# Lactate-Albumin Ratio: A Novel Predictor of Noninvasive Mechanical Ventilation Failure in Acute Hypercapnic Respiratory Failure

## TL;DR

This study shows that the lactate-albumin ratio can predict failure of noninvasive ventilation in patients with COPD-related respiratory failure.

## Contribution

The study is the first to evaluate lactate-albumin ratio as a predictor of noninvasive ventilation failure in acute hypercapnic respiratory failure due to COPD.

## Key findings

- NIMV failure occurred in 37% of patients with acute COPD exacerbation.
- LAR was a better predictor of NIMV failure than albumin or lactate levels alone.
- Each unit increase in LAR was associated with a 5.582-fold higher risk of intubation.

## Abstract

Background: Acute respiratory failure (ARF) is a leading cause of patient admissions to intensive care units (ICUs). Noninvasive mechanical ventilation (NIMV) is a cornerstone in the management of ARF, particularly in hypercapnic respiratory failure. However, NIMV failure can occur due to various factors, including the underlying cause of ARF. While the lactate/albumin ratio (LAR) has been studied as a prognostic biomarker in various critical conditions, this study is the first to specifically evaluate its role in predicting NIMV failure in patients with acute hypercapnic respiratory failure due to COPD exacerbation.

Methods: This retrospective study included 116 patients admitted to the Level 3 medical ICU at Marmara University Pendik Training and Research Hospital between January 1, 2019, and January 1, 2023. All patients were admitted for acute hypercapnic respiratory failure secondary to an exacerbation of chronic obstructive pulmonary disease (COPD) and were treated with NIMV. Only patients who were followed in the ICU for more than 24 hours were included.

Results: Of the 116 patients, 72 (62.6%) were male, with a mean age of 70±10 years. NIMV failure occurred in 37% of the cases. There were no statistically significant differences between the NIMV success and failure groups in terms of mean age, Acute Physiology and Chronic Health Evaluation-II (APACHE-II) scores, or heart rate, acidosis, consciousness, oxygenation, and respiratory rate (HACOR) scores at ICU admission (p=0.746, p=0.565, p=0.403, respectively). However, the NIMV failure group had significantly higher Sequential Organ Failure Assessment (SOFA) scores at ICU admission (p=0.002). Furthermore, the NIMV failure group exhibited lower serum albumin levels, higher serum lactate levels, and elevated LAR values (p=0.029, p=0.009, p=0.004, respectively). LAR (AUC: 0.718, p<0.001) proved to be a superior predictor of NIMV failure compared to serum albumin (AUC: 0.603, p=0.066) and blood lactate (AUC: 0.684, p=0.001) levels alone. A LAR cut-off value of 0.605 was identified as predictive of NIMV failure. Regression analysis indicated that each unit increase in LAR was associated with a 5.582-fold increase in the risk of intubation (p=0.015).

Conclusions: LAR was identified as a significant independent risk factor for NIMV failure. Early monitoring of LAR during NIMV application in 116 patients with acute COPD exacerbation may provide clinicians with valuable insight to guide timely intubation decisions, potentially improving patient outcomes.