Efficacy of Medical Device Alarm Integration into a Simulated H-60 Integrated Communication System.

INTRODUCTION: This study sought to examine the efficacy of integrating medical device alarms into the intercommunication set of a simulated HH-60, allowing medics to hear the alarms over the ambient noise of the aeromedical environment. MATERIALS AND METHODS: U.S. Army critical care flight paramedics were recruited as subjects for this study. Subjects participated in two testing scenarios: One with patient monitor alarms integrated into their communication lines and one without integrated alarms (the control condition). Testing took place in a simulated HH-60 interior with two priority-level patients per testing scenario, one on either side of the interior. Subjects provided care to these two patients for 30 minutes per scenario. After both scenarios were complete, the subjects were given a questionnaire to obtain their feedback on alarm integration. RESULTS: Six subjects took part in this study, so the results do not have sufficient power to represent the population. No statistically significant results were found. Looking at the trends in the data, implementing alarm integration showed the indications of reducing reaction time to alarms, decreasing or matching the amount of time spent with the patient monitor, and equivalent amounts of time dedicated to patient treatment when compared to the nonintegrated scenario.The feedback obtained from the subjects provided a list of perceived benefits, drawbacks, and improvements related to the integration of medical device alarms into the intercommunication set. CONCLUSIONS: Although the study was underpowered, the trends in the data indicate a benefit to the medics when integrating medical device alarms. When coupled with strongly favorable end-user feedback, the results provide justification for pursuing the effort of integrating alarms and performing future studies with improved integration systems to optimize the potential of the system.

Quantifying supine human discomfort in off-road whole-body vibration.

This work presents a new methodology to quantify supine human discomfort during transport when multi-axis whole-body vibration (WBV) and shocks are present. The methodology employs a new scheme to normalise the reported discomfort. Twenty-six human subjects were tested under different off-road conditions and their reported discomforts collected. The paired Wilcoxon signed-rank method was used to investigate the significant differences (p < 0.01) between different track sections on the normalised reported discomfort from the subjects. Analyses based on ISO 2631-1 showed weak correlation with the reported discomfort when significant lateral motions existed. The results with the new formulation showed that discomfort is highly correlated with the vibration dose value at the head of the supine human during WBV (p < 0.001). These results are consistent with previous published work showing that discomfort based on motion at the head-neck region comprises more than 70% of the reported discomfort during supine transport under multiple-axis WBV.Practitioner summary: There are shortcomings in the current approaches to quantifying discomfort of supine humans in multi-axis whole-body vibration where lateral motions are excessive. This study revealed that reported discomfort is strongly related to the vibration dose value at the head of supine subjects rather than the input motion to the body.Abbreviations: WBV: whole-body vibration; RMS: root-mean square; VDV: vibration dose value; PSD: power spectral density; RDn: reported discomfort; NDn: normalized discomfort; : discomfort scaling coefficient; aw(t): frequency-weighted acceleration; wRMS: weighted root-mean square; Aw: weighted root-mean square acceleration; Aw,p: point weighted root-mean square acceleration; Wd: frequency-weighting factor; Wk: frequency-weighting factor; kx: weighed acceleration multiplying factor in x-direction; ky: weighed acceleration multiplying factor in y-direction; kz: weighed acceleration multiplying factor in z-direction; CV: coefficient of variation; VDVp: point vibration dose value; SD: standard deviation; pVTV: point vibration total value.

Non-Linear Device Head Coupling and Temporal Delays in Large Animal Acceleration Models of Traumatic Brain Injury.

Accurate characterization of head kinematics following an external blow represents a fundamental aspect of traumatic brain injury (TBI) research. The majority of previous large animal studies have assumed an equivalent relationship between the device delivering the impulsive load and subsequent head kinematics rather than performing direct measurement (sensors or videography). The current study therefore examined factors affecting device/head coupling kinematics in an acceleration TBI model. Experiment 1 indicated ~ 50% reduction in peak angular velocity for swine head relative to the device, with an approximate doubling in temporal duration. The peak angular velocity for the head was not significantly altered by variations in restraint device (straps vs. cables), animal positioning or body mass. In Experiment 2, reducing the impulsive load by 32% resulted in only a 14% reduction in angular velocity of the head (approximately 69% head/device coupling ratio), with more pronounced differences qualitatively observed for angular momentum. A temporal delay was identified in initial device/head coupling, potentially a result of soft tissue deformation. Finally, similar head kinematics were obtained regardless of mounting the sensor directly to the skull or through the scalp (Experiment 3). Current findings highlight the importance of direct measurement of head kinematics for future studies.

17α-Ethinyl estradiol-3-sulfate increases survival and hemodynamic functioning in a large animal model of combined traumatic brain injury and hemorrhagic shock: a randomized control trial.

BACKGROUND: Traumatic brain injury (TBI) and severe blood loss resulting in hemorrhagic shock (HS) represent leading causes of trauma-induced mortality, especially when co-occurring in pre-hospital settings where standard therapies are not readily available. The primary objective of this study was to determine if 17α-ethinyl estradiol-3-sulfate (EE-3-SO4) increases survival, promotes more rapid cardiovascular recovery, or confers neuroprotection relative to Placebo following TBI + HS. METHODS: All methods were approved by required regulatory agencies prior to study initiation. In this fully randomized, blinded preclinical study, eighty (50% females) sexually mature (190.64 ± 21.04 days old; 28.18 ± 2.72 kg) Yucatan swine were used. Sixty-eight animals received a closed-head, accelerative TBI followed by removal of approximately 40% of circulating blood volume. Animals were then intravenously administered EE-3-SO4 formulated in the vehicle at 5.0 mg/mL (dosed at 0.2 mL/kg) or Placebo (0.45% sodium chloride solution) via a continuous pump (0.2 mL/kg over 5 min). Twelve swine were included as uninjured Shams to further characterize model pathology and replicate previous findings. All animals were monitored for up to 5 h in the absence of any other life-saving measures (e.g., mechanical ventilation, fluid resuscitation). RESULTS: A comparison of Placebo-treated relative to Sham animals indicated evidence of acidosis, decreased arterial pressure, increased heart rate, diffuse axonal injury and blood-brain barrier breach. The percentage of animals surviving to 295 min post-injury was significantly higher for the EE-3-SO4 (28/31; 90.3%) relative to Placebo (24/33; 72.7%) cohort. EE-3-SO4 also restored pulse pressure more rapidly post-drug administration, but did not confer any benefits in terms of shock index. Primary blood-based measurements of neuroinflammation and blood brain breach were also null, whereas secondary measurements of diffuse axonal injury suggested a more rapid return to baseline for the EE-3-SO4 group. Survival status was associated with biological sex (female > male), as well as evidence of increased acidosis and neurotrauma independent of EE-3-SO4 or Placebo administration. CONCLUSIONS: EE-3-SO4 is efficacious in promoting survival and more rapidly restoring cardiovascular homeostasis following polytraumatic injuries in pre-hospital environments (rural and military) in the absence of standard therapies. Poly-therapeutic approaches targeting additional mechanisms (increased hemostasis, oxygen-carrying capacity, etc.) should be considered in future studies.

Reproducibility and Characterization of Head Kinematics During a Large Animal Acceleration Model of Traumatic Brain Injury.

Acceleration parameters have been utilized for the last six decades to investigate pathology in both human and animal models of traumatic brain injury (TBI), design safety equipment, and develop injury thresholds. Previous large animal models have quantified acceleration from impulsive loading forces (i.e., machine/object kinematics) rather than directly measuring head kinematics. No study has evaluated the reproducibility of head kinematics in large animal models. Nine (five males) sexually mature Yucatan swine were exposed to head rotation at a targeted peak angular velocity of 250 rad/s in the coronal plane. The results indicated that the measured peak angular velocity of the skull was 51% of the impulsive load, was experienced over 91% longer duration, and was multi- rather than uni-planar. These findings were replicated in a second experiment with a smaller cohort (N = 4). The reproducibility of skull kinematics data was mostly within acceptable ranges based on published industry standards, although the coefficients of variation (8.9% for peak angular velocity or 12.3% for duration) were higher than the impulsive loading parameters produced by the machine (1.1 vs. 2.5%, respectively). Immunohistochemical markers of diffuse axonal injury and blood-brain barrier breach were not associated with variation in either skull or machine kinematics, suggesting that the observed levels of variance in skull kinematics may not be biologically meaningful with the current sample sizes. The findings highlight the reproducibility of a large animal acceleration model of TBI and the importance of direct measurements of skull kinematics to determine the magnitude of angular velocity, refine injury criteria, and determine critical thresholds.

Survival Rates and Biomarkers in a Large Animal Model of Traumatic Brain Injury Combined With Two Different Levels of Blood Loss.

INTRODUCTION: The pathology resulting from concurrent traumatic brain injury (TBI) and hemorrhagic shock (HS; TBI+HS) are leading causes of mortality and morbidity worldwide following trauma. However, the majority of large animal models of TBI+HS have utilized focal/contusional injuries rather than incorporating the types of brain trauma (closed-head injury caused by dynamic acceleration) that typify human injury. OBJECTIVE: To examine survival rates and effects on biomarkers from rotational TBI with two levels of HS. METHODS: Twenty-two sexually mature Yucatan swine (30.39 ±â€Š2.25 kg; 11 females) therefore underwent either Sham trauma procedures (n = 6) or a dynamic acceleration TBI combined with either 55% (n = 8) or 40% (n = 8) blood loss in this serial study. RESULTS: Survival rates were significantly higher for the TBI+40% (87.5%) relative to TBI+55% (12.5%) cohort, with the majority of TBI+55% animals expiring within 2 h post-trauma from apnea. Blood-based neural biomarkers and immunohistochemistry indicated evidence of diffuse axonal injury (increased NFL/Aß42), blood-brain barrier breach (increased immunoglobulin G) and inflammation (increased glial fibrillary acidic protein/ionized calcium-binding adaptor molecule 1) in the injured cohorts relative to Shams. Invasive hemodynamic measurements indicated increased shock index and decreased pulse pressure in both injury cohorts, with evidence of partial recovery for invasive hemodynamic measurements in the TBI+40% cohort. Similarly, although both injury groups demonstrated ionic and blood gas abnormalities immediately postinjury, metabolic acidosis continued to increase in the TBI+55% group ∼85 min postinjury. Somewhat surprisingly, both neural and physiological biomarkers showed significant changes within the Sham cohort across the multi-hour experimental procedure, most likely associated with prolonged anesthesia. CONCLUSION: Current results suggest the TBI+55% model may be more appropriate for severe trauma requiring immediate medical attention/standard fluid resuscitation protocols whereas the TBI+40% model may be useful for studies of prolonged field care.

Optimal Physical Space for En Route Care: Medic Posture and Injury Survey.

INTRODUCTION: An anonymous online survey was presented to active duty U.S. Army, Reserve, and National Guard Soldiers with experience as en route care medical providers with the intent of identifying factors which contribute to musculoskeletal disorders in U.S. Army en route care medical providers. The survey looked at transport vehicle design, equipment, and awkward postures that could play a role in causing injuries. MATERIALS AND METHODS: Survey responses were received from 60 en route care providers regarding postures assumed during administration of en route critical care tasks, routine medical transport scenarios, and patient loading. Care providers reported gender, height, weight, experience, tasks, and awkward postures experienced. They also reported occupational injuries that occurred as a result of performing job duties, such as back, neck, and joint pain, injuries, and discomfort. RESULTS: The survey was answered by 56 (93.3%) males and 4 females (6.7%) with an average of 7.34 years of experience as en route care personnel. Lower back injuries were suffered by 87% of respondents. The most common causes were awkward positions and lifting patients. There are statistically significant relationships between shoulder injuries and overextending, lower back injuries and overextending, and lower back injuries and reaching backwards, ankle injuries and care provider height, and knee injuries and the frequency at which care providers utilized the postures of kneeling, squatting, reaching behind themselves, and straining to lift a heavy weight. Loading and unloading patients from evacuation platforms was among the top causes of all awkward postures among respondents. CONCLUSION: Results of this survey emphasize the need for injury mitigation and prevention strategies to reduce impacts on soldier health and readiness.

A systematic review of large animal models of combined traumatic brain injury and hemorrhagic shock.

Traumatic brain injury (TBI) and severe blood loss (SBL) frequently co-occur in human trauma, resulting in high levels of mortality and morbidity. Importantly, each of the individual post-injury cascades is characterized by complex and potentially opposing pathophysiological responses, complicating optimal resuscitation and therapeutic approaches. Large animal models of poly-neurotrauma closely mimic human physiology, but a systematic literature review of published models has been lacking. The current review suggests a relative paucity of large animal poly-neurotrauma studies (N = 52), with meta-statistics revealing trends for animal species (exclusively swine), characteristics (use of single biological sex, use of juveniles) and TBI models. Although most studies have targeted blood loss volumes of 35-45%, the associated mortality rates are much lower relative to Class III/IV human trauma. This discrepancy may result from potentially mitigating experimental factors (e.g., mechanical ventilation prior to or during injury, pausing/resuming blood loss based on physiological parameters, administration of small volume fluid resuscitation) that are rarely associated with human trauma, highlighting the need for additional work in this area.

Responses of the Acutely Injured Spinal Cord to Vibration that Simulates Transport in Helicopters or Mine-Resistant Ambush-Protected Vehicles.

In the military environment, injured soldiers undergoing medical evacuation via helicopter or mine-resistant ambush-protected vehicle (MRAP) are subjected to vibration and shock inherent to the transport vehicle. We conducted the present study to assess the consequences of such vibration on the acutely injured spinal cord. We used a porcine model of spinal cord injury (SCI). After a T10 contusion-compression injury, animals were subjected to 1) no vibration (n = 7-8), 2) whole body vibration at frequencies and amplitudes simulating helicopter transport (n = 8), or 3) whole body vibration simulating ground transportation in an MRAP ambulance (n = 7). Hindlimb locomotor function (using Porcine Thoracic Injury Behavior Scale [PTIBS]), Eriochrome Cyanine histochemistry and biochemical analysis of inflammatory and neural damage markers were analyzed. Cerebrospinal fluid (CSF) expression levels for monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6, IL-8, and glial fibrillary acidic protein (GFAP) were similar between the helicopter or MRAP group and the unvibrated controls. Spared white/gray matter tended to be lower in the MRAP-vibrated animals than in the unvibrated controls, especially rostral to the epicenter. However, spared white/gray matter in the helicopter-vibrated group appeared normal. Although there was a relationship between the extent of sparing and the extent of locomotor recovery, no significant differences were found in PTIBS scores between the groups. In summary, exposures to vibration in the context of ground (MRAP) or aeromedical (helicopter) transportation did not significantly impair functional outcome in our large animal model of SCI. However, MRAP vibration was associated with increased tissue damage around the injury site, warranting caution around exposure to vehicle vibration acutely after SCI.

A quantitative model of the human-machine interaction and multi-task performance: a strategy function and the unity model paradigm.

A human-machine-interaction (HMI) model is developed for the human operator (HO) performing five simultaneous tasks and characterized by a strategy function. Five levels of total machine-initiated baud rate (B(IN)) are generated by the multi-attribute task battery (MATB) and five HO baud rates (B(O)) are then recorded. Total baud ratio (B ) is defined as the ratio of B(O) to B(IN). Results indicate that with increasing B(IN) levels: (1) there is an overall increase in B(O), and (2) there is an overall decrease in B . These results are due to a decreasing HMI performance and divergence of the strategy function from a unity model paradigm.