# Correlation Between End-Tidal Carbon Dioxide and Regional Cerebral Oxygen Saturation During Cardiopulmonary Resuscitation

## TL;DR

This study found a strong correlation between end-tidal CO2 and brain oxygen levels during CPR, suggesting these metrics could help assess resuscitation effectiveness.

## Contribution

The study demonstrates a novel correlation between ETCO2 and rSO2 during CPR, offering a potential new monitoring approach for resuscitation outcomes.

## Key findings

- A correlation coefficient of 0.641 was found between ETCO2 and rSO2 during CPR.
- The correlation increased to 0.873 in the last 4 minutes before ROSC.
- Concurrent monitoring of ETCO2 and rSO2 may predict CPR efficacy and ROSC likelihood.

## Abstract

Background/Objectives: Near-infrared spectroscopy (NIRS) enables the non-invasive assessment of cerebral oximetry, offering insights into the efficacy of oxygen supply to the brain. NIRS, when combined with other monitoring techniques such as capnography, may play a crucial role in advanced patient monitoring during sudden cardiac arrest and post-resuscitation treatment. This research assessed the relationship between end-tidal carbon dioxide (ETCO2) and regional cerebral oxygen saturation (rSO2) during cardiopulmonary resuscitation. Methods: The research was performed from 11 January 2023 until 31 January 2024, at the University Hospital in Poland. The cohort of responders included patients who had in-hospital cardiac arrest (IHCA). The Rapid Response Team attached the rSO2 and ETCO2 monitoring devices to each patient during cardiopulmonary resuscitation (CPR). The cohort included 104 patients. Results: The correlation coefficient between ETCO2 and rSO2 values was 0.641 (95% CI: 0.636–0.646), and during the last 4 min of CPR before ROSC, it was 0.873 (95% CI: 0.824–0.910). Conclusions: The positive correlation between ETCO2 and rSO2 may suggest that concurrent monitoring of both parameters during resuscitation might serve as a valuable predictor of CPR efficacy and the likelihood of achieving recovery of spontaneous circulation in a multimodal framework. In the lack of rapid ETCO2 monitoring capabilities, rSO2 may function as a simple and effective alternative for assessment.