March 15, 2000
In the continuing debate among emergency medical services (EMS) personnel regarding the best pre-hospital management for trauma patients, a new study by Johns Hopkins and the University of Southern California raises the bar on the importance of time. In a study of 103 people, the most critically injured patients transported by private means arrived at Los Angeles County (LAC) + USC Medical Center, a Level 1 trauma center, in nearly half the time of their counterparts transported by EMS -- an average of 15 minutes between time of injury and hospital arrival vs. 28 minutes. Despite this difference, deaths, complications and length of hospital stay were similar between the EMS and non-EMS transported patients. There was, however, a trend toward better outcomes for those who arrived at the trauma center more quickly following injury.
A 1996 retrospective study of 5,782 patients admitted to that center over a two-year period found that trauma patients transported by EMS had death rates twice as high as those transported by private means (28.2 percent vs. 17.9 percent). Results of the current study -- the first to look at the non-EMS group in detail -- were published in the March issue of Archives of Surgery.
"One might think that the importance of time is obvious, intuitive and, thus, not worth studying," says Edward E. Cornwell, M.D., lead author of the study and chief of trauma at Hopkins. "But just two years ago, we heard reports that Princess Diana was at the scene of the accident for 45 minutes and had a slow transport to the hospital."
About 4 to 15 percent of all major trauma patients arrive at a sampling of large, urban trauma centers by means other than EMS, Cornwell says. These patients represent the purest form of "scoop and run" – the philosophy that says EMS should rush patients straight to the hospital rather than first treating them on-scene. Others believe EMS should stay on scene a while and resuscitate patients with intravenous fluids or other means, then bring them to the hospital, otherwise known as "stay and play."
The best way for EMS to treat patients probably varies with the setting and circumstances of injury, Cornwell says, be it a gunshot wound vs. injuries sustained in an auto crash, for example. Proximity to a trauma center also is a factor.
"Paramedics adhere to pre-established protocols in transporting trauma patients, so our studies showed an amazing consistency in the injury-to-hospital-arrival time interval regardless of the severity of injury," Cornwell says. "By contrast, in the non-EMS group, the more critical the injury, the quicker patients got themselves to the emergency department, almost as if they recognized the severity of their own injuries."
For the current study, patients were enrolled between January and October 1997. Estimated time of injury and outcome for 38 patients who arrived at the center by private means were matched to those of 38 patients of similar ages and injuries who were transported by EMS. Twenty-seven random patients transported by EMS also were studied as a control. The general population was approximately 85 percent male, 80 percent Hispanic and 10 percent African-American.
The majority of patients had an injury severity score (ISS) of 13 or more on a 75-point scale. The ISS is calculated by dividing the body into quadrants and assigning a number to each quadrant based on severity of the injuries in each, then squaring those numbers and adding them together. An example of an ISS of 13 would be a gunshot wound to the chest and abdomen with injuries to the lung and a hemothorax (blood in the chest) and an injury to a peripheral segment of the liver.
Researchers created a model to assess the time of injury in each patient by interviewing the patient and any witnesses or friends, and combine their answers with data obtained from police, sheriff and medical examiner reports. No significant differences were observed in the two groups regarding mortality, length of hospital stays, days in the intensive care unit, complications or infections. Cornwell is continuing his studies of patient injuries, transport time to the hospital and outcomes.
The study was supported by the federal Centers for Disease Control and Prevention in Atlanta. Other authors were Howard Belzberg, M.D.; Karen Hennigan, Ph.D.; Cheryl Maxson, Ph.D.; George Montoya; Anna Rosenbluth; George C. Velmahos, M.D., Ph.D.; Thomas C. Berne, M.D.; and Demetrios Demetriades, M.D., Ph.D. Related Web sites:
Johns Hopkins Department of Emergency Medicine: http://www.acenet.jhmi.edu/emerg/
LAC+USC Trauma Surgery and Critical Care: http://www.usc.edu/hsc/medicine/surgery/trauma/index.html
American Association for the Surgery of Trauma: http://www.aast.org
Eastern Association for the Surgery of Trauma: http://www.east.org