Study of Utility of Basic Arterial Blood Gas Parameters and Lactate as Prognostic Markers in Patients With Severe Dengue

Abstract

Background The importance of prognostication in critical care cannot be over-emphasized, especially in the context of diseases like dengue, as their presentation may vary from mild fever to critical life-threatening illness. With the help of prognostic markers, it is possible to identify patients at higher risk and thus improve their outcome with timely intervention. Basic arterial blood gas (ABG) parameters, i.e., potential of hydrogen (pH), partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2) and bicarbonate are useful parameters, especially in critical care medicine as they are known to vary with the severity of illness. Hyperlactatemia is often referred to as a "powerful predictor of mortality". Basic ABG parameters and lactate have been used as an essential prognostic modality in critically ill patients for decades; however, the evidence remains limited for their role as prognostic markers in patients with severe dengue. Method We carried out an observational retrospective cohort study comprising 163 patients with severe dengue, admitted between July 2021 and November 2021 at Medical Intensive Care Unit (MICU) of Shri Ram Murti Smarak Institute of Medical Sciences (SRMS IMS), Bareilly, Uttar Pradesh, India. Basic ABG parameters and lactate levels at the time of admission to MICU were compared between survivor and non-survivor groups of patients with severe dengue in order to evaluate their prognostic utility as predictors of mortality. Results pH (p<0.0001), PO2 (p=0.01) and bicarbonate (<0.0001) levels were significantly lower, while PCO2 (p=0.002) and lactate (p<0.0001) levels were significantly higher in non-survivor group as compared to survivor group. Lactate was found to be the best prognostic marker with Area Under the Curve (AUC) of 88.7% on Receiver Operating Characteristics (ROC) analysis. Conclusion Basic arterial blood gas parameters and lactate can be used as feasible prognostic markers in patients with severe dengue.

Keywords: basic arterial blood gas parameters; lactate; prognostic marker; prognostic markers in severe dengue; severe dengue.

Figure 1. ROC curve of pH, PO2 and Bicarbonate

Diagonal segment in the image is produced by ties. HCO3=Bicarbonate PO2=PO₂

Figure 2. ROC curve of PCO2 and Lactate

Diagonal segment in the image is produced by ties. PCO2=PCO₂