What's New in Emergencies Trauma and Shock - Timing of Definitive Airway Management in Emergency Medical Services Patients: Is Earlier Better?

Airway management remains one of the most decisive interventions in emergency care. Endotracheal intubation (ETI) is often viewed as a definitive act, an intervention that secures oxygenation and ventilation, protects against aspiration, and stabilizes physiology. Yet, an enduring question persists: Does performing ETI in the prehospital environment improve outcomes compared with intubation after arrival in the emergency department (ED)?

In this issue, Siripakarn et al. present a retrospective cohort study from a physician-led Emergency Medical Services (EMS) system at Thammasat University Hospital in Thailand comparing outcomes between patients intubated in the prehospital setting and those intubated within 1 h of ED arrival. Crude and multivariable analyses suggested higher survival among patients intubated in the ED.[1] However, after propensity score matching to balance baseline characteristics, specifically the prevalence of cardiac arrest, the survival difference was no longer statistically significant.

This shift in findings underscores a familiar but critical challenge in airway research: Confounding by indication.

THE SICKEST PATIENTS ARE INTUBATED FIRST

Prehospital ETI is rarely performed electively. It is typically reserved for patients with cardiac arrest, severe traumatic brain injury (TBI), refractory hypoxia, or profound shock. Observational studies have often reported higher mortality among patients intubated before hospital arrival, but such findings may reflect underlying severity rather than procedural harm.[2,3,4]

In TBI, Davis et al. demonstrated worse outcomes among patients intubated prehospital compared with those intubated in the ED.[5] Similarly, Wang et al. also found higher mortality rates among certain trauma patients receiving prehospital ETI.[6] However, subsequent analyses suggested that physiologic instability, particularly hypotension and hypoxia, may account for much of this association.[7]

In the present study, cardiac arrest was disproportionately represented in the prehospital ETI group. Once balanced using propensity matching, the apparent survival advantage of ED intubation diminished.[1] This finding highlights the importance of careful adjustment when evaluating airway timing. Where the tube is placed may matter less than why it was required.

ENVIRONMENT AND SYSTEM EFFECTS

Prehospital intubation is frequently performed under challenging conditions: Limited space, suboptimal lighting, variable access to medications, and restricted personnel support. These factors can affect first-pass success and increase the risk of peri-intubation complications.[8,9] Prolonged scene times, observed in the prehospital group in this study, can potentially delay definitive care.

Notably, all intubations in this EMS system were performed by emergency medicine residents with structured airway training and physician supervision.[1] This differs from many EMS systems internationally, where paramedics perform intubation. Provider training and procedural experience significantly influence airway outcomes.[10]

The high overall success rates reported in both settings suggest that technical competence was unlikely to be the primary determinant of outcome differences in this cohort. Instead, patient physiology and case selection appear central.

HOSPITAL LENGTH OF STAY: A SURVIVOR EFFECT

The longer hospital length of stay (LOS) observed among ED-intubated patients in crude analyses likely reflects survivor bias. Patients who survive the acute phase of illness naturally accumulate more inpatient days, whereas early mortality shortens LOS in more severely ill cohorts.[11] After matching, this difference was no longer significant, reinforcing the need for cautious interpretation of LOS as an outcome measure.[1]

WHAT DOES THE BROADER LITERATURE SUGGEST?

Evidence on prehospital ETI remains equivocal. A meta-analysis of prehospital airway techniques demonstrated variable outcomes depending on provider type and patient population.[2] The AIRWAYS-2 trial, conducted in out-of-hospital cardiac arrest, found no superiority of tracheal intubation compared with supraglottic airway devices for functional outcome.[12] Systematic reviews focusing on TBI similarly report conflicting evidence, with potential benefit in some contexts and harm in others.[3,4]

WHAT THIS STUDY CONTRIBUTES

This investigation adds meaningful insight to the airway literature for several reasons:

1. It examines a single EMS system, reducing inter-system variability

2. It includes both medical and trauma patients

3. It uses propensity score matching to address confounding by indication.

Rather than advocating against prehospital intubation, the findings caution against simplistic conclusions.

A SYSTEMS-LEVEL QUESTION

The relevant question is not simply “prehospital versus ED,” but rather:

• Is the provider adequately trained?

• Are rapid sequence intubation medications available?

• Is physiologic optimization prioritized?

• Does intubation meaningfully delay transport?

In systems with short transport times and readily available ED resources, deferring intubation may be reasonable in selected patients. In contrast, prolonged transport environments may necessitate earlier airway control.

The key lesson from this study is not that prehospital ETI is harmful, nor that ED intubation is superior. Rather, it is that observational comparisons must account for severity and case selection before drawing causal conclusions.

In airway management, timing alone does not determine outcome. Context does.