation of highfrequency oscillatory ventilation (HFOV) in pediatric cardiac surgery that demonstrated shorter mechanical ventilation times and intensive care stays. Acute lung injury is common in adult patients undergoing surgery, yet there is scant reporting of the intraoperative utility of HFOV [2]. We initiated HFOV in a 49-year-old morbidly obese (body mass index of 69 kg/m 2 ) man who had aortic stenosis, pulmonary hypertension, and decompensated congestive heart failure and who was undergoing aortic valve replacement. Separation from cardiopulmonary bypass (CPB) with inverse-ratio pressure-control ventilation – fraction of inspired oxygen (FiO 2 ) of 1.0 and positive end-expiratory pressure (PEEP) of 18 cm H 2 O – failed because of hypoxia, defi ned as an arterial partial pressure of oxygen (PaO 2 ) of 64 mm Hg. HFOV was initiated (mean pressure airway of 33 cm H 2 O and FiO 2 of 1.0), yielding a PaO 2 of 74 mm Hg and allowing CPB separation. Th e patient was transitioned to conventional ventilation on postoperative day 3 and was extubated on postoperative day 5. Th is adult patient benefi ted from HFOV, as did the pediatric population of Bojan and colleagues. Continuous positive intrathoracic pressure is a concern as it may impede venous return and thereby limit cardiac output (CO) [3]. However, the transition from ventilation with PEEP to HFOV usually results in signifi cant changes in oxygenation/ventilation but not in CO [4]. In patients with pulmonary hypertension, HFOV has been demonstrated to increase CO and decrease pulmonary vascular resistance [5]. For our patient, HFOV allowed improved oxygenation without aff ecting hemodynamics. HFOV may be a safe and eff ective therapy to improve oxygenation/ventilation in patients undergoing cardiac surgery and possibly is underused because of unfounded hemodynamic concerns. HFOV needs exploration as a rescue tool after CPB for patients with hypoxia.

Plasma acetate, gluconate and interleukin-6 profiles during and after cardiopulmonary bypass: a comparison of Plasma-Lyte 148 with a bicarbonate-balanced solution

IntroductionAs even small concentrations of acetate in the plasma result in pro-inflammatory and cardiotoxic effects, it has been removed from renal replacement fluids. However, Plasma-Lyte 148 (Plasma-Lyte), an electrolyte replacement solution containing acetate plus gluconate is a common circuit prime for cardio-pulmonary bypass (CPB). No published data exist on the peak plasma acetate and gluconate concentrations resulting from the use of Plasma-Lyte 148 during CPB.MethodsThirty adult patients were systematically allocated 1:1 to CPB prime with either bicarbonate-balanced fluid (24 mmol/L bicarbonate) or Plasma-Lyte 148. Arterial blood acetate, gluconate and interleukin-6 (IL-6) levels were measured immediately before CPB (T1), three minutes after CPB commencement (T2), immediately before CPB separation (T3), and four hours post separation (T4).ResultsAcetate concentrations (normal 0.04 to 0.07 mmol/L) became markedly elevated at T2, where the Plasma-Lyte group (median 3.69, range (2.46 to 8.55)) exceeded the bicarbonate group (0.16 (0.02 to 3.49), P < 0.0005). At T3, levels had declined but the differential pattern remained apparent (Plasma-Lyte 0.35 (0.00 to 1.84) versus bicarbonate 0.17 (0.00 to 0.81)). Normal circulating acetate concentrations were not restored until T4. Similar gluconate concentration profiles and inter-group differences were seen, with a slower T3 decay. IL-6 increased across CPB, peaking at T4, with no clear difference between groups.ConclusionsUse of acetate containing prime solutions result in supraphysiological plasma concentrations of acetate. The use of acetate-free prime fluid in CPB significantly reduced but did not eliminate large acetate surges in cardiac surgical patients. Complete elimination of acetate surges would require the use of acetate free bolus fluids and cardioplegia solutions.Trial registrationAustralia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610000267055

Mechanical ventilation affects inflammatory mediators in patients undergoing cardiopulmonary bypass for cardiac surgery: A randomized clinical trial

Respiratory support for patients recovering from cardiopulmonary bypass and cardiac surgery uses large tidal volumes and a minimal level of positive end-expiratory pressure. Recent data indicate that these ventilator settings might cause pulmonary and systemic inflammation in patients with acute lung injury. We examined the hypothesis that high tidal volumes and low levels of positive end-expiratory pressure might worsen the inflammatory response associated to cardiopulmonary bypass. Forty patients undergoing elective coronary artery bypass were randomized to be ventilated after cardiopulmonary bypass disconnection with high tidal volume/low positive end-expiratory pressure (10-12 mL/kg and 2-3 cm H2O, respectively) or low tidal volume/high positive end-expiratory pressure (8 mL/kg and 10 cm H2O, respectively). Interleukin 6 and interleukin 8 levels were measured in the bronchoalveolar lavage fluid and plasma. Samples were taken before sternotomy (time 0), immediately after cardiopulmonary bypass separation (time 1), and after 6 hours of mechanical ventilation (time 2). Interleukin 6 and interleukin 8 levels in the bronchoalveolar lavage fluid and plasma significantly increased at time 1 in both groups but further increased at time 2 only in patients ventilated with high tidal volume/low positive end-expiratory pressure. Interleukin 6 and interleukin 8 levels in the bronchoalveolar lavage fluid and in the plasma at time 2 were higher with high tidal volume/low positive end-expiratory pressure than with low tidal volume/high positive end-expiratory pressure. Mechanical ventilation might be a cofactor able to influence the inflammatory response after cardiac surgery.