A Noninvasive Stroke Volume Monitoring for Early Detection of Minimal Blood Loss: A Pilot Study.

INTRODUCTION: Alternation in traditional vital signs can only be observed during advanced stages of hypovolemia and shortly before the hemodynamic collapse. However, even minimal blood loss induces a decrease in the cardiac preload which translates to a decrease in stroke volume, but these indices are not readily monitored. We aimed to determine whether minor hemodynamic alternations induced by controlled and standardized hypovolemia can be detected by a whole-body bio-impedance technology. METHODS: This was a non-randomized controlled trial that enrolled healthy blood donors. Vital signs, as well as shock index and stroke volume (SV), were recorded using noninvasive cardiac system, a noninvasive whole-body impedance-based hemodynamic analysis system, during phlebotomy. RESULTS: Sixty subjects were included in the study group and 20 in the control group. Blood loss of 450 mL resulted in a significant decrease in systolic blood pressure (5 mm Hg; 95% CI 3, 6) and SV (5.07 mL; 95% CI 3.21, 6.92), and increase in shock index (0.03 bpm/mm Hg; 95% CI 0.01, 0.05). Clinically detectable changes (≥10%) in blood pressure and shock index were detectable in 15% and 5%, respectively. SV decreased by more than 10% in 40% of blood donors. No significant changes occurred in the control group. CONCLUSION: Continuous noninvasive monitoring of SV may be superior to conventional indices (e.g., heart rate, blood pressure, or shock index) for early identification of acute blood loss. As an operator-independent and point-of-care technology, the SV whole body bio-impedance measurement may assist in accurate monitoring of potentially bleeding patients and early identification of hemorrhage.

Injuries associated with the use of ejection seats: a systematic review, meta-analysis and the experience of the Israeli Air Force, 1990-2019.

INTRODUCTION: All modern military jet aircraft are equipped with rocket-assisted ejection systems. Jet aircraft operate in the majority of the conflict regions throughout the world, and in nearly all modern countries during peacetime. Civilian and military emergency services may be called upon to treat aircrews that have ejected and should be familiar with the common injury patterns associated with aircraft ejection. METHODS: A systematic review and meta-analysis of the literature were undertaken using the preferred reporting for systematic reviews and meta-analyses (PRISMA) methodology. Peer-reviewed journal and conference papers published between 1 January 1971 and 15 June 2019 were included. Our primary outcomes of interest were mortality and major injury rates. The I2 test was used to assess heterogeneity among the included studies, and data were pooled under random effects models. In addition, all ejection cases in the Israeli Air Force (IAF) between 1990 and 2019 were studied. The data were manually extracted from the accident records and the electronic medical records system. RESULTS: We identified 14 studies that included 1710 aircrew ejections. Heterogeneity was high (I2>75%). Pooled mean mortality and major injury rates were 10.5% (95% CI 6.8-14.8%) and 29.8% (95% CI 20.1-40.6%), respectively. The major injuries included spinal fractures (61.6%), extremity trauma (27.3%), and head trauma (8.9%). During the IAF study period, a total of 37 aircrew ejected from 26 IAF aircraft. The fatality rate was 5.4% and 18.9% suffered major injuries. CONCLUSIONS: Although ejection is lifesaving, it is associated with unique injury patterns that should be addressed during clinical evaluation. Because of their high prevalence, spinal precautions are paramount until spinal injury can be ruled out, generally by advanced imaging. Looking forward, injury patterns will continue to evolve in parallel with improving ejection seat systems.