Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Observations on the NTSB HEMS Hearings

During today’s NTSB hearings[1] there were some interesting comments.

The first speaker, Dr. Ira Blumen,[2] looked carefully at the safety statistics for helicopters and fixed wing aircraft. He compared all types of aircraft safety data. He arrived at a crew fatality rate figure that would make HEMS employment the most dangerous, or second most dangerous job in America. The confidence intervals for this were not given, but the wide range of fatalities, from year to year, make it clear that this is going to be less accurate than many professions with many more employees in that particular field.

The fatality rate is calculated per 100,000 employees per year. There are only 12,000 employees in HEMS, so 1 fatality per year, if the employment level remains steady, equals just over 8 per 100,000. An improvement in safety, that prevents the death of one crew member per year, would have a much more dramatic effect on the fatality rate per 100,000 employees per year. A change that makes HEMS less safe, would have a similarly dramatic effect in making all other dangerous occupations seem safe by comparison.

He proceeded to calculate the death rate for patients. This was less than 1 per 100,000. This is a good thing. one of the reasons is that there are generally 3, or more crew members for each patient on board. another is that there is not always a patient on board, when there is a fatal crash. At the end of his presentation, he tried to compare these numbers to ground ambulance fatalities. He admitted that there are no firm statistics on these fatalities, so he decided to compare all motor vehicle fatalities to all HEMS patient fatalities. He concluded that HEMS transport is much safer.

First, he is comparing things that are not at all related. While it is true that there are no good statistics on ground ambulance fatalities, crew member fatalities, or patient fatalities, these can be estimated. It is wrong that these data are not tracked, but since they are not, we can only estimate the rate. If the numbers of patient fatalities in ground ambulances were comparable to the total motor vehicle fatality rate, there would be hundreds, or thousands of fatalities of EMS patients per year. Are the EMS black helicopters coming down and cleaning up all of these fatalities? Do all of these patients go to Area 51? I do not believe that this is a reasonable way of calculating the risk to ground transport patients. I think it is obvious that this overestimates the fatalities by a huge amount. In a, I used my own method of estimating the crew fatality risk, not the patient risk. The reason was that I was going by the EMS fatality rate. The EMS fatality rate is still not completely accurate, but there are people tracking EMS fatalities. I get emails every time there is a report of an EMS LODD (Line Of Duty Death). The suggestion that the fatality rate can be calculated from all motor vehicle deaths, yet it would not correlate at all with EMS LODDs, is not credible.

He also compares the fatality rate of all of HEMS to the IOM (Institute Of Medicine) iatrogenic death rate of 44,000 to 98,000 patients per year. This produces a number much higher than the overall motor vehicle fatality rate. This seems to suggest that the patient is safer in the helicopter, than in the hospital. It also suggests thsat the patient is safer in the ground transport ambulance, than in the hospital.

Obviously, I need a raise. But why should any of us transport patients to the hospital, if the hospital is so dangerous?

One thing to consider about the iatrogenic deaths – they cover the entire time the patient is in the hospital AND anything that happens that might be related to when the patient was in the hospital. The amount of time a patient is in the hospital is much greater than the amount of time the patient is in the helicopter. Typical patients will probably be spending more time in the waiting room of the hospital, than they will be spending in the helicopter. Maybe we should be comparing the iatrogenic death rate of the hospital waiting room to the fatal crash rate of HEMS. These comparisons are not valid.

But wait, the iatrogenic death rate of HEMS is not even considered in the HEMS fatality rate, unless the patient dies in a HEMS crash. Iatrogenic death for the hospitals includes just about every possible contribution to death that might lead to a preventable death.

Types of Errors


Error or delay in diagnosis
Failure to employ indicated tests
Use of outmoded tests or therapy
Failure to act on results of monitoring or testing


Error in the performance of an operation, procedure, or test
Error in administering the treatment
Error in the dose or method of using a drug
Avoidable delay in treatment or in responding to an abnormal test
Inappropriate (not indicated) care


Failure to provide prophylactic treatment
Inadequate monitoring or follow-up of treatment


Failure of communication
Equipment failure
Other system failure

SOURCE: Leape, Lucian; Lawthers, Ann G.; Brennan, Troyen A., et al. Preventing Medical Injury. Qual Rev Bull. 19(5):144–149, 1993.[3]

All of these conditions apply just as much to patient care in the helicopter as in the hospital. Care in the helicopter is restricted by the environment, so that in-flight assessment and treatment are limited, compared to in-hospital assessment and treatment. There is no consideration of diagnostic, treatment, preventive, or other criteria from HEMS. There is no follow-up of iatrogenic death that may result from HEMS transport. Comparing falling-out-of-the-sky risks, while ignoring all other risks, is very misleading. To be fair, this also ignores the same iatrogenic death contributions that occur in ground EMS transport, which has many of the same limitations on assessment and treatment.

This is not to diminish the rest of what Dr. Blumen said. I think that he did a commendable job when he was looking at the helicopter data. When he was using the helicopter data, he was familiar with the ways that the data might be misleading. He presented appropriate caveats and made it clear when he was drawing conclusions, that others might reasonably disagree with. When he tried to compare the non-HEMS data, he seemed to be adding them as an afterthought. These ground EMS and hospital iatrogenic death data, at least as used in Dr. Blumen’s presentation, are not relevant to the HEMS data.


^ 1 Safety of Helicopter Emergency Medical Services (HEMS) Operations
Public Hearing
February 3–6, 2009
Biographies for the Board of Inquiry and the Technical Panel
Witnesses’ Biographies
Live Webcast – Captioned!
Windows Media Player
Real Player

    • Tuesday 2/3 – 9 am
    • Wednesday 2/4 – 8:30 am
    • Thursday 2/5 – 8:30 am
    • Friday 2/6 – 8:30 am.
    • Archive links will be added after each day’s presentations have concluded

^ 2 Witness #1 Ira Blumen, M.D.,
Director, University of Chicago Hospitals, Chicago, Illinois
Dr. Blumen has been involved in air medical transport since 1985 and has been the program and medical director of the University of Chicago Aeromedical Network (UCAN) since 1987. Before that, he was the medical director of the MedStar helicopter program at St. Mary of Nazareth Medical Center in Chicago. Dr. Blumen served on the Board of Directors of the Association of Air Medical Services (AAMS) and was a founding member, board member, and past-president of the Air Medical Physician Association (AMPA). He has received numerous awards, including the 2004 AAMS Jim Charlson Award, which recognizes an individual for significant contributions to the overall enhancement, development, or promotion of aviation and aviation safety within the air medical transport community. In October 2008, Dr. Blumen received two additional awards for his continued work and dedication to HEMS safety research: the 2008 AAMS President’s Award, and the 2nd Annual American Eurocopter Vision Zero Aviation Safety Award, for research.
Witnesses’ Biographies

Late addition (21:00, 02/03/09):
Dr. Blumen’s slide presentation is An Analysis of HEMS Accidents and Accident Rates
Free PDF from NTSB of what was a PowerPoint presentation by Dr. Blumen.

This does not include the ground EMS calculation, which suggests that it was an afterthought. The IOM data are in here, which suggests that a little more thought went into that. Too bad. These data are not comparable. Dr. Blumen should have recognized this incompatibility.
Some of the presentations of the speakers are available at the Agenda link above in footnote [1].

^ 3 To Err is Human: Building a Safer Medical System
IOM (Institute of Medicine) PDF Summary
This is available in several different forms. The National Academies Press page that contains all of the links is here.
The pdf links download the pdf, they do not open it directly.
Free PDF Summary . . . . . Free PDF Report In Brief
or read the book online for free