ORIGINAL RESEARCH article
Front. Med.
Sec. Intensive Care Medicine and Anesthesiology
This article is part of the Research TopicBridging Physiology, Technology, and Human Factors in Anesthesiology and Critical CareView all 4 articles
Influence of Airway Pressure Release Ventilation on pulmonary gas exchange using Ventilatory Ratio
Provisionally accepted
Patrick Rehn1*
Emre Kiratlar1Benjamin Neetz2Lars Reinhardt1
Markus Weigand1
Christoph Lichtenstern1Werner Schmidt2Armin Kalenka1Mascha O. Fiedler-Kalenka1*- 1Heidelberg University Hospital, Heidelberg, Germany
- 2Thoraxklinik-Heidelberg gGmbH, Heidelberg, Germany
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Background The COVID-19 pandemic led to a surge in Acute Respiratory Distress Syndrome (ARDS) cases. Despite important advances in ventilation strategies, ARDS mortality remains high. Airway Pressure Release Ventilation (APRV), especially when used according to the Time-Controlled Adaptive Ventilation (TCAV) protocol, has shown potential in improving oxygenation and reducing mortality in ARDS. Methods This retrospective dual-center study included patients with moderate to severe ARDS, who were treated with APRV or Low Tidal Volume Ventilation (LTVV) between January 2018 and March 2022. Individuals receiving APRV for at least 72 hours after previously receiving LTVV were analyzed in further detail. PaO2/FiO2 Ratio and Ventilatory Ratio were measured 6, 12, 24, 48 and 72 hours after transition to APRV. Statistical analyses were performed using univariate repeated measures ANOVA and chi-squared test. Results Out of 107 patients, 48 received APRV. In 27 cases, APRV was applied according to TCAV-protocol. APRV was often used late in treatment or as a rescue therapy. Regarding the primary ventilation strategy, there was no significant difference in survival between APRV (44%) and LTVV (42%). In patients receiving APRV for at least 72 hours after being initially ventilated with LTVV (n = 8), mean PaO2/FiO2 ratio improved significantly over time (p = 0.039), while mean Ventilatory Ratio decreased (p < 0.001). Conclusions APRV demonstrated potential in improving gas exchange and ventilation efficiency in ARDS patients, particularly when used early and according to TCAV. However, no survival benefit was observed. The study's retrospective design and heterogeneity in APRV application limit its conclusions.
Keywords: Acute Respiratory Distress Syndrome, COVID-19, mechanical ventilation, time-controlled adaptive ventilation, Ventilatory ratio
Received: 14 Jan 2026; Accepted: 11 Feb 2026.
Copyright: © 2026 Rehn, Kiratlar, Neetz, Reinhardt, Weigand, Lichtenstern, Schmidt, Kalenka and Fiedler-Kalenka. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Patrick Rehn
Mascha O. Fiedler-Kalenka
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