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The following is a summary of “Utility of end-tidal carbon dioxide to guide resuscitation termination in prolonged out-of-hospital cardiac arrest,” published in the March 2024 issue of Emergency Medicine by Hambelton, et al.

For a study, researchers sought to assess whether changes in end-tidal carbon dioxide (ETCO2) levels over time offer improved predictive value for determining resuscitation futility compared to relying on a single ETCO2 value in prolonged, refractory non-shockable out-of-hospital cardiac arrest (OHCA).

The retrospective analysis utilized data from the Portland Cardiac Arrest Epidemiologic Registry (PDX Epistry) covering 2018 to 2021. The study focused on adult patients experiencing refractory, non-shockable, non-traumatic OHCA, defined as cases lacking a shockable rhythm or return of spontaneous circulation within 30 minutes of on-scene resuscitation. ETCO2 values were abstracted from emergency medical services (EMS) charts, with the primary outcome being survival to hospital discharge. Two ETCO2 cutoffs (10 mmHg and 20 mmHg) at 30 minutes into resuscitation were compared to the trend in ETCO2 levels from initial recording to the 30-minute mark (delta-ETCO2) using sensitivity, specificity, and area under the receiver operating curves (AUROC).

Among 3,837 adult OHCA cases, 2,850 were initially non-shockable, with 617 (16.1%) classified as refractory non-shockable OHCA at 30 minutes. After excluding cases with insufficient ETCO2 data, 297 cases met the inclusion criteria. Only 2 survivors (0.7%) were identified, with 30 min-ETCO2 levels >10 mmHg. Using delta-ETCO2, both survivors were in the increasing ETCO2 group. The AUROC was higher for delta-ETCO2 (0.803 [0.775–0.831]) compared to an absolute cutoff of 10 mmHg (0.563 [0.544–0.582]).

In EMS-treated adult patients with OHCA experiencing refractory non-shockable arrests after at least 30 minutes of ongoing resuscitation, the trend in ETCO2 levels following advanced airway placement may be more accurate in guiding decisions regarding termination of resuscitation than relying on absolute ETCO2 cutoffs of 10 or 20 mmHg.

Reference: sciencedirect.com/science/article/abs/pii/S0735675723006435