Changes in myocardial lactate, pyruvate and lactate-pyruvate ratio during cardiopulmonary bypass for elective adult cardiac surgery: Early indicator of morbidity

Factors associated with increased lactate levels in cardiac surgeries: scoping review

OBJECTIVES

to map the factors associated with increased lactate levels in the postoperative period of cardiac surgery using extracorporeal circulation.

METHODS

this is a scoping review carried out in December 2022, across ten data sources. It was prepared in accordance with the recommendations of the Joanna Briggs Institute and the Preferred Reporting Items for Systematic Reviews and Meta Analyses Extension for Scoping Reviews checklist.

RESULTS

the most recurrent findings in studies regarding the factors responsible for the increase in lactate were: tissue hypoperfusion, cardiopulmonary bypass time and use of vasoactive drugs. In 95% of studies, increased lactate was related to increased patient mortality.

CONCLUSIONS

discussing the causes of possible complications in cardiac surgery patients is important for preparing the team and preventing complications, in addition to ensuring quality recovery.

Hyperlactatemia is associated with increased risks of long-term mortality and major adverse cardiovascular events in sepsis survivors

INTRODUCTION

Serum lactate is a potentially valuable biomarker for risk assessment for patients with sepsis, as hyperlactatemia is associated with elevated short-term mortality risks. However, the associations between hyperlactatemia and long-term clinical outcomes in sepsis survivors remain unknown. The objective of this study was to investigate whether hyperlactatemia at the time of hospitalisation for sepsis was associated with worse long-term clinical outcomes in sepsis survivors.

METHODS

In total, of 4983 sepsis survivors aged ≥ 20 years were enrolled in this study between January 1, 2012, and December 31, 2018. They were divided into low (≤18 mg/dL; n = 2698) and high (>18 mg/dL; n = 2285) lactate groups. The high lactate group was then matched 1:1 by propensity-score method to the low lactate group. The outcomes of interest were all-cause mortality, major adverse cardiac events (MACEs), ischaemic stroke, myocardial infarction, hospitalisation for heart failure, and end-stage renal disease.

RESULTS

After propensity score matching, the high lactate group had greater risks of all-cause mortality (hazard ratio [HR] 1.54, 95% confidence interval [CI] 1.41-1.67), MACEs (HR 1.53, 95% CI 1.29-1.81), ischaemic stroke (HR 1.47, 95% CI 1.19-1.81), myocardial infarction (HR 1.52, 95% CI 1.17-1.99), and end-stage renal disease (HR 1.42, 95% CI 1.16-1.72). Subgroup analyses stratified by baseline renal function revealed almost similarity across groups.

CONCLUSION

We found that hyperlactatemia is associated with long-term risks of mortality and MACEs in sepsis survivors. Physicians may consider more aggressive and prompter management of sepsis in patients who present with hyperlactatemia to improve long-term prognoses.

A comparison of postoperative blood lactate concentrations and kinetics in cardiac surgical patients being and not being administered metformin

Aim. Early discontinuation of metformin before cardiac surgery is advised by several national societies but no hard evidence exist supporting this practice. This precaution is mostly extrapolated by data on different clinical settings. The aim of this study is to investigate the impact of preoperative metformin use on lactate concentrations and lactate clearance during the first postoperative day after cardiac surgery.Methods. Among 367 consecutive patients who underwent elective on-pump cardiac surgery from January 2019 to October 2019, 109 were diabetics, 74 of which were treated with metformin. Data on lactate concentrations and clearance during the first postoperative day were prospectively collected on arrival, H6, H12 and H24 in the ICU and compared. A subgroup analysis focusing only on diabetic patients was also performed. Repeated measures multivariate analysis of variance (MANOVA) was used to investigate the data based on group, time and their interaction effects.Results. Lactate concentrations were the same for both groups upon arrival in the ICU. Interestingly, metformin users had lower lactate concentrations than non-users on the following measurements (p = 0.003 at 6 h and p = 0.01 at 24 h). No significant interaction was found between the two groups (p = 0.76). No difference was found between the two groups in terms of lactate clearance (p = 0.53). In the subgroup analysis no difference was found between metformin users and non-users neither on lactate concentrations (p = 0.61) nor on lactate clearance (p = 0.86).Conclusions. In a post cardiac surgery ICU setting, using metformin up until the night before surgery was not associated with increased postoperative lactate concentrations or impaired lactate clearance.

Target blood pressure management during cardiopulmonary bypass improves lactate levels after cardiac surgery: a randomized controlled trial

Background

Hyperlactatemia is associated with a poor prognosis in cardiac surgery patients. This study explored the impact of target blood pressure management during cardiopulmonary bypass (CPB) on blood lactate levels after cardiac surgery.

Methods

Adult patients undergoing cardiac valve surgery between 20/1/2020 and 30/6/2020 at Shanghai Chest Hospital were enrolled. The patients were randomized into a low mean arterial pressure (L-MAP) group (target MAP between 50 and 60 mmHg) or a high mean arterial pressure (H-MAP) group (target MAP between 70 and 80 mmHg), n = 20 for each. Norepinephrine was titrated only during CPB to maintain MAP at the target level. Blood lactate levels in the two groups were detected before the operation (T0), at the end of CPB (T1), at the end of the operation (T2), 1 h after the operation (T3), 6 h after the operation (T4) and 24 h after the operation (T5). The primary outcome was the blood lactate level at the end of the operation (T2). The secondary outcomes included the blood lactate level at T1, T3, T4, and T5 and the dose of epinephrine and dopamine within 24 h after the operation, time to extubation, length of stay in the ICU, incidence of readmission within 30 days, and mortality within 1 year.

Results

Forty patents were enrolled and analyzed in the study. The lactate level in the H-MAP group was significantly lower than that in the L-MAP group at the end of the operation (3.1 [IQR 2.1, 5.0] vs. 2.1 [IQR 1.7, 2.9], P = 0.008) and at the end of CPB and 1 hour after surgery. The dose of epinephrine within 24 h after the operation, time to extubation and length of stay in the ICU in the L-MAP group were significantly higher than those in the H-MAP group.

Conclusions

Maintaining a relatively higher MAP during CPB deceased the blood lactate level at the end of surgery, reduced epinephrine consumption, and shortened the time to extubation and length of stay in the ICU after surgery.

Trial registration

This single-center, prospective, RCT has completed the registration of the Chinese Clinical Trial Center at 8/1/2020 with the registration number ChiCTR2000028941. It was conducted from 20/1/2020 to 30/6/2020 as a single, blinded trial in Shanghai Chest Hospital.

Hyperlactatemia: An Update on Postoperative Lactate

While hyperlactatemia in postoperative cardiac surgery patients was once believed to solely reflect hypoperfusion, either from the accumulated "oxygen debt" during bypass or ongoing inadequate perfusion, our understanding of lactate generation, clearance, and management has evolved. A contemporary understanding of lactate balance is critical to the management of the postoperative patient with hyperlactatemia. In this review, we summarize the current understanding of lactate metabolism in pediatric patients following cardiac surgery and highlight two types of hyperlactatemia: type A, which is secondary to inadequate oxygen delivery and tissue hypoxia, and type B, which in postoperative pediatric cardiac surgery patients largely reflects increased glycolysis driven by the stress response. Both types may coexist; thus, it is imperative that providers first assess the patient for evidence of hypoperfusion. In patients with evidence of adequate perfusion, a type B component is often associated with a concomitant balanced (normal anion gap) metabolic acidosis and hyperglycemia. These patients will benefit from a more nuanced approach to their type B hyperlactatemia, as many will have a benign course and may be managed expectantly.

Comparison of the cardioprotective effects of dexmedetomidineand remifentanil in cardiac surgery

Background/aim: Myocardial protection is an important factor of open heart surgery and biological biomarkers (lactate, CKMB, cardiac troponin I, and pyruvate) are used to assess myocardial damage. This study compares the effects of dexmedetomidine and remifentanil on myocardial protection during coronary artery bypass grafting (CABG) surgery. Materials and methods: Patients scheduled for elective CABG surgery (n = 60) were included in this study. Anesthesia induction was introduced with propofol, fentanyl, and vecuronium bromide. Anesthesia was maintained with remifentanil infusion and sevoflurane in the remifentanil group (Group R) and with dexmedetomidine infusion and sevoflurane in the dexmedetomidine group (Group D). Blood samples for biochemical markers were taken from the coronary sinus catheter before cardiopulmonary bypass (T1), 20 min after aortic cross-clamping (T2), 20 min after removal of the aortic cross-clamping (T3), and 10 min after separation from cardiopulmonary bypass (T4).Results: Demographic data were similar between the groups. Lactate level at the T2 period and CKMB levels during the study period were lower in Group D than in Group R. In both groups, all values except pyruvate significantly increased over time. Conclusion: The dexmedetomidine-sevoflurane combination may improve the cardioprotective effect in comparison with remifentanil-sevoflurane in CABG surgery.

Lactate Elevation During and After Major Cardiac Surgery in Adults: A Review of Etiology, Prognostic Value, and Management

Elevated lactate is a common occurrence after cardiac surgery. This review summarizes the literature on the complex etiology of lactate elevation during and after cardiac surgery, including considerations of oxygen delivery, oxygen utilization, increased metabolism, lactate clearance, medications and fluids, and postoperative complications. Second, the association between lactate and a variety of outcomes are described, and the prognostic role of lactate is critically assessed. Despite the fact that elevated lactate is strongly associated with many important outcomes, including postoperative complications, length of stay, and mortality, little is known about the optimal management of postoperative patients with lactate elevations. This review ends with an assessment of the limited literature on this subject.

Hyperlactatemia and Cardiac Surgery

The normal blood lactate level is 0-2 mmol/L, and a value above 3-5 mmol/L is variably used to define hyperlactatemia. In cardiac surgical patients, hyperlactatemia can arise from both hypoxic and non-hypoxic mechanisms. The major non-hypoxic mechanism is likely stress-induced accelerated aerobic metabolism, in which elevated lactate results from a mass effect on the lactate/pyruvate equilibrium. The lactate/pyruvate ratio is normal (<20) in this circumstance. Hyperlactatemia can also result from impaired global or regional oxygen delivery, in which case the lactate/pyruvate ratio is typically elevated (>20). Lactate is a strong anion that is virtually fully dissociated at physiological pH. As such, increased lactate concentration reduces the strong ion difference and exerts an acidifying effect on the blood. Hyperlactatemia in cardiac surgery patients has been categorized as either early or late onset. Early-onset hyperlactatemia is that which develops in the operating room or very early following intensive care unit (ICU) admission. Early-onset hyperlactatemia is strongly associated with adverse outcome and probably arises as a consequence of both hypoxic (e.g., microcirculatory shock) and non-hypoxic (accelerated aerobic metabolism) mechanisms. By contrast, late-onset hyperlactatemia is a benign, self-limiting condition that typically arises within 6-12 hours of ICU admission and spontaneously resolves within 24 hours. Late onset hyperlactatemia occurs in the absence of any evidence of global or regional tissue hypoxia. The mechanism of late onset hyperlactatemia is not understood. Hyperlactatemia is a common accompaniment to treatment with β₂-agonists such as epinephrine. Epinephrine-induced hyperlactatemia is thought to be due to accelerated aerobic metabolism and requires no specific intervention. Irrespective of the cause, the presence of hyperlactatemia should trigger a search for remedial causes of impaired tissue oxygenation, bearing in mind that normal-or even supranormal-indices of global oxygen delivery may exist despite regional tissue hypoperfusion.

Short-Term Effects and Safety Analysis of Retrograde Autologous Blood Priming for Cardiopulmonary Bypass in Patients with Cardiac Valve Replacement Surgery

This randomized, double-blind study evaluated the short-term effects and safety of perioperative retrograde autologous priming (RAP) for cardiopulmonary bypass (CPB) in patients with cardiac replacement surgery to determine if this approach is a better substitute for crystal liquids priming in patients with valvular heart disease. We observed that RAP significantly decreased the actual priming volume, preserved the hematocrit and hemoglobin level during CPB to a certain degree, and decreased lactate accumulation in CPB period. Moreover, RAP lowered the volume of transfusion and dosage blood products. Thus, our results showed that RAP approach effectively improved tissue perfusion and lowered intraoperative Lac levels, by reducing the hemodilution, which safely and reliably improve the microcirculation perfusion.

Effect of glucose-insulin-potassium on hyperlactataemia in patients undergoing valvular heart surgery: A randomised controlled study

BACKGROUND

Hyperlactataemia represents oxygen imbalance in the tissues and its occurrence during cardiac surgery is associated with adverse outcomes. Glucose-insulin-potassium (GIK) infusion confers myocardial protection against ischaemia-reperfusion injury and has the potential to reduce lactate release while improving its clearance.

OBJECTIVES

The objective of this study is to compare the effect of GIK on the incidence of hyperlactataemia in patients undergoing valvular heart surgery.

DESIGN

A randomised controlled study.

SETTING

Single university teaching hospital.

PATIENTS

One hundred and six patients scheduled for elective valvular heart surgery with at least two of the known risk factors for hyperlactataemia.

INTERVENTION

Patients were randomly allocated to receive either GIK solution (insulin 0.1 IU kg(-1) h(-1) and an infusion of 30% dextrose and 80 mmol l(-1) potassium at 0.5 ml kg(-1) h(-1)) or 0.9% saline (control) throughout surgery.

MAIN OUTCOME MEASURES

The primary outcome was the incidence of hyperlactataemia (lactate ≥ 4 mmol l(-1)) during the operation and until 24 h after the operation. Secondary outcomes included haemodynamic parameters, use of vasopressor or inotropic drugs, and fluid balance until 24 h postoperatively. Postoperative morbidity endpoints were also assessed.

RESULTS

The incidences of hyperlactataemia were similar in the groups (32/53 patients in each of the control and GIK groups, P > 0.999). There were no intergroup differences in haemodynamic parameters, use of vasopressor and inotropic drugs, or fluid balance. The incidences of postoperative morbidity endpoints were similar in both groups.

CONCLUSION

Despite its theoretical advantage, GIK did not provide beneficial effects in terms of the incidence of hyperlactataemia or outcome in patients undergoing valvular heart surgery.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT01825720.

Coronary Sinus Lactate as Marker of Myocardial Ischemia in Cardiac Surgery: Correlation with Morbidity and Mortality after Cardiac Surgery / Lactatul din sinusul coronarian - marker al ischemiei miocardice în chirurgia cardiacă: corelaţii cu morbiditatea şi mortalitatea postoperatorie

Introduction. Perioperative myocardial injuries are one of the most frequent causes of morbidity and mortality after cardiac surgery, the most common etiology being the poor myocardial protection during aortic crossclamp. During aortic crossclamp progressive accumulation of lactate and intracellular acidosis are well-known phenomena, and are associated with alteration of myocardial contractile function. Our objective was to study the coronary sinus lactate levels as a predictor of postoperative hemodynamic outcome in open-heart surgical patients.

Material and methods. We performed a prospective clinical trial, including 142 adult patients with elective cardiac surgery. Anterograde cardioplegia was administered in 82 patients, retrograde cardioplegia in 60 (in 30 patients it was administrated intermittently and in 30 continuously). Blood was collected simultaneously from the aortic cardioplegic line (inflow) and from coronary sinus or the aortic root (outflow) before aortic crossclamp, after crossclamp at every 10 minutes and after crossclamp removal at 0 and 10 minutes. All patients were operated on cardiopulmonary bypass with cardiac arrest, using warm-blood cardioplegia for cardioprotection.

Results. Lactate levels showed increasing values during aortic crossclamp, and a rapid decline after crossclamp removal. The incidence of low cardiac output was significantly higher in patients with lactate levels that exceeded 4 mmol/L. In patients who died in the postoperative period, lactate level was even higher (5 mmol/L), with only a modest recovery after crossclamp removal.

Conclusion. Monitoring lactate level in coronary sinus blood is a reliable method and has a good prognostic value regarding postoperative morbidity and mortality in open heart surgery

Serum Lactate Is not Correlated with Mixed or Central Venous Oxygen Saturation for Detecting Tissue Hypo Perfusion During Coronary Artery Bypass Graft Surgery: A Prospective Observational Study

OBJECTIVES

Effective assessment of tissue perfusion is highly important during Coronary Artery Bypass Graft (CABG). Mixed venous O2 saturation (Svo2) is one of the best and routinely used markers of tissue perfusion. However, this method is costly and leads to considerable complications. Thus, the present study aimed to determine whether the Svo2 can be substituted with central venous saturation (Scvo2) and if there is any correlation between lactate level and Svo2.

METHODS

This prospective observational study was conducted on 62 patients scheduled for CABG. After induction and maintenance of anesthesia, blood samples drawn from central venous, pulmonary artery, and radial artery were used to measure Scvo2, Svo2 and serum lactate level respectively before and after Cardio Pulmonary Bypass (CPB). Pearson's correlation test was used to determine the correlation between Svo2 and Scvo2 as well as between Svo2 and serum lactate level. Besides, P < 0.05 was considered as statistically significant.

RESULTS

Overall, 62 Patients, 33 males (53.2%) and 29 females (46.8%) were enrolled into the present study. The most common coexisting illness was hypertension detected in 33 patients (53.2%) followed by hypercholesterolemia in 28 ones (44.4%). In this study, Svo2 was positively correlated with Scvo2 (r = 0.63, P < 0.001). However, no correlation was found between Svo2 and lactate (r = 0.124, P = 0.348).

CONCLUSIONS

In summary, Scvo2 is considered as the best substitute of Svo2 for detecting tissue hypo perfusion during CPB. Although the lactate level had been considered as an appropriate marker of tissue perfusion and ischemia, it was not correlated to Svo2 during CABG.

Lactate and lactate clearance in acute cardiac care patients

Hyperlactataemia is commonly used as a diagnostic and prognostic tool in intensive care settings. Recent studies documented that serial lactate measurements over time (or lactate clearance), may be clinically more reliable than lactate absolute value for risk stratification in different pathological conditions. While the negative prognostic role of hyperlactataemia in several critical ill diseases (such as sepsis and trauma) is well established, data in patients with acute cardiac conditions (i.e. acute coronary syndromes) are scarce and controversial. The present paper provides an overview of the current available evidence on the clinical role of lactic acid levels and lactate clearance in acute cardiac settings (acute coronary syndromes, cardiogenic shock, cardiac surgery), focusing on its prognostic role.