Performance Characteristics of Fluid Warming Technology in Austere Environments.

Resuscitation of the critically ill or injured is a significant and complex task in any setting, often complicated by environmental influences. Hypothermia is one of the components of the "Triad of Death" in trauma patients. Devices for warming IV fluids in the austere environment must be small and portable, able to operate on battery power, warm fluids to normal body temperature (37°C), and perform under various conditions, including at altitude. The authors evaluated four portable fluid warmers that are currently fielded or have potential for use in military environments.

Evaluation of Intensive Care Unit Ventilators at Altitude.

INTRODUCTION: Devices may forgo US military air worthiness and safety testing in an attempt to expedite the availability of critical assets such as mechanical ventilators with a waiver for one-time use in extenuating circumstances. METHODS: We evaluated two Intensive Care Unit (ICU) level ventilators: Drager Evita XL and Puritan Bennett (PB) 840 in an altitude chamber at sea level and altitudes of 8,000 and 16,000 feet. RESULTS: Altitude affected delivered tidal volumes (VTs) in volume control mode (VCV) and Pressure Regulated Volume Controlled (PRVC) mode at altitude with the Evita XL but the differences were not considered clinically important with the PB 840. Sixty-seven percent of the VTs were outside the ASTM standard of ± 10% of set VT with the Evita XL at altitude. CONCLUSION: The PB 840 did not deliver VTs that were larger than the ASTM standard up to an altitude of 16,000 feet while the majority of the delivered VTs with the Därger XL were greater than the ASTM standard. This could present a patient safety issue. Caregivers must be aware of the capabilities and limitations of ICU ventilators when utilized in a hypobaric environment in order to provide safe care.

Impact of Oxygenation Status on the Noninvasive Measurement of Hemoglobin.

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 oxygenation in normal volunteers are associated with short-term SpHgb signal loss (<10 minutes), but no impact on the measured SpHgb.

Clinical Image: Visual Estimation of Blood Loss.

Military prehospital providers frequently have to make important clinical decisions with only limited objective information and vital signs. Because of this, accurate estimation of blood loss, at the point of injury, can augment any available objective information. Prior studies have shown that individuals significantly overestimate the amount of blood loss when the amount of hemorrhage is small, and they tend to underestimate the amount of blood loss with larger amounts of hemorrhage. Furthermore, the type of surface on which the blood is deposited can impact the visual estimation of the amount of hemorrhage. To aid providers with the ability to accurately estimate blood loss, we took several units of expired packed red blood cells and deposited them in different ways on varying surfaces to mimic the visual impression of combat casualties.

Performance of Portable Ventilators Following Storage at Temperature Extremes.

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.

Evaluation of Oxygen Concentrators and Chemical Oxygen Generators at Altitude and Temperature Extremes.

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.

Effective teamwork and communication mitigate task saturation in simulated critical care air transport team missions.

BACKGROUND: Critical Care Air Transport Teams (CCATTs) are a critical component of the United States Air Force evacuation paradigm. This study was conducted to assess the incidence of task saturation in simulated CCATT missions and to determine if there are predictable performance domains. METHODS: Sixteen CCATTs were studied over a 6-month period. Performance was scored using a tool assessing eight domains of performance. Teams were also assessed during critical events to determine the presence or absence of task saturation and its impact on patient care. RESULTS: Sixteen simulated missions were reviewed and 45 crisis events identified. Task saturation was present in 22/45 (49%) of crisis events. Scoring demonstrated that task saturation was associated with poor performance in teamwork (odds ratio [OR] = 1.96), communication (OR = 2.08), and mutual performance monitoring (OR = 1.9), but not maintenance of guidelines, task management, procedural skill, and equipment management. We analyzed the effect of task saturation on adverse patient outcomes during crisis events. Adverse outcomes occurred more often when teams were task saturated as compared to non-task-saturated teams (91% vs. 23%; RR 4.1, p < 0.0001). CONCLUSIONS: Task saturation is observed in simulated CCATT missions. Nontechnical skills correlate with task saturation. Task saturation is associated with worsening physiologic derangements in simulated patients.

Laboratory evaluation of the SAVe simplified automated resuscitator.

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.

Fluorous 2-Chloropyridinium Salt (Mukaiyama Condensation Reagent) for Amide Formation Reactions.

A new fluorous 2-chloropyridinium hexafluorophosphate was prepared as a modified Mukaiyama condensation reagent, and it was applied in amide formation reactions. Good to excellent purities of amides were obtained after fluorous solid-phase extraction of reaction mixtures without additional chromatography.