Susan Schmunk, CSTR, CAISS
From England comes a study, begun in 2014 and currently ongoing, analyzing blood changes that occur during the pre-hospital phase in trauma patients. The purpose of the study was to improve the understanding of what happens to the immune system within the first 60 minutes from the moment of traumatic injury. Lead author in this study, Dr. Jon Hazeldine, said: “Although the major and immediate cause of death following severe trauma is haemorrhage, many trauma victims later die following complications such as multi-organ dysfunction or sepsis, with the individual’s immune response to injury significantly influencing the chances of developing these life-threatening conditions.” Almost all prior studies researching the immune response to trauma looked at blood samples taken solely from post-hospital admission.
In emergency medicine, the golden hour refers to a period lasting for one hour or less, following trauma injury being sustained by a casualty or medical emergency, during which there is the highest likelihood that prompt medical treatment will prevent death. With that in mind, researchers set out to gather continual blood data not only on hospitalized patients, but with the assistance of specially trained paramedics, prehospital blood sampling at the scene of major traumas. (University of Birmingham, 2017) The objective was to look in-depth at the very early immune response to trauma and analyze the relationship to later development of multiple organ dysfunction syndrome. The blood of 89 trauma patients with a mean injury severity score (ISS) of 24 was drawn within one hour of injury, as well as at 4 to 12 hours and 48 to 72 hours post-injury. The blood was analyzed for the composition and function of immune cells as well as the concentrations of cytokines.
Prior to this study the immune system was known to be suppressed a few days after major trauma making patients susceptible to infection and sepsis. This study found that changes to the immune system happen very quickly and within minutes of a traumatic injury levels of immune cells and molecules were altered. In some cases, these cell and molecule levels increased compared to normal, while in others they decreased. It was previously known that the immune system is activated following trauma but at the same time makes a compensatory response trying to dampen down the inflammation. The hypothesis was that the dampening down happened after the activation, but this study found the two processes could happen simultaneously.
Further investigation looking at the immune response within the first hour after trauma showed many of the characteristics of this reaction were different than those seen at the post-hospitalization time points. There was an association found between natural killer T cell numbers in the hour after trauma and the eventual development of multiple organ dysfunction syndrome. Due to this finding development of a test to assess this response in patients is in the works, so that patients at risk can be identified and treated.
Jon Hazeldine, David N. Naumann, Emma Toman, David Davies, Jonathan R. B. Bishop, Zhangjie Su, Peter Hampson, Robert J. Dinsdale, Nicholas Crombie, Niharika Arora Duggal, Paul Harrison, Antonio Belli, Janet M. Lord. Prehospital immune responses and development of multiple organ dysfunction syndrome following traumatic injury: A prospective cohort study. PLOS Medicine, 2017; 14 (7): e1002338 DOI: 10.1371/journal.pmed.1002338