Aiolfi A, Benjamin E, Recinos G, De Leon Castro A, Inaba K, Demetriades D
J Emerg Med. 2018 Mar;54(3):328-334
BACKGROUND: The effect of prehospital helicopter emergency medical services (HEMS) on mortality has been analyzed previously in polytrauma patients with discordant results.
OBJECTIVE: Our aim was to compare outcomes in patients with isolated severe blunt traumatic brain injuries (TBIs) transported by HEMS or ground emergency medical services (GEMS).
METHODS: We conducted a National Trauma Data Bank study (2007-2014). All adult patients (≥16 years old) who sustained an isolated severe blunt TBI and were transported by HEMS or GEMS were included in the study.
RESULTS: There were 145,559 patients who met the inclusion criteria. Overall, 116,391 (80%) patients were transported via GEMS and 29,168 (20%) via HEMS. Median transportation time was longer for HEMS patients (41 vs. 25 min; p < 0.001). HEMS patients were more likely to have hypotension (2.7% vs. 1.5%; p < 0.001), Glasgow Coma Scale (GCS) score < 9 (38.2% vs. 10.9%; p < 0.001), and head Abbreviation Injury Scale (AIS) score of 5 (20.1% vs. 9.7%; p < 0.001). Stepwise logistic regression analysis identified age ≥ 65 years old, male sex, hypotension, GCS score < 9, prehospital intubation, and head AIS scores 4 and 5 as independent predictors of mortality. Helicopter transportation was independently associated with improved survival (odds ratio [OR] 0.55; 95% confidence interval [CI] 0.47-0.67; p < 0.001). Admission to a Level I trauma center was an independent predictor of survival (OR 0.64; 95% CI 0.53-0.82; p = 0.001). Regardless of head AIS, helicopter transport was an independent predictor of survival (AIS 3: OR 0.35; p < 0.001; AIS 4: OR 0.44; p < 0.001; AIS 5: OR 0.76; p < 0.001). A prolonged transport time was not an independent predictor of mortality.
CONCLUSIONS: Helicopter transport, in adult patients with isolated severe TBI, is associated with improved survival.
Bradfield C, Vavalle N, DeVincentis B, Wong E, Luong Q, Voo L, Carneal C
Mil Med. 2018 Mar 1;183(suppl_1):276-286
Combat helmets are expected to protect the warfighter from a variety of blunt, blast, and ballistic threats. Their blunt impact performance is evaluated by measuring linear headform acceleration in drop tower tests, which may be indicative of skull fracture, but not necessarily brain injury. The current study leverages a blunt impact biomechanics model consisting of a head, neck, and helmet with a suspension system to predict how pad stiffness affects both (1) linear acceleration alone and (2) brain tissue response induced by both linear and rotational acceleration. The approach leverages diffusion tensor imaging information to estimate how pad stiffness influences white matter tissue strains, which may be representative of diffuse axonal injury. Simulation results demonstrate that a softer pad material reduces linear head accelerations for mild and moderate impact velocities, but a stiffer pad design minimizes linear head accelerations at high velocities. Conversely, white matter tract-oriented strains were found to be smallest with the softer pads at the severe impact velocity. The results demonstrate that the current helmet blunt impact testing standards' standalone measurement of linear acceleration does not always convey how the brain tissue responds to changes in helmet design. Consequently, future helmet testing should consider the brain's mechanical response when evaluating new designs.
Regasa LE, Kaplan DA, Moy Martin EM, Langbein J, Johnson F, Chase LC.
J Head Trauma Rehabil. 2018 Mar/Apr;33(2):123-132
OBJECTIVE: To examine mortality among active duty US military service members (SMs) with the diagnosis of penetrating traumatic brain injury (PTBI) and a hospital admission between 2004 and 2014.
DESIGN: Data on SMs with PTBI and an admission to a military or civilian hospital were obtained from the 2004 to 2014 Military Health System data repository. After applying exclusion criteria, data on 1226 SMs were analyzed.
MAIN MEASURES: The number of observed deaths per 100 identified patients with PTBI and time to death from admission were used as main measures.
RESULTS: Approximately 25% of the 1226 patients with PTBI included in this study died following admission, with 44.6% of the all deaths occurring within a day following hospital admission and 75% occurring within the first week. Severe comorbid conditions and intentionally self-inflicted injuries are associated with higher mortality rate. SMs' gender, age, year of hospital admission, and service were significantly associated with likelihood of death following PTBI hospitalization. Males had a higher likelihood of dying following hospital admission compared with females (odds ratio = 2.7, confidence interval = 1.03-7.9). SMs in the 35- to 44-year-old and 45- to 64-year-old groups had up to a 2.6 times higher odds of death following their admission compared with the 25- to 34-year-old group. Age, admission year, service, and rank were significantly associated with SMs' time to death from hospitalization. Patients between the ages of 45 and 64 years were significantly more likely to die earlier than other age groups. Furthermore, cases in the Navy Afloat group had a higher fatality rate and were more likely to die earlier than patients in other services. PTBI comorbid conditions and injury type did not significantly affect time to death.
CONCLUSION: This study quantifies case fatality rate among hospitalized US SMs with the diagnosis of PTBI. We report a 23.1% crude case fatality rate among the current cohort. Early intensive care for these patients may be the key to improving survival rates.