Intraoperative lactate levels and postoperative complications of pediatric cardiac surgery

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.

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.

Intraoperative changes in blood lactate levels are associated with worse short-term outcomes after cardiac surgery with cardiopulmonary bypass

Background:

A high perioperative blood lactate level has been reported to be associated with poor outcomes after cardiac surgery. More than isolated peaks of lactate values, it should be more interesting to take into account changes in intraoperative blood lactate level (∆Lact). This large-scale retrospective study evaluated the relationship between ∆Lact and overall intensive care unit morbidity and 30-day all-cause mortality.

Methods:

Perioperative data from consecutive patients undergoing on-pump cardiac surgery between September 2010 and June 2016 were retrospectively analysed through our institutional database including clinical, transfusion and laboratory test results implemented prospectively by physicians. Blood lactate levels were initially measured after induction of anaesthesia (baseline) and periodically during the surgery. The ∆Lact was defined as the difference between the highest intraoperative blood lactate and the baseline lactate level and offered the opportunity to stratify patients into four subgroups: ⩽0, 0.1-0.9, 1-1.9 and ⩾2 mmol L−1.

Results:

From the 7,795 patients found eligible during the study period, 7,447 patients were analysed. The median ∆Lact of our patients was 0.6 (0.3-1) mmol L−1. Most of the studied patients (65.9%) exhibited a ∆Lact between 0.1 and 0.9 mmol L−1. A concentration-dependent relationship was observed between ∆Lact and intensive care unit morbidity and 30-day mortality. After adjustment for co-variables, all ∆Lact > 0 was associated with an increase in overall intensive care unit morbidity. An independent relationship was also found between ∆Lact and 30-day mortality as of a 1 mmol L−1 increase.

Conclusion:

Our results suggest that ∆Lact is associated with poor short-term outcomes in adult cardiac surgical patients.

Hyperlactatemia and Patient Outcomes After Pediatric Cardiac Surgery

Elevated serum lactate level, or hyperlactatemia, is often associated with alterations in tissue perfusion, increased risk for complications in the postoperative period, and patient mortality. Measuring lactate levels is a relatively simple and noninvasive method of obtaining useful data about an impending clinical deterioration in a seemingly hemodynamically stable patient. This article evaluates the current practice of measuring lactate levels in pediatric patients after cardiac surgery and the association between these levels and patient outcomes. The article addresses periods of increased risk for decreased perfusion, the critical postoperative period, use of lactate measurements in conjunction with a risk scoring system for pre-and postoperative congenital heart disease patients, and the implications of elevated lactate levels in nursing practice.

Metabolomic Fingerprinting of Infants Undergoing Cardiopulmonary Bypass: Changes in Metabolic Pathways and Association With Mortality and Cardiac Intensive Care Unit Length of Stay

Background Mortality for infants undergoing complex cardiac surgery is >10% with a 30% to 40% risk of complications. Early identification and treatment of high-risk infants remains challenging. Metabolites are small molecules that determine the minute-to-minute cellular phenotype, making them ideal biomarkers for postsurgical monitoring and potential targets for intervention. Methods and Results We measured 165 serum metabolites by tandem mass spectroscopy in infants ≤120 days old undergoing cardiopulmonary bypass. Samples were collected prebypass, during rewarming, and 24 hours after surgery. Partial least squares-discriminant analysis, pathway analysis, and receiver operator characteristic curve analysis were used to evaluate changes in the metabolome, assess altered metabolic pathways, and discriminate between survivors/nonsurvivors as well as upper/lower 50% intensive care unit length of stay. Eighty-two infants had preoperative samples for analysis; 57 also had rewarming and 24-hour samples. Preoperation, the metabolic fingerprint of neonates differed from older infants ( R2=0.89, Q2=0.77; P<0.001). Cardiopulmonary bypass resulted in progressive, age-independent metabolic disturbance ( R2=0.92, Q2=0.83; P<0.001). Multiple pathways demonstrated changes, with arginine/proline ( P=1.2×10-35), glutathione ( P=3.3×10-39), and alanine/aspartate/glutamate ( P=1.4×10-26) metabolism most affected. Six subjects died. Nonsurvivors demonstrated altered aspartate ( P=0.007) and nicotinate/nicotinamide metabolism ( P=0.005). The combination of 24-hour aspartate and methylnicotinamide identified nonsurvivors versus survivors (area under the curve, 0.86; P<0.01), as well as upper/lower 50% intensive care unit length of stay (area under the curve, 0.89; P<0.01). Conclusions The preoperative metabolic fingerprint of neonates differed from older infants. Large metabolic shifts occurred after cardiopulmonary bypass, independent of age. Nonsurvivors and subjects requiring longer intensive care unit length of stay showed distinct changes in metabolism. Specific metabolites, including aspartate and methylnicotinamide, may differentiate sicker patients from those experiencing a more benign course.

A Review of Goal-Directed Cardiopulmonary Bypass Management in Pediatric Cardiac Surgery

Cardiopulmonary bypass perfusion management significantly affects postoperative outcomes. In recent years, the principles of goal-directed therapy have been applied to the field of cardiothoracic surgery to improve patient outcomes. Goal-directed therapy involves continuous peri- and postoperative monitoring of vital clinical parameters to tailor perfusion to each patient's specific needs. Closely measured parameters include fibrinogen, platelet count, lactate, venous oxygen saturation, central venous oxygen saturation, mean arterial pressure, perfusion flow rate, and perfusion pulsatility. These parameters have been shown to influence postoperative fresh frozen plasma transfusion rate, coagulation state, end-organ perfusion, and mortality. In this review, we discuss the recent paradigm shift in pediatric perfusion management toward goal-directed perfusion.

Postoperative Serum Troponin Trends in Infants Undergoing Cardiac Surgery

Troponin-I (TN-I) levels are elevated following pediatric cardiac surgery with speculation that particular patterns may have prognostic significance. There is lack of procedure-specific data regarding postoperative TN-I levels in infants undergoing cardiac surgery. We hypothesized that TN-I elevation varies with type of surgery and persistent elevation predicts poor prognosis. We prospectively measured serial TN-I levels (preoperatively, 4, 8, 12, 24, and 48 hours postoperatively) in 90 infants (age < 1 year) undergoing cardiac surgery: off cardiopulmonary bypass (CPB) (n = 15), on CPB (n = 43), and on CPB with ventricular incision (CPB with ventricular incision; n = 32). All patients had undetectable baseline TN-I levels. The area under the curve of TN-I levels over the 48-hour period was significantly different among the surgical groups (P < 0.002), and highest in patients with CPB with ventricular incision. Generally, TN-I levels peaked by 4 hours after surgery and returned to near-normal levels within 48 hours. A persistent TN-I rise beyond 8 hours after surgery was a strong predictor of postoperative hypoperfusion injury (defined as a composite endpoint of end-organ injury resulting from inadequate perfusion, odds ratio 21.5; P = 0.001) and mortality (30% in those with persistently high TN-I, compared with 3.5% in the remaining patients; P < 0.001), independent of patient age, anatomy and/or complexity of surgery, and level of postoperative support. Our data provide benchmark values for TN-I levels following cardiac surgery in infants. Extent of TN-I elevation correlates with type of surgery. Persistent TN-I elevation beyond 8 hours after surgery is strongly associated with postoperative hypoperfusion injury and mortality.

Predictors of severe postoperative hyperglycemia after cardiac surgery in infants: a single-center, retrospective, observational study

PURPOSE

Hyperglycemia is a common issue in infants after cardiac surgery for congenital heart disease. Poor glycemic control is suspected to be associated with adverse postoperative outcomes. This study was performed to investigate clinical factors contributing to hyperglycemia in the perioperative period in infats.

METHODS

A total of 69 infants (aged 1-12 months) who were admitted to Yokohama City University Hospital Intensive Care Unit (ICU) after surgical repair of congenital heart diseases with cardiopulmonary bypass (CPB) were retrospectively analysed. Hyperglycemia was defined as blood glucose ≥ 250 mg/dL on ICU admission. Clinical background, operative factors, and postoperative factors were compared between the hyperglycemic and non-hyperglycemic groups. Additionally, multivariate analysis was performed to identify factors contributing to hyperglycemia.

RESULTS

Nineteen (27.5%) and 50 (72.5%) infants were classified into the hyperglycemic and non-hyperglycemic groups, respectively. Hyperglycemic infants were significantly younger, shorter, and weighed less, with a higher rate of chromosomal abnormalities. Intraoperatively, they also experienced longer CPB and surgery times and had higher peak lactate levels and higher inotropic requirements. Hyperglycemia was related to longer mechanical ventilation and longer ICU stays. Multivariate analysis detected intraoperative hyperglycemia, longer CPB time, younger age and chromosomal abnormality as significant factors.

CONCLUSION

Adding to hyperglycemia during the operation, longer CPB time younger age and chromosomal abnormality were identified as predictors of high blood glucose levels at ICU admission.

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.

Prognostic role of BNP in children undergoing surgery for congenital heart disease: analysis of prediction models incorporating standard risk factors

BACKGROUND

The routine use of brain natriuretic peptide (BNP) in pediatric cardiac surgery remains controversial. Our aim was to test whether BNP adds information to predict risk in pediatric cardiac surgery.

METHODS

In all, 587 children undergoing cardiac surgery (median age 6.3 months; 1.2-35.9 months) were prospectively enrolled at a single institution. BNP was measured pre-operatively, on every post-operative day in the intensive care unit, and before discharge. The primary outcome was major complications and length ventilator stay >15 days. A first risk prediction model was fitted using Cox proportional hazards model with age, body surface area and Aristotle score as continuous predictors. A second model was built adding cardiopulmonary bypass time and arterial lactate at the end of operation to the first model. Then, peak post-operative log-BNP was added to both models. Analysis to test discrimination, calibration, and reclassification were performed.

RESULTS

BNP increased after surgery (p<0.001), peaking at a mean of 63.7 h (median 36 h, interquartile range 12-84 h) post-operatively and decreased thereafter. The hazard ratios (HR) for peak-BNP were highly significant (first model HR=1.40, p=0.006, second model HR=1.44, p=0.008), and the log-likelihood improved with the addition of BNP at 12 h (p=0.006; p=0.009). The adjunction of peak-BNP significantly improved the area under the ROC curve (first model p<0.001; second model p<0.001). The adjunction of peak-BNP also resulted in a net gain in reclassification proportion (first model NRI=0.089, p<0.001; second model NRI=0.139, p=0.003).

CONCLUSIONS

Our data indicates that BNP may improve the risk prediction in pediatric cardiac surgery, supporting its routine use in this setting.

Retuning mortality risk prediction in paediatric cardiac surgery: the additional role of early postoperative metabolic and respiratory profile

OBJECTIVES

The existing risk stratification scores for paediatric patients undergoing cardiac surgery include the Aristotle Basic Complexity (ABC) Score, the Risk Adjustment in Congenital Heart Surgery-1 (RACHS-1) Score and the Aristotle Comprehensive Complexity (ACC) Score. They are all based on the nature of the surgical operation (ABC and RACHS-1 Scores) with possible adjustment for a number of patient conditions (ACC Score). The present study investigates if the early postoperative parameters may be used to improve the preoperative mortality risk prediction.

METHODS

A retrospective study on 1392 consecutive patients aged ≤12 years old, undergoing cardiac surgery with cardiopulmonary bypass and without a residual right-to-left shunt was conducted. The ABC Score and metabolic and respiratory postoperative parameters at arrival in the intensive care unit were tested for association and discriminative power for operative mortality.

RESULTS

The ABC yielded a c-statistic of 0.746. Additional independent predictors of operative mortality were postoperative hypoxia [Formula: see text] and arterial blood lactates. In a multivariable model including the ABC Score, postoperative hypoxia and arterial blood lactates remained independently associated with operative mortality. A modified ABC Score was created, consisting of the ABC Score plus 1.5 points in case of postoperative hypoxia plus 1 point per each 1 mmol/l of arterial blood lactates. The new model was significantly (P = 0.043) more discriminative than the ABC Score, with a c-statistic of 0.803.

CONCLUSIONS

Early postoperative respiratory and metabolic parameters increased the accuracy and discrimination of the ABC Score. An external validation is needed to confirm our results.

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.

Relationship between early postoperative C-reactive protein elevation and long-term postoperative major adverse cardiovascular and cerebral events in patients undergoing off-pump coronary artery bypass graft surgery: a retrospective study

BACKGROUND

Inflammation plays a key role in the pathogenesis of vascular occlusive diseases, such as myocardial infarction and stroke. Additionally, these conditions are predicted by C-reactive protein (CRP), a general inflammation marker. We hypothesized that the inflammation induced by surgery itself augments vascular occlusive disease. We retrospectively evaluated the relationship between postoperative CRP elevation and postoperative major adverse cardiovascular and cerebral events (MACCE) in patients undergoing off-pump coronary artery bypass surgery (OPCAB).

METHODS

The electronic medical records of 1046 patients who underwent OPCAB were reviewed retrospectively. The relationship between postoperative serum CRP and long-term postoperative MACCE (median follow-up 28 months) was investigated.

RESULTS

Patients were divided into quartiles according to maximum postoperative CRP levels (<18, 18-22, 22-27, ≥27 mg dl(-1)). The adjusted hazard ratios (HRs) were 2.15, 2.45, and 2.81, respectively (P=0.004), compared with the lowest quartile (<18 mg dl(-1)). In the multivariate analysis, the postoperative CRP quartile (HR 2.81; P=0.004), postoperative non-use of statins (HR 1.86; P=0.003), and postoperative maximum troponin I (HR 1.02; P<0.001) independently predicted postoperative MACCE, while preoperative CRP did not (P=0.203). Several parameters were correlated with postoperative maximum CRP level: body temperature (P=0.001) and heart rate (P<0.001) at the end of surgery; intraoperative last lactate (P<0.001) and base excess (P<0.001); and red blood cell transfusion (P=0.019).

CONCLUSIONS

Postoperative CRP elevation was associated with long-term postoperative MACCE in OPCAB patients. This was mitigated by postoperative statin medication. Furthermore, postoperative CRP elevation was associated with intraoperative parameters reflecting hypoperfusion and inflammation.