---
title: "Correlation of End-tidal CO2 and Arterial Bicarbonate in Emergency and Critical Care Patients"
id: "pubmed-42757558"
canonical_url: "https://medichelpline.com/clinical-feed/pubmed-42757558"
content_type: "clinical_feed_article"
specialty: "Critical Care"
source_name: "PubMed / NCBI"
source_url: "https://pubmed.ncbi.nlm.nih.gov/42757558/"
doi: "10.4103/aam.aam_95_26"
published_at: "2026-09-21T00:00:00.000Z"
evidence_level: "Journal Article"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Correlation of End-tidal CO2 and Arterial Bicarbonate in Emergency and Critical Care Patients
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/pubmed-42757558
- **Specialty:** [Critical Care](https://medichelpline.com/clinical-feed/critical-care.md)
- **Primary Source:** PubMed / NCBI
- **Source URL:** [Original Journal Publication](https://pubmed.ncbi.nlm.nih.gov/42757558/)
- **DOI:** [10.4103/aam.aam_95_26](https://doi.org/10.4103%2Faam.aam_95_26)
- **Published At:** 2026-09-21T00:00:00.000Z
- **Evidence Rating:** Journal Article
## Executive GIST (TL;DR)
- This prospective observational study evaluated the relationship between **end-tidal carbon dioxide (ETCO2)** measured by quantitative waveform capnography and arterial blood gas (ABG) parameters in adult patients with acid–base disorders presenting to the emergency department and critical care unit of a tertiary teaching hospital. - One hundred adults (age ≥18 years) with acid–base disturbances were enrolled. ETCO2 and ABG sampling were performed simultaneously; ABG measured pH, PaCO2, PaO2, and **HCO3-** (bicarbonate). - The mean patient age was 59.22 ± 9.30 years and gender distribution was approximately equal. - Analysis used Pearson correlation coefficients to assess relationships between ETCO2 and ABG variables. - ETCO2 demonstrated a statistically significant positive correlation with **arterial bicarbonate (HCO3-)** and **PaCO2**, indicating higher ETCO2 values were associated with higher HCO3- and PaCO2. - ETCO2 showed a statistically significant negative correlation with pH; lower ETCO2 values were associated with lower pH and thus more severe metabolic acidosis. - The authors concluded that while **ETCO2** monitoring cannot replace arterial blood gas analysis, it may serve as a rapid, noninvasive adjunct for early assessment of metabolic derangements in emergency settings. - The study was carried out in a single tertiary care teaching hospital emergency department and critical care unit; detailed information on exclusion criteria, specific correlation coefficients, confidence intervals, and other statistical values were not reported in the abstract.
## Clinical Analysis & Structured Key Points
Relationship between End-tidal Carbon Dioxide and Arterial Blood Gas Bicarbonate Levels in Patients with Acid-base Disorders Presenting to the Emergency Department and Critical Care Unit - PubMed This site needs JavaScript to work properly. Please enable it to take advantage of the complete set of features! Clipboard, Search History, and several other advanced features are temporarily unavailable. Skip to main page content The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site. The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. 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Sunday Monday Tuesday Wednesday Thursday Friday Saturday Report format: Summary Summary (text) Abstract Abstract (text) PubMed Send at most: 1 item 5 items 10 items 20 items 50 items 100 items 200 items Send even when there aren't any new results Optional text in email: Save Cancel Create a file for external citation management software Create file Cancel Your RSS Feed Name of RSS Feed: Number of items displayed: 5 10 15 20 50 100 Create RSS Cancel RSS Link Copy Full text links Wolters Kluwer Full text links Actions Cite Collections Add to Collections Create a new collection Add to an existing collection Name your collection: Name must be less than 100 characters Choose a collection: Unable to load your collection due to an error Please try again Add Cancel Permalink Permalink Copy Display options Display options Format Abstract PubMed PMID Full text links Cite Display options Display options Format Abstract PubMed PMID Abstract in English, French Background: Acid-base disorders are frequently encountered in the emergency department and critical care unit and require prompt assessment for timely management. Arterial blood gas analysis remains the gold standard for evaluating acid-base status; however, it is invasive, painful, time-consuming, and costly. End-tidal carbon dioxide (ETCO2) monitoring using capnography is a noninvasive technique that reflects ventilation and metabolic status and may serve as a surrogate marker for certain arterial blood gas parameters. Aim: To determine the relationship between ETCO2 and arterial blood gas bicarbonate (HCO3-) levels in patients presenting with acid-base disorders. Study design and setting: This prospective, observational, and analytical study was conducted in the emergency department and critical care unit of a tertiary care teaching hospital. Subjects and methods: A total of 100 adult patients aged 18 years and above presenting with acid-base disorders were included. ETCO2 values were recorded using quantitative waveform capnography and arterial blood gas analysis was performed simultaneously to measure pH, PaCO2, PaO2, and HCO3- levels. Correlation between ETCO2 and arterial blood gas parameters was analyzed using Pearson correlation coefficient. Results: The mean age of the study population was 59.22 ± 9.30 years, with a near-equal gender distribution. ETCO2 showed a statistically significant positive correlation with arterial bicarbonate and PaCO2 levels, and a significant negative correlation with pH. These findings indicate that lower ETCO2 values were associated with more severe metabolic acidosis. Conclusion: ETCO2 monitoring demonstrates a significant correlation with arterial bicarbonate and PaCO2 levels in patients with acid-base disorders. While ETCO2 cannot replace arterial blood gas analysis, it may serve as a rapid, noninvasive adjunct for the early assessment of metabolic derangements in emergency settings. Résumé Contexte: Les troubles acido-basiques sont fréquemment rencontrés au service des urgences et en unité de soins intensifs et nécessitent une évaluation rapide pour une prise en charge en temps opportun. L’analyse des gaz du sang artériel demeure la méthode de référence pour évaluer l’état acido-basique; cependant, elle est invasive, douloureuse, chronophage et coûteuse. La mesure du dioxyde de carbone en fin d’expiration (ETCO2) par capnographie est une technique non invasive qui reflète l’état ventilatoire et métabolique et peut servir de marqueur substitutif de certains paramètres des gaz du sang artériel. Objectif: Déterminer la relation entre l’ETCO2 et les taux de bicarbonate artériel (HCO3−) chez les patients présentant des troubles acido-basiques. Type d’étude et cadre: Cette étude prospective, observationnelle et analytique a été menée au service des urgences et en unité de soins intensifs d’un hôpital universitaire tertiaire. Sujets et méthodes: Un total de 100 patients adultes âgés de 18 ans et plus présentant des troubles acido-basiques ont été inclus. Les valeurs d’ETCO2 ont été enregistrées à l’aide d’une capnographie quantitative avec courbe, et une analyse des gaz du sang artériel a été réalisée simultanément pour mesurer le pH, la PaCO2, la PaO2 et les taux de HCO3−. La corrélation entre l’ETCO2 et les paramètres des gaz du sang artériel a été analysée à l’aide du coefficient de corrélation de Pearson. Résultats: L’âge moyen de la population étudiée était de 59,22 ± 9,30 ans, avec une répartition des sexes presque équivalente. L’ETCO2 présentait une corrélation positive statistiquement significative avec le bicarbonate artériel et les niveaux de PaCO2, ainsi qu’une corrélation négative significative avec le pH. Ces résultats indiquent que des valeurs plus faibles d’ETCO2 étaient associées à une acidose métabolique plus sévère. Conclusion: La surveillance de l’ETCO2 montre une corrélation significative avec les taux de bicarbonate artériel et de PaCO2 chez les patients présentant des troubles acido-basiques. Bien que l’ETCO2 ne puisse pas remplacer l’analyse des gaz du sang artériel, elle peut constituer un outil complémentaire rapide et non invasif pour l’évaluation précoce des désordres métaboliques en situation d’urgence. Keywords: Acid–base disorders; Troubles acido-basiques; arterial blood gas; bicarbonate; capnographie; capnography; dioxyde de carbone en fin d’expiration; end-tidal carbon dioxide; gaz du sang artériel. Copyright © 2026 Annals of African Medicine. 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