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Introduction: Extracorporeal life support (ECLS) patients are at risk for complications caused by gaseous microemboli (GME). GMEs can cause hypoxia, inflammation, coagulation, and end-organ damage. The objective of this in vitro study was to assess dynamics of GME formation during circulation of whole blood or a glycerol blood surrogate. We hypothesized that there is no difference in GME counts and sizes between whole blood and the glycerol blood surrogate and that the membrane lung reduces GME counts over time., Methods: A circulation platform was developed using the Cardiohelp ECLS system to run either donor blood or glycerol solution. We conducted 10 repetitions consisting of three phases of ultrasound GME detection using the EDAC ™ Quantifier (Luna Innovations, Charlottesville, VA, USA) for each group. Phases were 3-minute recordings at the initiation of 2 L/min flow (Phase 1), post-injection of a GME suspension (Phase 2), and 10 minutes after injection (Phase 3). The number and size of GME pre- and post-ML were recorded separately and binned based on diameter ranges., Results: In Phase 1, GME count in blood was higher than in glycerol. In Phase 2, there was a large increase in GME counts; however, most GME were reduced post-membrane in both groups. In Phase 3, there was a significant decrease in GME counts compared to Phase 2. GME > 100 μm in glycerol decreased post membrane., Conclusions: We demonstrated GME formation and decay dynamics during in vitro circulation in an ECLS system with blood and glycerol. GME counts were higher in blood, likely due to varying rheological properties. There were decreases in GME levels post membrane in both groups after GME injection, with the membrane lung effectively trapping the GME, and additional reduction 10 minutes after GME injection.

Background: We assessed the use of an FDA-cleared transport ventilator with limited functions and settings during ground transport in a swine model of ground evacuation. We hypothesized that when used as an adjunct to extracorporeal life support (ECLS), the device would enable safe mobile ventilatory support during ground evacuation., Methods: Female Yorkshire swine (n = 11; mean, 52.4 ± 1.3 kg) were sedated and anesthetized and received mechanical ventilation (MV) with a standard intensive care unit (ICU) ventilator and were transitioned to the Simplified Automated Ventilator II (SAVe II; AutoMedx) during ground transport. MV served as an adjunct to ECLS in all animals. Ventilator performance was assessed in the uninjured state on day 1 and after bilateral pulmonary contusion on day 2. Data were collected pre- and post-transport on both days., Results: During 33 transports, the SAVe II provided similar ventilation support as the ICU ventilator. Mean total transport time was 38.8 ± 2.1 minutes. The peak inspiratory pressure (PIP) limit was the only variable to show consistent differences pre- and post-transport and between ventilators. No adverse events occurred., Conclusion: As an adjunctive supportive device during ground transport, the SAVe II performed adequately without failure or degradation in subject status. Further testing is warranted to elucidate the clinical limits of this device during standalone use., (2022.)

Background: We investigated the expression of high mobility group box 1 (HMGB1) protein in a combat-relevant polytrauma/ acute respiratory distress syndrome (ARDS) model. We hypothesized that systemic HMGB1 expression is increased after injury and during aeromedical evacuation (AE) at altitude., Methods: Female Yorkshire swine (n =15) were anesthetized and cannulated with a 23Fr dual-lumen catheter. Venovenous extracorporeal life support (VV ECLS) was initiated via the right jugular vein and carried out with animals uninjured on day 1 and injured by bilateral pulmonary contusion on day 2. On both days, animals underwent transport and simulated AE. Systemic HMGB1 expression was measured in plasma by ELISA. Plasma-free Hb (pfHb) was measured with the use of spectrophotometric methods., Results: Plasma HMGB1 on day 1 was transiently higher at arrival to the AE chambers, increased significantly after injury, reaching highest values at 8,000 ft on day 2, after which levels decreased but remained elevated versus baseline at each time point. pfHb decreased on day 1 at 30,000 ft and significantly increased on day 2 at 8,000 ft and postflight., Conclusions: Systemic HMGB1 demonstrated sustained elevation after trauma and altitude transport and may provide a useful monitoring capability during en route care., (2020.)

Background: Coagulation monitoring capabilities during transport are limited. Thromboelastography (TEG) is a whole-blood clotting test measuring clot formation, stabilization, and fibrinolysis and is traditionally performed in a laboratory. We evaluated a new point-of-care TEG analyzer, TEG 6s (Haemonetics, Braintree, MA), in a large animal model of combat-relevant trauma managed with extracorporeal life support during ground and high-altitude aeromedical evacuation. The objective was to compare TEG 6s used during transport versus the predicate device, TEG 5000, used in the laboratory. We hypothesized that TEG 6s would be comparable with TEG 5000 during dynamically changing transport conditions., Methods: Thromboelastography parameters (R, K, angle, MA, LY30) derived by TEG 6s and TEG 5000 were compared during transport of 8 swine. TEG 6s was transported with animals during ground transport and flight. TEG 5000 was stationary in an adjacent building. TEG 6s activated clotting time (ACT) was compared with a Hemochron Junior ACT analyzer (Accriva Diagnostics, San Diego, CA). Statistics were performed using SAS 9.4 with Deming regressions, Spearman correlations, and average differences compared., Results: Correlation between devices was stronger at sea-level (R, r = 0.7413; K, r = 0.7115; angle, r = 0.7192; MA, r = 0.8386; LY30, r = 0.9099) than during high-altitude transport (R, r = 0.4787; K, r = 0.4007; angle, r = 0.3706; MA, r = 0.6573; LY30, r = 0.8481). Method agreement was comparable during stationary operation (R, r = 0.7978; K, r = 0.7974; angle, r = 0.7574; MA, r = 0.7841; LY30, r = 0.9140) versus ground transport (R, r = 0.7927; K, r = 0.6246; angle, r = 0.6967; MA, r = 0.9163; LY30, r = 0.8603). TEG 6s ACT trended higher than Hemochron ACT when subjects were heparinized (average difference, 1,442 ± 1,703 seconds) without a methodological difference by Deming regression., Conclusion: Mobile TEG 6s during ground and altitude transport is feasible and provides unprecedented information to guide coagulation management. Future studies should assess the precision and accuracy of TEG 6s during transport of critically ill.