Serial blood lactate levels as a predictor of mortality in children after cardiopulmonary bypass surgery

Carbon dioxide production index (VCO2i) predicts hyperlactatemia during cardiopulmonary bypass in ediatric carDiac surGery (pGDP- VCO2i): Study protocol for a nested case-control trial

BACKGROUND

Hyperlactatemia (HL) during cardiopulmonary bypass (CPB) is relatively frequent in infants and associates with increased morbidity and mortality. Studies on adults have shown that carbon dioxide production index (VCO2i) during CPB is linked to the occurrence of HL, with 'critical thresholds' for VCO2i reported to be 60 mL/min/m2. However, considering infants have a higher metabolic rate and lower tolerance to hypoxia, the critical threshold of VCO2i in infants cannot be replied to the existing adults' standards. The objective of this study is to investigate the association of VCO2i during CPB and HL, and explore the critical VCO2i threshold during CPB in infants.

METHODS

VCO2i predicts hyperlactatemia during cardiopulmonary bypass in pediatric cardiac surgery (pGDP-VCO2i) is a nested case-control study. A cohort of consecutive pediatric patients of less than 3 years of age, undergoing congenital cardiac surgeries between May 2021 and December 2023 in West China Hospital will be enrolled. The VCO2i levels of each patient will be recorded every 5 min during CPB. The primary outcome is the rate of HL. The infants will be divided into two groups based on the presence or not of HL. Pre- and intraoperative factors will be tested for independent association with HL. Then, we will make an analysis, and the critical value of VCO2i will be obtained. The postoperative outcome of patients with or without HL will be compared.

DISCUSSION

This will be the first trial to investigate the association of VCO2i during CPB and HL, and explore the critical VCO2i threshold during CPB in pediatrics. The results of this study are expected to lay a foundation for clinical application of goal-directed perfusion (GDP) management strategy, and optimize the perfusion strategy and improve the prognosis of pediatric patients undergoing cardiac surgery.

TRIAL REGISTRATION

Chictr.org.cn, ChiCTR2100044296 on 16 March 2021.

Association between Serum Lactate and Morbidity and Mortality in Neonates: A Systematic Review and Meta-Analysis

OBJECTIVE

Lactate is a marker of hypoperfusion in critically ill patients. Whether lactate is useful for identifying and stratifying neonates with a higher risk of adverse outcomes remains unknown. This study aimed to investigate the association between lactate and morbidity and mortality in neonates.

METHODS

A meta-analysis was performed to determine the association between blood lactate levels and outcomes in neonates. Ovid MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov were searched from inception to 1 May 2021. A total of 49 observational studies and 14 data accuracy test studies were included. The risk of bias was assessed using the Newcastle-Ottawa Scale for observational studies and the QUADAS-2 tool for data accuracy test studies. The primary outcome was mortality, while the secondary outcomes included acute kidney injury, necessity for renal replacement therapy, neurological outcomes, respiratory morbidities, hemodynamic instability, and retinopathy of prematurity.

RESULTS

Of the 3184 articles screened, 63 studies fulfilled all eligibility criteria, comprising 46,069 neonates. Higher lactate levels are associated with mortality (standard mean difference, -1.09 [95% CI, -1.46 to -0.73]). Using the estimated sensitivity (0.769) and specificity (0.791) and assuming a prevalence of 15% for adverse outcomes (median of prevalence among studies) in a hypothetical cohort of 10,000 neonates, assessing the lactate level alone would miss 346 (3.46%) cases (false negative) and wrongly diagnose 1776 (17.76%) cases (false positive).

CONCLUSIONS

Higher lactate levels are associated with a greater risk of mortality and morbidities in neonates. However, our results do not support the use of lactate as a screening test to identify adverse outcomes in newborns. Research efforts should focus on analyzing serial lactate measurements, rather than a single measurement.

Defining the optimal historical control group for a phase 1 trial of mesenchymal stromal cell delivery through cardiopulmonary bypass in neonates and infants

OBJECTIVE

The Mesenchymal Stromal Cell Delivery through Cardiopulmonary Bypass in Pediatric Cardiac Surgery study is a prospective, open-label, single-centre, dose-escalation phase 1 trial assessing the safety/feasibility of delivering mesenchymal stromal cells to neonates/infants during cardiac surgery. Outcomes will be compared with historical data from a similar population. We aim to define an optimal control group for use in the Mesenchymal Stromal Cell Delivery through Cardiopulmonary Bypass in Pediatric Cardiac Surgery trial.

METHODS

Consecutive patients who underwent a two-ventricle repair without aortic arch reconstruction within the first 6 months of life between 2015 and 2020 were studied using the same inclusion/exclusion criteria as the Phase 1 Mesenchymal Stromal Cell Delivery through Cardiopulmonary Bypass in Pediatric Cardiac Surgery trial (n = 169). Patients were allocated into one of three diagnostic groups: ventricular septal defect type, Tetralogy of Fallot type, and transposition of the great arteries type. To determine era effect, patients were analysed in two groups: Group A (2015-2017) and B (2018-2020). In addition to biological markers, three post-operative scoring methods (inotropic and vasoactive-inotropic scores and the Pediatric Risk of Mortality-III) were assessed.

RESULTS

All values for three scoring systems were consistent with complexity of cardiac anomalies. Max inotropic and vasoactive-inotropic scores demonstrated significant differences between all diagnosis groups, confirming high sensitivity. Despite no differences in surgical factors between era groups, we observed lower inotropic and vasoactive-inotropic scores in group B, consistent with improved post-operative course in recent years at our centre.

CONCLUSIONS

Our studies confirm max inotropic and vasoactive-inotropic scores as important quantitative measures after neonatal/infant cardiac surgery. Clinical outcomes should be compared within diagnostic groupings. The optimal control group should include only patients from a recent era. This initial study will help to determine the sample size of future efficacy/effectiveness studies.

Use of CO2-Derived Variables in Cardiac Intensive Care Unit: Pathophysiology and Clinical Implications

Shock is a life-threatening condition, and its timely recognition is essential for adequate management. Pediatric patients with congenital heart disease admitted to a cardiac intensive care unit (CICU) after surgical corrections are particularly at risk of low cardiac output syndrome (LCOS) and shock. Blood lactate levels and venous oxygen saturation (ScVO₂) are usually used as shock biomarkers to monitor the efficacy of resuscitation efforts, but they are plagued by some limitations. Carbon dioxide (CO₂)-derived parameters, namely veno-arterial CO₂ difference (ΔCCO₂) and the VCO₂/VO₂ ratio, may represent a potentially valuable addition as sensitive biomarkers to assess tissue perfusion and cellular oxygenation and may represent a valuable addition in shock monitoring. These variables have been mostly studied in the adult population, with a strong association between ΔCCO₂ or VCO₂/VO₂ ratio and mortality. In children, particularly in CICU, few studies looked at these parameters, while they reported promising results on the use of CO₂-derived indices for patients' management after cardiac surgeries. This review focuses on the physiological and pathophysiological determinants of ΔCCO₂ and VCO₂/VO₂ ratio while summarizing the actual state of knowledge on the use of CO₂-derived indices as hemodynamical markers in CICU.

Evaluation of the Performance of Vasoactive Ventilation Renal Score in Predicting the Duration of Mechanical Ventilation and Intensive Care Hospitalization After Pediatric Cardiac Surgery

Various methods have been used to evaluate the predictivity of some markers during the recovery process after cardiac surgery in children. The aim herein was to evaluate the vasoactive ventilation renal (VVR) score in predicting the clinical outcomes of children who underwent congenital cardiac surgery within the early period in the pediatric intensive care unit (PICU). Patients who underwent congenital heart surgery (CHS) between November 2016 and March 2020 were enrolled and evaluated prospectively. The VVR score was calculated as follows: vasoactive inotrope score (VIS) + ventilation index + (change in serum creatinine level based on the baseline value × 10). The relationship between the duration of mechanical ventilation and the length of stay (LOS) in the PICU was evaluated via receiver operating characteristic (ROC) curve analysis and the cut-off values were calculated. At all of the time points identified in the study, the VVR score had a higher area under the ROC curve (AUC) when compared to the VIS and serum lactate levels, and the 48-h VVR score had the highest AUC (AUC 0.851, 95% confidence interval (CI) 0.761-0.942/LOS in the PICU; AUC 0.946, 95% CI 0.885-1.000/duration of mechanical ventilation). The 48-h VVR score for the LOS in the PICU was 6.7 (sensitivity 70%, specificity 92%) and that for the duration of mechanical ventilation was 9.1 (sensitivity 87%, specificity 97%). As a result, in our study, it was found that the VVR score is a new and effective predictor of the duration of mechanical ventilation and LOS in the PICU in postoperative CHS patients.

Vasoactive-ventilation-renal score and outcomes in infants and children after cardiac surgery

Introduction

There is a need to index important clinical characteristics in pediatric cardiac surgery that can be obtained early in the postoperative period and accurately predict postoperative outcomes.

Methodology

A prospective cohort study was conducted in the pediatric cardiac ICU and ward on all children aged <18 years undergoing cardiac surgery for congenital heart disease from September 2018 to October 2020. The vasoactive-ventilation-renal (VVR) score was analyzed to predict outcomes of cardiac surgeries with a comparison of postoperative variables.

Results

A total of 199 children underwent cardiac surgery during the study period. The median (interquartile range) age was 2 (0.8-5) years, and the median weight was 9.3 (6-16) kg. The most common diagnoses were ventricular septal defect (46.2%) and tetralogy of Fallot (37.2%). At the 48th h, area under the curve (AUC) (95% CI) values were higher for the VVR score than those for other clinical scores measured. Similarly, at the 48th h, AUC (95% CI) values were higher for the VVR score than those for the other clinical scores measured for the length of stay and mechanical ventilation.

Discussion

The VVR score at 48 h postoperation was found to best correlate with prolonged pediatric intensive care unit (PICU) stay, length of hospitalization, and ventilation duration, with the greatest AUC-receiver operating characteristic (0.715, 0.723, and 0.843, respectively). The 48-h VVR score correlates well with prolonged ICU, hospital stay, and ventilation.

Evaluation of plasma lactate parameters for predicting mortality of septic patients

Objective

To compare the accuracy of serum lactate parameters, including lactate peak concentration (LACpeak), lactate time area (LACarea), and lactate clearance (LC) for predicting mortality of the septic patients, and to compare with the predictive accuracy of National Early Warning Score (NEWS) and Sequential Organ Failure Assessment (SOFA) scores.

Methods

This study retrospectively screened the septic patients admitted to the ICU in the Medical Information Mart for Intensive Care IV (MIMIC-IV) from 2008 to 2019. The baseline data and outcomes of patients were gathered. The subjects were divided into the non-survival group and the survival group. SOFA, NEWS, LACpeak, and LACarea were recorded. The LC was calculated 6 h after LACpeak. The above parameters were compared by the T-test and Mann-Whitney U test, and odds ratios were calculated adjusting for age and sex. The receiver operating characteristic curves (ROCs) of subjects were plotted according to SOFA, NEWS, LACpeak, and LACarea within 24h, and LC at 6h of ICU admission. The Areas under the ROC curve (AUCs), sensitivity, and specificity were compared with R version 4.1.1.

Results

1,169 septic patients were involved, and 366 (31.3%) patients died within 28 days. Compared to the survival group, the LACpeak of the non-survival group was higher [4.85 (3.2, 7.9) vs. 3.4 (2.6, 5.25) mmol/L, adjusted odds ratio 1.18, P < 0.001], and the LACarea of the non-survivals was higher than the survivals too [18.44 (10.36, 27.63) vs. 13.65 (9.01, 21.73), adjusted odds ratio 1.03, P < 0.001)]. The LC of the survivals at 6 h after LACpeak was significantly higher than that of the non-survivals [0.26 (0.14.0.42) vs. 0.19 (0.10, 0.33), adjusted odds ratio 0.06, P < 0.01]. Within 24h of ICU admission, the AUCs of mortality prediction in descending order were NEWS [0.73 (0.70, 0.76)], SOFA [0.69 (0.66, 0.73)], LACpeak [0.64 (0.61, 0.68)], and LACarea [0.60 (0.56, 0.63)]. There were 204 patients with 6-hour LC after LACpeak the AUCs of LACarea, LACpeak and LC were 0.73(0.65, 0.80), 0.71(0.62,0.78) and 0.65 (0.56, 0.73), respectively.

Conclusions

The predictive accuracy of LC was not superior to LACpeak and LACarea for the mortality of the septic patients and the predictive value of all the above lactate parameters for mortality maybe not better than SOFA and NEWS.

[Hemodynamic monitoring in pediatric anesthesia]

Perioperative mortality and morbidity in childhood essentially depend on the quality of the anesthesia. The Safe Anesthesia for every Tot (SafeTots) initiative takes this into account and has defined normotension, normovolemia and normal heart rate as quality criteria in pediatric anesthesia. Appropriate monitoring of pediatric hemodynamics is necessary to fulfil these criteria. This article provides an overview of currently used methods and techniques for instrumental and non-instrumental cardiovascular monitoring in children. The current study situation, recommendations and guidelines on the application as well as practical aspects of the measurement methods are explained as far as possible. For a better understanding, procedures not routinely used in clinical practice are described in more detail.

Serum Lactate and Mortality during Pediatric Admissions: Is 2 Really the Magic Number?

The primary objective of this study was to determine if serum lactate level at the time of hospital admission can predict mortality in pediatric patients. A systematic review was conducted to identify studies that assessed the utility of serum lactate at the time of admission to predict mortality in pediatric patients. The areas under the curve from the receiver operator curve analyses were utilized to determine the pooled area under the curve. Additionally, standardized mean difference was compared between those who survived to discharge and those who did not. A total of 12 studies with 2,099 patients were included. Out of these, 357 (17%) experienced mortality. The pooled area under the curve for all patients was 0.74 (0.67-0.80, p  < 0.01). The pooled analyses for all admissions were higher in those who experienced mortality (6.5 vs. 3.3 mmol/L) with a standardized mean difference of 2.60 (1.74-3.51, p  < 0.01). The pooled area under the curve for cardiac surgery patients was 0.63 (0.53-0.72, p  < 0.01). The levels for cardiac surgery patients were higher in those who experienced mortality (5.5 vs. 4.1 mmol/L) with a standardized mean difference of 1.80 (0.05-3.56, p  = 0.04). Serum lactate at the time of admission can be valuable in identifying pediatric patients at greater risk for inpatient mortality. This remained the case when only cardiac surgery patients were included.

Hyperlactataemia as a predictor of adverse outcomes post-cardiac surgery in neonates with congenital heart disease

OBJECTIVE

To evaluate the discriminative ability of hyperlactataemia for early morbidity and mortality in neonates with CHD following cardiac surgery.

METHODS

Retrospective, observational study of neonates who underwent cardiac surgery on cardiopulmonary bypass at a tertiary care children's hospital from June 2015 to June 2019. The primary predictor was lactate. The primary composite outcome was defined as ≥1 of the following: cardiac arrest or extracorporeal membrane oxygenation within 72 hours or 30-day mortality post-operatively. The secondary outcome was the presence of major residual lesions, according to the Technical Performance Score.

RESULTS

Of 432 neonates, 28 (6.5%) sustained the composite outcome. On univariate analysis, peak lactate within 48 hours, increase in lactate from ICU admission through 12 hours, and single ventricle physiology were significantly associated with the composite outcome. The peak lactate occurred at a median of 2.9 hours (interquartile range: 1, 35) before the event. Through multi-variable analysis, a multi-variable risk algorithm was created. Predicted probabilities demonstrated an increasing risk based on single ventricle status and delta lactate, ranging from 1.8% (95% CI: 0.9, 3.9) to 52.4% (95% CI: 32.4, 71.7). The model had good discriminative ability for the composite outcome on receiver operating characteristic analysis (area under the curve = 0.79; 95% CI: 0.75, 0.89). Moreover, a peak lactate of 7.3 mmol/l or greater was significantly associated with the presence of a major residual lesion (odds ratios: 5.16, 95% CI: 3.01, 8.87).

CONCLUSIONS

We present a simple, two-variable model, including delta lactate in the immediate post-operative period and single ventricle status, to prognosticate the risk of early morbidity and mortality in neonates undergoing cardiac surgery for potential intervention.

Validation of the Vasoactive-Ventilation-Renal Score for Neonatal Heart Surgery

OBJECTIVES

 We aimed to validate the vasoactive-ventilation-renal (VVR) score and to compare it with other indices as a predictor of outcome in neonates recovering from surgery for critical congenital heart disease. We also sought to determine the optimal time at which the VVR score should be measured.

METHODS

We retrospectively reviewed neonates recovering from cardiac surgery between July 2017 and June 2020. The VVR score was calculated at admission, 24, 48, and 72 hours postoperatively. Max values, defined as the highest of the four scores, were also recorded. The main end result of interest was a composite outcome which included prolonged intensive care unit stay and mortality. Receiver operating characteristic curves were generated, and areas under the curve with 95% confidence intervals were calculated for all time points. Multivariable logistic regression modeling was also performed.

RESULTS

We reviewed 73 neonates and 21 of them showed composite outcomes. The area under the curve value for VVR score as a predictor of composite outcome was greatest at postoperative 72-hour max (AUC= 0.967; 95% confidence interval, (0.927-1). On multivariable regression analysis, the VVR max 72 hours remained a strong independent predictor of prolonged ICU stay and mortality (odds ratio, 1.452; 95% confidence interval, 1.036-2.035).

CONCLUSIONS

We validated the utility of the VVR score in neonatal cardiac surgery for critical congenital heart disease. The VVR follow-up in postoperative 72 hours is superior to other indices and especially the maximum VVR value is a potentially powerful clinical tool to predict ICU stay and mortality.

Predictors of Increased Lactate in Neonatal Cardiac Surgery: The Impact of Cardiopulmonary Bypass

OBJECTIVE

Hyperlactatemia develops intraoperatively during cardiac surgery and is associated with postoperative mortality. This study aimed to determine the factors that lead to an increase in lactate during cardiopulmonary bypass (CPB) in neonates undergoing cardiac surgery.

DESIGN

Retrospective study from July 2015 to December 2018.

SETTING

Academic tertiary children's hospital.

PARTICIPANTS

The study comprised 376 neonates.

INTERVENTIONS

No interventions were performed.

MEASUREMENTS AND MAIN RESULTS

Lactate measurements at prebypass, upon initiation of CPB and before coming off CPB, last in the operating room, and first in the cardiac intensive care unit were collected. The changes in lactate levels were compared using the nonparametric Wilcoxon signed rank test for paired data. Univariate and multivariate median regression models of the change during CPB were determined. The cohort characteristics were male (60%), median age 5 days (range 1-30), and weight 3.2 kg (range 1.5-4.7). Most patients had a STAT score of 4 (45%) or 5 (23%). Significant increases in lactate were observed from pre-CPB to start of CPB (p < 0.001) and from start to end of CPB (p < 0.001). In the multivariate regression analysis, duration of circulatory arrest (coefficient = 1.216; 95% confidence interval [CI] 0.754-1.678; p < 0.001), duration of mean arterial pressure < 25 mmHg (coefficient = 0.423; 95% CI 0.196-to- 0.651; p < 0.001), and duration of mean arterial pressure between 35 and 39 mmHg (coefficient = -0.246; 95% CI -0.397 to -0.095; p = 0.001) were identified as significant independent predictors of the lactate change per 30- minutes duration.

CONCLUSION

These results emphasized the importance of blood pressure management during CPB and the importance of the duration of circulatory arrest.

Met-Hemoglobin Is a Biomarker for Poor Oxygen Delivery in Infants Following Surgical Palliation

BACKGROUND

Infants with cyanotic congenital heart disease demonstrate wide fluctuations in hemoglobin (Hb), oxygen saturation, and cardiac output following palliation. Methemoglobin (Met-Hb), the product of Hb oxidation, may represent a compensatory mechanism during hypoxia and may be utilized as a biomarker.

METHODS

Arterial and venous Met-Hb levels were obtained from infants requiring palliation. The primary outcome was to describe the relationship between Met-Hb and other indices of tissue oxygenation (venous saturation, estimated arteriovenous oxygen difference [Est AV-Diff], and lactate). Secondary outcomes were to determine the impact of elevated Met-Hb levels ≥1.0% and the effect of red blood cell (RBC) transfusion on Met-Hb levels.

RESULTS

Fifty infants and 465 Met-Hb values were studied. Venous Met-Hb levels were significantly higher than arterial levels (venous: 0.84% ± 0.36% vs arterial: 0.45% ± 0.18%; P < .001). Venous Met-Hb demonstrated a significant inverse relationship with venous oxygen saturation (R = -0.6; P < .001) and Hb (R = -0.3, P < .001) and a direct relationship with the Est AV-Diff (R = 0.3, P < .001). A total of 129 (29.6%) venous Met-Hb values were elevated (≥1.0%) and were associated with significantly lower Hb and venous saturation levels and higher Est AV-Diff and lactate levels. Methemoglobin levels decreased significantly following 65 RBC transfusions (0.94 ± 0.40 vs 0.77 ± 0.34; P < .001). Linear mixed models demonstrated that higher venous Met-Hb levels were associated with lower measures of tissue oxygenation and not related to any preoperative clinical differences.

CONCLUSION

Methemoglobin may be a clinically useful marker of tissue oxygenation in infants following surgical palliation.

Multicenter Validation of the Vasoactive-Ventilation-Renal Score as a Predictor of Prolonged Mechanical Ventilation After Neonatal Cardiac Surgery

OBJECTIVES

We sought to validate the Vasoactive-Ventilation-Renal score, a novel disease severity index, as a predictor of outcome in a multicenter cohort of neonates who underwent cardiac surgery.

DESIGN

Retrospective chart review.

SETTING

Seven tertiary-care referral centers.

PATIENTS

Neonates defined as age less than or equal to 30 days at the time of cardiac surgery.

INTERVENTIONS

Ventilation index, Vasoactive-Inotrope Score, serum lactate, and Vasoactive-Ventilation-Renal score were recorded for three postoperative time points: ICU admission, 6 hours, and 12 hours. Peak values, defined as the highest of the three measurements, were also noted. Vasoactive-Ventilation-Renal was calculated as follows: ventilation index + Vasoactive-Inotrope Score + Δ creatinine (change in creatinine from baseline × 10). Primary outcome was prolonged duration of mechanical ventilation, defined as greater than 96 hours. Receiver operative characteristic curves were generated, and abilities of variables to correctly classify prolonged duration of mechanical ventilation were compared using area under the curve values. Multivariable logistic regression modeling was also performed.

MEASUREMENTS AND MAIN RESULTS

We reviewed 275 neonates. Median age at surgery was 7 days (25th-75th percentile, 5-12 d), 86 (31%) had single ventricle anatomy, and 183 (67%) were classified as Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Category 4 or 5. Prolonged duration of mechanical ventilation occurred in 89 patients (32%). At each postoperative time point, the area under the curve for prolonged duration of mechanical ventilation was significantly greater for the Vasoactive-Ventilation-Renal score as compared to the ventilation index, Vasoactive-Inotrope Score, and serum lactate, with an area under the curve for peak Vasoactive-Ventilation-Renal score of 0.82 (95% CI, 0.77-0.88). On multivariable analysis, peak Vasoactive-Ventilation-Renal score was independently associated with prolonged duration of mechanical ventilation, odds ratio (per 1 unit increase): 1.08 (95% CI, 1.04-1.12).

CONCLUSIONS

In this multicenter cohort of neonates who underwent cardiac surgery, the Vasoactive-Ventilation-Renal score was a reliable predictor of postoperative outcome and outperformed more traditional measures of disease complexity and severity.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

Blood Versus Crystalloid Cardioplegia in Pediatric Cardiac Surgery: A Systematic Review and Meta-analysis

The benefit of blood cardioplegia (BCP) compared to crystalloid cardioplegia (CCP) is still debatable. Our aim was to systematically review and synthesize all available evidence on the use of BCP and CCP to assess if any modality provides superior outcomes in pediatric cardiac surgery. A systematic literature search of the PubMed and Cochrane databases was performed with respect to the PRISMA statement (end-of-search date: January 30th, 2017). We extracted data on study design, demographics, cardioplegia regimens, and perioperative outcomes as well as relevant biochemical markers, namely cardiac troponin I (cTnI), lactate, and ATP levels at baseline, after reperfusion and postoperatively at 1, 4, 12, and 24 h as applicable. Data were appropriately pooled using random and mixed effects models. Our systematic review includes 56 studies reporting on a total of 7711 pediatric patients. A meta-analysis of the 10 eligible studies directly comparing BCP (n = 416) to CCP (n = 281) was also performed. There was no significant difference between the two groups with regard to cTnI and Lac at any measured time point, ATP levels after reperfusion, length of intensive care unit stay (WMD: -0.08, 95% CI -1.52 to 1.36), length of hospital stay (WMD: 0.13, 95% CI -0.85 to 1.12), and 30-day mortality (OR 1.11, 95% CI 0.43-2.88). Only cTnI levels at 4 h postoperatively were significantly lower with BCP (WMD: -1.62, 95% CI -2.07 to -1.18). Based on the available data, neither cardioplegia modality seems to be superior in terms of clinical outcomes, ischemia severity, and overall functional recovery.

Determination of tissue hypoxia by physicochemical approach in premature anemia

BACKGROUND

Anemia is a common problem in premature infants and its most rapid and effective therapy is erythrocyte transfusion. However, owing to inherent risks of transfusion in this population, transfusions should be administered only when adequate oxygen delivery to tissues is impaired. The aim of this study was to determine tissue acid levels using Stewart method in an attempt to evaluate the tissue oxygenation level and thereby the accuracy of transfusion timing.

METHODS

This study included 47 infants delivered at gestational age below 34 weeks who required erythrocyte transfusion for premature anemia. Strong ion gap (SIG), unmeasurable anions (UMA), tissue acid levels (TA), and Cl/Na ratios were calculated before and after transfusion.

RESULTS

The mean birth weight and gestational age of the study population were 1210 ± 365 g and 29.2 ± 2.7 weeks, respectively. Tissue acid levels were increased (TA ≥ 4) and tissue hypoxia developed in 10 (16.6%) of 60 erythrocyte transfusions administered according to the restrictive transfusion approach. The patients were divided into two groups according to tissue acid levels as low (<4) and high (≥4) tissue acid groups. The group with tissue hypoxia (TA ≥ 4) had significantly higher UMA levels but a significantly lower Cl/Na ratio; and UMA levels decreased and Cl/Na ratio increased after transfusion in this group. Tissue hypoxia secondary to anemia was shown to be improved by erythrocyte transfusion.

CONCLUSION

The results of the present study suggest that the determination of the level of tissue hypoxia by the Stewart approach may be an alternative to restrictive transfusion guidelines for timing of transfusion in premature anemia. It also showed that a low Cl/Na ratio can be used as a simple marker of tissue hypoxia.

Persistent Hyperlactatemia as the Predictor of Poor Outcome in Critically Ill Children: A Single-Center, Prospective, Observational Cohort Study

Objective  To study incidence of hyperlactatemia and its correlation with outcome in critically ill children. Design  Single-center, prospective cohort study. Setting  Eight-bedded PICU. Method  Serial serum lactate levels were measured in 140 critically ill children at 0, 12, 24, and 48 hours. Results  A total of 45% children had hyperlactatemia. Lactate levels were significantly ( p  = 0.000) higher in nonsurvivors at all intervals. Lactate levels decreased significantly ( p  = 0.000) in survivors while increased in nonsurvivors. Normalized lactate load was found to be an independent predictor of mortality ( p  = 0.023). Conclusion  Persistent hyperlactatemia serves as a possible predictor of poor outcome in critically ill children.

Basic arterial blood gas biomarkers as a predictor of mortality in tetralogy of Fallot patients

Background:

Serum lactate and base deficit have been shown to be a predictor of morbidity and mortality in critically ill patients. Poor preoperative oxygenation appears to be one of the significant factors that affects early mortality in tetralogy of Fallot (TOF). There is little published literature evaluating the utility of serum lactate, base excess (BE), and oxygen partial pressure (PO₂) as simple, widely available, prognostic markers in patients undergoing surgical repair of TOF.

Materials and Methods:

This prospective, observational study was conducted in 150 TOF patients, undergoing elective intracardiac repair. PO₂, BE, and lactate levels at three different time intervals were recorded. Arterial blood samples were collected after induction (T1), after cardiopulmonary bypass (T2), and 48 h (T3) after surgery in the Intensive Care Unit (ICU). To observe the changes in PO₂, BE, and lactate levels over a period of time, repeated measures analysis was performed with Bonferroni method. The receiver operating characteristics (ROC) analysis was used to find area under curve (AUC) and cutoff values of various biomarkers for predicting mortality in ICU.

Results:

The patients who could not survive showed significant elevated lactate levels at baseline (T1) and postoperatively (T2) as compared to patients who survived after surgery (P < 0.001). However, in nonsurvivors, the BE value decreased significantly in the postoperative period in comparison to survivors (−2.8 ± 4.27 vs. 5.04 ± 2.06) (P < 0.001). In nonsurvivors, there was a significant fall of PO₂ to a mean value of 59.86 ± 15.09 in ICU (T3), whereas those who survived had a PO₂ of 125.86 ± 95.09 (P < 0.001). The ROC curve analysis showed that lactate levels (T3) have highest mortality predictive value (AUC: 96.9%) as compared to BE (AUC: 94.5%) and PO₂ (AUC: 81.1%).

Conclusion:

Serum lactate and BE may be used as prognostic markers to predict mortality in patients undergoing TOF repair. The routine analysis of these simple, fast, widely available, and cost-effective biomarkers should be encouraged to predict prognosis of TOF patients.

The role of blood lactate clearance as a predictor of mortality in children undergoing surgery for tetralogy of Fallot

Background:

The identification of biomarkers for predicting morbidity and mortality, particularly in pediatric population undergoing cardiac surgery will contribute toward improving the patient outcome. There is an increasing body of literature establishing the clinical utility of hyperlactatemia and lactate clearance as prognostic indicator in adult cardiac surgical patients. However, the relationship between lactate clearance and mortality risk in the pediatric population remains to be established.

Objective:

To assess the role of lactate clearance in determining the outcome in children undergoing corrective surgery for tetralogy of Fallot (TOF).

Methods and Study Design:

A prospective, observational study.

Setting:

A tertiary care center.

Study Population:

Two hundred children undergoing elective surgery for TOF.

Study Method:

Blood lactate levels were obtained as baseline before operation (T0), postoperatively at admission to the cardiac intensive care unit after surgery (T1), and then at every 6 h for the first 24 h of Intensive Care Unit (ICU) stay (T6, T12, T18, and T24, respectively). The lactate clearance in the study is defined by the equation ([lactate initial – lactate delayed]/lactate initial) ×100%. Lactate clearance was determined at T1–T6, T1–T12, T1–T18, and T1–T24 time interval, respectively. The primary outcome measured was mortality. Secondary outcomes measured were the duration of mechanical ventilation, duration of inotropic requirement, and duration of ICU stay.

Results:

Eleven out of the two hundred patients enrolled in the study died. Nonsurvivors had higher postoperative lactate concentration (P < 0.05) and low-blood lactate clearance rate during 24 h (P < 0.05) in comparison to the survivors. Lactate clearance was significantly higher in survivors than in nonsurvivors for the T1–T6 period (19.55 ± 14.28 vs. 5.24 ± 27.79%, P = 0.009) and remained significantly higher for each studied interval in first 24 h. Multivariate logistic regression analysis of statistically significant univariate variables showed early lactate clearance to have a significant relationship with mortality. Patients with a lactate clearance >10%, relative to patients with a lactate clearance <10%, in the early postoperative period, had improved outcome and lower mortality.

Conclusion:

Lactate clearance in the early postoperative period (6 h) is associated with decreased mortality rate. Patients with higher lactate clearance (>10%) after 6 h have improved outcome compared with those with lower lactate clearance.

Clinical Pharmacology Studies in Critically Ill Children

Developmental and physiological changes in children contribute to variation in drug disposition with age. Additionally, critically ill children suffer from various life-threatening conditions that can lead to pathophysiological alterations that further affect pharmacokinetics (PK). Some factors that can alter PK in this patient population include variability in tissue distribution caused by protein binding changes and fluid shifts, altered drug elimination due to organ dysfunction, and use of medical interventions that can affect drug disposition (e.g., extracorporeal membrane oxygenation and continuous renal replacement therapy). Performing clinical studies in critically ill children is challenging because there is large inter-subject variability in the severity and time course of organ dysfunction; some critical illnesses are rare, which can affect subject enrollment; and critically ill children usually have multiple organ failure, necessitating careful selection of a study design. As a result, drug dosing in critically ill children is often based on extrapolations from adults or non-critically ill children. Dedicated clinical studies in critically ill children are urgently needed to identify optimal dosing of drugs in this vulnerable population. This review will summarize the effect of critical illness on pediatric PK, the challenges associated with performing studies in this vulnerable subpopulation, and the clinical PK studies performed to date for commonly used drugs.

Biomarkers in Pediatric Cardiac Critical Care

OBJECTIVES

In this review, we discuss the physiology, pathophysiology, and clinical role of troponin, lactate, and B-type natriuretic peptide in the assessment and management of children with critical cardiac disease.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSION

Lactate, troponin, and B-type natriuretic peptide continue to be valuable biomarkers in the assessment and management of critically ill children with cardiac disease. However, the use of these markers as a single measurement is handicapped by the wide variety of clinical scenarios in which they may be increased. The overall trend may be more useful than any single level with a persistent or rising value of more importance than an elevated initial value.

The Effects of On-Pump and Off-Pump Coronary Artery Bypass Surgery on Metabolic Profiles in the Early Postoperative Period

OBJECTIVE

Hyperlactatemia and base deficit (BD) are markers of adverse outcome after cardiac surgery, and their derangement can be influenced by the use of extracorporeal circulation. The authors hypothesized a better postoperative metabolic profile in off-pump coronary artery bypass grafting (OPCABG) compared with "on-pump" coronary artery bypass grafting (ONCABG).

DESIGN

This was a retrospective study, with consecutive data collected for 1 year from electronic medical records.

SETTING

Cardiothoracic intensive care unit at a tertiary university hospital.

PARTICIPANTS

The study comprised 339 patients who underwent elective coronary artery bypass grafting (ONCABG [n = 215], OPCABG [n = 124]).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The metabolic (arterial lactatemia, pH, and BD) and hemodynamic (inotropic/vasopressor support) parameters of OPCABG and ONCABG patients were compared at 7 predefined time points (intensive care admission and the 1st, 3rd, 6th, 12th, 18th, and 24th postoperative hours). For each output of interest, mixed-effects linear regression models were used (with time as random-effect to allow for clustering of repeated measures) and adjusted for a predetermined set of covariates. Arterial lactatemia and pH were comparable at all time points; BD was worse in the ONCABG group overall (p = 0.01) and at most time points (except at the 1st and 24th postoperative hours). For the whole period, inotropic support was more common in ONCABG patients (p<0.05), whereas vasopressor use was more frequent in the OPCABG group (p< 0.05).

CONCLUSIONS

Improved postoperative BD values were demonstrated in the OPCABG group, although pH and lactatemia were similar between groups. Inotropic support was less common in the OPCABG group at the expense of more frequent vasopressor support.

Prospective Validation of a Novel Vasoactive-Ventilation-Renal Score as a Predictor of Outcomes After Pediatric Cardiac Surgery

BACKGROUND

We sought to further validate the novel vasoactive-ventilation-renal (VVR) score in a prospective study of a heterogeneous cohort of children undergoing cardiac surgery that includes patients with single-ventricle anatomy and residual mixing lesions.

METHODS

We prospectively performed an observational study of all children less than 18 years of age who underwent surgery for congenital heart disease at our center from November 2013 to June 2014. We calculated VVR score as follows: vasoactive-inotrope score + ventilation index + (change in serum creatinine from baseline × 10). Admission, peak, and 48-hour measurements were recorded. Outcomes of interest were prolonged duration of mechanical ventilation and intensive care unit and hospital stays, represented by the upper 25% for all patients. Areas under the receiver-operating characteristic curves (AUC) were determined for all study timepoints and outcome variables.

RESULTS

Ninety-two patients were analyzed; their median age was 0.65 (range, 3 days to 17.9 years), and 17 (18%) had single-ventricle anatomy. The VVR measurements outperformed vasoactive-inotrope scores in isolation at all timepoints, with higher AUC values for all outcomes. Of the three timepoints assessed, the 48-hour VVR score most consistently predicted poor outcome, especially with regard to prolonged duration of mechanical ventilation (AUC 0.980) and prolonged intensive care unit stay (AUC 0.919).

CONCLUSIONS

In a heterogeneous population of children undergoing cardiac surgery, the 48-hour VVR score was a very strong predictor of outcomes, and outperformed the more traditional vasoactive-inotrope score. The VVR score, therefore, represents a novel and potentially powerful means of predicting clinical outcomes relatively early in the hospital course of these patients.

Masquerading acidosis after cardiopulmonary bypass: a case of propionic acidemia and congenital heart disease

We report the case of a child with both propionic acidemia and cyanotic congenital heart disease. The presence of an underlying inborn error of metabolism confounded the management of this patient in the postoperative period, resulting in therapeutic misdirection until the true etiology of hyperlactemia was recognized.

An unusual cause of persisting hyperlactatemia in a neonate undergoing open heart surgery

Being a reflection of the degree of global tissue anoxia, serum lactate levels therefore can be used as a marker of organ damage and eventual outcome. A statistically significant association was observed between serum lactate levels and subsequent mortality and morbidity in critically ill adults, children, and neonates. In cardiac critical care, hyperlactatemia is usually multifactorial in origin, resulting from a combination of etiologies. Many centers are using serial lactate levels in conjugation with other parameters of cellular oxygen delivery, consumption, or extraction to monitor prognosis after pediatric cardiac surgery. A single initial lactate level has a lesser predictive value for morbidity and mortality after pediatric cardiac surgery than its failure to fall within 48 hours of surgery. In case of persistently high lactate levels with no other evidence of cellular hypoperfusion, other possibilities must be considered. There has been an established association of lactic acidosis with thiamine deficiency, but this has not yet been reported in newborns undergoing congenital cardiac surgery. We present one such rare case.

Normalized lactate load is associated with development of acute kidney injury in patients who underwent cardiopulmonary bypass surgery

BACKGROUND AND OBJECTIVE

Cardiac surgery associated acute kidney injury is a major postoperative complication and has long been associated with adverse outcomes. However, the association of lactate and AKI has not been well established. The study aimed to explore the association of normalized lactate load with AKI in patients undergoing cardiac surgery.

METHODS

This was a prospective observational cohort study conducted in a 47-bed ICU of a tertiary academic teaching hospital from July 2012 to January 2014. All patients undergoing cardiopulmonary bypass surgery were included. Normalized lactate load (L) was calculated by the equation: [Formula: see text], where ti was time point for lactate measurement and vi was the value of lactate. L was transformed by natural log (Lln) to improve its normality. Logistic regression model was fitted by using stepwise method. Scale of Lln was examined by using fractional polynomial approach and potential interaction terms were explored.

RESULTS

A total of 117 patients were included during study period, including 17 AKI patients and 100 non-AKI patients. In univariate analysis Lln was significantly higher in AKI as compared with non-AKI group (1.43±0.38 vs 1.01±0.45, p = 0.0005). After stepwise selection of covariates, the main effect logistic model contained variables of Lln (odds ratio: 11.1, 95% CI: 1.22-101.6), gender, age, baseline serum creatinine and fluid balance on day 0. Although the two-term fractional polynomial model was the best-fitted model, it was not significantly different from the linear model (Deviance difference = 6.09, p = 0.107). There was no significant interaction term between Lln and other variables in the main effect model.

CONCLUSIONS

Our study demonstrates that Lln is independently associated with postoperative AKI in patients undergoing CPB. There is no significant interaction with early postoperative fluid balance.

Blood versus crystalloid cardioplegia for pediatric cardiac surgery: a meta-analysis

OBJECTIVE

Blood and crystalloid cardioplegia are the main myocardial protective solutions used in pediatric cardiac surgery. However, the effectiveness of these two solutions on myocardial metabolism, reperfusion injury and clinical outcomes in pediatric patients is still under debate. The purpose of this meta-analysis was to compare the efficacy of these two cardioplegia solutions in pediatric cardiac surgery.

METHODS

Keyword searches were performed on PUBMED, EMBASE and The Cochrane Library for randomized, controlled, clinical studies which were primarily comparing blood and crystalloid cardioplegia in pediatric cardiac surgery and provided data of postoperative cardiac troponin I (cTnI), lactate, mechanical ventilation time, length of intensive care unit (ICU) stay and inotropic support. Databases were searched from 1966 to June 2013 and were restricted to peer-reviewed English language publications of human subjects. We summarized the combined results of the data as mean difference (MD, when outcome measurements were made on the same scale) or standard mean difference (SMD, when the studies assess the same outcome with different scales), with 95% confidence intervals.

RESULTS

Five studies were identified, with a total of 323 patients. Lactate level after cardiopulmonary bypass (CPB) was significantly lower after blood cardioplegia compared with crystalloid cardioplegia (SMD 1.09, 95%CI 0.12 to 2.06, p=0.03); cTnI release postoperatively at 4-6 h (MD 0.92 ng/ml, 95%CI -0.13 to 1.97, p=0.09), 12 h (MD 0.2 ng/ml, 95% CI -0.43 to 0.84, p=0.53) and 24 h (MD 0.98 ng/ml, 95%CI -0.26 to 2.22, p=0.12) was not significantly different between the groups; ventilation duration (MD 5.15 hours, 95%CI -7.51 to 17.81, p=0.42) and length of ICU stay (SMD -0.3, 95%CI -0.80 to 0.21, p=0.25) were not significantly different between the groups either.

CONCLUSION

Myocardial metabolism was better in the blood cardioplegia group compared with the crystalloid cardioplegia group. However, there was no evidence of improvement in myocardial damage or clinical outcome for either cardioplegia solution.

Introducing intravascular microdialysis for continuous lactate monitoring in patients undergoing cardiac surgery: a prospective observational study

Introduction

Lactate is a marker of hypoperfusion and may be used for risk assessment in critically ill patients. Although evidence suggests that repeated lactate measurements are of clinical interest, how and when lactate should be analyzed is controversial. Intravascular microdialysis provides a novel method for the continuous monitoring of lactate, which may be clinically beneficial in critically ill patients.

Methods

Circulating lactate levels were continuously monitored in 80 patients undergoing cardiac surgery using either a separate single-lumen microdialysis catheter or a triple-lumen central venous catheter with an integrated microdialysis function. The catheter was placed with the tip positioned in the superior vena cava. Arterial blood gas samples were taken every hour to obtain reference values, and the lactate levels were analyzed in a blood gas analyzer.

Results

A total of 1,601 paired microdialysis–arterial blood gas lactate samples were obtained. Bland-Altman analysis showed a bias (mean difference) ± limits of agreement (±1.96 SD) of 0.02 ± 0.42 mmol/L. The regression coefficient was 0.98 (P = 0.0001).

Conclusions

Central venous microdialysis is an accurate and reliable method for continuous blood lactate monitoring in patients undergoing cardiac surgery. The system may be useful for early lactate-guided therapy in critically ill patients.

Effectiveness of predicting in-hospital mortality in critically ill children by assessing blood lactate levels at admission

Background

Hyperlactatemia upon admission is a documented risk factor for mortality in critically ill adult patients. However, the predictive significance of a single lactate measurement at admission for mortality in the general population of critically ill children remains uncertain. This study evaluated the predictive value of blood lactate levels at admission and determined the cut-off values for predicting in-hospital mortality in the critically ill pediatric population.

Methods

We enrolled 1109 critically ill children who were admitted to a pediatric intensive care unit between July 2008 and December 2010. Arterial blood samples were collected in the first 2 hours after admission, and the lactate levels were determined. The Pediatric Risk of Mortality III (PRISM III) scores were calculated during the first 24 hours after admission.

Results

Of the 1109 children admitted, 115 (10.4%) died in the hospital. The median (interquartile range) blood lactate level in critically ill children was 3.2 mmol/l (2.2-4.8). Among the children, 859 (77.5%) had a lactate concentration >2.0 mmol/l. The blood lactate level upon admission was significantly associated with mortality (odds ratio [OR] = 1.38; 95% confidence interval [CI], 1.30-1.46; p <0.001), even after adjustment for age, gender, and illness severity assessed by PRISM III (OR = 1.27; p <0.001). Multivariate regression analysis showed that a high blood lactate level (OR = 1.17; 95% CI, 1.07-1.29; p = 0.001), a high PRISM III score (OR = 1.15; 95% CI, 1.11-1.20; p <0.001), and a low serum albumin (OR =0.92; 95% CI, 0.88-0.96; p <0.001) were independent risk factors for mortality in critically ill children. Blood lactate achieved an area under-the-receiver-operating-characteristic curve (AUC) of 0.79 (p <0.001) for predicting mortality that was similar to that of PRISM III (AUC = 0.82; p <0.001). The p-value for a comparison of both AUCs was 0.318. Blood lactate displayed a sensitivity of 61% and a specificity of 86% in predicting mortality at the optimal cut-off value of 5.55 mmol/l, and the positive and negative likelihood ratios were 4.5 and 0.45, respectively.

Conclusions

A high blood lactate level at admission is independently associated with and predictive of in-hospital mortality in the general population of critically ill children.

Hemodynamic monitoring in the cardiac intensive care unit

Hemodynamic monitoring is central to the management of critically ill patients in the cardiac intensive care unit (CICU). The goals of hemodynamic monitoring are to anticipate threats and complications before they arise, to gauge the effectiveness of interventions, and to avoid progression to a decompensated shock state. Although there are numerous modalities of hemodynamic monitoring in the CICU, discordance exists between assessments based on physical exam and standard hemodynamic parameters and those based on measurements of cardiac output. This article will review both the standard and advanced hemodynamic monitoring strategies employed in the CICU.

Biomarkers and clinical tools in critically ill children: are we heading toward tailored drug therapy?

In pediatric critical care, validated biomarkers are essential for guiding drug therapy. The aim of this article is to present examples of current biomarker developments in its full breadth, including biochemical substances, physiological measurements and clinical scoring tools, with a focus on the field of circulatory, renal and neurophysiologic failure. Within each field we consecutively discuss the rationale for the selected biomarkers, studies in critically ill children, biomarker validation stage and biomarker use or potential use in drug studies and clinical drug dosing. This article demonstrates that there is paucity of properly validated biomarkers. Nevertheless, recent developments in, for instance, the field of sepsis, point us toward a future wherein, for critically ill children, drug therapy may be personalized using proteomic profiling instead of a small number of biomarkers, in order to establish a personal and dynamic disease profile.

The impact of intraoperative vasopressin infusion in complex neonatal cardiac surgery

OBJECTIVES

Although recent advances have led to a better understanding of the beneficial effects of vasopressin on haemodynamics in paediatric cardiac surgery, not much information is available on the adverse effects. The objective of this study was to assess the impact of intraoperative vasopressin infusion on postoperative liver, renal and haemostatic function and lactate levels in neonates undergoing cardiac surgery.

METHODS

We reviewed data from 34 consecutive neonates who had undergone complex cardiac surgery. The cohort was divided into two groups according to the use of vasopressin. Seventeen patients received vasopressin [vasopressin (+) group], and 17 patients did not [vasopressin (-) group].

RESULTS

No differences between the groups in terms of age, weight, cardiopulmonary bypass time, Risk Adjustment for Congenital Heart Surgery-1 score or the comprehensive Aristotle score were seen. No differences in the systolic or diastolic arterial blood pressures, heart rate or inotropic score upon admission to the intensive care unit were observed between the groups. No adverse effects on the aminotransferase levels were seen. The vasopressin (+) group had higher urea and creatinine levels. All the patients except one received peritoneal dialysis on the day of surgery. Thirteen patients in the vasopressin (+) group and 7 patients in the vasopressin (-) group continued to require peritoneal dialysis on postoperative day 5 (POD 5) (P = 0.04). The platelet count had decreased to a significantly lower level in the vasopressin (+) group on POD 5 [97 x 10(3)/mm(3) (range: 40-132 x 10(3)/mm(3))]. A tendency toward a high lactate concentration was seen in the vasopressin (+) group. In comparison with the vasopressin (-) group, the number of patients whose lactate level remained above 2.0 mmol/l was higher in the vasopressin (+) group on PODs 2 and 3 (17 patients vs 8 patients, P < 0.01 and 15 patients vs 7 patients, P = 0.01, respectively).

CONCLUSIONS

These findings suggest that the intraoperative use of vasopressin extends the period of peritoneal dialysis, reduces platelet counts and delays the recovery of the lactate concentration. Intraoperative vasopressin infusion should not be used routinely, but only in catecholamine-refractory shock.

The interpretation of perioperative lactate abnormalities in patients undergoing cardiac surgery

Hyperlactataemia and lactic acidosis are commonly encountered during and after cardiac surgery. Perioperative lactate production increases in the myocardium, skeletal muscle, lungs and in the splanchnic circulation during cardiopulmonary bypass. Hyperlactataemia has a bimodal distribution in the perioperative period. An early increase in lactate levels, arising intraoperatively or soon after intensive care unit admission, is a familiar and concerning finding for most clinicians. It is highly suggestive of tissue ischaemia and is associated with a prolonged intensive care unit stay, a prolonged requirement for respiratory and cardiovascular support and increased postoperative mortality. Its presence should prompt a thorough search for potential causes of tissue hypoxia. In contrast, late-onset hyperlactataemia, a less well recognised complication, occurs 4 to 24 hours after completion of surgery and is typically associated with preserved cardiac output and oxygen delivery. Risk factors for late-onset hyperlactataemia include hyperglycaemia, long cardiopulmonary bypass time and elevated endogenous catecholamines. Although patients with this complication may have a longer duration of ventilation and intensive care unit length of stay than those with normolactataemia, an association with increased mortality has not been demonstrated. The discovery of late-onset hyperlactataemia should not delay the postoperative progress of an otherwise stable patient following cardiac surgery.

Intraoperative lactate levels and postoperative complications of pediatric cardiac surgery

OBJECTIVES

Correlate arterial lactate levels during the intraoperative period of children undergoing cardiac surgery and the occurrence of complications in the postoperative period.

AIM

Arterial lactate levels can indicate hypoperfusion states, serving as prognostic markers of morbidity and mortality in this population.

BACKGROUND

Anesthesia for cardiac pediatric surgery is frequently performed on patients with serious abnormal physiological conditions. During the intraoperative period, there are significant variations of blood volume, body temperature, plasma composition, and tissue blood flow, as well as the activation of inflammation, with important pathophysiological consequences.

METHODS/MATERIALS

Chart data relating to the procedures and perioperative conditions of the patients were collected on a standardized form. Comparisons of arterial lactate values at the end of the intraoperative period of the patients that presented, or not, with postoperative complications and frequencies related to perioperative conditions were established by odds ratio and nonparametric univariate analysis.

RESULTS

After surgeries without cardiopulmonary bypass (CPB), higher levels of arterial lactate upon ICU admission were observed in patients who had renal complications (2.96 vs 1.31 mm) and those who died (2.93 vs 1.40 mm). For surgeries with CPB, the same association was observed for cardiovascular (2.90 mm × 2.06 mm), renal (3.34 vs 2.33 mm), respiratory (2.98 vs 2.12 mm) and hematological complications (2.99 vs 1.95 mm), and death (3.38 vs 2.40 mm).

CONCLUSION

Elevated intraoperative arterial lactate levels are associated with a higher morbidity and mortality in low- and medium-risk procedures, with or without CPB, in pediatric cardiac surgery.

Prognostic Value of Perioperative Near-Infrared Spectroscopy During Neonatal and Infant Congenital Heart Surgery for Adverse In-Hospital Clinical Events

Background: Perioperative monitoring with multisite near-infrared spectroscopy (NIRS) for congenital cardiac surgery with cardiopulmonary bypass may aid in predicting adverse clinical outcomes. Methods: Forty-one consecutive neonates and infants undergoing bypass were monitored with right + left cerebral and renal NIRS. Near-infrared spectroscopy and lactate were measured at 20 time points, from baseline 1 day preoperatively, during bypass and modified ultrafiltration (MUF; 10 minutes), until 24 hours postoperatively. Adverse events were extracorporeal membrane oxygenation (ECMO)/death, prolonged intensive care unit (ICU) or length of hospital stay. Results: Perioperative mean renal NIRS remained higher than baseline (n = 41) as did cerebral NIRS in all undergoing biventricular repair. During bypass (n = 41), mean right and left cerebral NIRS were equal. During MUF, cerebral and renal NIRS values increased ( P < .001). Cerebral NIRS and lactate inversely correlated during the first six postoperative hours. Extracorporeal membrane oxygenation /death occurred in four patients, correlating with cerebral and renal NIRS below 45% ( P = .030) and 40% ( P = .019) at anytime, respectively, and with mean lactate levels >9.3 mmol/L in the first postoperative 24 hours ( P < .001). Among survivors, renal NIRS below 30% at any time predicted a longer ICU stay. Conclusions: At bypass conclusion, 10 minutes of MUF does not adversely affect cerebral or renal NIRS. Left and right cerebral NIRS are equal, so that biparietal cerebral NIRS monitoring is probably not warranted. Perioperative cerebral and renal NIRS readings, respectively, below 45% and 40% correlate with ECMO/death and renal NIRS below 30% with prolonged ICU stay. Cerebral NIRS and lactate levels showed a strong inverse correlation during the first six postoperative hours.

Lactate levels predict mortality and need for peritoneal dialysis in children undergoing congenital heart surgery

BACKGROUND

The purpose of this study was to investigate whether an initial post-operative lactate level is a predictor of mortality, need for peritoneal dialysis (PD), duration of intubation or length of stay (LOS) in the intensive care unit (ICU) in children undergoing cardiac surgery.

METHOD

A retrospective, observational follow-up study was conducted in 206 children undergoing cardiac surgery from 2006 to 2007. Multivariate logistics regression analyses were performed to determine whether the lactate level was an independent risk factor. The lactate concentration at arrival in the ICU, outcome and risk factors (patient demographics, surgical complexity, duration of cardiopulmonary bypass and inotropic score) were obtained from the electronic patient data management program and medical records.

RESULT

The median (interquartile range) lactate level was 1.9 mmol/l (1.3-2.7) in children immediately after cardiac surgery and a mortality of 3.9%. Eight percent of the children had a lactate level higher than 4.5 mmol/l. An increased lactate level ≥4.5 mmol/l resulted in an odds ratio (95% confidence intervals) of 8.4 (1.5-46.1) for mortality and an odds ratio of 16.9 (2.7-106.8) for PD after adjusting for Risk Adjustment for Congenital Heart Surgery 1. Because of the low number of deaths, limited confounder analysis was performed. Duration of intubation and LOS in the ICU were not associated with the initial lactate level when adjusting for confounders.

CONCLUSION

The initial post-operative lactate level was a predictor of mortality and need for PD in children undergoing surgery for congenital heart disease.

Lactate and acid base as a hemodynamic monitor and markers of cellular perfusion

BACKGROUND

: The intra- and postoperative monitoring of lactate and acid-base has been advocated in pediatric cardiac critical care as surrogate markers of cardiac output, oxygen delivery, and cellular perfusion. Many clinicians use lactate and base excess routinely as markers of tissue perfusion and to assess the effectiveness of their intervention. This review discusses the strengths and weaknesses of using these measurements in pediatric cardiac critical care.

METHODOLOGY

: A search of MEDLINE, EMBASE, PubMed, and the Cochrane Database was conducted to find controlled trials of lactate and base excess. Adult and pediatric data were considered. Guidelines published by the Society of Critical Care Medicine, the American Heart Association, the American Academy of Pediatrics, and the International Liaison Committee on Resuscitation were reviewed including further review of references cited.

RESULTS AND CONCLUSIONS

: Many factors other than tissue hypoxia may contribute to hyperlactemia in critical illness. Although the presence of hyperlactemia on admission appears to be associated with intensive care unit mortality and morbidity in some retrospective analyses, significant overlap between survivors and nonsurvivors means that nonsurvivors cannot be predicted from admission lactate measurement. Persistently elevated postoperative lactate is associated with increased morbidity and mortality in the pediatric cardiac population. To date there is no randomized control trial of goal-directed therapy in adult or pediatric cardiac care that includes normalization of lactate as a target. Overall equivalent time measurements of base excess, anion gap, and pH have a low predictive value for morbidity and mortality in children after cardiac surgery. Lactate is one of a cluster of markers of cellular perfusion and oxygen delivery. Alone, as a single measurement, it has minimal predictive value and is nondiscriminatory for survival.

The importance of blood lactate clearance as a predictor of early mortality following the modified Norwood procedure

OBJECTIVE

Optimisation of Norwood physiology, with focus on systemic perfusion, has beneficial effects on haemodynamic stability and perioperative mortality following the Norwood procedure for hypoplastic left heart syndrome. Early identification of high-risk patients during the postoperative phase might allow for institution of alternative management strategies with the possibility of avoiding poor outcome. Several studies have suggested that arterial blood lactate level, as an index of systemic perfusion and oxygen delivery, can to some extent predict mortality following paediatric cardiac surgery, though these studies have included heterogeneous groups of patients with only few Norwood patients. We sought to determine whether the blood lactate profile could be used to derive a simple, clinically applicable decision algorithm to direct therapy in a pre-emptive manner and perhaps identify patients for elective extracorporeal life support following the Norwood procedure.

METHODS

We retrospectively analysed all patients at our institution who had undergone modified Norwood procedures between March 2002 and May 2008. All patients had received right ventricle-pulmonary artery conduits. Patients with systemic-pulmonary shunts were excluded. Outcome measures included 7-day and 30-day mortality. Serial arterial blood lactate measurements were taken in all patients for at least 72h. Conditional inference tree modelling was used to determine the discriminatory value of the lactate profile and other pre- and intra-operative risk factors in terms of selecting survivors.

RESULTS

As many as 221 patients were included. The 7-day ICU mortality was 26/219 (11.8%) with total 30-day mortality of 35/219 (15.8%). There were 21 interstage deaths. Mortality modelling demonstrated that an inability to clear blood lactate levels to <6.76mmoll(-1) within the first 24h was highly discriminatory in terms of predicting death within the first 30 days. A total of 11 out of 12 patients in this group died. Other risk factors examined, including weight, ascending aorta size, cardiopulmonary bypass and ischaemic times, were not as predictive in our model.

CONCLUSION

We have identified minimum blood lactate level within the first 24h after the Sano-Norwood procedure as a highly discriminatory predictor of perioperative mortality. These patients might benefit from elective institution of early mechanical circulatory support.

Evaluation of initial plasma lactate values as a predictor of gastric necrosis and initial and subsequent plasma lactate values as a predictor of survival in dogs with gastric dilatation-volvulus: 84 dogs (2003-2007)

OBJECTIVE

To test whether an initial plasma lactate ≥ 6.0 mmol/L is associated with the presence of macroscopic gastric wall necrosis and overall survival in dogs presenting with gastric dilatation-volvulus (GDV). Additionally, if no association was identified we sought to identify a different predictive initial plasma lactate concentration and to examine whether serial plasma lactate concentrations provide better prediction of survival.

DESIGN

Retrospective study over a 5-year period (2003-2007).

SETTING

Urban private referral small animal teaching hospital.

ANIMALS

Eighty-four client-owned dogs with a diagnosis of GDV and plasma lactate measurements.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There was no statistically significant relationship found between survival and the presence of macroscopic gastric wall necrosis with the initial plasma lactate ≥ 6 mmol/L. There was a significant relationship between the initial plasma lactate >2.9 mmol/L for predicting necrosis and <4.1 mmol/L for predicting survival to discharge. Forty dogs that had an increased initial plasma lactate (>2.5 mmol/L) also had a subsequent plasma lactate measured within 12 hours of presentation, with 37/40 dogs surviving and 70% of these surviving dogs having the subsequent lactate decrease by ≥ 50% within 12 hours. The 3/40 that died failed to decrease their plasma lactate by ≥ 50% from the initial blood lactate.

CONCLUSION

The results of this study indicate that an initial presenting plasma lactate concentration ≥ 6.0 mmol/L is not predictive of macroscopic gastric wall necrosis or survival in dogs presenting with GDV. A decrease in plasma lactate concentrations ≥ 50% within 12 hours may be a good indicator for survival. Limitations to the study include its retrospective nature, the small number of patients, and the number of dogs that were euthanized rather than allowed to progress to a natural outcome.

Relative hyperlactatemia and hospital mortality in critically ill patients: a retrospective multi-centre study

Introduction

Higher lactate concentrations within the normal reference range (relative hyperlactatemia) are not considered clinically significant. We tested the hypothesis that relative hyperlactatemia is independently associated with an increased risk of hospital death.

Methods

This observational study examined a prospectively obtained intensive care database of 7,155 consecutive critically ill patients admitted to the Intensive Care Units (ICUs) of four Australian university hospitals. We assessed the relationship between ICU admission lactate, maximal lactate and time-weighted lactate levels and hospital outcome in all patients and also in those patients whose lactate concentrations (admission n = 3,964, maximal n = 2,511, and time-weighted n = 4,584) were under 2 mmol.L^-1 (i.e. relative hyperlactatemia).

Results

We obtained 172,723 lactate measurements. Higher admission and time-weightedlactate concentration within the reference range was independently associated with increased hospital mortality (admission odds ratio (OR) 2.1, 95% confidence interval (CI) 1.3 to 3.5, P = 0.01; time-weighted OR 3.7, 95% CI 1.9 to 7.00, P < 0.0001). This significant association was first detectable at lactate concentrations > 0.75 mmol.L^-1. Furthermore, in patients whose lactate ever exceeded 2 mmol.L^-1, higher time-weighted lactate remained strongly associated with higher hospital mortality (OR 4.8, 95% CI 1.8 to 12.4, P < 0.001).

Conclusions

In critically ill patients, relative hyperlactataemia is independently associated with increased hospital mortality. Blood lactate concentrations > 0.75 mmol.L^-1 can be used by clinicians to identify patients at higher risk of death. The current reference range for lactate in the critically ill may need to be re-assessed.

Venoarterial extracorporeal membrane oxygenation in adult patients: predictors of mortality

BACKGROUND

Extracorporeal membrane oxygenation is a cardiopulmonary supportive therapy. In this study, we reviewed our experience with extracorporeal membrane oxygenation support and tried to identify measurable values which might predict in-hospital mortality.

METHODS

From January 2004 through December 2008, 50 of 21,298 adult patients received venoarterial extracorporeal membrane oxygenation. We retrospectively analyzed clinical records of these 50 consecutive patients. Details of demographics, preoperative measurements, clinical characteristics at the time of extracorporeal membrane oxygenation implantation, extracorporeal membrane oxygenation-related complications and in-hospital mortality were collected. Logistic regression analyses were performed to investigate predictors of mortality. A p-value < or = 0.05 was accepted as significant.

RESULTS

Thirty-eight patients were weaned from extracorporeal membrane oxygenation and 33 patients survived to discharge. The overall survival rate was 66%. In a multiple logistic regression analysis, blood lactate level before initiation of extracorporeal membrane oxygenation was a risk factor associated with in-hospital mortality (OR 1.27 95% CI 1.042-1.542). To evaluate the utility of the lactate in predicting mortality, a conventional receiver operating characteristic curve was produced. Sensitivity and specificity were optimal at a cut-off point of 12.6 mmol/L, with an area under the curve of 0.752. The positive and negative predictive values were 73.3% and 83.9%, respectively.

CONCLUSIONS

Extracorporeal membrane oxygenation is a justifiable alternative treatment for postoperative refractory cardiac and pulmonary dysfunction which could rescue more than sixty percent of otherwise fatal patients. Patients with pre-extracorporeal membrane oxygenation lactate levels above 12.6 mmol/L are at higher risks for in-hospital death. Evidence-based therapy for this group of high risk patients is needed.