The apnea interval—defined as the time without ventilation during CPR—has a critical impact on patient outcomes. Recent evidence shows that when this interval exceeds 60 seconds, survival and neurological recovery rates significantly decrease.
Apnea can result not only from intubation attempts but also from ineffective bag-valve-mask ventilation. Reducing apnea duration is essential. EOlife is currently the only device capable of monitoring tidal volume in real time during CPR. It provides a vital tool to improve resuscitation quality and outcomes.
Understanding apnea interval in CPR
What is an “apnea interval” ?
During cardiopulmonary resuscitation (CPR), an apnea interval is defined as a period during which the patient does not receive any ventilation. No oxygen is delivered during this time. Carbon dioxide gradually accumulates.
What are the main factors of apnea intervals?
Several factors can lead to apnea:
- ineffective ventilation with significant leaks
- high airway resistance making ventilation difficult
- prolonged and unsuccessful intubation attempts
EOlife, the only Ventilation Feedback Device (VFD) to display the volume of gas reaching the patient’s lungs (Tidal Volume).
CE-marked and FDA-cleared medical device enabling real-time measurement of insufflated volume, tidal volume, and ventilation frequency. It provides visual feedback to deliver ventilation following ERC or AHA recommendations.
Impact of apnea interval on patient’s outcomes
In a recent publication (1), D.L. Murphy et al. studied the impact of ventilation interruption caused by tracheal intubation and its association with cardiac arrest care and outcomes. The authors conducted a cohort study of 254 adult out-of-hospital cardiac arrest (OHCA) patients. These patients underwent tracheal intubation before return of spontaneous circulation (ROSC), within a metropolitan EMS system between 2017 and 2020.
In this study, the apnea interval was defined as the elapsed time between the last breath delivered before, and the first breath delivered after, the intubation attempt. The researchers compared two groups based on apnea interval duration: ≤60 seconds vs >60 seconds. They analyzed outcomes including ROSC, survival to hospital discharge, and favorable neurological recovery.
Consequences on survival rate and neurological outcomes
These results underscore the critical impact of the apnea interval on patient outcomes. When the apnea interval exceeded 60 seconds, ROSC decreased by 16%, survival by 14%, and favorable neurological outcomes by 16%. The median apnea interval was 84 seconds (IQR: 64–113s).
A prolonged apnea during CPR leads to :
- lower survival rates
- reduced Return of Spontaneous Circulation (ROSC)
- poorer neurological outcomes
Beyond intubation, other causes of ventilation interruption
While this study focused on the apnea caused by intubation, this is not the only situation where dangerous ventilation interruptions occur.
Mask leakage, another reason of apnea
A recent study by the Paris Fire Brigade (2) showed that healthcare providers experience very high leak rates during bag-valve-mask (BVM) ventilation. This leads to critically low tidal volumes. In extreme cases—where ventilation is so inefficient that tidal volume is minimal—the situation may closely resemble apnea, with the patient receiving almost no meaningful ventilation.
This issue is even more pronounced during 30:2 ventilation, where two ventilations are followed by 30 chest compressions. In cases where ventilations are missed or ineffective—especially during mechanical chest compressions(3)—the resulting apnea intervals can be prolonged. As demonstrated by Murphy et al., these intervals significantly impair outcomes.
Reducing apnea duration to improve survival
Minimizing the duration of the apnea interval is therefore essential to improving survival. When mask leakage is present or ventilation quality is uncertain, the only way to detect and address ineffective ventilation is through continuous monitoring with real-time feedback.
EOlife: the only Ventilation Feedback Device to calculate Tidal Volume
EOlife currently stands as the only ventilation feedback device capable of monitoring tidal volume during CPR. It offers a crucial advantage in resuscitation efforts. By measuring and displaying ventilation parameters breath-by-breath, EOlife enables providers to ensure that each insufflation is effective. It helps to quickly identify when a patient is hypoventilated or experiencing a prolonged apnea interval.
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References
(1) Murphy, D. L., King, J. A., Blackwood, J., Kwok, H., Sharar, S. R., Latimer, A. J., Kudenchuk, P. J., Johnson, N. J., & Rea, T. D. (2025). The apnea interval: Ventilation interruption during tracheal intubation and its association with cardiac arrest resuscitation care and outcome. Resuscitation, 110588. Advance online publication.
(2) Evaluation of ventilation quality of BLS Firefighter teams during OHCA : The VECARS – 1 study. F. Lemoine, D. Jost, B Tassart, A. Petermann, S. Lemoine, M. Salome, B. Frattini, S. Travers.
(3) Doeleman, L. C., Boomars, R., Radstok, A., Schober, P., Dellaert, Q., Hollmann, M. W., Koster, R. W., & van Schuppen, H. (2024). Ventilation during cardiopulmonary resuscitation with mechanical chest compressions: How often are two insufflations being given during the 3-second ventilation pauses?. Resuscitation, 199, 110234.