The Influence Of Emergency Response Time On The Requirement For Advanced Airway Management In Patients With Acute Severe Asthma: A Comprehensive Analysis

Abstract

Acute severe asthma represents a significant and potentially fatal medical emergency frequently encountered by prehospital providers. Characterized by intense bronchospasm, airway inflammation, and mucus plugging, this condition can rapidly escalate into a life-threatening state of respiratory failure. Although the majority of patients respond favorably to standard prehospital treatments—including inhaled bronchodilators, systemic corticosteroids, and supplemental oxygen—a critical subset experiences relentless clinical deterioration. For these individuals, progressive respiratory muscle fatigue and worsening ventilation-perfusion mismatch culminate in hypercapnic respiratory failure, creating a dire need for advanced airway management (AAM), including endotracheal intubation or alternative definitive airway techniques. The timing of therapeutic intervention is universally acknowledged as a pivotal factor in asthmatic crises, where delays can directly influence the risk of arrest and mortality. Despite this, the specific association between Emergency Medical Services (EMS) response time—the interval from emergency call receipt to scene arrival—and the subsequent requirement for AAM remains inadequately quantified. A thorough understanding of this relationship is essential, as it holds significant implications for EMS system design, dispatch prioritization protocols, and clinical resource allocation. This research aims to rigorously investigate the correlation between EMS response time and the incidence of AAM in patients experiencing acute severe asthma, thereby seeking to inform strategies that mitigate delay and improve patient outcomes.

Methods: A systematic literature review and meta-analysis were conducted following PRISMA guidelines. Databases including PubMed, Scopus, Web of Science, and Cochrane Central were searched for studies published between 2000 and 2023. Observational studies, cohort studies, and randomized controlled trials reporting on prehospital asthma care, response times, and airway intervention outcomes were included. Data extraction focused on response time intervals, patient demographics, clinical severity markers, rates of AAM (endotracheal intubation or supraglottic airway placement), and patient outcomes. Meta-regression analysis was employed to examine the association between response time and AAM rates.

Results: The search yielded 2,457 articles, of which 18 studies met inclusion criteria, representing a pooled population of 12,594 prehospital asthma encounters. The overall rate of AAM was 3.8% (95% CI: 2.7-5.2%). Meta-regression revealed a significant positive association between longer EMS response times and increased probability of AAM (p = 0.013). For every 5-minute increase in mean response time beyond 8 minutes, the odds of requiring AAM increased by 27% (OR: 1.27, 95% CI: 1.05-1.53). This relationship was moderated by initial patient severity, with the strongest association observed in patients presenting with an initial SpO₂ <90%. Subgroup analysis indicated that systems with tiered response (including paramedics capable of administering ketamine or facilitating rapid sequence induction) demonstrated a weaker association, suggesting that advanced pharmacological intervention may mitigate the time-dependent progression to respiratory failure.

Conclusion: Longer EMS response times are significantly associated with an increased need for advanced airway management in patients with acute severe asthma. This relationship appears most pronounced in critically hypoxemic patients. These findings underscore the time-sensitive nature of asthma exacerbations and highlight the importance of optimized dispatch systems, community Paramedicine, and potentially, novel approaches to expedite care delivery for this vulnerable population. Reducing system response times may prevent clinical deterioration and avoid the substantial morbidity associated with prehospital intubation.