Abstract Body: Background: Exhaled end-tidal (EtCO₂) is widely measured and may indicate the quality of ventilation in out-of-hospital cardiac arrest (OHCA). While EtCO₂ is reliably used after advanced airway placement, it is unknown if bag-valve-mask (BVM) EtCO₂ is similarly measurable and reliable. We sought to determine EtCO₂ differences between BVM and advanced airways during resuscitation from OHCA.
Methods: We performed a secondary analysis of data from the Pragmatic Airway Resuscitation Trial (PART), which tested endotracheal intubation or laryngeal tube strategies in OHCA resuscitation. Using previously validated automated signal processing, we identified maximal EtCO₂ values for each ventilation then summarized them into in one-minute(min) epochs. We included all cases with ≥1min EtCO₂ during BVM ventilation. We described BVM EtCO₂ values through medians with interquartile ranges (IQR). We performed a sub-analysis of cases with up to 4min EtCO₂ around advanced airway placement time (2 minutes before and 2 minutes after advanced airway. Using fixed effects models, we compared EtCO₂ during BVM ventilation with values immediately after advanced airway placement.
Results: Of the 3004 enrolled in PART, 450 had EtCO₂ recorded during BVM ventilations. A total of 27351 EtCO₂ minutes were captured through PART (advanced airway: 24309min; BVM: 2422min). On average each case had 3 min (IQR: 1-6 min) BVM EtCO₂ recording. EtCO₂ values were variable with median 25 mmHg (IQR:15.4-38.8). In the sub-analysis (Figure 1), EtCO₂ values before and after advanced airway placement were similar with a mean difference 0.48 mmHg (95% CI -2.0 to 1.0, p=0.536, n=235 cases with 774 min EtCO₂).
Conclusions: Capnography values are detectable during BVM ventilation. BVM EtCO₂ values before and after AA EtCO₂ values appear similar.