Objectives: To examine the impact of early myocardial workload on in-hospital mortality following isolated severe traumatic brain injury.
Design: Retrospective cohort study.
Setting: Data from the National Trauma Databank, a multicenter trauma registry operated by the American College of Surgeons, from 2007 to 2014.
Patients: Adult patients with isolated severe traumatic brain injury (defined as admission Glasgow Coma Scale < 8 and head Abbreviated Injury Score ≥ 4).
Interventions: Admission rate-pressure product, categorized into five levels based on published low, normal, and submaximal human thresholds: less than 5,000; 5,000-9,999; 10,000-14,999; 15,000-19,999; and greater than 20,000.
Measurements and main results: Data from 26,412 patients were analyzed. Most patients had a normal rate-pressure product (43%), 35% had elevated rate-pressure product, and 22% had depressed rate-pressure product at hospital admission. Compared with the normal rate-pressure product group, in-hospital mortality was 22 percentage points higher in the lowest rate-pressure product group (cumulative mortality, 50.2%; 95% CI, 43.6-56.9%) and 11 percentage points higher in the highest rate-pressure product group (cumulative mortality, 39.2%; 95% CI, 37.4-40.9%). The lowest rate-pressure product group was associated with a 50% increased risk of mortality, compared with the normal rate-pressure product group (adjusted relative risk, 1.50; 95% CI, 1.31-1.76%; p < 0.0001), and the highest rate-pressure product group was associated with a 25% increased risk of mortality, compared with the normal rate-pressure product group (adjusted relative risk, 1.25; 95% CI, 1.18-1.92%; p < 0.0001). This relationship was blunted with increasing age. Among patients with normotension, those with depressed and elevated rate-pressure products experienced increased mortality.
Conclusions: Adults with severe traumatic brain injury experience heterogeneous myocardial workload profiles that have a "U-shaped" relationship with mortality, even in the presence of a normal blood pressure. Our findings are novel and suggest that cardiac performance is important following severe traumatic brain injury.