Is time to first CT scan in patients with isolated severe traumatic brain injury prolonged when prehospital arterial cannulation is performed? A retrospective non-inferiority study.

BACKGROUND: Invasive blood pressure measurement is the in-hospital gold standard to guide hemodynamic management and consecutively cerebral perfusion pressure in patients with traumatic brain injury (TBI). Its prehospital use is controversial since it may delay further care. The primary aim of this study was to test the hypothesis that patients with severe traumatic brain injury who receive prehospital arterial cannulation, compared to those with in-hospital cannulation, do not have a prolonged time between on-scene arrival and first computed tomography (CT) of the head by more than ten minutes. METHODS: This retrospective study included patients 18 years and older with isolated severe TBI and prehospital induction of emergency anaesthesia who received treatment in the resuscitation room of the University Hospital of Graz between January 1st, 2015, and December 31st, 2022. A Wilcoxon rank-sum test was used to test for non-inferiority (margin = ten minutes) of the time interval between on-scene arrival and first head CT. RESULTS: We included data of 181 patients in the final analysis. Prehospital arterial line insertion was performed in 87 patients (48%). Median (25-75th percentile) durations between on-scene arrival and first head CT were 73 (61-92) min for prehospital arterial cannulation and 75 (60-93) min for arterial cannulation in the resuscitation room. Prehospital arterial line insertion was significantly non-inferior within a margin of ten minutes with a median difference of 1 min (95% CI - 6 to 7, p = 0.003). CONCLUSION: Time-interval between on-scene arrival and first head CT in patients with isolated severe traumatic brain injury who received prehospital arterial cannulation was not prolonged compared to those with in-hospital cannulation. This supports early out-of-hospital arterial cannulation performed by experienced providers.

Lasing dynamics in single ZnO nanorods.

We study the lasing dynamics of individual ZnO nanorods by time-resolved mu-photoluminescence. The distinct laser modes show gain competition and pronounced shifts as a function of excitation density. This behavior can be understood in terms of many-particle effects within an inverted electron-hole plasma and of the calculated mode spectra of the particular nanorod, whose geometry is known from electron microscope investigations.