Arterial pH and short-term mortality in adult non-traumatic acute patients

INTRODUCTION: Acid-base disturbances are common in the emergency department, with acidosis and alkalosis being associated with an elevated risk of mortality and morbidity. Understanding the relationship between pH and mortality may serve to optimise patient outcomes. The primary objective was to describe the association between arterial blood pH and 0-2-day mortality in adult non-traumatic acute visits. The secondary objective was to describe this association for 3-7-day mortality.

METHODS: This population-based, multicentre cohort study included all adult non-traumatic acute visits in the Region of Southern Denmark between 2016 and 2018 who had an arterial blood gas (ABG) drawn within four hours of arrival. We described 0-2- and 3-7-day mortality stratified by pH level, controlled for confounding factors and reported as hazard ratio (HR) compared to normal pH.

RESULTS: A total of 64,725 acute visits in 31,650 individuals with an ABG were included. The overall mortality rate for index visits was 2.4% on days 0-2 and 2.1% on days 3-7. Patients with severe acidosis (pH less-than 7.20) had 20.8% and 8.9% mortality rates (HR = 9.6 and 5.2), whereas patients with acidosis (pH 7.20-7.34) had mortality rates of 7.4% and 5.2% (HR = 4.1 and 2.7) on day 0-2 and 3-7, respectively. Our secondary analysis found a 0-2-day mortality rate of nearly 60% in patients with a pH less-than 6.90.

CONCLUSION: The short-term mortality rates increased with the severity of acidosis. The highest mortality rate was found in patients with a pH less-than 6.90.

FUNDING: None.

TRIAL REGISTRATION: Not relevant.