Factors affecting on serum lactate after cardiac surgery

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.

Machine learning predicts blood lactate levels in children after cardiac surgery in paediatric ICU

BACKGROUND

Although serum lactate levels are widely accepted markers of haemodynamic instability, an alternative method to evaluate haemodynamic stability/instability continuously and non-invasively may assist in improving the standard of patient care. We hypothesise that blood lactate in paediatric ICU patients can be predicted using machine learning applied to arterial waveforms and perioperative characteristics.

METHODS

Forty-eight post-operative children, median age 4 months (2.9-11.8 interquartile range), mean baseline heart rate of 131 beats per minute (range 33-197), mean lactate level at admission of 22.3 mg/dL (range 6.3-71.1), were included. Morphological arterial waveform characteristics were acquired and analysed. Predicting lactate levels was accomplished using regression-based supervised learning algorithms, evaluated with hold-out cross-validation, including, basing prediction on the currently acquired physiological measurements along with those acquired at admission, as well as adding the most recent lactate measurement and the time since that measurement as prediction parameters. Algorithms were assessed with mean absolute error, the average of the absolute differences between actual and predicted lactate concentrations. Low values represent superior model performance.

RESULTS

The best performing algorithm was the tuned random forest, which yielded a mean absolute error of 3.38 mg/dL when predicting blood lactate with updated ground truth from the most recent blood draw.

CONCLUSIONS

The random forest is capable of predicting serum lactate levels by analysing perioperative variables, including the arterial pressure waveform. Thus, machine learning can predict patient blood lactate levels, a proxy for haemodynamic instability, non-invasively, continuously and with accuracy that may demonstrate clinical utility.

Does severe hyperlactatemia during cardiopulmonary bypass predict a worse outcome?

INTRODUCTION

The aim of the current study was to evaluate the impact of increased blood lactate levels during cardiopulmonary bypass (CPB) on immediate results in patients who underwent open heart surgery.

MATERIALS AND METHODS

We performed a retrospective single-center study on 1290 patients. Adult cardiac surgical patients who underwent valve surgery, coronary artery bypass graft, combined procedure, adult congenital anomalies and aortic surgery were enrolled. Patients with associated comorbidities such as liver dysfunction, hemodynamic instability before surgery were excluded. Arterial blood lactate concentration was measured immediately after weaning from CPB and evaluated together with clinical data and outcomes including in hospital mortality. Patients were classified into 3 groups according to their peak arterial lactate level: group I [normal lactatemia, lactate ˂ 2 mmol/l (n = 749)], group II [mild hyperlactatemia, lactate 2-5 mmol/l (n = 489)], group III [severe hyperlactatemia, lactate ˃ 5 mmol/l (n = 52)].

RESULTS

When comparing outcomes across the 3 groups, severe hyperlactatemia was correlated with worse outcomes including higher in-hospital mortality, low output cardiac syndrome, postoperative renal insufficiency, myocardial infarction, red blood cell transfusion (RBC) transfusion, prolonged mechanical ventilation and longer intensive care unit (ICU) stay hours.

CONCLUSION

Blood lactate level above 5 mmol/l and more during CPB is associated with higher in-hospital mortality rate and postoperative complications. More attention must be given to correct the common abnormalities conditions inherent of CPB in order to conduct adequate tissue perfusion and reduce the risk of hyperlactatemia.

Acute perioperative hyperlactatemia in oncoplastic reconstructive surgeries: What is the significance?

Background and Aims:

We aim to study the significance of intraoperative hyperlactatemia in reconstructive oncoplastic surgery.

Material and Methods:

A retrospective observational study was conducted on a cohort of patients who underwent reconstructive oncoplastic surgery with free flap for oral cancer over a 6-month period. The study population was divided into two groups based on peak lactate levels. Group N with peak lactate level less than 2 mmol/L and Group H peak lactate level more than 2 mmol/L. The various parameter studied were patient's comorbidities; intraoperative events (vasopressor requirement, blood transfusion, and duration of surgery); postoperative parameters including the need for re- exploration and duration of stay in hospital and intensive care unit.

Results:

The study demonstrates that intraoperative rise of lactate was not influenced by comorbidities. None of the intraoperative parameters studied influenced the lactate levels. Baseline lactate level was found to correlate with peak lactate level intraoperatively. But it was observed that there was normalization of lactate level within 24 hours postoperatively in both the groups. There was no difference in outcome parameters in the two groups.

Conclusion:

Intraoperative hyperlactatemia is not a significant prognostic factor for outcome in oncoplastic reconstructive surgery.

Systematic review on peri-operative lactate measurements to predict outcomes in patients undergoing liver resection

Lactate measurements have proven utility as a triage tool, therapeutic guide, and prognostic indicator, with broad use in Acute Care and transplantation. Its value in guiding therapy and predicting outcomes following liver resection is less well‐defined. This systematic review in accordance with Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines assessed the relationship between peri‐operative lactate levels and morbidity and mortality after liver resection. Seven relevant studies comprising 2573 patients in total were identified. Six studies assessed intra‐operative or early postoperative lactate levels, one publication examined pre‐operative levels. All studies demonstrated a significant association between peri‐operative lactate levels and adverse outcomes. The influence of pre‐operative diabetes and cirrhosis on postoperative lactate levels was shown in one study each, no study assessed the association of lactate with post‐hepatectomy liver failure according to defined criteria. The heterogeneity of study measurements and end‐points precluded a meta‐analysis from being performed. Early postoperative lactate >3‐3.7 mmol/L is associated with mortality but validation of clear cut‐off levels for outcome prediction is pending. Literature suggests lactate is a useful predictive marker for outcomes post liver surgery, especially when measured in the early postoperative phase. Further research is required to standardize the use of lactate measurements in a meaningful therapeutic manner.

Effect of Dexmedetomidine Infusion on Sublingual Microcirculation in Patients Undergoing On-Pump Coronary Artery Bypass Graft Surgery: A Prospective Randomized Trial

OBJECTIVES

Cardiac surgery is characterized by attenuation of microcirculatory perfusion. Dexmedetomidine has been proved to attenuate the microcirculatory derangements evoked by experimental sepsis. The authors investigated the effects of dexmedetomidine infusion on sublingual microcirculation in patients undergoing on-pump coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective, randomized blinded study.

SETTINGS

Tertiary university hospital.

PARTICIPANTS

A total of 70 adults undergoing elective on-pump CABG surgery.

INTERVENTION

After a standard general anesthesia, participants were allocated randomly to receive either propofol continuous intravenous infusion, 50 to 70 µg/kg/min, or propofol infusion, 50 to 70 µg/kg/min plus dexmedetomidine infusion, 0.5 µg/kg/h, during cardiopulmonary bypass. Microcirculation was studied with side-stream dark field imaging at 3 times: immediately before starting bypass (T0), 30 minutes after initiation of bypass (T1), and 30 minutes after weaning from bypass (T2).

MEASUREMENTS AND MAIN RESULTS

Microvascular flow index was significantly higher in the dexmedetomidine group at T2 compared to the control group (2.20 ± 0.29 and 1.47 ± 0.30, respectively; p = 0.001). The perfused vessel density was significantly higher in the dexmedetomidine group at T2 compared to the control group (6.1 [3-8.9] mm/mm² and 3.3 [2.2-4.3] mm/mm², respectively; p = 0.01). The total vascular density was significantly higher in the dexmedetomidine group compared to the control group at T1 and T2 (9.9 [7.8-12.6] mm/mm² v 7.4 [6.1-9] mm/mm², p = 0.005; and 9.27 ± 2.27 mm/mm² v 7.24 ± 1.66 mm/mm², p = 0.003, respectively).

CONCLUSION

This trial demonstrated that dexmedetomidine infusion improved sublingual microcirculation indices in patients undergoing on-pump CABG surgery.

Single-Dose Lignocaine-Based Blood Cardioplegia in Single Valve Replacement Patients

Objective

Myocardial protection is the most important in cardiac surgery. We compared our modified single-dose long-acting lignocaine-based blood cardioplegia with short-acting St Thomas 1 blood cardioplegia in patients undergoing single valve replacement.

Methods

A total of 110 patients who underwent single (aortic or mitral) valve replacement surgery were enrolled. Patients were divided in two groups based on the cardioplegia solution used. In group 1 (56 patients), long-acting lignocaine based-blood cardioplegia solution was administered as a single dose while in group 2 (54 patients), standard St Thomas IB (short-acting blood-based cardioplegia solution) was administered and repeated every 20 minutes. All the patients were compared for preoperative baseline parameters, intraoperative and all the postoperative parameters.

Results

We did not find any statistically significant difference in preoperative baseline parameters. Cardiopulmonary bypass time were 73.8±16.5 and 76.4±16.9 minutes (P=0.43) and cross clamp time were 58.9±10.3 and 66.3±11.2 minutes (P=0.23) in group 1 and group 2, respectively. Mean of maximum inotrope score was 6.3±2.52 and 6.1±2.13 (P=0.65) in group 1 and group 2, respectively. We also did not find any statistically significant difference in creatine-phosphokinase-MB (CPK-MB), Troponin-I levels, lactate level and cardiac functions postoperatively.

Conclusion

This study proves the safety and efficacy of long-acting lignocaine-based single-dose blood cardioplegia compared to the standard short-acting multi-dose blood cardioplegia in patients requiring the single valve replacement. Further studies need to be undertaken to establish this non-inferiority in situations of complex cardiac procedures especially in compromised patients.

Comparing the Effects of 5% Albumin and 6% Hydroxyethyl Starch 130/0.4 (Voluven) on Renal Function as Priming Solutions for Cardiopulmonary Bypass: A Randomized Double Blind Clinical Trial

Background:

The ideal strategy to prime the cardiopulmonary bypass (CPB) circuit in adult cardiac surgery is still a matter of debate.

Objectives:

In this retrospective study, we examined Albumin solution and hydroxyethyl starch (HES) for priming the CPB circuit and evaluated the differences in kidney function and bleeding and coagulation status in the two groups of patients.

Patients and Methods:

Sixty consecutive patients undergoing elective coronary artery bypass grafting were studied. Patients were excluded due to emergency surgery, history of cardiac surgery, history of receiving medication with antiplatelet agents except ASA 80 (mg/day) within the previous five days, preoperative coagulation disorder, left ventricular ejection fraction less than 50%, preoperative renal dysfunction (serum creatinine > 1.4 mg/dL), preoperative hepatic dysfunction (serum aspartate/alanine amino transferase > 60 U/l), preoperative electrolyte imbalance, known hypersensitivity to HES and chronic diuretic therapy. The patients were divided randomly into two groups of HES (n = 30) and Albumin (n = 30). Hemodynamic parameters, serum creatinine concentrations and glomerular filtration rate, PT, PTT and INR were measured. Early bleeding was measured according to the first 24-hour drainage from the tube. Hemodynamics and all laboratory measurements were performed after induction of anesthesia and at the morning of the first, second and third postoperative days in the ICU.

Results:

GFR differences were statistically lower in Albumin group in comparison with Group B at 24, 48 and 72 hours postoperation. Platelet count difference and postoperative bleeding were significantly lower in Albumin group.

Conclusions:

Administration of Albumin compared to HES in patients with a normal renal function results in a lower drop of GFR and platelet count, less bleeding and lower rise of serum creatinine.