# Venous Blood Gas (VBG) Analysis Is as Safe and Equally Reliable as Arterial Blood Gas (ABG) Analysis in the Determination of Prognosis in Chronic Liver Disease Patients: A Study Conducted in a Tertiary Care Hospital in Uttar Pradesh, India

## TL;DR

This study shows that venous blood gas analysis is as effective as arterial blood gas analysis in predicting outcomes for patients with chronic liver disease, offering a safer alternative.

## Contribution

The study demonstrates that venous blood gas parameters, especially lactate levels, are reliable predictors of prognosis in chronic liver disease patients.

## Key findings

- Elevated lactate levels strongly correlate with disease severity and mortality in CLD patients.
- Venous blood gas parameters like pH and bicarbonate differ significantly across disease severity classes.
- Kaplan-Meier analysis confirmed that higher lactate levels are linked to reduced 30-day survival rates.

## Abstract

Introduction

Chronic liver disease (CLD) frequently causes systemic complications, including acid-base disturbances, significantly influencing patient prognosis. Arterial blood gas (ABG) analysis is traditionally utilized to monitor these disturbances, but presents procedural risks, especially in patients with coagulopathies, which is a well-known complication of chronic liver disease (CLD). Venous blood gas (VBG) analysis has emerged as a safer alternative, yet its prognostic significance in CLD requires further investigation.

Aim & objective

This study aimed to evaluate the prognostic significance of venous blood gas parameters in chronic liver disease patients. The objectives included assessing VBG parameters in CLD patients, correlating these parameters with disease severity using the Child-Turcotte-Pugh (CTP) score, and determining their predictive role in patient outcomes and mortality.

Methodology

A hospital-based observational cross-sectional study was conducted from November 2022 to January 2025 at S. N. Medical College, Agra, including 253 patients diagnosed with CLD. VBG parameters such as pH, pCO₂, bicarbonate (HCO₃⁻), base excess, and serum lactate were measured upon admission. Clinical severity was classified using the CTP score, and outcomes including complications, hospital stay, and mortality were analyzed. Data analysis employed descriptive and inferential statistical methods using SPSS version 26 (IBM Corp., Armonk, NY, USA).

Results

Among participants, 63.24% were male, with alcohol-related liver disease being the most common etiology (47.8%). Significant differences were observed in VBG parameters across CTP classes, with lower pH (7.21±0.09) and bicarbonate (16.3±4.1 mmol/L) and elevated lactate (4.9±1.7 mmol/L) in CTP Class C (p<0.001). Strong correlations existed between lactate levels and CTP scores (r=0.82, p<0.001). Elevated lactate (>4.5 mmol/L) was the most potent independent mortality predictor (adjusted HR=7.1). Kaplan-Meier analysis showed significantly decreased 30-day survival rates with increased lactate and worsening CTP class (p<0.001).

Conclusion

VBG parameters, particularly elevated lactate and decreased pH, provide critical prognostic information in CLD patients, correlating strongly with disease severity and mortality. Incorporating VBG analysis in routine clinical practice enhances risk stratification and management of hospitalized CLD patients, offering a safer, reliable, and practical alternative to arterial blood gas analysis.