Correlation between Arterial versus Venous Lactate Level in Assessing Outcome of Shock Patient Based on Lactate Clearance Following Surgery

Open Access

Abstract

Background: Postoperative shock may lead to poor tissue perfusion, organ dysfunction, and death. Serial measurement of lactate levels and assessment of lactate clearance are helpful in monitoring resuscitation, and venous lactate might provide a less invasive option compared to taking blood from an artery. Objective of the study: The objective of this study was to examine the correlation between arterial and venous lactate levels and their clearance, and to evaluate the relationship between these factors and mortality in patients with postoperative shock. Methods & Materials: A prospective observational study was carried out among 105 patients who had postoperative shock and were admitted to the ICU at Rangpur Medical College Hospital in Bangladesh. The study lasted for one year, from January 2025 to December 2025. Arterial and venous lactate levels were measured at 0, 6, 24, and 72 hours, and lactate clearance was calculated based on the baseline value. The outcomes were divided into survivor and non-survivor. The data were analysed using SPSS version 26.0, with the appropriate comparative and correlation tests, and a p-value less than 0.05 was regarded as statistically significant. Results: In the group of 105 patients with postoperative shock, the mean age was 51.1 ± 12.3 years, 63.8% of the patients were male, and septic shock was the most frequent type (53.3%). At all time points, arterial and venous lactate levels were very highly correlated (r=0.975-0.985, p<0.001), with only small mean differences. The overall mortality rate was 29.5%. Non-survivors had significantly higher baseline arterial and venous lactate levels than survivors, the levels being 7.1 ± 1.3 mmol/L compared with 4.5 ± 1.4 mmol/L for arterial lactate and 7.4 ± 1.3 mmol/L compared with 4.8 ± 1.4 mmol/L for venous lactate (p<0.001). On the other hand, lactate clearance was significantly greater in survivors, showing that persistent hyperlactatemia and reduced clearance were linked to mortality. Conclusion: There was a strong correlation between arterial and venous lactate levels in patients with postoperative shock. Persistent elevation of lactate levels and reduced lactate clearance were associated with mortality, which supports the use of serial lactate monitoring, including venous lactate, for assessing outcomes and for monitoring treatment.