Young versus old: factors affecting mortality after blunt traumatic injury

Advanced age predicts poor outcome after trauma. We have previously demonstrated that prolonged occult hypoperfusion (POH), defined as serum lactic acid >2.4 mmol/L persisting for >12 hours, is also associated with worse outcomes. We hypothesized that older patients--a group with potentially less physiologic reserve--would be at greater risk from POH. Prospective data from adult blunt trauma patients admitted to a surgical/trauma intensive care unit from January 1, 1998 through December 31, 1999 were analyzed. Mortality, POH, Injury Severity Score (ISS), chronic health designation (CH) from the Acute Physiology and Chronic Health Evaluation, emergency department Glasgow Coma Scale score (EDGCS), emergency department systolic blood pressure (EDSBP), and gender were compared between older (>55 years) and younger (<56 years) patients and then between nonsurvivors and survivors within age cohorts. Two hundred sixty-four patients were analyzed: 195 younger and 69 older. Mortality was 8.3 per cent (22/264). Older patients had higher mortality (20.3% vs 4.1%, P < 0.05), higher CH (42.9% +/- 1.3 vs 8.4% +/- 0.6), lower ISS (22.6 +/- 1.5 vs 25.6 +/- 0.8, P < 0.05), higher EDGCS (12.9 +/- 0.5 vs 10.7 +/- 0.4, P < 0.05), and higher EDSBP (141.5 +/- 4.1 vs 129.3 +/- 2.2). There were no differences in incidence of POH and gender. Within both age cohorts nonsurvivors had higher ISS, lower EDGCS, and higher CH. Older patients with POH had 34.6 per cent mortality as compared with 11.6 per cent for no POH (P < 0.05). Mortality in younger patients was no different in the presence of POH, and all non-survivors were male. Despite lower ISS and higher EDGCS and EDSBP older patients had five times the mortality of younger patients. Age-specific mortality was influenced by POH and gender. POH was associated with higher mortality only in older patients. With less physiologic reserve older patients may not have been able to adequately compensate for POH; this emphasizes the importance of rapidly correcting serum lactic acid as an endpoint in resuscitation in this population.