Background

“The Golden Hour”, a widely accepted concept that transport of the trauma patient within the initial 60 minutes after injury purports better outcomes has little empiric evidence directly supporting this relationship between time and outcome.  While there have been many studies that suggest a survival benefit to shorter on-scene time and shorter transit time; most studies fail to substantiate a relationship. There have been many challenges and limitations in previous studies in the attempt to establish the time-outcome association. 

Assuming time is an important determinant of survival this study intends to identify subgroups of trauma patients most likely to benefit from shorter out-of-hospital time.

Clinical Question

Is there an association between total out-of-hospital time and outcomes in patients with traumatic shock or traumatic brain injury?

Population

Two separate cohorts of injured adults:
1. Patients with clinical evidence of hemorrhagic shock: defined as, SBP < 70mm Hg or SBP of 71 - 90 mm Hg with pulse of 108 or greater. 2. Patients with traumatic brain injury: defined as, GCS of 8 or less

Intervention

Analysis of the primary exposure variable of total out-of-hospital time, calculated as time from initial 911 call to time of arrival in receiving hospital Emergency Department.

Outcomes

Primary: Shock Cohort - 28-day mortality
Primary: TBI Cohort - Glasgow Outcome Scale Extended (6 months)

Design

Secondary analysis of two cohorts of trauma patients(shcok and TBI), previously enrolled in an out-of-hospital clinical trial evaluation hypertonic saline and dextran after injury.
Multiple sub-group analysis including: Out-of-hospital physiology and procedures; Mechanism of injury; Hospital type Injury severity score; Interventions in the first 24 hours.

Primary Results

  • Shock cohort: Total out of hospital time was not associated with 28-day mortality
  • TBI cohort: Total out of hospital time was not associated with neurologic outcome at 6 months or 28-day mortality
  • Median out-of -hospital time for the entire sample was 44 minutes (Range 33 – 60)
  • Shock cohort 41 minutes (range 31 – 59)
  • TBI cohort 46 minutes (range 35 – 61)

Critical Findings

  • Association between out-of-hospital time > 60 minutes and increased mortality
  • Adjusted Odds Ratio: 2.37 (CI 1.05-5.37)
  • Sub-Group Analysis: Shock groups requiring early critical interventions e.g.: transfusion, surgery, IR, ORIF, in the first 24 hours

Strengths

  • Large, multi-EMS system trial
  • Asks a clinically important question

Limitations

  • Data was not originally collected for this analysis.
  • Many factors influence out-of-hospital time
  • There are multiple patient and injury factors, EMS systems and procedural differences that may confound the results

Author's Conclusions

"Among out-of-hospital trauma patients meeting physiologic criteria for shock and traumatic brain injury, there was no association between time and outcome. However, the subgroup of shock patients requiring early critical resources and arriving after 60 minutes had higher mortality."

Our Conclusions

The primary outcomes are consistent with other larger studies however, this study elucidates a sub-group of injured patients in shock who will require intervention in the first 24 hours that benefit fro shorter out-of-hospital time.

Potential Impact To Current Practice

None at this time. Without understanding how to identify which patients will benefit, we will continue to transfer patients as rapidly as possible.

Bottom Line

It will be critical to identify those most likely to require these interventions and devote resources to ensuring shorter transit to Level I trauma centers while understanding other injured persons are less likely to benefit from the shorter out-of -hospital time.

Read More

Delbridge TR, Yealy DM. Has the Golden hour lost its luster? Ann Emerg Med 2015; 66(1): 42-44.