B54-08 Association Between Pre-intubation Metabolic Acidemia and Post-intubation Outcomes

Abstract Rationale Acidemia is common among critically ill patients requiring tracheal intubation and mechanical respiratory support. To date, the relationship between acidemia and outcomes following tracheal intubation has not been well characterized. Methods We conducted a multicenter, retrospective cohort study of adult patients undergoing emergent tracheal intubation outside the operating room to evaluate the association between pre-intubation acidemia and post-intubation hemodynamic decompensation. Patients with metabolic acidemia (defined as pH 7.30, pCO2 45 mmHg, and HCO3⁻ 18 mEq/L) and respiratory acidemia (pH 7.35, pCO2 45 mmHg, and HCO3⁻ 22 mEq/L) were compared to patients without acidemia (pH 7.35) in the primary analyses. An analysis stratifying patients by pre-intubation HCO3⁻ was also performed. Patients without arterial or venous blood gases within six hours prior to intubation, with DNR/DNI orders, or intubation for a cardiac arrest were excluded. The primary outcome was a composite of increasing vasopressor requirement ( ≥10 µg/min increase in norepinephrine dose equivalents) or death within six hours following intubation. A multivariable logistic regression model adjusting for demographics, comorbidities, intubation indication, location, and year of intubation assessed associations with outcomes. Using the same model (adding HCO3⁻ and pCO2 as exposures), patients were stratified into three tiers based on predicted odds ratios relative to the population median. These tiers were then visualized on an acid-base nomogram to assess adjusted risk by each patient’s acid-base status. Results A total of 8,058 emergent intubations were analyzed. The median age was 65 years, 56% were male. The median pre-intubation SOFA score was 6 (IQR 3, 9) and hypoxemic respiratory failure (47%) was the most common indication for intubation. 773 (9.6%) patients met criteria for metabolic acidemia and 2,308 (28.6%) for respiratory acidemia. The primary composite outcome occurred in 36.7% of patients with metabolic acidemia, 14.6% with respiratory acidemia, and 19.3% without acidemia (p 0.01). These corresponded to adjusted odds ratios (aOR) of 2.72 (95% CI 2.22-3.35, p 0.01) for patients with metabolic acidemia versus 0.55 (95% CI 0.48-0.68, p 0.01) with respiratory acidemia. When stratified by decreasing HCO3⁻ levels, patients with a HCO3⁻ 10 mEq/L had increased odds for the primary outcome when compared to a HCO3⁻ 22 mEq/L (aOR 4.38, 95% CI 3.12-6.14, p 0.01). Conclusion Pre-intubation metabolic acidemia is independently associated with increased odds of post-intubation hemodynamic decompensation or death. These findings highlight the importance of early recognition and pre-intubation optimization for patients with metabolic acidemia, and support future research investigating strategies to mitigate this risk. This abstract is funded by: None