Arterial to end-tidal carbon dioxide gap and its characterization in mechanically ventilated adults in the emergency department.

To evaluate early measurement of the arterial to end-tidal carbon dioxide (PaCO 2 -PetCO 2) gap, a surrogate for physiologic dead space, and its association with clinical outcomes in intubated adults in the emergency department (ED). Observational cohort study of invasively mechanically ventilated adults in an academic medical center (years 2009 to 2016). The association of the PaCO 2 -PetCO 2 gap was evaluated with respect to clinical outcomes; the primary outcome was in-hospital mortality. 519 patients were included. 325 (63%) patients had an elevated (>5 mmHg) PaCO 2 -PetCO 2. Patients with an elevated PaCO 2 -PetCO 2 were significantly older, had higher APACHE II scores, more frequently had chronic obstructive pulmonary disease (COPD), had lower arterial oxygen to fraction of inspired oxygen (P:F) ratios, and were more likely to be intubated for exacerbation of COPD or sepsis. There was no difference in mortality for patients with an elevated PaCO 2 -PetCO 2 (25% vs 26%) in unadjusted analysis (p = 0.829) or adjusted analysis (aOR = 0.81 [95% CI: 0.53–1.26]), as compared to a non-elevated PaCO 2 -PetCO 2. An elevated PaCO 2 -PetCO 2 gap is common in the post-intubation period in the ED, but not significantly associated with clinical outcomes. • An elevated PaCO 2 to PetCO 2 gap is a surrogate for physiologic dead space. • An elevated PaCO 2 to PetCO 2 gap is common among intubated adults in the ED. • Elevated gap was associated with age, illness severity, and intubation for COPD and sepsis. • There was no difference in mortality stratified by PaCO 2 to PetCO 2 gap. [ABSTRACT FROM AUTHOR]