Predictive value of venous bicarbonate levels for survival to hospital discharge in out-of- hospital cardiac arrest patients

Predictive value of venous bicarbonate levels for survival to hospital discharge in out-of- hospital cardiac arrest patients

Out-of-hospital cardiac arrest, Metabolic acidosis, Venous bicarbonate levels, Survival, Resuscitation
strategies

Abstract
Background Acid-base disturbances significantly impact cardiac function and prognostic outcomes in cardiac arrest.
Previous studies have highlighted the correlation between pH levels from arterial blood gas (ABG) analyses during
cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA) and survival outcomes. However, ABG
measurements are often impractical in resource-limited settings. This study explores the relationship between serum
bicarbonate levels and survival outcomes in patients with OHCA.
Methods This retrospective cohort study examined patients with OHCA who presented at Srinagarind Hospital
(Thailand) between 2015 and 2021. We analyzed venous bicarbonate levels and other laboratory markers (Na+,
K+, BUN, Creatinine). Demographic and clinical data were extracted from electronic medical records. The primary
objective was to assess the association between venous bicarbonate levels and survival and to determine the optimal
cutoff values for predicting survival in these patients.
Results Of the 461 identified patients, 19% survived hospital discharge. Survivors exhibited higher bicarbonate and
BUN levels but lower potassium levels. Bicarbonate levels≥12.6 demonstrated a sensitivity of 74% and specificity
of 47%, with an 88.44% negative predictive value (NPV) for survival. A sensitivity analysis, which reclassified patients
who left against medical advice as non-survivors, revealed that a bicarbonate cutoff of 13.9 mmol/L yielded the
best predictive value, with a sensitivity of 93.8% and a specificity of 52.1%. Factors associated with increased survival
included BUN≥19.5, bicarbonate≥12.6, private transport, and initial PEA or VT/VF rhythms, while potassium≥5.1
decreased survival likelihood.
Conclusion Bicarbonate levels, particularly with a threshold greater than 12.6 mmol/L, may be effective prognostic
indicators. Other factors influencing survival include BUN, potassium levels, private transport, and initial cardiac
rhythm. These insights can help clinicians improve resuscitation strategies and prognosis assessment, especially in
resource-limited settings.

Pariwat Phungoen1 , John M. O’Donnell2,3, Jirat Tosibphanom1

, Praew Kotruchin1 , Thummasorn Phurisetthasak1

and Thanat Tangpaisarn1*

https://doi.org/10.1186/s12245-025-00851-1

2025

Peri Irawan

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