Emergency Medical Services Intervals and Survival in Trauma – Assessment of the “Golden Hour”

There is a very important paper due to be published in the Annals of Emergency Medicine.^[1] I expect that there will be a lot of criticism of this paper. There will be many reasons for being cautious in implementing the suggestions of the authors, but bad research is not one of them.

One of the difficult things about this paper is that the authors are very good about identifying potential confounding influences. They explain that there are many factors that may have affected the results. They are thorough in pointing out the many different ways they analyzed the data to try to minimize any potential confounding influences. While many may look at this study, see the amount of doubt the authors express throughout the study, and conclude that there is too much uncertainty to pay any attention to this study, they would be wrong to do so.

Trusting in the certainty of those promoting the Golden Hour is the true error. Anxious exhortations to Panic! and Faster! and Panic faster! are not substitutes for good patient care.

The Golden Hour has been around for decades. This is the idea that seriously injured patients need to receive definitive care within 60 minutes of that serious injury.

The amount of information used by Dr. R Adams Cowley to concoct the Golden Hour could fit onto a cocktail napkin. According to legend, it was dreamed up in a bar, so maybe it did fit onto a cocktail napkin. The Golden Hour is not science. The Golden Hour is marketing, and very successful marketing. There are still plenty of people citing the Golden Hour as their excuse for all sorts of mistreatment of patients – But we have to get them to the trauma center inside the Golden Hour. A more appropriate term is the Bogus Hour.

The commonly used 8 minute response time (or 8 minutes 59 second response time in some places) limit (in at least 90% of responses) is based on the AHA’s (American Heart Association’s) Chain of Survival. The interesting thing is that cardiac arrest survival appears to be the only condition that has good science supporting a short response time.

To date, patients with out-of-hospital cardiac arrest remain the only field-based patient population with a consistent association between time (response interval) and survival.^18,19[2]

The authors of this study probably looked at far more data on trauma time intervals than any other study. They evaluated the data in as many different ways as they could think of, to see if there were any ways that there could be a connection between prehospital time and survival. In spite of all of these different ways of evaluating the data, the conclusion based on all of the evidence is – time does not make a significant difference in survival for unstable trauma patients.

This was not a study just looking at all trauma patients, the patients meeting only anatomic criteria were not included. The same is true for patients only meeting mechanism criteria. In other words, they excluded most of the patients transported to trauma centers.

Why?

Because these patients do not have serious enough injuries to expect time to make a difference. Even though these patients are rushed to trauma centers, their injuries have not resulted in unstable vital signs/level of consciousness. Therefore, they are not considered to have significant injuries for the purposes of this study.

Here are some representative anatomic criteria and mechanism criteria for trauma triage –

Anatomic Criteria:
• Penetrating injury to head, neck, torso and extremities proximal to elbow or knee (unless obviously superficial)
• Chest injuries with respiratory distress (for example, flail chest)
• Two or more proximal long-bone (humerus or femur) fractures
• Pelvic fractures
• Limb paralysis (spinal cord injury)
• Amputation proximal to wrist or ankle^[3]

None of these qualify to get the patient into the study – shooting, stabbing, nibbled at by a lion, – unless the patient has signs of being unstable.

Mechanism of Injury:
• Death of another occupant in same vehicle
• Auto vs. pedestrian (bicycle) injury with significant impact
• Pedestrian thrown or run over
• Extrication time > 20 minutes
• Falls from > 20 feet
• Ejection from vehicle
• Vehicle rollover
• High-energy vehicle crash (e.g. significant intrusion into
passenger compartment)
• Motorcycle crash with separation of rider from motorcycle
Other factors combined with traumatic injuries:
• Age 55 years
• Combination of trauma with burns
• Known heart disease, CHF, or COPD
• Known bleeding disorder or taking coumadin/ heparin
• Pregnancy (>20 weeks)
• Rigid or diffusely tender abdomen
• Amputation of fingers with possibility of reattachment^[3]

These are the kind of criteria that Maryland was using to fly patients. When they had their fatal crash last year, these mechanism criteria required permission from medical command to fly patients. Flights dropped by about two thirds and outcomes do not appear to have changed. Few of these criteria are useful for predicting instability. This study was only concerned with patients who really are unstable, not those with significant damage to their cars or trucks.

So, what is unstable in the study?

The criteria from the study –

Injured patients with one or more of the following criteria were included: systolic blood pressure (SBP) less than or equal to 90 mmHg, Glasgow Coma Scale (GCS) score less than or equal to 12, respiratory rate less than 10 or greater than 29 breaths/min, or advanced airway intervention (tracheal intubation, supraglottic airway, or cricothyrotomy). “Injury” was broadly defined as any blunt, penetrating, or burn mechanism for which the EMS provider(s) believed trauma to be the primary clinical insult.^[2]

And still they have 10 physiologically unstable patients per day, if averaged over a year – with a few left over. Remember, this is after excluding most of the patients who would automatically be flown to trauma centers, because the authors do not believe that those patients are injured enough for time to make a difference in their outcomes.

Editor’s Capsule Summary

What is already known on this topic

The “golden hour” concept in trauma is pervasive despite little evidence to support it.

What question this study addressed

Is there an association between various emergency medical services (EMS) intervals and in hospital mortality in seriously injured adults?

What this study adds to our knowledge

In 3,656 injured patients with substantial perturbations of vital signs or mental status, transported by 146 EMS agencies to 51 trauma centers across North America, no association was found among any EMS interval and mortality.

How this might change clinical practice

This study suggests that in our current out-of-hospital and emergency care system time may be less crucial than once thought. Routine lights-and-sirens transport for trauma patients, with its inherent risks, may not be warranted.^[2]

So, if time is not making a difference in survival, maybe we should stop killing people just to get patients to the hospital a little bit faster.

Some more details from the paper –

. . . total EMS time was not associated with mortality . . . for every minute of total time . . . When the sample was assessed with 10-minute increments for total EMS time, there was no evidence of increased mortality with increasing field times . . . Similar results were obtained when total times were grouped by quartile . . . We were also unable to demonstrate independent associations between mortality and any other EMS interval for the overall sample . . . ^[2]

No matter how they broke down the time intervals, there was no detectable change in outcome.

For categorized response interval, there was no association with mortality for patients with a 4- to 8-minute interval . . . or greater than 8-minute interval . . . compared with patients with a response less than 4 minutes.^[2]

The same for response times.

In multivariable logistic regression models, there was no demonstrable association between time and mortality for any subgroup.^[2]

Although some seriously injured individuals may require time-dependent EMS interventions to survive (eg, airway obstruction, respiratory arrest, external hemorrhage at a compressible site), faster application of such interventions may not have a measureable effect on outcomes for most trauma patients.^[2]

There may be isolated patients, who benefit from less prehospital time, but there are not enough to make any detectable difference in the outcomes of these unstable patients. No difference in the cumulative outcomes. No difference in any of the subgroup analyses. No difference in any of the time subgroups. How many people are being injured and killed, just to get EMS crews there faster, because in EMS we just know that faster is better. Are we killing more people trying to get to the occasional patient who might benefit from a more rapid response, or a more rapid transport, than we are helping?

That little bit faster is insignificant, except psychologically. Perhaps we should refer those in need of lights, sirens, speed, and helicopters for CISM (Critical Incident Stress Management) in stead. Oops, that is also a treatment that lacks evidence to support it.^[4]

The authors conclude with this bit of common sense –

In the setting of a perceived “emergency,” the public may not necessarily value whether faster EMS time and expeditious care have been shown to save lives for the majority of clinical conditions. However, meeting these expectations costs money (eg, establishment of fire houses and positioning of EMS crews to achieve predefined response intervals), can place EMS providers, patients, and the nearby public at risk,^20-22 and is a common reason (ie, emergency vehicle crashes) for tort claims against EMS agencies.^58[2]

The big questions are –

Will more than a handful of people in EMS pay any attention to this?

Will we wait until lawyers force us to do what is right?

Why do we continue to choose mythology and expert opinion over science?

Dr. Bledsoe provides his own commentary on this trauma paper.^[5] Peter Canning also writes about this.^[6]

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Footnotes –

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^[1] Emergency Medical Services Intervals and Survival in Trauma: Assessment of the “Golden Hour” in a North American Prospective Cohort.
Newgard CD, Schmicker RH, Hedges JR. at al.
Ann Emerg Med. 2009;(in press, may end up with a 2010 publication date)
PMID: 19783323 [PubMed – as supplied by publisher]

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^[2] This is the same as footnote [1].

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^[3] Statewide BLS Protocols Effective November 2008
Pennsylvania
Page with link to the full text PDF of the protocols.

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^[4] Critical Incident Stress Debriefing and Mythology
Rogue Medic
November 10, 2009
Article

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^[5] Speed and Time in Prehospital Trauma Care
The EMS Contrarian
by Bryan E. Bledsoe
EMS1.com
Article

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^[6] The Golden Hour
Street Watch
Article

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Newgard CD, Schmicker RH, Hedges JR, Trickett JP, Davis DP, Bulger EM, Aufderheide TP, Minei JP, Hata JS, Gubler KD, Brown TB, Yelle JD, Bardarson B, Nichol G, & Resuscitation Outcomes Consortium Investigators (2009). Emergency Medical Services Intervals and Survival in Trauma: Assessment of the “Golden Hour” in a North American Prospective Cohort. Annals of emergency medicine PMID: 19783323

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