Selection of blood sampling source to measure lactate levels in patients with septic shock

The initial lactate level has been used as one of mortality predictors in patients with septic shock. Different studies measured the concentrations of blood lactate obtained from different vessels. Even in some retrospective studies, blood lactate levels from heterogeneous sources (artery, central vein, and peripheral vein) have been used. Practicing physicians face following questions: what data have the best predictive value, can they replace each other? In our observations, а high positive linear correlation was found between lactate concentrations in arterial and central venous blood (R = 0.895; P < 0.001). Both indicators have satisfactory values for predicting treatment outcome. Lactate level in arterial blood had a slightly better predictive value compared to its concentration in central venous blood.

Lactate Arterial-Central Venous Gradient among COVID-19 Patients in ICU: A Potential Tool in the Clinical Practice

Objective. In physiological conditions, arterial blood lactate concentration is equal to or lower than central venous blood lactate concentration. A reversal in this rate (i.e., higher lactate concentration in central venous blood), which could reflect a derangement in the mitochondrial metabolism of lung cells induced by inflammation, has been previously reported in patients with ARDS but has been never explored in COVID-19 patients. The aim of this study was to explore if the COVID-19-induced lung cell damage was mirrored by an arterial lactatemia higher than the central venous one; then if the administration of anti-inflammatory therapy (i.e., canakinumab 300 mg subcutaneous) could normalize such abnormal lactate a-cv difference. Methods. A prospective cohort study was conducted, started on March 25, 2020, for a duration of 10 days, enrolling 21 patients affected by severe COVID-19 pneumonia undergoing mechanical ventilation consecutively admitted to the ICU of the Rimini Hospital, Italy. Arterial and central venous blood samples were contemporarily collected to calculate the difference between arterial and central venous lactate (Delta a-cv lactate) concentrations within 24 h from tracheal intubation (T0) and 24 hours after canakinumab administration (T1). Results. At T0, 19 of 21 (90.5%) patients showed a pathologic Delta a-cv lactate (median 0.15 mmol/L; IQR 0.07–0.25). In the 13 patients undergoing canakinumab administration, at T1, Delta a-cv lactate decreased in 92.3% of cases, the decrease being statistically significant (T0: median 0.24, IQR 0.09–0.31 mmol/L; T1: median −0.01, IQR −0.08–0.04 mmol/L; p=0.002). Conclusion. A reversed Delta a-cv lactate might be interpreted as one of the effects of COVID-19-related cytokine storm, which could reflect a derangement in the mitochondrial metabolism of lung cells induced by severe inflammation or other uncoupling mediators. In addition, Delta a-cv lactate decrease might also reflect the anti-inflammatory activity of canakinumab. Our preliminary findings need to be confirmed by larger outcome studies.

Establishment of a Linear Correlation Model of Central Venous Blood Oxygen Saturation and Lactate in Sepsis

Introduction: Studies have shown that there is a complex relationship between lactate and ScvO2. Methods: A retrospective study was carried out in 37 intensive care patients with sepsis or septic shock. The relationship between lactate and ScvO2 was explored with correlation analysis and simple linear modelling. Results: Lactate and ScvO2 were significantly correlated in patients with septic shock (r2 = 0.46, p = 0.001; y = -4.11x+ 82.62), but not in sepsis. y Significant correlation between these parameters was also found in the group of patients who went on to die (r2 = 0.67, p < 0.01; y = -3.70x + 78.61), but not in patients who survived. Conclusions: In sepsis, the correlation between ScvO2 and lactate is not constant over the sepsis course and may be dynamic. In the resuscitation of sepsis and/or septic shock, changes in ScvO2 requires further study.

Association of intraoperative blood gas analysis with patient outcome after adult cardiac surgery

Background: The associations of the different blood gas parameters from different blood samples harvested at different stages during adult cardiac surgery with the postoperative outcomes are inadequately studied. Methods: Adult patients undergoing elective cardiac surgery with cardiopulmonary bypass (CPB) participated in this prospective observational study. Blood gas parameters from arterial, central venous, and jugular bulb venous blood samples harvested simultaneously at pre-determined time points (baseline with the patient awake, post-anesthesia induction but before CPB, during CPB at 30°C, during CPB at 37°C (rewarming), and at the end of surgery) were correlated with postoperative outcomes including the length of mechanical ventilation (LMV), intensive care unit stay (LICU), hospital stay (LOH), and major organ morbidity and mortality. Results: Data from 193 patients were analyzed. Multiple parameters of different blood harvested at different stages significantly correlated with one or more outcome measures based on univariate analysis (p < 0.05). However, only the jugular bulb venous blood pH and carbon dioxide tension and the central venous blood pH at the end of surgery (pHcv-end) were significantly correlated with LMV, LICU, and LOH (p < 0.05). A more alkaline blood correlated with more favorable outcomes. After adjusting for age, surgical time, and total intravenous volume administered, multivariate analysis showed that only pHcv-end remained independently associated with LMV and LICU (p < 0.05). Conclusion: More alkaline blood, especially the central venous blood at the end of surgery, is associated with more favorable outcomes after adult cardiac surgery. Trial registration ChiCTR-POC-17013942, Date of registration December 15, 2017.