Capillary Refill Time and Serum Lactate as Predictors of Mortality and Postoperative Extracorporeal Membrane Oxygenation Requirement in Congenital Heart Surgery

Multiple tissue perfusion markers are described to guide therapy in critically ill pediatric patients undergoing congenital heart surgery. Given the advantages of capillary refill time, our goal is to determine its predictive capacity for mortality and postoperative extracorporeal oxygenation requirements in congenital heart surgery and compare it to serum lactate. We conducted a prospective cohort observational study in a single high-complexity university hospital. Serum lactate and capillary refill time were measured at five predetermined time points: preoperative, immediate postoperative, 6, 12, and 24 h after the surgery. Prolonged immediate postoperative, 6 h, and 12 h capillary refill time measurements turned out to be independent risk factors for both outcomes. The capillary refill time area under the curve ranged between 0.70 and 0.80, while the serum lactate resulted between 0.79 and 0.92 for both outcomes. Both tissue perfusion markers resulted in mortality and extracorporeal oxygenation requirement predictors. Given the advantages of capillary refill time over serum lactate, a monitoring strategy including these two perfusion markers should be considered for congenital heart surgeries.

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.

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.

Correlation between regional tissue perfusion saturation and lactate level during cardiopulmonary bypass

Background

Cardiopulmonary bypass (CPB) can cause systemic hypoperfusion, which remains undetected by routine monitoring of physiological parameters. Noninvasive tissue perfusion monitoring offers a clinical benefit by detecting low systemic perfusion. In this study, we tried to evaluate whether regional tissue perfusion saturation reflects systemic hypoperfusion during CPB.

Methods

This retrospective study included 29 patients with American Society of Anesthesiologists physical status II–III, who required cardiac surgery with CPB. We evaluated the correlations of serum lactate and delivery oxygen with organ perfusion values of peripheral tissue oxygen saturation and cerebral oxygen saturation. Data were recorded at different stages of CPB: T1 (pre-CPB), T2 (cooling), T3 (hypothermia), T4 (rewarming), and T5 (post-CPB).

Results

Lactate levels were elevated after CPB and up to weaning (P < 0.05). The levels of peripheral and tissue oxygen saturation decreased after the start of CPB (P < 0.05). Lactate levels were negatively correlated with peripheral tissue oxygen saturation levels at T4 (R = −0.384) and T5 (R = −0.370) and positively correlated with cerebral oxygen saturation at T3 (R = 0.445). Additionally, delivery oxygen was positively correlated with peripheral tissue oxygen saturation at T4 (R = 0.466).

Conclusions

In this study, we demonstrated that peripheral tissue oxygen saturation can be a reliable tool for monitoring systemic hypoperfusion during CPB period. We also believe that peripheral tissue oxygen saturation is a valuable marker for detecting early stages of hypoperfusion during cardiac surgery.

Near-Infrared Spectroscopy and Vascular Occlusion Test for Predicting Clinical Outcome in Pediatric Cardiac Patients: A Prospective Observational Study

OBJECTIVES

This study is designed to determine the feasibility and utility of vascular occlusion test variables as measured by INVOS Medtronic, Dublin, Ireland) in pediatric cardiac patients.

DESIGN

A prospective observational study.

SETTING

A tertiary children's hospital.

PATIENTS

Children less than or equal to 8 years old who were scheduled for elective cardiac surgery under cardiopulmonary bypass.

INTERVENTIONS

A vascular occlusion test (3 min of ischemia and reperfusion) was performed on the calf at three time points: after induction of anesthesia (T0), during cardiopulmonary bypass (T1), and after sternal closure (T2).

MEASUREMENTS AND MAIN RESULTS

Baseline regional tissue hemoglobin oxygen saturation, deoxygenation rate, minimum regional tissue hemoglobin oxygen saturation, and reoxygenation rate were measured using INVOS. Influence of age on variables at each measurement point was also checked using linear regression analysis. Receiver operating characteristics curve analysis was performed to determine the ability of vascular occlusion test variables at T2 to predict the occurrence of major adverse events. Both the deoxygenation and reoxygenation rates were lowest in T1. There was a tendency to decreased regional tissue hemoglobin oxygen saturation in younger patients at T0 (r = 0.37; p < 0.001), T1 (r = 0.33; p < 0.001), and T2 (r = 0.42; p < 0.001) during vascular occlusion. Minimum regional tissue hemoglobin oxygen saturation was correlated with age at T0 (r = 0.51; p < 0.001) and T2 (r = 0.35; p = 0.001). Patients with major adverse events had similar baseline regional tissue hemoglobin oxygen saturation but lower minimum regional tissue hemoglobin oxygen saturation (48.8% ± 19.3% vs 63.3% ± 13.9%; p < 0.001) and higher reoxygenation rate (4.30 ± 3.20 vs 2.57 ± 2.39 %/s; p = 0.008) at T2 compared with those without. The minimum regional tissue hemoglobin oxygen saturation less than 51% after sternal closure could predict the occurrence of major adverse events with a sensitivity of 61.1% and a specificity of 85.4%.

CONCLUSIONS

Vascular occlusion test using INVOS can be applied in children undergoing cardiac surgery. Vascular occlusion test variables are influenced by age and cardiopulmonary bypass. The minimum regional tissue hemoglobin oxygen saturation less than 51% after sternal closure is associated with worse clinical outcomes in pediatric cardiac patients.

Metabolic acidosis and the role of unmeasured anions in critical illness and injury

Acid-base disorders are frequently present in critically ill patients. Metabolic acidosis is associated with increased mortality, but it is unclear whether as a marker of the severity of the disease process or as a direct effector. The understanding of the metabolic component of acid-base derangements has evolved over time, and several theories and models for precise quantification and interpretation have been postulated during the last century. Unmeasured anions are the footprints of dissociated fixed acids and may be responsible for a significant component of metabolic acidosis. Their nature, origin, and prognostic value are incompletely understood. This review provides a historical overview of how the understanding of the metabolic component of acid-base disorders has evolved over time and describes the theoretical models and their corresponding tools applicable to clinical practice, with an emphasis on the role of unmeasured anions in general and several specific settings.

Metabolic Profiling of Children Undergoing Surgery for Congenital Heart Disease

Supplemental Digital Content is available in the text.

Objective:

Inflammation and metabolism are closely interlinked. Both undergo significant dysregulation following surgery for congenital heart disease, contributing to organ failure and morbidity. In this study, we combined cytokine and metabolic profiling to examine the effect of postoperative tight glycemic control compared with conventional blood glucose management on metabolic and inflammatory outcomes in children undergoing congenital heart surgery. The aim was to evaluate changes in key metabolites following congenital heart surgery and to examine the potential of metabolic profiling for stratifying patients in terms of expected clinical outcomes.

Design:

Laboratory and clinical study.

Setting:

University Hospital and Laboratory.

Patients:

Of 28 children undergoing surgery for congenital heart disease, 15 underwent tight glycemic control postoperatively and 13 were treated conventionally.

Interventions:

Metabolic profiling of blood plasma was undertaken using proton nuclear magnetic resonance spectroscopy. A panel of metabolites was measured using a curve-fitting algorithm. Inflammatory cytokines were measured by enzyme-linked immunosorbent assay. The data were assessed with respect to clinical markers of disease severity (Risk Adjusted Congenital heart surgery score-1, Pediatric Logistic Organ Dysfunction, inotrope score, duration of ventilation and pediatric ICU-free days).

Measurements and Main Results:

Changes in metabolic and inflammatory profiles were seen over the time course from surgery to recovery, compared with the preoperative state. Tight glycemic control did not significantly alter the response profile. We identified eight metabolites (3-d-hydroxybutyrate, acetone, acetoacetate, citrate, lactate, creatine, creatinine, and alanine) associated with surgical and disease severity. The strength of proinflammatory response, particularly interleukin-8 and interleukin-6 concentrations, inversely correlated with PICU-free days at 28 days. The interleukin-6/interleukin-10 ratio directly correlated with plasma lactate.

Conclusions:

This is the first report on the metabolic response to cardiac surgery in children. Using nuclear magnetic resonance to monitor the patient journey, we identified metabolites whose concentrations and trajectory appeared to be associated with clinical outcome. Metabolic profiling could be useful for patient stratification and directing investigations of clinical interventions.

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.