Acute Radiation Exposure Increases Mortality to Traumatic Hemorrhage

Abstract

It is anticipated that both ionizing radiation and traumatic injury may occur simultaneously in future terrorist attacks and battlefield scenarios. However, it is not known how radiation combined with injuries (RCI) will impact physiological compensatory responses to traumatic hemorrhage and survival. We hypothesized that the addition of radiation to our established traumatic hemorrhage model (Klemcke et al., J Appl Physiol 2021) would increase mortality. Male rats (n=6/group) were randomly assigned to 1 of 4 groups: sham (no injury; no radiation); radiation injury (RI) only; traumatic hemorrhage alone (CI); or RI combined with traumatic hemorrhage (RCI). For RI and RCI rats, whole-body irradiation was performed with a single, sub-lethal X-ray dose of 5.5 Gy delivered at 1 Gy/min (MultiRad 350). CI consisted of extremity trauma (fibular fracture + penetrating and soft tissue injury, performed under isoflurane anesthesia) followed by conscious hemorrhage of 37% of blood volume. Rats were monitored for 14 days following injury or sham procedures. Sham rats had 100% survival to Day 14, while RI and CI rats had 50% and 50% mortality, respectively, at this point. RCI rats, however, demonstrated 100% mortality at Day 14; differences in survival proportions were significant (P=0.005). We therefore developed a new rat model of RCI by combining X-ray irradiation with traumatic hemorrhage which allows acute (hours) as well as chronic (days) observations. While RI alone produced significant mortality, the addition of traumatic hemorrhage increased mortality to 100%. Future work will elucidate physiological mechanisms potentiating the lethal effect of either RI or CI alone. Biomedical Advanced Research and Development Authority (BARDA). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.