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

Association between lactic acidosis and multiple organ dysfunction syndrome after cardiopulmonary bypass

Background

The relationship between hyperlactatemia and prognosis after cardiopulmonary bypass (CPB) is controversial, and some studies ignore the presence of lactic acidosis in patients with severe hyperlactacemia. This study explored the association between lactic acidosis (LA) and the occurrence of multiple organ dysfunction syndrome (MODS) after cardiopulmonary bypass.

Methods

This study was a post hoc analysis of patients who underwent cardiac surgery between February 2017 and August 2018 and participated in a prospective study at Taizhou Hospital. The data were collected at: ICU admission (H0), and 4, 8, 12, 24, and 48 h after admission. Blood lactate levels gradually increased after CPB, peaking at H8 and then gradually decreasing. The patients were grouped as LA, hyperlactatemia (HL), and normal control (NC) based on blood test results 8 h after ICU admission. Basic preoperative, perioperative, and postoperative conditions were compared between the three groups, as well as postoperative perfusion and oxygen metabolism indexes.

Results

There were 22 (19%), 73 (64%), and 19 (17%) patients in the LA, HL, and NC groups, respectively. APACHE II (24h) and SOFA (24h) scores were the highest in the LA group (P < 0.05). ICU stay duration was the longest for the LA group (48.5 (42.5, 50) h), compared with the HL (27 (22, 48) h) and NC (27 (25, 46) h) groups (P = 0.012). The LA group had the highest incidence of MODS (36%), compared with the HL (14%) and NC (5%) groups (P = 0.015). In the LA group, the oxygen extraction ratio (O2ER) was lower (21.5 (17.05, 32.8)%) than in the HL (31.3 (24.8, 37.6)%) and the NC group (31.3 (29.0, 35.4) %) (P = 0.018). In the univariable analyses, patient age (OR = 1.054, 95% CI [1.003-1.109], P = 0.038), the LA group (vs. the NC group, (OR = 10.286, 95% CI [1.148-92.185], P = 0.037), and ΔPCO2 at H8 (OR = 1.197, 95% CI [1.022-1.401], P = 0.025) were risk factor of MODS after CPB.

Conclusions

We speculated that there was correlation between lactic acidosis and MODS after CPB. In addition, LA should be monitored intensively after CPB.

Evaluation of perioperative risk factors in pediatric patients with left ventricle outflow tract obstruction

Introduction

Left ventricular outflow tract obstructions (LVOTO) presents as complex cardiac diseases accompanied by other cardiac anomalies in the pediatric age group. Postoperative complications, especially cardiac, pulmonary, and renal complications, that may develop after pediatric cardiac surgery can become life-threatening. If the perioperative risk factors for these complications are known in pediatric patients with LVOTO, anesthesiologists and surgeons may take precautions to eliminate undesirable outcomes.

Aim

To evaluate the perioperative risk factors that may contribute to the development of postoperative complications in pediatric patients operated on for LVOTO in a pediatric cardiac surgery clinic.

Material and methods

The study retrospectively investigated 58 patients who were operated on for LVOTO in a pediatric cardiac surgery clinic. The patients were divided into two groups, those with and without postoperative complications. Preoperative laboratory test results, anesthesia time, operation time, aortic cross-clamp time, cardiopulmonary bypass (CPB) time, postoperative inotropes, first postoperative laboratory tests, intraoperative and postoperative complications, mechanical ventilation time, intensive care unit stay, and hospital stay were recorded.

Results

The most common postoperative complications were endocrine complications, followed by hepatic complications. The preoperative lymphocyte count was significantly higher (p < 0.05), and the neutrophil-to-lymphocyte ratio (NLR) was significantly lower (p < 0.05) in the group with postoperative complications. The postoperative pH, glucose, creatinine, and aspartate aminotransferase (AST) levels were significantly lower (p < 0.05), and the postoperative calcium level was significantly higher (p < 0.05) in the group without postoperative complications. Intraoperative platelet transfusion rate was found to be significantly lower (p < 0.05) in the group with postoperative complications.

Conclusions

It is critical to identify predictive factors to prevent postoperative complications in pediatric patients undergoing surgery for LVOTO. Preoperative NLR, intraoperative platelet transfusion, and postoperative calcium, glucose, pH and AST levels may help in the prediction of complications.

Cardiopulmonary bypass in neonates and infants: advantages of high flow high hematocrit bypass strategy-clinical practice review

Cardiopulmonary bypass is an integral and indispensable part of surgical repair of congenital heart defects. While the complications and morbidity secondary to the use of cardiopulmonary bypass has decreased considerably, there remains a significant incidence of clinically relevant renal and neurological injury. To provide more physiological delivery of oxygenated blood to the end-organs, our center has been successfully using a high-flow, high hematocrit cardiopulmonary bypass strategy since 2006. The essential components of this strategy include maintaining high flows (typically 200 mL/kg/min in neonates, 150-175 mL/kg/min in older infants weighing <10 kg, and 2.6 L/min/m2 in older children) throughout the duration of cardiopulmonary bypass irrespective of patient temperature, as well as maintaining a hematocrit of at least 32% on cardiopulmonary bypass. The incidence of post-operative acute kidney injury (around 3%) and clinical acute neurological events (<1%) with this strategy is considerably less when compared to other contemporary publications using the conventional cardiopulmonary bypass strategy. In this review, we discuss the rationale behind our approach and present evidence to support the high-flow, high-hematocrit strategy. We also discuss the practical aspects of our strategy and describe the adjuncts we use to derive additional benefits. These adjuncts include the use of a hybrid pH/alpha stat strategy during cooling/rewarming, aggressive use of conventional ultrafiltration during cardiopulmonary bypass, a terminal hematocrit of 40-45%, and avoidance of milrinone and albumin in the early peri-operative period. This results in a very low incidence of post-operative bleeding, facilitates chest closure in the operating room even in most neonates, helps in reducing the need for post-operative blood product transfusion and helps in achieving a favorable post-operative fluid balance early after surgery.

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

Introduction

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

Methodology

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

Results

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

Discussion

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

Cardiac Arrest in Children Following Cardiac Surgery: A Scoping Review of Contributing Factors

Nearly half of children experiencing cardiac arrest following cardiac surgery do not survive hospital discharge and patients who survive often experience significant neurological impairment. Additionally, increased resource utilization following cardiac arrest translates into adverse logistical and financial consequences. Although some studies have identified patient characteristics that increase the risk of cardiac arrest after pediatric cardiac surgery, modifiable risk factors, which could provide a foundation for effective prevention strategies, have been elusive. This scoping review explores the current knowledge surrounding risk factors associated with cardiac arrest in children following cardiac surgery and provides recommendations for future research.

Admission serum lactate is associated with all-cause mortality in the pediatric intensive care unit

OBJECTIVE

Our aim was to assess the relationship between serum lactate levels at intensive care unit (ICU) admission and all-cause mortality in the pediatric ICU.

METHODS

We used the pediatric intensive care (PIC) database (a large pediatric intensive care database in China from 2010 to 2018) to conduct a retrospective analysis to evaluate the serum lactate levels at ICU admission of 12,213 critically ill children admitted to the ICU. We analyzed the association between serum lactate and all-cause mortality. Adjusted smoothing spline plots, subgroup analysis, and segmented multivariate logistic regression analysis were conducted to estimate the relative risk between proportional risk between serum lactate and all-cause mortality.

RESULTS

Of the 12,213 children, 755 (6.18%) died. After fully adjusting for confounding factors, serum lactate was an independent risk factor for all-cause mortality in pediatric ICU (adjusted OR=1.14, 95% CI: 1.12, 1.17). The results of sensitivity analysis showed that in different stratified analyses, the effect of serum lactate on all-cause mortality remained stable.

CONCLUSIONS

Admission serum lactate is a risk factor, which is independent of the presence of acid-base disorders, inflammation, malnutrition, and renal or hepatic dysfunction, for all-cause mortality in the pediatric intensive care unit.

Analysis of prognostic factors for in-hospital mortality in patients with unplanned re-exploration after cardiovascular surgery

Objective

To explore the prognostic factors for in-hospital mortality in patients with unplanned re-exploration after cardiovascular surgery.

Methods

We retrospectively analyzed the data of 100 patients who underwent unplanned re-exploration after cardiovascular surgery in our hospital between May 2010 and May 2020. There were 77 males and 23 females, aged (55.1 ± 15.2) years. Demographic characteristics, surgical information, perioperative complications were collected to establish a database. These patients were divided into surviving and non-surviving groups according to in-hospital mortality. Logistic regression was used for multivariable analysis to explore the prognostic factors of in-hospital mortality. These statistically significant indicators were selected for drawing the receiver operating characteristic curve of the evaluation model, calculating the area under the curve (AUC) and evaluating the effectiveness of the new model with Hosmer–Lemeshow C-statistic.

Results

In-hospital mortality in patients with unplanned re-exploration after cardiovascular surgery was 26.0% (26/100). Multivariate logistics regression revealed that the operation time of unplanned re-exploration, the worst blood creatinine value within 48 h before the re-exploration, the worst lactate value within 24 h after the re-exploration, cardiac insufficiency, respiratory insufficiency, and acute kidney injury were independent prognostic factors (P < 0.05). The AUC of the new assessment model constituted by these prognostic factors was 0.910, and the Hosmer–Lemeshow C-statistic was 4.153 (P = 0.762).

Conclusions

Operation time of unplanned re-exploration, worst serum creatinine value within 48 h before re-exploration, worst lactate value within 24 h after re-exploration, cardiac insufficiency, respiratory insufficiency, and acute kidney injury are the main prognostic factors for in-hospital mortality in patients with unplanned re-exploration after cardiovascular surgery. Identifying these prognostic factors can effectively facilitate preventive measures and improve patient outcomes.

Prognostic value of peak lactate during cardiopulmonary bypass in adult cardiac surgeries: A retrospective cohort study

Objective:

Tissue hypoperfusion during cardiopulmonary bypass (CPB) affects cardiac surgical outcomes. Lactate, an end product of anaerobic glycolysis from oxygen deficit, is a marker of tissue hypoxia. In this study, we aimed to identify the prognostic value of blood lactate level during CPB in predicting outcomes in adults undergoing cardiac surgeries.

Materials and Methods:

We retrospectively reviewed the medical records of patients who underwent cardiac surgeries with CPB from January 2015 to December 2015. Data about the characteristics of patients, preoperative status, type of surgery, and intraoperative lactate levels were collected. The outcomes were in-hospital mortality and complications. The receiver operating characteristics (ROC) curves were used to assess the ability of peak lactate level during CPB in predicting in-hospital mortality.

Results:

A total of 97 patients, including 61 who underwent emergent or urgent surgery, were enrolled. The types of surgery included coronary artery bypass grafting (CABG, n = 52), valve surgery (n = 27), combined surgery (CABG and valve surgery, n = 4), great vessel surgery (including aortic dissection, n = 9), and others (n = 5). The median CPB time was 139 min (interquartile range = 120–175). The median initial lactate and peak lactate levels during CPB were 0.9 and 4.2 mmol/L, respectively. In-hospital mortality was 14.4%, which was significantly associated with age and peak lactate level in the multivariate logistic regression model. When the peak lactate level during CPB reached 7.25 mmol/L, in-hospital mortality could be predicted with an area under the ROC curve of 0.75 (95% confidence interval: 0.59–0.90; P = 0.003), with a sensitivity of 57% and specificity of 93%.

Conclusion:

Hyperlactatemia during CPB was associated with increased in-hospital mortality. Thus, early detection of such conditions and aggressive postoperative care are important.

Peripheral perfusion index predicting prolonged ICU stay earlier and better than lactate in surgical patients: an observational study

Background

Peripheral perfusion index (PPI) is an indicator reflecting perfusion. Patients undergoing long time surgeries are more prone to hypoperfusion and increased lactate. Few studies focusing on investigating the association between PPI and surgical patients’ prognoses. We performed this study to find it out.

Methods

From January 2019 to September 2019, we retrospected all surgical patients who were transferred to ICU, Xinyang Central hospital, Henan province, China. Inclusive criteria: age ≥ 18 years old; surgical length ≥ 120 min. Exclusive criteria: died in ICU; discharging against medical advice; existing diseases affecting blood flow of upper limbs, for example, vascular thrombus in arms; severe liver dysfunction.

We defined “prolonged ICU stay” as patients with their length of ICU stay longer than 48 h. According to the definition, patients were divided into two groups: “prolonged group” (PG) and “non-prolong group” (nPG). Baseline characteristics, surgical and therapeutic information, ICU LOS, SOFA and APACHE II were collected. Besides we gathered data of following parameters at 3 time points (T0: ICU admission; T1: 6 h after admission; T2: 12 h after admission): mean artery pressure (MAP), lactate, heart rate (HR), PPI and body temperature. Data were compared between the 2 groups. Multivariable binary logistic regression and ROC (receiver operating characteristic) curves were performed to find the association between perfusion indictors and ICU LOS.

Results

Eventually, 168 patients were included, 65 in PG and 103 in nPG. Compared to nPG, patients in PG had higher blood lactate and lower PPI. PPI showed significant difference between two groups earlier than lactate (T₀ vs T₁). The value of PPI at two time points was lower in PG than nPG(T0: 1.09 ± 0.33 vs 1.41 ± 0.45, p = 0.001; T1: 1.08 ± 0.37 vs 1.49 ± 0.41, p < 0.001).

Increased lactate_T1(OR 3.216; 95% CI 1.253–8.254, P = 0.015) and decreased PPI_T1 (OR 0.070; 95% CI 0.016–0.307, P < 0.001) were independently associated with prolonged ICU stay. The area under ROC of the PPI_T1 for predicting ICU stay> 48 h was 0.772, and the cutoff value for PPI_T1 was 1.35, with 83.3% sensitivity and 73.8% specificity.

Conclusions

PPI and blood lactate at T₁(6 h after ICU admission) are associated with ICU LOS in surgical patient. Compared to lactate, PPI indicates hypoperfusion earlier and more accurate in predicting prolonged ICU stay.

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.

Glucocorticoid Receptor Polymorphisms in Children Undergoing Congenital Heart Surgery with Cardiopulmonary Bypass

We conducted a candidate gene association study to test the hypothesis that different gene polymorphisms will be associated with corticosteroid responsiveness and study outcomes among children undergoing congenital heart surgery. This is a prospective observational cohort study at a large, tertiary pediatric cardiac center on children undergoing corrective or palliative congenital heart surgery. A total of 83 children were enrolled. DNA was isolated for three polymorphisms of interest namely N363 (rs56149945) and 9β (rs6198) associated with increased sensitivity to corticosteroids and Bcl I (rs41423247) associated with decreased sensitivity to corticosteroids. Duration of inotropic use, low cardiac output scores (LCOS), and vasoactive inotrope scores were examined in relation to these three polymorphisms. Using Kaplan-Meier analysis, heterozygous individuals showed longer transcriptional intermediary factor (TIF) compared with wild type for N363 polymorphism ( p  = 0.05). In multivariable Cox regression, heterozygous alleles for 9β polymorphism showed significantly shorter TIF compared with wild type (hazard ratio = 2.04 [1.08-3.87], p  = 0.03). The relationship between lower LCOS scores and alleles groups was significant for 9β heterozygous polymorphism only (1.5 [1-2.2], p  = 0.01) in comparison to wild type and homozygous. The presence of heterozygote alleles for the increased corticosteroid sensitivity is associated with longer TIF compared with wild type. Conversely, the presence of heterozygous alleles for the decreased sensitivity to corticosteroids is associated with shorter TIF compared with wild type.

Lactate Measurements and Their Association With Mortality in Pediatric Severe Sepsis in India: Evidence That 6-Hour Level Performs Best

PURPOSE

To investigate association of static and dynamic lactate indices with early mortality (within 48 hours of admission), as well as need for vasopressors and mechanical ventilation in pediatric severe sepsis/shock. To explore optimal cutoffs of lactate indices. We hypothesized that dynamic indices are superior to static indices in predicting early mortality.

METHODS

This prospective cohort study involved children (aged <14 years) admitted in emergency department, tertiary care teaching hospital in North India with severe sepsis/shock (2015-2016). Arterial lactate was measured at admission (X0) and after 6 hours (X6). Primary outcome of the measurement was early mortality. Association between lactate indices- lactate at 0 hours (Lac0), lactate after 6 hours (Lac6), time-weighted average (LacTW), delta (ΔLac), clearance (LacCl%) and early mortality, need for vasopressors, and mechanical ventilation-was assessed using Student t test/Mann-Whitney test. Area under the receiver operating characteristic curve (AUROC) for early mortality deduced for all lactate indices and compared with reference (Lac0). Optimal cutoffs (maximizing both sensitivity and specificity) and their positive predictive value (PPV) and negative predictive value (NPV) were determined.

RESULTS

During the study period, 116 children were assessed. Septic shock was present at admission in 56.9% children; 50% of children died during the next 48 hours. Lac0, Lac6, and LacTW were significantly higher, and LacCl% was lower in nonsurvivors versus survivors (all P < .001). Lac6 (0.837 [0.76-0.91]) had significantly higher AUROC (95% confidence interval) than Lac0 (0.77; P = .03). Abnormal lactate metrics (higher Lac0, Lac6, LacTW, and lower LacCl%) were associated with vasopressors need and mechanical ventilation. On logistic regression, Lac6 emerged as an independent predictor of early mortality as well as vasopressor and mechanical ventilation need. The optimal cutoff of Lac6 for identifying early mortality with good sensitivity, specificity, PPV, and NPV was ≥2.65 (76, 85, 83, 78).

CONCLUSIONS

Lactate6 is the best marker associated with early mortality and higher level of care in severe sepsis/septic shock in resource-poor regions.

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.

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.

Assessment of changes in lactate concentration with intravascular microdialysis during high-risk cardiac surgery using the trend interchangeability method

Background

Blood lactate is a strong predictor of mortality, and repeated blood lactate assays are recommended during surgery in high-risk patients. We hypothesized that the use of intravascular microdialysis incorporated in a central venous catheter would be interchangeable with the reference blood gas technique to monitor changes in blood lactate.

Methods

Microdialysis and central venous blood lactate measurements were recorded simultaneously in high-risk cardiac surgical patients. The correlation between absolute values was determined by linear regression, and the Bland-Altman test for repeated measurements was used to compare bias, precision, and limits of agreement. Changes in lactate measurements were evaluated with a four-quadrant plot and trend interchangeability method (TIM).

Results

In the 23 patients analysed, the central venous catheter was used as part of standard care, with no complications. The correlation coefficient for absolute values ( n =104) was 0.96 ( P <0.0001). The bias, precision, and limits of agreement were -0.19, 0.51, and -1.20 to 0.82 mmol litre -1 , respectively. The concordance rate for changes in blood lactate measurements ( n =80) was 94% with the four-quadrant plot. In contrast, the TIM showed that 23 (29) changes in lactate measurements were not interpretable, and among the remaining 57 (71) interpretable changes, 18 (32) were interchangeable, 8 (14) were in the grey zone, and 31 (54) were not interchangeable.

Conclusions

Microdialysis with a central venous catheter appears to provide reliable absolute blood lactate values. Although changes in blood lactate measurements showed an excellent concordance rate, changes between the two methods were poorly interchangeable with the TIM.

Clinical trial registration

NCT02296593.

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.

Evaluation of a novel in-line point-of-care blood gas analyser

Point-of-care testing is becoming increasingly relevant to the practice of anaesthesia and critical care medicine, especially in terms of minimisation of sample volumes and decreased time to decision making. We performed a prospective observational study to evaluate a novel, in-line blood gas analysis device against a conventional benchtop model, and assessed it while placing the enrolled patients under extreme physiological conditions, specifically deep hypothermic circulatory arrest. Eight patients were studied, and had between seven and 11 samples analysed for seven variables (pH, pCO2 , pO2 , HCO3 (-) , base excess [BE], K(+) and haematocrit [Hct]), using the device during the process of cooling to 20 °C on cardiopulmonary bypass, and subsequent rewarming to normothermia. After Passing-Bablok analysis, the variables were evaluated for bias, limits of agreement and percentage error at above and below 30 °C. Of the measured variables, only pH (percentage error 2.4%) and potassium (19.8%) demonstrated acceptable (< 30%) percentage error over the full range of temperatures measured. Carbon dioxide, when stratified by temperature, was acceptable (< 30 °C percentage error 24.6%, > 30 °C percentage error 9.9%), but the overall percentage error of the dataset (45.8%) was excessively high. Bicarbonate and haematocrit both had an acceptable percentage error above 30 °C (25.2% and 18.5%, respectively), but similar to carbon dioxide, percentage error for the full range of temperatures exceeded 30%. These data differ from previous work examining this device, and highlights the difference between derived measures using different apparatuses when exposed to extreme physiological conditions.

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.