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IntroductionWithin the Military Health System, the process of transporting patients from an initial point of injury and throughout the entire continuum of care is called “en route care.” A Committee on En Route Combat Casualty Care was established in 2016 as part of the DoD Joint Trauma System to create practice guidelines, recommend training standards, and identify research priorities within the military en route care system.Materials and MethodsFollowing an analysis of currently funded research, future capabilities, and findings from a comprehensive scoping study, members of a sub-working group for research identified the top research priorities that were needed to better guide evidence-based decisions for practice and policy, as well as the future state of en route care.ResultsBased on the input from the entire committee, 10 en route care research topics were rank-ordered in the following manner: (1) medical documentation, (2) clinical decision support, (3) patient monitoring, (4) transport physiology, (5) transfer of care, (6) maintaining normothermia, (7) transport timing following damage control resuscitation or surgery, (8) intelligent tasking, (9) commander’s risk assessment, and (10) unmanned transport. Specific research questions and technological development needs were further developed by committee members in an effort to guide future research and development initiatives that can directly support operational en route care needs. The research priorities reflect three common themes, which include efforts to enhance or increase care provider capability and capacity; understand the impact of transportation on patient physiology; and increase the ability to coordinate, communicate, and facilitate patient movement. Technology needs for en route care must support interoperability of medical information, equipment, and supplies across the global military health system in addition to adjusting to a dynamic transport environment with the smallest possible weight, space, and power requirements.ConclusionsTo ensure an evidence-based approach to future military conflicts and other medical challenges, focused research and technological development to address these 10 en route care research gaps are urgently needed.

Introduction: Intrathoracic pressure regulation (ITPR) can be utilized to enhance venous return and cardiac preload by inducing negative end expiratory pressure in mechanically ventilated patients. Previous preclinical studies have shown increased mean arterial pressure (MAP) and decreased intracranial pressure (ICP) with use of an ITPR device. The aim of this study was to evaluate the hemodynamic and respiratory effects of ITPR in a porcine polytrauma model of hemorrhagic shock and acute lung injury (ALI). Methods: Swine were anesthetized and underwent a combination of sham, hemorrhage, and/or lung injury. The experimental groups included: no injury with and without ITPR (ITPR, Sham), hemorrhage with and without ITPR (ITPR/Hem, Hem), and hemorrhage and ALI with and without ITPR (ITPR/Hem/ALI, Hem/ALI). The ITPR device was initiated at a setting of −3 cmH2O and incrementally decreased by 3 cmH2O after 30 minutes on each setting, with 15 minutes allowed for recovery between settings, to a nadir of −12 cmH2O. Histopathological analysis of the lungs was scored by blinded, independent reviewers. Of note, all animals were chemically paralyzed for the experiments to suppress gasping at ITPR pressures below −6 cmH2O. Results: Adequate shock was induced in the hemorrhage model, with the MAP being decreased in the Hem and ITPR/Hem group compared with Sham and ITPR/Sham, respectively, at all time points (Hem 54.2 ± 6.5 mmHg vs. 88.0 ± 13.9 mmHg, p

Background Military transport of critically ill/injured patients requires judicious use of resources. Maintaining oxygen (O2) supplies for mechanically ventilated is crucial. O2 cylinders are difficult to transport due to the size and weight and add the risk of fire in an aircraft. The proposed solution is the use of a portable oxygen concentrator (POC) to supply O2 for mechanical ventilation. As long as power is available, a POC can provide an endless supply of O2. Anecdotal evidence suggests that as little as 3 L/min of O2 could manage as many as 2/3 of the mechanically ventilated military aeromedical transport patients. Materials and Methods We evaluated two each of the AutoMedx SAVe II, Hamilton T1, Zoll 731, and Ventec VOCSN portable ventilators over a range of settings paired with 1 and 2 Caire SAROS POCs at ground level and simulated altitudes of 8,000 feet, 16,000 feet, and 22,000 feet. The Ventec VOCSN has the capability of utilizing an internal O2 concentrator that uses pulsed dose technology, which was also evaluated. Each ventilator was attached to a Michigan Instruments Training Test Lung. Output from the POC was bled into each ventilator via the mechanism provided with each device. A Fleisch pneumotach was used to measure delivered tidal volume (VT), and a fast-response O2 analyzer was used to measure FiO2 within the simulated lung. Ventilator parameters and FiO2 were continuously measured and recorded at each altitude. One-way analysis of variance was used to determine statistically significant differences (P Results Delivered FiO2 varied widely between ventilator models and between devices of the same model with some testing conditions. Differences in FiO2 between ventilators at a majority (98.5%) of testing conditions were statistically significant (P Conclusions Oxygen delivery utilizing POCs is dependent upon multiple factors including ventilator operating characteristics, ventilator settings, altitude, and the use of pulsed dose or continuous flow O2. Careful patient selection would be paramount to provide safe mechanical ventilation using this method of O2 delivery.

INTRODUCTION: Adequate oxygenation is one of the primary goals of mechanical ventilation. Maintenance of adequate oxygenation and prevention of hypoxemia are the primary goals for the battlefield casualty, but military operations have unique concerns. In military operations, oxygen is a limited resource. A portable oxygen concentrator has the advantage of operating solely from electrical power and theoretically is a never-exhausting supply of oxygen. Our previous bench work demonstrated that the pulsed dose setting of the concentrator can be used in concert with the ventilator to maximize oxygen delivery. We evaluated this ventilator/concentrator system with closed loop control of oxygen output in a porcine model. MATERIALS AND METHODS: The Zoll 731 portable ventilator and Sequal Saros portable oxygen concentrator were used for this study. The ventilator and concentrator were connected via a USB cable to allow communication. The ventilator was modified to allow closed loop control of oxygen based on the oxygen saturation (SpO2) via the integral pulse oximetry sensor. The ventilator communicates with the concentrator to increase or decrease oxygen bolus size to maintain a target SpO2 of 94%. Three separate experiments were conducted in this study. Experiments 1 and 2 used oxygen bolus sizes 16-96 mL in 16-mL increments and experiment 3 used 1 mL increments. The oxygen bolus was delivered from the concentrator and injected into the ventilator circuit at the patient connector. Six pigs were used for each experiment. Experiment 1, done without lung injury, was completed to determine the optimum timing during the respiratory cycle for injecting the oxygen bolus. Lung injury for experiments 2 and 3 was induced in the animals by warmed saline lavage via the endotracheal tube until PaO2/FIO2 decreased to

Background: Noninvasive monitoring of hemoglobin (SpHgb) via pulse oximetry has the potential to alert caregivers to blood loss. Previous studies have demonstrated that changes in oxygenation may impact accuracy. Methods: Twenty normal volunteers were monitored using SpHgb at sea level, during ascent to 14,000 feet, at 14,000 feet with 100% oxygen delivery, and again at sea level. Each period consisted of 15 minutes of monitoring. SpHgb measurements were compared to a blood sample using Bland Altman analysis. The loss of the SpHgb signal was also recorded. Results: The mean difference in measured hemoglobin (Hgb) between a venous sample and SpHgb was −2.6 ± 0.96 at 14,000 feet. Ascent to 14,000 feet resulted in a predictable fall in SpO2 and was associated with loss of the SpHgb signal for half the period of observation (7.4 minutes). In the other three conditions, SpHgb signal was missing 1 to 12.6% of the time. The nadir SpO2 was not predictive of the loss of SpHgb signal. Discussion: Changes in...

In the current theater of operation, medical devices are often shipped and stored at ambient conditions. The effect of storage at hot and cold temperature extremes on ventilator performance is unknown. We evaluated three portable ventilators currently in use or being evaluated for use by the Department of Defense (731, Impact Instrumentation; T1, Hamilton Medical; and Revel, CareFusion) at temperature extremes in a laboratory setting. The ventilators were stored at temperatures of 60°C and -35°C for 24 hours and were allowed to acclimate to room temperature for 30 minutes before evaluation. The T1 required an extra 15 to 30 minutes of acclimation to room temperature before the ventilator would deliver breaths. All delivered tidal volumes at room temperature and after storage at temperature extremes were less than the ±10% American Society for Testing and Materials standard with the Revel. Delivered tidal volumes at the pediatric settings were less than the ±10% threshold after storage at both temperatures and at room temperature with the 731. Storage at extreme temperature affected the performance of the portable ventilators tested. This study showed that portable ventilators may need an hour or more of acclimation time at room temperature after storage at temperature extremes to operate as intended.

Oxygen cylinders are heavy and present a number of hazards, and liquid oxygen is too heavy and cumbersome to be used in far forward environments. Portable oxygen concentrators (POCs) and chemical oxygen generators (COGs) have been proposed as a solution. We evaluated 3 commercially available POCs and 3 COGs in a laboratory setting. Altitude testing was done at sea level and 8,000, 16,000, and 22,000 ft. Temperature extreme testing was performed after storing devices at 60°C and -35°C for 24 hours. Mean FIO2 decreased after storage at -35°C with Eclipse and iGo POCs and also at the higher volumes after storage at 60°C with the Eclipse. The iGo ceased to operate at 16,000 ft, but the Eclipse and Saros were unaffected by altitude. Oxygen flow, duration of operation, and total oxygen volume varied between COGs and within the same device type. Output decreased after storage at -35°C, but increased at each altitude as compared to sea level. This study showed significant differences in the performance of POCs and COGs after storage at temperature extremes and with the COGs at altitude. Clinicians must understand the performance characteristics of devices in all potential environments.

Objective: To evaluate the SAVe simplified automated ventilator in a laboratory setting to determine performance characteristics, accuracy of tidal volume delivery at various lung compliance, and battery life at sea level and at altitude. Methods: Three SAVe ventilators were used for the evaluation. Each ventilator was attached to a test lung with volume, pressure, and flow measured with a fixed orifice pneumotachometer and FIO2 measured with a fast-response oxygen analyzer. All measurements were made at sea level, 4,000, 8,000, 12,000, and 18,000 feet. Results: Delivered tidal volume and inspiratory time varied when changing lung model conditions as well as between devices within the same lung model condition. The largest reduction in tidal volume was at the lowest compliance. Conclusions: The SAVe could potentially be used for ventilatory support of carefully selected military casualties but caregivers must be aware of the limitations.

The objective of this study was to determine the effects of inspired oxygen concentration (FIO2), positive end-expiratory pressure (PEEP), and breath type on the battery life of the LTV-1000 external lithium ion battery (LiB).An LTV-1000 ventilator and external LiB were tested in the laboratory. The ventilator was operated using pressure and volume breaths set to deliver a tidal volume of 750 mL. FIO2 was varied from room air (0.21) to 1.0. PEEP was set a 0, 10, and 20 cm of H2O. Duration of operation was determined from measurements of delivered tidal volume.At a baseline of volume control at an FIO2 of 0.21 and a PEEP of 0 cm of H2O, the ventilator operated for 300 +/- 11.6 minutes. Increasing FIO2 to 1.0 reduced battery life to 247 +/- 2.1 minute (p0.001). The addition of PEEP to 20 cm of H2O reduced battery life to 211 +/- 3.5 minutes (p0.001). The combination of FIO2 of 1.0 and PEEP of 20 cm of H2O further reduced battery life to 188 +/- 6.3 minutes (p0.001). At the baseline FIO2 and PEEP (0.21 and 0 cm of H2O), the use of pressure control reduced battery life to 142 +/- 3.5 minutes.Battery life of the external LiB is significantly reduced by the use of pressure control, increasing PEEP, and increasing FIO2. This information is critical to resource planning for medical missions.

The pulse oximeter serves as an indicator of arterial oxygen saturation. We present two cases in which methylene blue injection during urological surgery appeared to cause arterial oxygen desaturation by pulse oximetry and methemoglobinemia by arterial blood gas co-oximetry. Methylene blue interferes with light absorption and gives a false estimate of the percentage of oxyhemoglobin and arterial oxygen saturation. The co-oximeter interprets methylene blue as methemoglobin and gives a false indication of methemoglobinemia. The surgical team must be familiar with conditions and agents that interfere with their ability to safely monitor surgical patients.

A patient presented with an unusual case of a breast mass. History and meticulous physical examination led to the diagnosis of metastatic melanoma, which was confirmed by biopsy. The differential diagnosis of metastasis to breast is discussed.

The pulse oximeter serves as an indicator of arterial oxygen saturation. We present two cases in which methylene blue injection during urological surgery appeared to cause arterial oxygen desaturation by pulse oximetry and methemoglobinemia by arterial blood gas co-oximetry. Methylene blue interferes with light absorption and gives a false estimate of the percentage of oxyhemoglobin and arterial oxygen saturation. The co-oximeter interprets methylene blue as methemoglobin and gives a false indication of methemoglobinemia. The surgical team must be familiar with conditions and agents that interfere with their ability to safely monitor surgical patients.

A patient presented with an unusual case of a breast mass. History and meticulous physical examination led to the diagnosis of metastatic melanoma, which was confirmed by biopsy. The differential diagnosis of metastasis to breast is discussed.