Investigating the Airway Opening Index during cardiopulmonary resuscitation. (September 2022)

• Record Type: Journal Article
• Authors: Bhandari, Shiv; Coult, Jason; Counts, Catherine R.; Bulger, Natalie E.; Kwok, Heemun; Latimer, Andrew J.; Sayre, Michael R.; Rea, Thomas D.; Johnson, Nicholas J.
• Is Part Of: Resuscitation. Volume 178(2022)
• Page Start: 96
• Page End: 101
• Publication Date: 2022-09
• Subjects: Out-of-hospital cardiac arrest -- Respiration, Artificial -- Emergency Medical Services -- End-tidal carbon dioxide; Resuscitation -- Periodicals; Resuscitation -- Periodicals; Réanimation -- Périodiques; Electronic journals; 616.025
• DOI: 10.1016/j.resuscitation.2022.07.015
• Languages: English
• ISSNs: 0300-9572

Abstract

Abstract: Introduction: Chest compressions during CPR induce oscillations in capnography (ET CO2 ) waveforms. Studies suggest ET CO2 oscillation characteristics are associated with intrathoracic airflow dependent on airway patency. Oscillations can be quantified by the Airway Opening Index (AOI). We sought to evaluate multiple methods of computing AOI and their association with return of spontaneous circulation (ROSC). Methods: We conducted a retrospective study of 307 out-of-hospital cardiac arrest (OHCA) cases in Seattle, WA during 2019. ET CO2 and chest impedance waveforms were annotated for the presence of intubation and CPR. We developed four methods for computing AOI based on peak ET CO2 and the oscillations in ET CO2 during chest compressions (ΔET CO2 ). We examined the feasibility of automating ΔET CO2 and AOI calculation and evaluated differences in AOI across the methods using nonparametric testing (α = 0.05). Results: Median [interquartile range] AOI across all cases using Methods 1–4 was 28.0 % [17.9–45.5 %], 20.6 % [13.0–36.6 %], 18.3 % [11.4–30.4 %], and 22.4 % [12.8–38.5 %], respectively ( p < 0.001). Cases with ROSC had a higher median AOI than those without ROSC across all methods, though not statistically significant. Cases with ROSC had a significantly higher median [interquartile range] ΔET CO2 of 7.3 mmHg [4.5–13.6 mmHg] compared to those without ROSC (4.8 mmHg [2.6–9.1 mmHg], p < 0.001). Conclusion: We calculated AOI using four proposed methods resulting in significantly different AOI. Additionally, AOI and ΔET CO2 were larger in cases achieving ROSC. Further investigation is required to characterize AOI's ability to predict OHCA outcomes, and whether this information can improve resuscitation care.