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Abstract

Introduction: No studies have described the perfusion status of seriously injured combat casualties as they move across the continuum of care. This study is the first to describe the perfusion state of seriously injured combat casualties pre/post MEDEVAC transport from point of injury (POI) or after initial resuscitation when the casualty is being evacuated from Role II (field hospital) to a higher level of care. Methods: Prospective observational study of 30 seriously injured combat casualties in Afghanistan. Phase I: POI to Role II (n = 6). Phase II (n = 24): Immediately before evacuation from Role II to higher level of care. Results: Phase I: Mechanism of injury (MOI): Mortar (n=2), IED (n =1), GSW (n = 3); 5/6 with severe extremity trauma requiring tourniquets. Time from injury to initial VS/StO2: 22 ± 7 min. POI: 2 patients with SBP < 90, both with StO2 < 75% (ex: bowel evisceration; SBP 90/HR 140/StO2 34%). In 4 patients with SBP > 90/HR < 120; field StO2 > 75% in 2 who had mild hypoperfusion and 2 with normal perfusion on admission to Role II. Role II Admit: Hypoperfusion: 4 cases (3 occult). In above case, StO2 identified worsening perfusion despite SBP correction (SBP 111/HR 130/StO2 25%/Lactate 8.9 mmol/L). 3 cases mild/moderate occult hypoperfusion: StO2 < 75% (n = 2)/StO2 93% (n = 1). In 2 patients with normal perfusion, StO2 normal or increased. Phase II: MOI: IED/explosion or GSW. Care before transport: Surgery (n= 18), intubated (n = 17), PRBCs (n = 17; 9.5 ± 6 units); whole blood (n = 8; 4 ± 3.6 units), crystalloids 4.3 ± 2.8L. At time of Role II transport (7.1 hours post-injury): Hypoperfusion in 13/24 patients: Mild: 6/Severe: 7; Occult: 6. StO2 abnormal in 5/6 occult hypoperfusion cases: StO2 < 75% (n=2)/StO2 > 90% (n=3). However StO2 was abnormal in only 2/7 cases with increased BD and abnormal VS. Conclusions: In seriously injured combat casualties, at POI, post-transport from the field and before evacuation from Role II, there was a high incidence of hypoperfusion. In these patients, StO2 < 75% detected occult hypoperfusion and StO2 > 90% also suggested hypoperfusion. A normal StO2 (75%-90%) did not rule out hypoperfusion. A single abnormal StO2 (< 75% or > 90%) indicates a need for reassessment of the patient and may be beneficial as the patient moves along the care continuum. IRB: USFOR-A-09-022.