Airway obstruction time and outcomes after foreign body airway obstruction: a nationwide prospective cohort study from the MOCHI registry

BACKGROUND: Foreign body airway obstruction (FBAO) is a time-sensitive, preventable cause of hypoxic brain injury and death, yet the quantitative time-outcome relationship remains poorly quantified in prospective cohorts. We evaluated the association between airway obstruction time and outcomes in patients with FBAO to evaluate whether any clinical "safe" time window exists. METHODS: We conducted a secondary analysis of the nationwide, prospective MOCHI registry in Japan. To minimize the influence of outliers, the primary analysis was restricted to patients with airway obstruction times of 0-25 min. The primary outcome was 30-day survival; the secondary outcome was 30-day favorable neurological outcome, defined as Cerebral Performance Category 1-3. Odds ratios (ORs) per 1-min increase were estimated using multivariable logistic regression and spline models. RESULTS: Of 409 patients, 229 met the primary inclusion criteria. Median age was 81 years and 48% were male; 60% survived to 30 days and 47% had favorable neurological outcome. Longer obstruction duration was independently associated with lower odds of survival (adjusted OR [aOR] 0.86; 95% confidence interval [CI] 0.81-0.90) and favorable neurological outcome (aOR 0.85; 95% CI 0.80-0.89). Spline models showed a steep monotonic decline in predicted outcomes immediately from onset without evidence of a distinct threshold or "safe" time window. CONCLUSIONS: Outcomes declined continuously per minute of unresolved obstruction, with no inflection point or "safe" time window. This highlights that every minute of delay worsens prognosis, reinforcing the need for immediate bystander intervention.