Tag Archives: helicopter

Helicopter Transport of Trauma Patients Saves Lives

Helicopter EMS (HEMS) transport of trauma patients is used primarily to decrease the amount of time between injury and arrival at the trauma center. Unfortunately, efficacy studies have provided conflicting answers as to whether this is actually true. Last year, the CDC completed a large sample study of this issue using the National Trauma Data Bank (NTDB) in an attempt to determine if HEMS flights are effective.

Using almost 150,000 entries in the NTDB for 2007, they were able to isolate over 56,000 adult records with complete data points. They looked for mortality patterns based on age, injury severity, and revised trauma score, comparing patients who were transported by air vs ground.

They found the following:

  • Odds of dying in-hospital were 39% lower overall when transported by helicopter
  • This survival advantaged disappeared for patients age 55 and older, possibly because of decreased reserve, comorbidities, more complications, or medications that interfere with successful resuscitation
  • Regardless of type of transport, males always fared worse than females

Bottom line: This is a large and intriguing study. About 85% of the US population has access to a Level I or II trauma center within an hour. However, a third of those can only get there in that period of time if transported by air. This mode of transport has a significantly lower mortality rate. However, there are cost and safety considerations as well. The key now is to figure out which patients will have the best outcomes after air transport. This will require more work, looking at more than just mortality (e.g. disability, complications). And what’s the deal with men having poorer outcomes???

Reference: Reduced mortality in injured adults transported by helicopter emergency medical services. Prehospital Emerg Care 15(3):295-302, 2011.

Trauma Survival and Air vs Ground Transport

Wartime experience has shown that rapid transport from the battlefield scene of injury to definitive care dramatically improves survival. This has been translated into civilian trauma care by making helicopter transport to a trauma center more widely available. But this resource is still somewhat limited, and very expensive compared to ground EMS transport. Is this expense warranted, or in other words, does it improve survival?

Many have tried to answer this question. Several of these studies did show improved survival with air transport, but most had significant flaws that made their conclusions hard to interpret. The current issue of JAMA has published an article from MIEMSS and Johns Hopkins that tries to do it right.

The authors used the National Trauma Data Bank (1.8M records) and whittled it down to 223K by using pertinent exclusion criteria. About 25% were transported by air and 72% were taken to Level I centers (vs Level II). A sophisticated regression model was used to adjust for missing data and clustering by trauma centers.

They found that there is roughly a 1.5% survival advantage in taking patients to trauma centers by air. About 65 patients need to be transported to a Level I center, or 69 patients to a Level II center, to save a life. There are some issues with the statistics, primarily due to the nature of the NTDB data, but overall the paper is nicely done.

Bottom line: It looks like helicopter transport of seriously injured trauma patients conveys a very small survival advantage. However, this does not mean that everybody now needs to be flown in. This is not an ideal world, and not everybody is in an area that can provide such transport. Furthermore, in many areas ground EMS is still faster than air. And finally, air transport is much more expensive than the incremental survival increase may be worth. We will have to come to grips as a society to figure out what we can really afford.

Reference: Association between helicopter vs ground emergency medical services and survival for adults with major trauma. JAMA 307(15):1602-1610, April 18, 2012.

Helicopter Transport of Trauma Patients Saves Lives

Helicopter EMS (HEMS) transport of trauma patients is used primarily to decrease the amount of time between injury and arrival at the trauma center. Unfortunately, efficacy studies have provided conflicting answers as to whether this is actually true. Last year, the CDC completed a large sample study of this issue using the National Trauma Data Bank (NTDB) in an attempt to determine if HEMS flights are effective.

Using almost 150,000 entries in the NTDB for 2007, they were able to isolate over 56,000 adult records with complete data points. They looked for mortality patterns based on age, injury severity, and revised trauma score, comparing patients who were transported by air vs ground.

They found the following:

  • Odds of dying in-hospital were 39% lower overall when transported by helicopter
  • This survival advantaged disappeared for patients age 55 and older, possibly because of decreased reserve, comorbidities, more complications, or medications that interfere with successful resuscitation
  • Regardless of type of transport, males always fared worse than females

Bottom line: This is a large and intriguing study. About 85% of the US population has access to a Level I or II trauma center within an hour. However, a third of those can only get there in that period of time if transported by air. This mode of transport has a significantly lower mortality rate. However, there are cost and safety considerations as well. The key now is to figure out which patients will have the best outcomes after air transport. This will require more work, looking at more than just mortality (e.g. disability, complications).

Reference: Reduced mortality in injured adults transported by helicopter emergency medical services. Prehospital Emerg Care 15(3):295-302, 2011.

Helicopter Transport and Civilian Trauma

Military helicopter experience led to widespread adoption in the US for civilian trauma beginning in the 1970s. This has had the significant side effect of extending the reach of trauma centers to a significant percentage of the US population. But because of safety considerations and concerns about appropriate use, the overall benefit continues to be questioned.

Most existing studies have been small, single institution projects. Researchers at the University of Rochester designed a very large study using the National Trauma Databank. They identified over 250,000 patients transported from the injury scene, 16% of whom were transported by ‘copter, the remainder by ground. 

Patients transported by air were more severely injured and were more likely to have a severe head injury or abnormal vital signs. They also had longer hospital and ICU stays, and were more likely to require a ventilator or emergency surgery.

Despite the fact that response and scene times were longer for helicopter transports, air transport was a predictor of survival when injury severity was taken into consideration. This type of study can’t tell why survival is better, but possibilities include distance traveled and a higher level of care provided by air EMS personnel. Aeromedical EMS personnel are more likely to trained to perform advanced techniques such as intubation, crich, and transfusion, and generally have more experience with trauma patients.

Use of this scarce resource for trauma patient transport remains expensive, and as recent accident statistics imply, somewhat dangerous. Trauma centers and systems need to develop evidence-based guidelines that use helicopters intelligently for benefit of the patient, not the aeromedical service owners.

Reference: Helicopters and the civilian trauma system: national utilization patterns demonstrate improved outcomes after trauma injury. J Trauma 69(5):1030-6, 2010.

Making Aeromedical Flights Safer

There are about 840 EMS helicopters operating nationwide. The fatal accident rate has doubled from the mid-90’s to the growth spurt seen in the earlier part of this decade. Since late 2007, 57 crew members and patients have died in these helicopter crashes. According to the FAA, the most frequent causes of these crashes were controlled flight into terrain, inadvertent flight into instrument conditions, and disorientation during night flight.

The FAA is now proposing to change the rules and add extra equipment to these flights in an attempt to improve safety. These changes would include:

  • Installing a ground proximity warning system
  • Tightening the restrictions that limit proximity to bad weather. Currently, pilots must stay half a mile away from clouds during the daytime and one mile away at night.
  • Boosting bad weather training requirements for pilots so they are better equipped to escape from bad weather
  • Installing flight data recorders. New, lightweight models need to be developed for helicopters first, though.

It looks like this is a win-win proposition. Lawmakers, families of crash victims and the aeromedical industry appear to be on board with these changes. Once approved, they would go into effect next year. Unfortunately for the families of crew and patients killed in these crashes, the changes can’t come soon enough.