Serum lactates correlate with mortality after operations for complex congenital heart disease

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.

The effect of clinical and haemodynamic variables on post-operative length of stay immediately upon admission after biventricular repair with Yasui operation following an earlier Norwood operation

BACKGROUND

There are a variety of approaches to biventricular repair in neonates and infants with adequately sized ventricles and left-sided obstruction in the presence of a ventricular septal defect. Those who undergo this in a staged manner initially undergo a Norwood procedure followed by a ventricular septal defect closure such that the neo-aorta is entirely committed to the left ventricle and placement of a right ventricular to pulmonary artery conduit (Yasui operation). This study aimed to determine clinical and haemodynamic factors upon paediatric cardiac ICU admission immediately after the two-stage Yasui operation that was associated with post-operative length of stay.

METHODS

This was a retrospective review of patients who underwent the Yasui procedure after the initial Norwood operation between 1 January 2011 and 31 December 2020. Patients with complete data on admission were identified and analysed using Bayesian regression analysis.

RESULTS

A total of 15 patients were included. The median age was 9.0 months and post-operative length of stay was 6days. Bayesian regression analysis demonstrated that age, weight, heart rate, mean arterial blood pressure, central venous pressure, pulse oximetry, cerebral near infrared spectroscopy, renal near infrared spectroscopy, pH, pCO2, ionised calcium, and serum lactate were all associated with post-operative length of stay.

CONCLUSION

Discrete clinical and haemodynamic factors upon paediatric cardiac ICU admission after staged Yasui completion are associated with post-operative length of stay. Clinical target ranges can be developed and seem consistent with the notion that greater systemic oxygen delivery is associated with lower post-operative length of stay.

Comparison of cases with and without additional lower body perfusion in newborns undergoing aortic arch reconstruction with antegrade selective cerebral perfusion method

Background

The aim of this study was to analyze the effect of additional lower body perfusion, compared to antegrade selective cerebral perfusion, on early postoperative outcomes after aortic arch repair in neonates with biventricular morphology.

Methods

Between January 2017 and April 2020, a total of 46 neonates (34 males, 12 females; median age: 10 days; range, 7 to 14 days) with biventricular morphology underwent an aortic arch reconstruction were retrospectively analyzed. The effects of antegrade selective cerebral perfusion and additional lower body perfusion techniques on vital organ preservation and mortality were evaluated in these patients who underwent arch reconstruction.

Results

In the univariate analysis of the whole cohort, postoperative creatinine level was lower in the additional lower body perfusion group, while there was no significant difference between the other parameters. In the multivariate analysis, intraoperative highest lactate level (odds ratio: 1.7; 95% confidence interval: 1.07-2.68; p=0.02) and postoperative 4th t o 6 th h lactate levels (odds ratio: 2.34; 95% confidence interval: 1.08-5.09; p=0.03) were independent predictors of early mortality. Mortality rate was higher in the antegrade selective cerebral perfusion group (22% vs. 7%), although it did not reach statistical significance. In the receiver operating characteristic curve analysis, the cut-off value for intraoperative lactate was 6.2 mmol/L (sensitivity: 85.7%, specificity: 71.1%) and the cut-off value for the lactate level at the postoperative 4th to 6th h was 4.9 mmol/L (sensitivity: 85.7%, specificity: 73.7%). Above these lactate levels were found to be associated with mortality.

Conclusion

Additional lower body perfusion may have a role in vital organ protection in aortic arch repair of neonates, compared to antegrade selective cerebral perfusion.

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.

Case Report: Novel Monitoring for Anaerobic Conditions Detected by Respiratory Quotient in a Critically Ill Pediatric Patient

BACKGROUND

Hyperlactemia after cardiopulmonary bypass is associated with adverse events during the early postoperative period in children. Serum lactate levels, a standard marker of anaerobic metabolism, are determined by the production, conversion and clearance of lactate, and may lag behind the anaerobic response. Here, we report a neonatal case under anaerobic conditions after cardiac surgery, whose expired gas parameters dramatically changed before a rise in blood lactate.

CASE PRESENTATION

A 23-day-old girl with tetralogy of Fallot was admitted to the pediatric intensive care unit after modified Blalock-Taussig shunt operation. As hemoconcentration increased and pleural fluid and ascites accumulated, we performed partial exchange transfusion to prevent shunt occlusion. Ten minutes after partial exchange transfusion, oxygen uptake and carbon dioxide production measured by indirect calorimetry suddenly dropped, while the respiratory quotient began to rise steeply before hyperlactatemia developed a few hours later.

CONCLUSION

Analysis of expired gas in critically ill children can detect the transition from aerobic to anaerobic conditions before hyperlactatemia.

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.

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.

Lower limit of adequate oxygen delivery for the maintenance of aerobic metabolism during cardiopulmonary bypass in neonates

BACKGROUND

The objective of cardiopulmonary bypass (CPB) is to maintain an adequate balance between oxygen delivery (Ḋo2) and consumption. The critical Ḋo2 is that at which consumption becomes supply dependent. This study aimed to identify the critical Ḋo2 in neonates, who have higher metabolic rates than adults.

METHODS

In a retrospective cohort of neonates, Ḋo2 was calculated from CPB parameters recorded during aortic cross-clamping. High lactate concentration measured after aortic unclamping (lactOFF) was used to identify anaerobic metabolism. Data were analysed using mixed linear and proportional odds regression models. The relationship between Ḋo2 and temperature was analysed in a subgroup of patients with lactOFF <2.5 mM, thought to have had balanced oxygen delivery and consumption. The estimated regression coefficient was further used to adjust hypothetical Ḋo2 thresholds, and Ḋo2 excursions below the threshold were quantified as magnitude-durations. The lowest threshold that provided magnitude-durations and linked with an increase in lactOFF was used as the lowest suitable (critical) Ḋo2 at 37°C.

RESULTS

Overall, 22 896 time points were analysed in 180 neonates. In 40 patients with lactOFF <2.5 mM, Ḋo2 varied by 22.87 (0.70) ml min-1 m-2 °C-1. When varying the Ḋo2 threshold between 340 and 380 ml min-1 m-2, excursions below the threshold were linked with incremental lactOFF. A 100 ml m-2 excursion below the 340 ml min-1 m-2Ḋo2 threshold increased the risk of a 1 mM increment in lactOFF by 22% (odds ratio: 1.22; 95% confidence interval: 1.02-1.45).

CONCLUSIONS

It was found that 340 ml min-1 m-2 is likely to represent the lowest suitable Ḋo2 required in neonates to maintain aerobic metabolism during normothermic CPB.

Frequency and Outcomes of Elevated Perioperative Lactate Levels in Adult Congenital Heart Disease Patients Undergoing Cardiac Surgery

OBJECTIVES

To assess whether lactate levels are associated with clinical outcomes in adult congenital heart disease patients who undergo cardiac surgery.

DESIGN

Retrospective study.

SETTING

Single quaternary academic referral center.

PARTICIPANTS

Adult congenital heart disease patients (≥18 y old) with congenital heart disease undergoing cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

Participants were classified into 3 groups according to their peak arterial lactate level within the first 48 hours of surgery.

MEASUREMENTS AND MAIN RESULTS

In-hospital 30-day mortality, hospital and intensive care unit length of stay, duration of mechanical ventilation after surgery, acute kidney injury defined by Acute Kidney Injury Network criteria, and intensive care unit and hospital readmission within 30 days of surgery were examined. There was no significant difference among different lactate level groups in acute kidney injury, hospital length of stay, intensive care unit length of stay, hours of mechanical ventilation, need for redo surgery, or rates of hospital or intensive care unit readmission. In multivariable analysis, which included cardiopulmonary bypass time, redo surgery, nonelective case, and the adult congenital heart disease complexity score, lactate levels were not a significant predictor of either acute kidney injury or hospital length of stay.

CONCLUSIONS

The appeal of using lactate levels to risk stratify-patients or to develop a model to predict mortality and morbidity has potential merit, but currently there is insufficient evidence to use lactate levels as a predictor of outcomes in adult patients with congenital heart disease undergoing cardiac surgery.

Association Between Lactates, Blood Glucose, and Systemic Oxygen Delivery in Children After Cardiopulmonary Bypass

Objective: Lactate is often used as a surrogate marker of inappropriate oxygen delivery. It has been shown that hyperlactatemia is associated with worse clinical outcome in children after cardiac surgery. The purpose of this study is to evaluate the association of hyperlactatemia, low systemic oxygen delivery, and hyperglycemia, in children admitted to the pediatric critical care unit after cardiopulmonary bypass. Design: Secondary analysis of an observational cohort study. Setting: Tertiary pediatric critical care unit (PICU). Patients: Ninety-three patients, aged 6 months to 16 years, undergoing cardiac surgery with cardiopulmonary bypass. Interventions: None. Measurements and Main Results: Metabolic tests (blood glucose, lactate, lactate/pyruvate ratio, and ketones) and oxygen extraction (SaO₂-SvO₂) were performed before anesthesia, at the end of cardiopulmonary bypass, at PICU admission, and at 4 and 12 h after PICU admission. Four hours after PICU admission, 62% of the patients had hyperlactatemia (>2 mmol/L), of whom 55% had normal oxygen extraction (SaO₂-SvO₂ < 30%). There was no correlation between lactate and oxygen extraction (R = -0.09, p = 0.41) but there was a moderate correlation between lactate and blood glucose (R = 0.55, p < 0.001). Using a logistic regression model, hyperlactatemia at 4 h after PICU admission was independently associated with hyperglycemia (p = 0.007) and lactate/pyruvate ratio (p = 0.007) at the same timepoint, as well as with lactate at PICU admission (p = 0.002), but not with weight (p = 0.45), severity of the cardiac lesion (p = 0.85), duration of bypass (p = 0.16), or oxygen extraction, as evaluated by SaO₂-SvO₂ (p = 0.54). At 12 h after PICU admission, there was a very week correlation between lactate and blood glucose (R = 0.27, p = 0.007), but none between lactate and oxygen extraction (R = 0.13, p = 0.20). Conclusion: In children after cardiopulmonary bypass, lactates are not correlated with higher oxygen extraction, but are correlated with hyperglycemia, at both 4 and 12 h after PICU admission. Future research is warranted to better define this relationship.

Retrospective analysis of cardiac index and lactate production on cardiopulmonary bypass for a congenital cardiac patient population

Background:

Providing adequate metabolic support is the principal concern during cardiopulmonary bypass (CPB) with different strategies utilized to enhance oxygen delivery to the patient. Modifying temperature, hematocrit (Hct) and cardiac index (CI) during CPB are primary techniques which aid in this effort. Based upon surgeon preference, the study institution employs differing perfusion strategies (PS) during congenital cardiac surgery requiring CPB. One method utilizes a 2.4 L/min/m2 CI and nadir Hct of 28% (PS1) and the other a 3.0 L/min/m2 CI with a nadir Hct of 25% (PS2).

Methods:

Cardiopulmonary bypass cases during which the PS1 or PS2 strategies were applied were retrospectively examined, finding no significant difference in pre-CPB lactate, maximum lactate on CPB or maximum change in lactate on CPB.

Results:

While the post-CPB lactate was statistically significantly higher in the PS2 group (p=0.024), the magnitude of difference (0.15 mmol/L) was small.

Conclusions:

This study illustrates that, when oxygen delivery or tissue perfusion is suspected as the primary cause of lactate production during CPB, increasing the CI to a 3.0 rather than a 2.4 CI may be more advantageous than packed red blood cell administration.

Correlation between serum lactate levels and outcome in pediatric patients undergoing congenital heart surgery

Background

This study aimed to investigate the correlation between perioperative arterial lactate levels and morbidity and mortality in children undergoing cardiac surgery.

Methods

A total of 236 patients who underwent open heart surgery due to congenital heart disease (121 males, 115 females; mean age 56.4 month (median: 42 month): range, 1 day to 204 month) between June 2014 and May 2016 were retrospectively analyzed. The arterial blood gas analysis results at baseline (after insertion of arterial cannula), during the cooling and warming-up phases in cardiopulmonary bypass, during the sternal closure, and at 0, 6, 12, and 24 hours in the postoperative intensive care unit stay were recorded. The patients were divided into two groups according to their lactate levels: Group 1 (lactate level <4.5 mmol/L, n=183) and Group 2 (lactate level ≥4.5 mmol/L, n=53). Correlation between the lactate groups and demographic data, intraoperative and postoperative variables, postoperative complications, and mortality were investigated.

Results

Sixty-nine patients (29.2%) had cyanotic heart disease. A total of 53 patients (22.5%) had lactate levels of ≥4.5 mmol/L. At least one complication occurred in 41% of the patients. Development of at least one complication (p=0.027) and mortality rate (p<0.001) were significantly higher in the patients with lactate levels of ≥4.5 mmol/L. Seventeen patients (7.2%) died in the postoperative period, and 15 of them had lactate levels of ≥4.5 mmol/L at least once within the first 24 hours. In terms of mortality, lactate levels of ≥4.5 mmol/L at any time, prolonged mechanical ventilation (>48 hours), and undergoing complex surgery (high the Risk-adjusted Classification for Congenital Heart Surgery-1 score, category 4-6) were the independent risk factors for mortality.

Conclusion

Blood arterial lactate level of ≥4.5 mmol/L was found to be a risk factor for postoperative morbidity and mortality in pediatric patients undergoing congenital heart surgery.

Correlation of Lactic Acid and Base Deficit Values Obtained From Arterial and Peripheral Venous Samples in a Pediatric Population During Intraoperative Care

Lactic acid and base deficit (BD) values are frequently monitored in the intensive care unit and operating room setting to evaluate oxygenation, ventilation, cardiac output, and peripheral perfusion. Although generally obtained from an arterial cannula, such access may not always be available. The current study prospectively investigates the correlation of arterial and peripheral venous values of BD and lactic acid. The study cohort included 48 patients. Arterial BD values ranged from -8 to 4 mEq/L and peripheral venous BD values ranged from -8 to 4 mEq/L. Arterial lactic acid values ranged from 0.36 to 2.45 μmol/L and peripheral venous lactic acid values ranged from 0.38 to 4 μmol/L. The arterial BD (-0.4 ± 2.2 mEq/L) was not significantly different from the peripheral venous BD (-0.6 ± 2.2 mEq/L). The arterial lactic acid (1.0 ± 0.5 μmol/L) was not significantly different from the peripheral venous lactic acid (1.1 ± 0.6 μmol/L). Pearson correlation coefficients demonstrated a very high correlation between arterial and peripheral venous BD ( r = .88, P < .001) and between arterial and peripheral venous lactic acid ( r = .67, P < .001). Bland-Altman plots of both pairs of measures showed that the majority of observations fell within the 95% limits of agreement. Least-squares regression indicated that a 1-unit increase in arterial BD corresponded to a 0.9-unit increase in peripheral venous BD (95% confidence interval [CI]: 0.7-1.0; P < .001) and a 1-unit increase in arterial lactic acid corresponded to a 0.9-unit increase in peripheral venous lactic acid (95% CI: 0.6-1.2; P < .001). These data demonstrate that there is a clinically useful correlation between arterial and peripheral venous lactic acid and BD values.

Neonatal Aortic Arch Reconstruction With Direct Splanchnic Perfusion Avoids Deep Hypothermia

BACKGROUND

Neonatal aortic arch reconstruction, typically performed with deep hypothermia and selective cerebral perfusion, leaves splanchnic organ protection dependent on hypothermia alone. A simplified method of direct in-field descending aortic perfusion during neonatal arch reconstruction permits the avoidance of deep hypothermia. We hypothesize that direct splanchnic perfusion at mild hypothermia provides improved or equivalent safety compared with deep hypothermia and may contribute to postoperative extracardiac organ recovery.

METHODS

Included were 138 biventricular patients aged younger than 90 days undergoing aortic arch reconstruction with cardiopulmonary bypass. Patients were grouped according to perfusion method A (selective cerebral perfusion with deep hyperthermia at 18° to 20°C) or method B (selective cerebral perfusion and splanchnic perfusion at 30° to 32°C). Patient characteristics and perioperative clinical and serologic data were analyzed. Significance was assigned for p of less than 0.05.

RESULTS

Of the 138 survivors, 63 underwent method A and 75 underwent method B. The median age at operation was 8.5 days (range, 6 to 15 days), and median weight was 3.2 kg (range, 2.8 to 3.73 kg), with no significant differences between groups. Cardiopulmonary bypass times were comparable between the two perfusion methods (p = 0.255) as were the ascending aortic cross-clamp times (p = 0.737). The postoperative glomerular filtration rate was significantly different between our groups (p = 0.028 to 0.044), with method B achieving a higher glomerular filtration rate. No significant differences were seen in ventilator time, postoperative length of stay, fractional increase of postoperative serum creatinine over preoperative serum creatinine, and postoperative lactate.

CONCLUSIONS

A simplified method of direct splanchnic perfusion during neonatal aortic arch reconstruction avoids the use of deep hypothermia and provides renal protection at least as effective as deep hypothermia.

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.

Hemodynamic coherence in critically ill pediatric patients

Differences in physiology and pathophysiology make the treatment of developing, critically ill children particularly challenging as compared to that of adults. Significant differences in the cardiovascular system of neonates and children in size, weight, body proportions, and metabolism should be considered. Hemodynamic monitoring is crucial for early warning of pending deterioration and to guide therapy. Current monitoring is limited to the macrocirculation, but an adequately functioning macrocirculation does not guarantee a well-functioning microcirculation. Research in children revealed loss of hemodynamic coherence, i.e., microcirculatory alterations despite normal systemic hemodynamics. Implementing the framework of hemodynamic coherence in microcirculatory monitoring in children can aid physicians in titrating therapy on both macrocirculatory and microcirculatory effects to assure optimal oxygen delivery. Monitoring the microcirculation at the bedside requires further technical development. Although more research is necessary to validate the concept of hemodynamic coherence in children, the possibilities of applying this concept in children seem promising.

Effects of fresh versus old stored blood in the priming solution on whole blood lactate levels during paediatric cardiac surgery

It has been suggested that lactate levels may predict morbidity and mortality in paediatric patients during corrective open-heart surgery. Packed red blood cells (PRBC) are frequently necessary for priming the reservoir used in cardiopulmonary bypass (CPB). The storage of PRBC might cause a significant increase in lactate levels. The purpose of the present study was to quantify the increase in lactate levels in stored red blood cells over time and to compare lactate levels after transfusions of fresh (≤ 12 days) versus old blood (>12 days) in 20 patients. We found an increase in lactate levels from 6.0 to 44.7 mmol/L (mean 17.09 ± 7.8 mmol/L) during storage. Lactate levels were also significantly higher after the onset of CPB in paediatric patients transfused with old blood than in patients transfused with fresh blood (1.439 ± 0.36 versus 3.469 ± 0.63, p=0.0006). Our results suggest that the higher lactate levels found after the initiation of CPB should be used with caution when assessing tissue hypoxia and predicting outcome.

The Use of the Ratio between the Veno-arterial Carbon Dioxide Difference and the Arterial-venous Oxygen Difference to Guide Resuscitation in Cardiac Surgery Patients with Hyperlactatemia and Normal Central Venous Oxygen Saturation

Background:

After cardiac surgery, central venous oxygen saturation (ScvO₂) and serum lactate concentration are often used to guide resuscitation; however, neither are completely reliable indicators of global tissue hypoxia. This observational study aimed to establish whether the ratio between the veno-arterial carbon dioxide and the arterial-venous oxygen differences (P(v−a)CO₂/C(a−v)O₂) could predict whether patients would respond to resuscitation by increasing oxygen delivery (DO₂).

Methods:

We selected 72 patients from a cohort of 290 who had undergone cardiac surgery in our institution between January 2012 and August 2014. The selected patients were managed postoperatively on the Intensive Care Unit, had a normal ScvO₂, elevated serum lactate concentration, and responded to resuscitation by increasing DO₂ by >10%. As a consequence, 48 patients responded with an increase in oxygen consumption (VO₂) while VO₂ was static or fell in 24.

Results:

At baseline and before resuscitative intervention in postoperative cardiac surgery patients, a P(v−a)CO₂/C(a−v)O₂ ratio ≥1.6 mmHg/ml predicted a positive VO₂ response to an increase in DO₂ of >10% with a sensitivity of 68.8% and a specificity of 87.5%.

Conclusions:

P(v−a)CO₂/C(a−v)O₂ ratio appears to be a reliable marker of global anaerobic metabolism and predicts response to DO₂ challenge. Thus, patients likely to benefit from resuscitation can be identified promptly, the P(v−a)CO₂/C(a−v)O₂ ratio may, therefore, be a useful resuscitation target.

Intraoperative change of lactate level is associated with postoperative outcomes in pediatric cardiac surgery patients: retrospective observational study

Background

A change of serum lactate concentrations appeared to be useful for predicting outcomes in various acute ill settings. However, there is little information on intraoperative change of lactate level in pediatric cardiac surgery patients.

Methods

We conducted a retrospective observational study of 459 children who received pediatric cardiac surgery to determine the association between change of lactate level after cardiopulmonary bypass (CPB) and patient prognosis (length of ICU stay and incidence of postoperative serious adverse events (SAEs)). We defined change of lactate level after CPB (LAC⊿) as (final lactate level measurement in the operating room) – (lactate level measured at the end of CPB). To study the independent association of LAC⊿ with length of ICU stay, we used linear regression model.

Results

There were 1145 lactate measurements after CPB in this study cohort. After weaning from CPB, the serum lactate levels significantly increased from 2.1 mmol/L to 2.5 mmol/L (p < 0.001). Patients with higher LAC⊿ had significantly longer stay in ICU (p = 0.017) and higher incidence of SAEs (p = 0.002). In multivariate linear regression analysis, higher LAC⊿ showed a significant independent association with longer length of ICU stay.

Conclusions

Increased lactate level after CPB was associated with the longer duration of ICU stay and increased risk of postoperative SAEs in pediatric cardiac surgery patients. Future studies should be conducted to determine the clinical utility of intraoperative trend of lactate levels.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-015-0007-y) contains supplementary material, which is available to authorized users.

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.

Metabolomic strategy for studying the intervention and the synergistic effects of the shexiang baoxin pill for treating myocardial infarction in rats

A metabolomic approach has been developed for evaluating the therapeutic effects of the bioactive components and the synergistic efficacy of the Shexiang Baoxin Pill (SBP) on myocardial infarction (MI) in rats. The MI rats were administered the SBP, muscone, cinnamic acid, bufalin, ginsenoside Re, ginsenoside Rb1, cholic acid, borneol, and a combined version of these bioactive components (SFSBP). Liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) was used to obtain the mass data from the rats' serum. The number of biomarkers that were reversed by SFSBP was greater than any of the monotherapy groups. The PLS-DA score plots demonstrated that the SFSBP group results were located closer to the sham group than any of the monotherapy groups and that the SBP group was located closer to the sham group than the SFSBP treatment group. The reversing results observed with SFSBP showed synergistic effects when compared with those of the individual bioactive components that were used as monotherapy. Meanwhile, the SBP displayed superior regulation efficacy to SFSBP in MI rats, indicating that there must be other active components in the SBP that were responsible for the treatment of MI that were not included in the SFSBP treatment.

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.

Point of care serum lactate levels as a prognostic marker of outcome in complex pediatric cardiac surgery patients: Can we utilize it?

BACKGROUND

Post-operative course after complex pediatric cardiac surgery is unpredictable. Although, change in arterial lactate levels has been used as a surrogate marker for many years, scientific evidence correlating the early perioperative lactate levels with outcome is still lacking.

OBJECTIVE

To evaluate the trends in lactate levels from intraoperative period to an extended post-operative period in pediatric intensive care unit (PICU) and to assess its usefulness as a prognostic marker.

DESIGN

Prospective observational study.

SETTING

Tertiary pediatric cardiac surgical unit.

PATIENTS

Thirty-five non-consecutive children aged 1-140 months who underwent surgery for congenital heart diseases (CHD) on cardiopulmonary bypass (CPB).

INTERVENTION

None.

MATERIALS AND METHODS

ARTERIAL BLOOD LACTATE LEVELS WERE OBTAINED AT THE FOLLOWING TIME POINTS: After induction of anesthesia, 15 and 45 min after institution of CPB, at the start of rewarming, after sternotomy closure, then at 1, 6, 24, and 48 h in PICU. Other hemodynamic and clinical variables, CPB variables, blood gas values, and laboratory variables were also recorded.

RESULTS

Four patients died out of 35 patients (11.4%). Non-survivors showed significant persistent elevation in lactates (>4.0 mmol/l). Peak lactates correlate significantly with longer aortic cross clamp time, CPB duration, ventilation hours and PICU stay.

CONCLUSION

Early point of care lactate can be a useful prognostic marker in post-cardiac surgery patients in adjunct with other parameters measured in PICU. This reiterates the importance of measuring lactates and timely recognition of at-risk patients, which on early intervention can help in reducing post-operative morbidity and mortality.

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 markers of mortality after congenital heart defect surgery]

INTRODUCTION

Our aim is to identify risk factors for mortality after surgery for congenital heart disease in children, in order to establish indications for extracorporeal membrane oxygenation (ECMO).

PATIENTS AND METHODS

One hundred and eighty six children underwent cardiac surgery with extracorporeal circulation from April 2007 to June 2009. The following parameters were measured serially during their stay in Paediatric Intensive Care (PICU): Arterial and venous blood pH, pCO2, base excess, oxygen saturation, arterio-venous oxygen saturation difference, oxygen extraction ratio, ventilatory dead space and intrapulmonary shunting.

RESULTS

Hospital mortality was 13,4%. The following risk factors for mortality were identified: age, bypass time, inotropic score, lactate level upon arrival in PICU including its peak value and its rate of variation, mixed venous saturation, base excess, ventilatory dead space, oxygen extraction ratio, and intrapulmonary shunting. However, the strongest predictors of mortality were bypass time, lactate levels upon admission on PICU, and the peak lactate level. Multivariate analysis showed a lactate level of 6.3mmol/l and a high blood lactate for 24hours to be independent predictors of mortality.

CONCLUSIONS

The peak lactate level is a strong predictor of mortality. As such, it would be a useful indicator of the need for ECMO support.

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.

The association of blood lactate concentration with outcome in dogs with idiopathic immune-mediated hemolytic anemia: 173 cases (2003-2006)

OBJECTIVE

To determine the association of blood lactate with outcome and response to transfusion therapy in dogs with idiopathic immune-mediated hemolytic anemia (IMHA).

DESIGN

Retrospective study.

SETTING

Urban veterinary small animal emergency hospital.

ANIMALS

One hundred and seventy-three client-owned dogs with IMHA.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serial blood lactate concentration, therapeutic interventions, and outcome were recorded. Nonsurvivors were defined as those that died or were euthanized. One hundred and thirty-three dogs (77%) survived, 35 (20%) were euthanized, and 5 (3%) died. One hundred forty-five dogs (84%; 145/173) had a lactate concentration above the laboratory reference interval [0.46-2.31 mmol/L] on presentation. Blood lactate at presentation was higher in the nonsurvivors (median 4.8 mmol/L; 0.5-13.6) compared with survivors (median 2.9 mmol/L; 0.3-13.2) (P<0.01). All dogs presenting with hyperlactatemia that normalized (<2.0 mmol/L) within 6 hours of admission survived, whereas, 71% of dogs that had a persistent hyperlactatemia at 6 hours survived (P=0.034). Lactate was positively correlated with age, BUN, and alkaline phosphatase, and inversely correlated with PCV. Receiver operating curve analysis for lactate concentration at admission as a test for outcome had an area under the curve of 0.69 with an optimal lactate cutoff concentration of 4.4 mmol/L correctly predicting outcome 73% of the time (sensitivity 60%, specificity 77%).

CONCLUSIONS

Lactate concentration at presentation was significantly higher in nonsurvivors than survivors. Lactate was significantly correlated with previously reported outcome variables but lactate concentration at admission, as a predictor for outcome was less than optimal. However, serial lactate concentration measurements may be more predictive as patients with persistent hyperlactatemia 6 hours after admission were less likely to survive. Prospective studies evaluating serial lactate concentration while controlling for other variables may provide further insight into lactate measurement as a prognostic indicator in animals with IMHA.

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.

Objective assessment of cardiac output in infants after cardiac surgery

An accurate measurement of cardiac performance in infants after cardiopulmonary bypass has long been considered to be an important part of postoperative management. To be useful in clinical decision making, such measurements should ideally be reproducible, non invasive and accurately reflect tissue perfusion and oxygen delivery. Historically, we have relied on intermittent measurements of cardiac output using indicator dilution methods; and more recently, technologies that use pulse contour analysis, bio-impedance, or Doppler methodology. These all have the same shortcoming, that they provide a number that the information as to whether it provides adequate tissue perfusion. There is increasing emphasis being placed on the measurement of oxygen delivery either by mixed venous oxygen saturation and serum lactate, which are important markers of the adequacy of organ perfusion; and relating this to outcome, the development of organ dysfunction and length of ICU stay.

Blood lactate levels differ significantly between surviving and nonsurviving patients within the same risk-adjusted Classification for Congenital Heart Surgery (RACHS-1) group after pediatric cardiac surgery

This study aimed to examine the association between lactate levels in the first hours after surgery for congenital heart defects and the results of Risk-Adjusted Classification for Congenital Heart Surgery (RACHS-1) scoring and to evaluate serial lactate levels over time to determine whether they can serve as a supplementary tool for postoperative assessment within the same RACHS-1 group of patients. A retrospective cohort study was performed using data retrieved from a clinical database of 255 children who had surgery for congenital heart defects between 1999 and 2001 at Sheba Medical Center. Lactate levels were measured postoperatively four times (mg/dL units). The last sample was taken at the end of the surgical procedure, and lactate levels were measured at admission to the pediatrics critical care unit, then 6 and 12 h after admission. The lactate level was measured via arterial blood gases. A total of 27 deaths occurred, yielding a mortality rate of 7.4% when Norwood operations were excluded and 10.16% when they were included. The mean initial postoperative lactate level was significantly lower for survivors (42.2 ± 32.0 mg/dL) than for nonsurvivors (85.4 ± 54.1 mg/dL) (p < 0.01). The serial mean lactate levels decreased progressively for all surviving patients (r (2) = 0.96) compared with nonsurvivors (r (2) = 0.02). The lactate levels correlated with the RACHS-1 subgroups at each time point (r (2) > 0.96 for all). The Pearson correlations between postoperative lactate levels (last lactate measurement taken in the operating room) and cardiopulmonary bypass (CPB) duration (r = 0.549), clamp duration (r = 0.586), and the inotropic score (r = 0.466) (p < 0.001 for all) were significantly positive. The correlations between the maximum lactate levels (during the first 12 postoperative hours) and CPB duration (r = 0.496), clamp duration (r = 0.509), and the inotropic score (r = 0.633) (p < 0.001 for all) were extremely positive. The early elevation of lactate levels in RACHS-1 subgroups 1 to 3 were highly correlated with poor prognosis and death (p < 0.03). In addition, the lactate levels differed significantly between survivors and nonsurvivors within the same RACHS-1 subgroup. The survivors in RACHS-1 subgroups 1 to 3 had lower mean lactate levels than the nonsurvivors in this group (P = 0.011), and this also held true for the survivors and nonsurvivors in RACHS-1 subgroups 4 to 6 (P = 0.026). Lactate levels differed significantly between survivors and nonsurvivors within the same RACHS-1 subgroup. This combination allows the targeting of appropriately intensive interventions and therapies toward the sickest patients.

Central venous oxygen saturation and blood lactate levels during cardiopulmonary bypass are associated with outcome after pediatric cardiac surgery

INTRODUCTION

Central venous oxygen saturation and blood lactate are different indices of the adequacy of oxygen delivery to the oxygen needs. In pediatric cardiac surgery, lactate level and kinetics during and after cardiopulmonary bypass are associated with outcome variables. The aim of this study was to explore the hypothesis that the lowest central venous oxygen saturation and the peak lactate value during cardiopulmonary bypass, used alone or in combination, may be predictive of major morbidity and mortality in pediatric cardiac surgery.

METHODS

We conducted a retrospective analysis of 256 pediatric (younger than 6 years) patients who had undergone cardiac surgery with continuous monitoring of central venous oxygen saturation and serial measurement of blood lactate.

RESULTS

Peak lactate was significantly increased when the nadir central venous oxygen saturation was < 68%. Both nadir central venous oxygen saturation and peak lactate during cardiopulmonary bypass were independently associated with major morbidity and mortality, with the same accuracy for major morbidity and a higher accuracy of peak lactate for mortality. A combined index (central venous oxygen saturation < 68% and peak lactate > 3 mmol/L) provided the highest sensitivity and specificity for major morbidity, with a positive predictive value of 89%.

CONCLUSIONS

The combination of a continuous monitoring of central venous oxygen saturation and serial measurements of blood lactate during cardiopulmonary bypass may offer a predictive index for major morbidity after cardiac operations in pediatric patients. This study generates the hypothesis that strategies aimed to preserve oxygen delivery during cardiopulmonary bypass may reduce the occurrence of low values of central venous oxygen saturation and elevated lactate levels. Further studies should consider this hypothesis and take into account other time-related factors, such as time of exposure to low values of central venous oxygen saturation and kinetics of lactate formation.

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

OBJECTIVE

To assess the role of serial lactate levels in determining outcome after cardiopulmonary bypass surgery in children.

DESIGN

Analysis of retrospectively collected data.

SETTING

Cardiac intensive care unit of a tertiary care children's hospital.

PATIENTS

Patients were 129 children who underwent surgery for congenital cardiac defects.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Patients were categorized for disease severity using the Risk Adjustment for Congenital Heart Surgery method. Blood lactate levels were obtained at admission to the cardiac intensive care unit and then serially until they were <2 mmol/L. Lactime, time during which the lactate remains >2 mmol/L, was noted for each patient. The primary outcome measured was mortality. Secondary outcomes measured were ventilator days and hospital days. Six patients died, and of these five were neonates. Nonsurvivors had higher initial postoperative lactate concentration (p = .01), peak postoperative lactate concentration (p = .003), and lactime (p = .05). In binomial logistic regression analysis, lactime was the strongest predictor of mortality (p = .03). The positive predictive value for all age groups was highest for lactime >48 hrs, with a positive predictive value of 60%, and among the neonates it was 75%. Initial lactate level >6 mmol/L had a positive predictive value of only 6%, and the peak lactate level >6 mmol/L had a positive predictive value of only 15%. Lactime also had a significant association with ventilator days and hospital days among the survivors (p = .001).

CONCLUSIONS

Lactime was a useful predictor of mortality in children undergoing repair or palliation of congenital cardiac defects under cardiopulmonary bypass. Initial and peak lactate levels had a poor positive predictive value for mortality. Lactime also was associated with the number of ventilator days and hospital days in those who survived.

Validation of the Mortality in Emergency Department Sepsis (MEDS) score in patients with the systemic inflammatory response syndrome (SIRS)

OBJECTIVE

To prospectively and externally validate the Mortality in Emergency Department Sepsis (MEDS) score as a predictor of 28-day mortality in patients who present to the emergency department with a systemic inflammatory response syndrome.

DESIGN

Multicentered prospective cohort study.

SETTING

Emergency departments at the University of Colorado Hospital and Denver Health Medical Center in Denver, CO, and Albert Einstein Medical Center and the Hospital of the University of Pennsylvania in Philadelphia, PA.

SUBJECTS

Adult patients who presented to the emergency department, who met criteria for systemic inflammatory response syndrome, and who were admitted to the hospital.

MEASUREMENTS

The MEDS score was calculated by recording the presence of terminal illness, tachypnea or hypoxemia, septic shock, platelet count <150,000 cells/mm3, band count as a percentage of total white blood cell count >5%, age >65 yrs, lower respiratory infection, nursing home residence, and altered mental status.

OUTCOME

Mortality within 28 days or discharged alive from the hospital.

RESULTS

In all, 385 patients were enrolled between 18 and 100 yrs of age. The overall mortality was 9%. As in the original article, the MEDS score was categorized into five groups: very low, low, moderate, high, and very high for 28-day mortality. Mortality rates for each group were 0.6% (95% confidence interval [CI], 0%-3%), 5% (95% CI, 1%-13%), 19% (95% CI, 11%-29%), 32% (95% CI, 15%-54%), and 40% (95% CI, 12%-74%), respectively. The MEDS score had an area under the receiver operating characteristic curve of 0.88 (95% CI, 0.83-0.92).

CONCLUSIONS

The MEDS score accurately predicts 28-day mortality in patients who present to the emergency department with systemic inflammatory response syndrome and who are admitted to the hospital.

B-type natriuretic peptide levels predict outcome after neonatal cardiac surgery

OBJECTIVES

Neonates undergoing cardiac surgery are at high risk for adverse outcomes. B-type natriuretic peptide is used as a biomarker in patients with cardiac disease, but the predictive value of B-type natriuretic peptide after cardiac surgery in neonates has not been evaluated. Therefore, the objective of this study was to determine the predictive value of perioperative B-type natriuretic peptide levels for postoperative outcomes in neonates undergoing cardiac surgery.

METHODS

Plasma B-type natriuretic peptide determinations were made before and 2, 12, and 24 hours after surgery in 36 consecutive neonates. B-type natriuretic peptide levels and changes in perioperative B-type natriuretic peptide were evaluated as predictors of postoperative outcome.

RESULTS

B-type natriuretic peptide levels at 24 hours were lower than preoperative levels (24-h/pre B-type natriuretic peptide ratio < 1) in 29 patients (81%) and higher (24-h/pre B-type natriuretic peptide ratio > or = 1) in 7 patients (19%). A 24-hour/pre B-type natriuretic peptide level of 1 or greater was associated with an increased incidence of low cardiac output syndrome (100% vs 34%, P = .002) and fewer ventilator-free days (17 +/- 13 days vs 26 +/- 3 days, P = .002), and predicted the 6-month composite end point of death, an unplanned cardiac operation, or cardiac transplant (57% vs 3%, P = .003). A 24-hour/pre B-type natriuretic peptide level of 1 or greater had a sensitivity of 80% and a specificity of 90% for predicting a poor postoperative outcome (P = .003).

CONCLUSION

In neonates undergoing cardiac surgery, an increase in B-type natriuretic peptide 24 hours after surgery predicts poor postoperative outcome.

Lactate in veterinary critical care: pathophysiology and management

The measurement of blood lactate in people has proven to be a useful tool in the diagnosis, monitoring, and prognosis of a wide range of clinical syndromes. Its use in small animals is increasing, and several studies have been completed that demonstrate its potential role in critical care. This article summarizes the current state of knowledge regarding the physiology and pathophysiology of lactate production and lactic acidosis; current indications and the utility of measurement in a critical care setting are described; novel applications in the evaluation of cavitary effusions are highlighted; and a guide to the therapy of lactic acidosis is presented.

Hyperlactemia can predict the prognosis of liver resection

Although hyperlactemia is known to accompany hepatic failure and metabolic acidosis, few reports examined the relationships between lactate concentrations and outcome after liver resection. We examined the ability of arterial plasma lactate concentration to predict the patient outcome after hepatectomy. The relationships of arterial lactate and base excess (BE) measured on admission to the intensive care unit (ICU) after hepatectomy to postoperative outcome were investigated in 151 consecutive patients. Lactate level was significantly higher in nonsurvivors than in survivors (P < 0.001), and in patients with postoperative complications than in those without complications (P < 0.001). Base excess was significantly reduced in nonsurvivors (P < 0.001) and in patients with postoperative complications (P = 0.004). The area under the receiver-operator curve of lactate to mortality was 0.86, whereas that of BE to the mortality was 0.82. Moderate correlation was observed between the lactate level at ICU admission and the highest total bilirubin concentration measured within 14 days after the surgery (r = 0.61), whereas the correlation between BE and bilirubin levels was lower (r = 0.35). Using multivariate analysis, the lactate level independently predicted mortality (P = 0.008) and morbidity (P = 0.013). Lactate (P < 0.001) and BE (P = 0.0068) levels both independently predicted the highest bilirubin concentration. The arterial plasma lactate concentration measured on admission to ICU seemed an excellent predictor of patient outcome after liver resection.

The lactate:pyruvate ratio following open cardiac surgery in children

OBJECTIVE

To explore the relationship between lactate:pyruvate ratio, hyperlactataemia, metabolic acidosis, and morbidity.

DESIGN AND SETTING

Prospective observational study in the paediatric intensive care unit (PICU) of a university hospital.

PATIENTS

Ninety-seven children after open cardiac surgery. Most children (94%) fell into low-moderate operative risk categories; observed PICU mortality was 1%.

INTERVENTIONS

Blood was sampled on admission for acid-base analysis, lactate, and pyruvate. Metabolic acidosis was defined as standard bicarbonate lower than 22 mmol/l, raised lactate as higher than 2 mmol/l, and raised lactate:pyruvate ratio as higher than 20.

MEASUREMENTS AND RESULTS

Median cardiopulmonary bypass and aortic cross-clamp times were 80 and 46 min. Metabolic acidosis occurred in 74%, hyperlactataemia in 42%, and raised lactate:pyruvate ratio in 45% of children. In multivariate analysis lactate:pyruvate ratio increased by 6.4 in children receiving epinephrine infusion and by 0.4 per 10 min of aortic cross-clamp. Duration of inotropic support increased by 0.29 days, ventilatory support by 0.27 days, and PICU stay by 0.42 days, for each 1 mmol/l increase in lactate. Neither standard bicarbonate nor lactate:pyruvate ratio were independently associated with prolongation of PICU support.

CONCLUSIONS

Elevated lactate:pyruvate ratio was common in children with mild metabolic acidosis and low PICU mortality. Hyperlactataemia, but not elevated lactate:pyruvate ratio or metabolic acidosis, was associated with prolongation of PICU support. Routine measurement of lactate:pyruvate ratio is not warranted for children in low-moderate operative risk categories.

Relevance of the measurement of the concentration of lactate in the serum subsequent to the Fontan procedure in small children

BACKGROUND

To determine the clinical relevance of change in the level of lactate in the serum as a meanings of establishing the efficacy of the circulation immediately after the Fontan procedure in small children.

METHODS

We measured the concentration of lactate in the serum consecutively in 30 patients undergoing the Fontan procedure, without fenestration, under the age of 2 years. Of these, we did not use cardiopulmonary bypass in 13.

RESULTS

Concentrations gradually increased during the first several hours after establishment of the Fontan circulation, and then eventually decreased, reaching the normal range within 48 hours, with specific values of 0.9 plus or minus 0.3 pre-operatively, 2.3 plus or minus 1.1 immediately after creation of the Fontan circulation, 4.0 plus or minus 2.4 at 6 hours, 1.6 plus or minus 0.6 at 24 hours, and finally 1.3 plus or minus 0.4 millimoles per litre at 48 hours. This trend was irrespective of use or no use of cardiopulmonary bypass. The higher initial level in the intensive care unit was related to higher systemic venous pressure, higher transpulmonary pressure gradient, higher maximal level of alanine transaminase and blood urea nitrogen, and longer duration of peritoneal drainage, the latter as a monitor of sequestration of fluid rather than peritoneal dialysis. In patients with initial levels greater than 3.0 millimoles per litre, there was extended duration of endotracheal intubation.

CONCLUSIONS

Postoperative changes in the levels of lactate in the serum subsequent to creation of the Fontan procedure were peculiar, not necessarily correlated with the cardiac output, but relevant to the clinical course.