Continuous Right Ventricular Pressure Monitoring in Cardiac Surgery.

OBJECTIVE: 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. DESIGN: Prospective study. SETTING: Tertiary care cardiac institute. PARTICIPANTS: Cardiac surgical patients. INTERVENTION: Cardiac surgery. MEASUREMENTS AND MAIN RESULTS: 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. CONCLUSION: 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.

Inhaled Epoprostenol and Milrinone Effect on Right Ventricular Pressure Waveform Monitoring.

BACKGROUND: Pulmonary hypertension (PH) and right ventricular (RV) dysfunction are major complications in cardiac surgery. This study aimed to evaluate the change in RV pressure waveform in patients receiving a combination of inhaled epoprostenol and inhaled milrinone (iE&iM) before cardiopulmonary bypass (CPB) and to assess the safety of this approach with a matched case-control group. METHODS: A prospective single-centre cohort study of adult patients undergoing cardiac surgery administered iE&iM through an ultrasonic mesh nebulizer. RV pressure waveform monitoring was obtained by continuously transducing the RV port of the pulmonary artery (PA) catheter. RESULTS: The final analysis included 26 patients receiving iE&iM. There was a significant drop in mean PA pressure (MPAP) (-4.8 ± 8.7, P = 0.010), systolic PA pressure (SPAP) (-8.2 ± 12.8, P = 0.003), RV end-diastolic pressure (RVEDP) (-2.1 ± 2.8, P < 0.001) and RV diastolic pressure gradient (RVDPG) (-1.7 ± 1.4, P < 0.001) after 17 ± 9 minutes of iE&iM administration. Patients also had a significant increase in RV outflow tract (RVOT) gradient (3.7 ± 4.7, P < 0.001), RV maximal rate of pressure rise during early systole (dP/dt max) (68.3 ± 144.7, P = 0.024), and left ventricular (LV) dP/dt max (66.4 ± 90.1, P < 0.001). Change in RVOT gradient was only observed in those with a positive pulmonary vasodilator response to treatment. Treatment with iE&iM did not present adverse effects when compared with a matched case-control group. CONCLUSIONS: Coadministration of iE&iM in cardiac surgery patients presenting with PH or signs of RV dysfunction is a safe and effective treatment approach in improving RV function. Appearance of a transient increase in RVOT gradient after iE&iM could be useful to predict response to treatment.

Pulmonary Vasodilator Response of Combined Inhaled Epoprostenol and Inhaled Milrinone in Cardiac Surgical Patients.

BACKGROUND: Pulmonary hypertension (PH) and right ventricular (RV) dysfunction are major complications in cardiac surgery. Intraoperative management of patients at high risk of RV failure should aim to reduce RV afterload and optimize RV filling pressures, while avoiding systemic hypotension, to facilitate weaning from cardiopulmonary bypass (CPB). Inhaled epoprostenol and inhaled milrinone (iE&iM) administered in combination before CPB may represent an effective strategy to facilitate separation from CPB and reduce requirements for intravenous inotropes during cardiac surgery. Our primary objective was to report the rate of positive pulmonary vasodilator response to iE&iM and, second, how it relates to perioperative outcomes in cardiac surgery. METHODS: This is a retrospective cohort study of consecutive patients with PH or RV dysfunction undergoing on-pump cardiac surgery at the Montreal Heart Institute from July 2013 to December 2018 (n = 128). iE&iM treatment was administered using an ultrasonic mesh nebulizer before the initiation of CPB. Demographic and baseline clinical data, as well as hemodynamic, intraoperative, and echocardiographic data, were collected using electronic records. An increase of 20% in the mean arterial pressure (MAP) to mean pulmonary artery pressure (MPAP) ratio was used to indicate a positive response to iE&iM. RESULTS: In this cohort, 77.3% of patients were responders to iE&iM treatment. Baseline systolic pulmonary artery pressure (SPAP) (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.24-2.16 per 5 mm Hg; P = .0006) was found to be a predictor of pulmonary vasodilator response, while a European System for Cardiac Operative Risk Evaluation (EuroSCORE II) score >6.5% was a predictor of nonresponse to treatment (≤6.5% vs >6.5% [reference]: OR, 5.19; 95% CI, 1.84-14.66; P = .002). Severity of PH was associated with a positive response to treatment, where a higher proportion of responders had MPAP values >30 mm Hg (42.4% responders vs 24.1% nonresponders; P = .0237) and SPAP values >55 mm Hg (17.2% vs 3.4%; P = .0037). Easier separation from CPB was also associated with response to iE&iM treatment (69.7% vs 58.6%; P = .0181). A higher proportion of nonresponders had a very difficult separation from CPB and required intravenous inotropic drug support compared to responders, for whom easy separation from CPB was more frequent. Use of intravenous inotropes after CPB was lower in responders to treatment (8.1% vs 27.6%; P = .0052). CONCLUSIONS: A positive pulmonary vasodilator response to treatment with a combination of iE&iM before initiation of CPB was observed in 77% of patients. Higher baseline SPAP was an independent predictor of pulmonary vasodilator response, while EuroSCORE II >6.5% was a predictor of nonresponse to treatment.

Right Ventricular Outflow Tract Obstruction in Adults: A Systematic Review and Meta-analysis.

BACKGROUND: Right ventricular outflow tract obstruction (RVOTO) is a cause of hemodynamic instability that can occur in several situations, including cardiac surgery, lung transplantation, and thoracic surgery, and in critically ill patients. The timely diagnosis of RVOTO is important because it requires specific considerations, including the adverse effects of positive inotropes, and depending on the etiology, the requirement for urgent surgical intervention. METHODS: The objective of this systematic review and meta-analysis was to determine the prevalence of RVOTO in adult patients, and the distribution of all reported cases by etiology. RESULTS: Of 233 available reports, there were 229 case reports or series, and 4 retrospective cohort studies, with one study also reporting a prospective cohort. Of 291 reported cases of RVOTO, 61 (21%) were congenital, 56 (19%) were iatrogenic, and 174 (60%) were neither congenital nor iatrogenic (including intracardiac tumour). The mechanism of RVOTO was an intrinsic obstruction in 169 cases (58%), and an extrinsic obstruction in 122 cases (42%). A mechanical obstruction causing RVOTO was present in 262 cases (90%), and 29 cases of dynamic RVOTO (10%) were reported. In the 5 included cohorts, with a total of 1122 patients, the overall prevalence was estimated to be 4.0% (1%-9%). CONCLUSIONS: RVOTO, though rare, remains clinically important, and therefore, multicentre studies are warranted to better understand the prevalence, causes, and consequences of RVOTO.

CONTEXTE: L'obstruction de la chambre de chasse du ventricule droit (OCCVD) est une cause d'instabilité hémodynamique qui peut survenir dans plusieurs situations, y compris une chirurgie cardiaque, une transplantation pulmonaire ou une chirurgie thoracique, ou encore chez des patients en phase critique. Il est important que le diagnostic d'OCCVD soit posé rapidement, car d'une part cette affection exige la prise en compte d'éléments particuliers, y compris les effets indésirables des agents inotropes positifs et, d'autre part, en fonction de l'étiologie, une intervention chirurgicale d'urgence pourrait être nécessaire. MÉTHODOLOGIE: L'objectif de cette revue systématique associée à une méta-analyse était de déterminer la prévalence de l'OCCVD chez les patients adultes ainsi que la distribution de tous les cas rapportés en fonction de leur étiologie. RÉSULTATS: Sur les 233 rapports disponibles, on comptait 229 études ou séries de cas, et quatre études de cohortes rétrospectives, dont une qui présentait également les résultats d'une cohorte prospective. Sur 291 cas d'OCCVD rapportés, 61 (21 %) étaient d'origine congénitale, 56 (19 %) étaient d'origine iatrogène et 174 (60 %) avaient une origine qui n'était ni congénitale ni iatrogène (dont une tumeur intracardiaque). Le mécanisme de l'OCCVD était une obstruction intrinsèque dans 169 cas (58 %), et une obstruction extrinsèque dans 122 cas (42 %). Une obstruction mécanique causant l'OCCVD était présente dans 262 cas (90 %), et 29 cas d'OCCVD dynamique (10 %) ont été rapportés. Dans les 5 cohortes incluses, comptant au total 1 122 patients, la prévalence globale était estimée à 4,0 % (de 1 % à 9 %). CONCLUSIONS: L'OCCVD, malgré sa rareté, n'en est pas moins importante sur le plan clinique; la réalisation d'études multicentriques serait donc justifiée pour permettre de mieux comprendre la prévalence, les causes et les conséquences de cette affection.

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

OBJECTIVE: 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. DESIGN: Retrospective analysis. SETTING: Single-center university hospital. PARTICIPANTS: One hundred seventy-six patients (4.6%) undergoing on-pump cardiac surgery. INTERVENTIONS: 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. MEASUREMENTS AND MAIN RESULTS: 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. CONCLUSION: 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.

Noninvasive Administration of Inhaled Epoprostenol and Inhaled Milrinone in Extubated, Spontaneously Breathing Patients With Right Ventricular Failure and Portal Hypertension: A Report of 2 Cases.

We describe the cases of 2 patients free from mechanical ventilation after a cardiac surgery with systemic venous congestion from right ventricular (RV) failure. Management of these patients included RV preload reduction with diuretics and RV afterload reduction with inhaled pulmonary vasodilators. Noninvasive combination of inhaled epoprostenol and inhaled milrinone through the AirLife filtered nebulizer system (CareFusion) was used. Reduction of splanchnic venous congestion was assessed by Doppler portal flow pulsatility.

Aerosolized Vasodilators for the Treatment of Pulmonary Hypertension in Cardiac Surgical Patients: A Systematic Review and Meta-analysis.

BACKGROUND: In cardiac surgery, pulmonary hypertension is an important prognostic factor for which several treatments have been suggested over time. In this systematic review and meta-analysis, we compared the efficacy of inhaled aerosolized vasodilators to intravenously administered agents and to placebo in the treatment of pulmonary hypertension during cardiac surgery. We searched MEDLINE, CENTRAL, EMBASE, Web of Science, and clinicaltrials.gov databases from inception to October 2015. The incidence of mortality was assessed as the primary outcome. Secondary outcomes included length of stay in hospital and in the intensive care unit, and evaluation of the hemodynamic profile. METHODS: Of the 2897 citations identified, 10 studies were included comprising a total of 434 patients. RESULTS: Inhaled aerosolized agents were associated with a significant decrease in pulmonary vascular resistance (-41.36 dyne·s/cm, P= .03) and a significant increase in mean arterial pressure (8.24 mm Hg, P= .02) and right ventricular ejection fraction (7.29%, P< .0001) when compared to intravenously administered agents. No significant hemodynamically meaningful differences were observed between inhaled agents and placebo; however, an increase in length of stay in the intensive care unit was shown with the use of inhaled aerosolized agents (0.66 days, P= .01). No other differences were observed for either comparison. CONCLUSIONS: The administration of inhaled aerosolized vasodilators for the treatment of pulmonary hypertension during cardiac surgery is associated with improved right ventricular performance when compared to intravenously administered agents. This review does not support any benefit compared to placebo on major outcomes. Further investigation is warranted in this area of research and should focus on clinically significant outcomes.

Clinical Significance of Portal Hypertension Diagnosed With Bedside Ultrasound After Cardiac Surgery.

BACKGROUND: Portal venous flow pulsatility detected by Doppler ultrasound is a sign of congestive heart failure in noncritically ill patients. The assessment of portal and splenic venous flows has never been reported in patients undergoing cardiac surgery. METHODS: This is a case series performed in patients undergoing cardiac surgery between February 2014 and February 2015 in which portal and/or splenic venous flows were assessed by the attending anesthesiologist during surgery or by the intensivist after surgery using transthoracic echography in 9 patients or transesophageal echocardiography in 5 patients. Data collection was done retrospectively by reviewing intraoperative and postoperative monitoring documents. The technique of assessment is detailed in this article. RESULTS: We report the abnormal portal and/or splenic venous flow pulsatility from 14 patients perioperatively. At the time of pulsatility detection, patients had a median cumulative fluid balance of 3.8 L (interquartile range: 0-4.6 L) and a median right atrial pressure of 14.0 mm Hg (interquartile range: 12.0-15.5 mm Hg). In some patients (4/14), signs of right ventricular dysfunction on echocardiography and/or right ventricular pressure monitoring were present. CONCLUSIONS: Doppler evaluation of portal and splenic venous flow using transthoracic echography and transesophageal echocardiography may represent a promising modality to assess end-organ venous congestion in cardiac surgery patients.

A score to estimate 30-day mortality after intensive care admission after cardiac surgery.

OBJECTIVE: Several risk-scoring systems have been developed to predict surgical mortality and complications in cardiac surgical patients, but none of the current systems include factors related to the intraoperative period. The purpose of this study was to develop a score that incorporates both preoperative and intraoperative factors so that it could be used for patients admitted to a cardiac surgical intensive care unit (ICU) immediately after surgery. METHOD: Preoperative and intraoperative data from 30,350 patients in four hospitals were used to build a multiple logistic regression model estimating 30-day mortality after cardiac surgery. Sixty percent of the patients were used as a derivation group and forty percent as a validation group. RESULTS: Mortality occurred in 2.6% of patients (n = 790). Preoperative factors identified in the model were age, female sex, emergency status, pulmonary hypertension, peripheral vascular disease, renal dysfunction, diabetes, peptic ulcer disease, history of alcohol abuse, and refusal of blood products. Intraoperative risk factors included the need for an intra-aortic balloon pump, ventricular assist device or extracorporeal membrane oxygenation leaving the operating room, presence of any intraoperative complication reported by the surgeon, the use of inotropes, high-dose vasopressors, red blood cell transfusion, and cardiopulmonary bypass time. When used after surgery at ICU admission, the model had C-statistics of 0.86 in both derivation and validation sets to estimate the 30-day mortality. CONCLUSIONS: Preoperative and intraoperative variables can be used on admission to a cardiac surgical ICU to estimate 30-day mortality. The score could be used for risk stratification after cardiac surgery and evaluation of performance of cardiac surgical ICUs.

A multicentre randomized-controlled trial of inhaled milrinone in high-risk cardiac surgical patients.

PURPOSE: Inhaled milrinone (iMil) has been used for the treatment of pulmonary hypertension (PH) but its efficacy, safety, and prophylactic effects in facilitating separation from cardiopulmonary bypass (CPB) and preventing right ventricular (RV) dysfunction have not yet been evaluated in a clinical trial. The purpose of this study was to investigate if iMil administered before CPB would be superior to placebo in facilitating separation from CPB. METHODS: High-risk cardiac surgical patients with PH were randomized to receive iMil or placebo after the induction of anesthesia and before CPB. Hemodynamic parameters and RV function were evaluated by means of pulmonary artery catheterization and transesophageal echocardiography. The groups were compared for the primary outcome of the level of difficulty in weaning from CPB. Among the secondary outcomes examined were the reduction in the severity of PH, the incidence of RV failure, and mortality. RESULTS: Of the 124 patients randomized, the mean (standard deviation [SD]) EuroSCORE II was 8.0 (2.6), and the baseline mean (SD) systolic pulmonary artery pressure (SPAP) was 53 (9) mmHg. The use of iMil was associated with increases in cardiac output (P = 0.03) and a reduction in SPAP (P = 0.04) with no systemic hypotension. Nevertheless, there was no difference in the combined incidence of difficult or complex separation from CPB between the iMil and control groups (30% vs 28%, respectively; absolute difference, 2%; 95% confidence interval [CI], -14 to 18; P = 0.78). There was also no difference in RV failure between the iMil and control groups (15% vs 14%, respectively; difference, 1%; 95% CI, -13 to 12; P = 0.94). Mortality was increased in patients with RV failure vs those without (22% vs 2%, respectively; P < 0.001). CONCLUSION: In high-risk cardiac surgery patients with PH, the prophylactic use of iMil was associated with favourable hemodynamic effects that did not translate into improvement of clinically relevant endpoints. This trial was registered at ClinicalTrials.gov; identifier: NCT00819377.

RéSUMé: OBJECTIF: La milrinone inhalée est utilisée pour traiter l'hypertension pulmonaire (HP) mais son efficacité, son innocuité et ses effets prophylactiques pour faciliter le sevrage de la circulation extracorporelle (CEC) et prévenir la dysfonction ventriculaire droite (VD) n'ont pas encore été évalués dans le cadre d'une étude clinique. L'objectif de cette étude était d'examiner si la milrinone inhalée avant la CEC serait supérieure à un placebo pour faciliter le sevrage de la CEC. MéTHODE: Des patients de chirurgie cardiaque à risque élevé et souffrant d'HP ont été randomisés à recevoir de la milrinone inhalée ou un placebo après l'induction de l'anesthésie et avant la CEC. Les paramètres hémodynamiques et la fonction VD ont été évalués à l'aide d'un cathéter de l'artère pulmonaire et d'une échocardiographie transœsophagienne. Les groupes ont été comparés selon notre critère d'évaluation principal, soit le niveau de difficulté du sevrage de la CEC. Parmi les critères d'évaluation secondaires examinés figuraient la réduction de la gravité de l'HP, l'incidence d'insuffisance cardiaque droite et la mortalité. RéSULTATS: Au total, 124 patients ont été randomisés. Le score EuroSCORE II moyen (écart type [ÉT]) était de 8,0 (2,6), et la pression systolique de l'artère pulmonaire moyenne de base (ÉT) était de 53 (9) mmHg. L'utilisation de milrinone inhalée a été associée à des augmentations du débit cardiaque (P = 0,03) et à une réduction de la pression systolique de l'artère pulmonaire (P = 0,04) sans hypotension systémique. Toutefois, aucune différence n'a été observée dans l'incidence combinée de sevrage difficile ou complexe de la CEC entre le groupe milrinone inhalée et le groupe témoin (30 % vs 28 %, respectivement; différence absolue, 2 %; intervalle de confiance [IC] 95 %, −14 à 18; P = 0,78). Aucune différence n'a été observée non plus en matière d'insuffisance cardiaque droite entre le groupe milrinone inhalée et le groupe témoin (15 % vs 14 %, respectivement; différence, 1 %; IC 95 %, −13 à 12; P = 0,94). La mortalité était augmentée chez les patients avec insuffisance cardiaque droite (22 % vs 2 %, respectivement; P < 0.001). CONCLUSION: Chez les patients de chirurgie cardiaque à risque élevé atteints de HP, l'utilisation prophylactique de milrinone inhalée a été associée à des effets hémodynamiques favorables qui ne se sont pas traduits en améliorations des critères pertinents d'un point de vue clinique. Cette étude a été enregistrée au ClinicalTrials.gov; identifiant : NCT00819377.

Long-Term Effects of Postoperative Delirium in Patients Undergoing Cardiac Operation: A Systematic Review.

Delirium is an acute syndrome that involves fluctuating changes in attention and cognition. Although delirium is the most common neurologic complication after cardiac operation, data about its impact on long-term outcomes are lacking. The purpose of this systematic review was to examine the effect of postoperative delirium (PoD) on long-term outcomes, including morbidity, probability of death, cognitive decline, institutionalization, and health-related quality of life (HRQoL) in patients undergoing cardiac operation. After performing this systematic review we determined that PoD after cardiac operation is associated with an increased risk of probability of death and readmission to the hospital and a decrease in cognitive function, overall function, and HRQoL.

Pearls and pitfalls in managing right heart failure in cardiac surgery.

PURPOSE OF REVIEW: To review the recent insights in the evaluation and management of perioperative (RHF). RECENT FINDINGS: Recent studies highlight the potential role of myocardial deformation imaging in the evaluation of patients at risk of postoperative RHF. There is also a growing interest to study the value of load-adaptation indices of the right heart in the setting of pulmonary hypertension or left ventricular assist device implantation. Finally, the field of temporary extracorporeal life support devices for RHF is rapidly evolving and new strategies are emerging. SUMMARY: An integrated approach for assessing the cardiopulmonary axis combining imaging, hemodynamic and tissue perfusion monitoring is emerging, as particularly helpful in the field. Several developments in the field of temporary right heart support including the pumpless interventional lung assist membrane ventilator are offering new opportunities to support the right-heart pulmonary circulation. Future multicenter studies are needed to develop more effective preventive and therapeutic strategies for RHF.

Preliminary experience with combined inhaled milrinone and prostacyclin in cardiac surgical patients with pulmonary hypertension.

OBJECTIVE: To retrospectively evaluate the effects of combined inhaled prostacyclin and milrinone to reduce the severity of pulmonary hypertension when administered prior to cardiopulmonary bypass. DESIGN: Retrospective case control analysis of high-risk patients undergoing cardiac surgery. SETTING: Single cardiac center. PARTICIPANTS: Sixty one adult cardiac surgical patients with pulmonary hypertension, 40 of whom received inhalation therapy. INTERVENTION: Inhaled milrinone and inhaled prostacyclin were administered before cardiopulmonary bypass (CPB). MEASUREMENTS AND MAIN RESULTS: Administration of both inhaled prostacyclin and milrinone was associated with reductions in central venous pressure, and mean pulmonary artery pressure, increases in cardiac index, heart rate, and the mean arterial-to-mean pulmonary artery pressure ratio (p < 0.05), with no significant change in mean arterial pressure. The rate of difficult and complex separation from CPB was 51% in the inhaled group and 70% in the control group (p = 0.1638). Postoperative vasoactive requirement was reduced at 12 hours (35.9 v 73.7% p<0.01) and 24 hours (25.6 v 57.9% p<0.05) postoperatively in the combined inhaled agent group. Hospital length of stay and mortality were similar between the groups. CONCLUSION: Preemptive treatment of pulmonary hypertension with a combination of inhaled prostacyclin and milrinone before CPB was associated with a reduction in the severity of pulmonary hypertension. In addition, a significant reduction in vasoactive support in the intensive care unit during the first 24 hours after cardiac surgery was observed. The impact of this strategy on postoperative survival needs to be determined.