A Qualitative Investigation of Space Exploration Medical Evacuation Risks.

INTRODUCTION: Exploration beyond low Earth orbit requires innovative solutions to support the crew medically, especially as the opportunity for timely evacuation to Earth diminishes. This includes assessing the risks and benefits that a complicated medical evacuation (MEDEVAC) poses to the injured crewmember, the crew, and the mission. This qualitative study identifies common MEDEVAC risk assessment principles used in spaceflight and other extreme environments to better inform future risk assessment tools and exploration mission concepts.METHODS: Semistructured interviews were conducted with subject matter experts in spaceflight and analog domains, including polar operations, undersea operations, combat medicine, and mountaineering. Transcripts were analyzed using the qualitative method of Thematic Analysis with the technique of consensus, co-occurrence, and comparison.RESULTS: Subject matter experts described 18 themes divided into two main categories: Primary Risk Considerations (e.g., crew, mission, resources, time) and Contributing Factors (e.g., psychological considerations, medical preparation, politics).DISCUSSION: Primary Risk Considerations can assess MEDEVAC risk across mission phases, with Contributing Factors acting as premission tools to adjust those risks. Inter- and intracategory connections identified medical support considerations, MEDEVAC support considerations, and philosophy as the most impactful Contributing Factors. Medical support considerations, psychological considerations, and political considerations were found to have unique aspects given the distances and societal impact of exploration vs. low Earth orbit spaceflight. The Contributing Factor theme of decision making was determined to be unique due to its impacts across both categories. These findings expand current considerations and are important inputs for exploration mission MEDEVAC Concepts of Operations.Almand A, Ko SY, Anderson A, Keller RJ, Zero M, Anderson AP, Laws JM, Lehnhardt K, Easter BD. A qualitative investigation of space exploration medical evacuation risks. Aerosp Med Hum Perform. 2023; 94(12):875-886.

The use of mechanical ventilation in the ED.

OBJECTIVES: Although EDs are responsible for the initial care of critically ill patients and the amount of critical care provided in the ED is increasing, there are few data examining mechanical ventilation (MV) in the ED. In addition, characteristics of ED-based ventilation may affect planning for ventilator shortages during pandemic influenza or bioterrorist events. The study examined the epidemiology of MV in US EDs, including demographic, clinical, and hospital characteristics; indications for MV; ED length of stay (LOS); and in-hospital mortality. METHODS: This study was a retrospective review of the 1993 to 2007 National Hospital Ambulatory Medical Care Survey ED data sets. Ventilated patients were compared with ED patients admitted to the intensive care unit (ICU) and to all other ED visits. RESULTS: There were 3.6 million ED MV visits (95% confidence interval [CI], 3.2-4.0 million) over the study period. Sex, age, race, and payment source were similar for mechanically ventilated and ICU patients (P > .05 for all). Approximately 12.5% of ventilated patients underwent cardiopulmonary resuscitation compared with 1.7% of ICU admissions and 0.2% of all other ED visits (P < .0001). Accordingly, in-hospital mortality was significantly higher for ventilated patients (24%; 95% CI, 13.1%-34.9%) than both comparison groups (9.3% and 2.5%, respectively). Median LOS for ventilated patients was 197 minutes (interquartile range, 112-313 minutes) compared with 224 minutes for ICU admissions and 140 minutes for all other ED visits. CONCLUSIONS: Patients undergoing ED MV have particularly high in-hospital mortality rates, but their ED LOS is sufficient for implementation of evidence-based ventilator interventions.

The influence of perceived stress on the human microbiome.

OBJECTIVE: Microbial dysbiosis, a shift from commensal to pathogenic microbiota, is often associated with mental health and the gut-brain axis, where dysbiosis in the gut may be linked to dysfunction in the brain. Many studies focus on dysbiosis induced by clinical events or traumatic incidents; however, many professions in austere or demanding environments may encounter continuously compounded stressors. This study seeks to explore the relationship between microbial populations and stress, both perceived and biochemical. RESULTS: Eight individuals enrolled in the study to provide a longitudinal assessment of the impact of stress on gut health, with four individuals providing enough samples for analysis. Eleven core microbial genera were identified, although the relative abundance of these genera and other members of the microbial population shifted over time. Although our results indicate a potential relationship between perceived stress and microbial composition of the gut, no association with biochemical stress was observed. Increases in perceived stress seem to elucidate a change in potentially beneficial Bacteroides, with a loss in Firmicutes phyla. This shift occurred in multiple individuals, whereas using cortisol as a stress biomarker showed contradictory responses. These preliminary data provide a potential mechanism for gut monitoring, while identifying targets for downstream modulation.

Bridging the gap between military prolonged field care monitoring and exploration spaceflight: the compensatory reserve.

The concept of prolonged field care (PFC), or medical care applied beyond doctrinal planning timelines, is the top priority capability gap across the US Army. PFC is the idea that combat medics must be prepared to provide medical care to serious casualties in the field without the support of robust medical infrastructure or resources in the event of delayed medical evacuation. With limited resources, significant distances to travel before definitive care, and an inability to evacuate in a timely fashion, medical care during exploration spaceflight constitutes the ultimate example PFC. One of the main capability gaps for PFC in both military and spaceflight settings is the need for technologies for individualized monitoring of a patient's physiological status. A monitoring capability known as the compensatory reserve measurement (CRM) meets such a requirement. CRM is a small, portable, wearable technology that uses a machine learning and feature extraction-based algorithm to assess real-time changes in hundreds of specific features of arterial waveforms. Future development and advancement of CRM still faces engineering challenges to develop ruggedized wearable sensors that can measure waveforms for determining CRM from multiple sites on the body and account for less than optimal conditions (sweat, water, dirt, blood, movement, etc.). We show here the utility of a military wearable technology, CRM, which can be translated to space exploration.

The stability of metabolic syndrome in children and adolescents.

CONTEXT: Some studies suggest the presence of metabolic syndrome before adulthood may identify those at high risk for later cardiovascular morbidity, but there are few data examining the reliability of pediatric metabolic syndrome. OBJECTIVE: To examine the short- and long-term stability of pediatric metabolic syndrome. DESIGN: Metabolic syndrome was defined as having at least three of the following: waist circumference, blood pressure, and fasting serum triglycerides in the 90th or higher percentile for age/sex; high-density lipoprotein-cholesterol 10th or lower percentile for age/sex; and fasting serum glucose of at least 100 mg/dl. Short-term metabolic syndrome stability (repeated measurements within 60 d) was assessed in obese youth ages 6-17 yr. Long-term metabolic syndrome stability (repeated measurements more than 1.5 yr apart) was studied in 146 obese and nonobese children age 6-12 yr at baseline. PATIENTS AND SETTING: Convenience samples of obese and nonobese youth ages 6-17 yr participating in research studies were collected at a clinical research hospital. RESULTS: Short-term metabolic syndrome stability (repeat measurements performed 19.7 +/- 13.1 d apart) was assessed in 220 children. The diagnosis of metabolic syndrome was unstable in 31.6% of cases. At their short-term follow-up visit, incidence of metabolic syndrome among participants who did not have metabolic syndrome at baseline was 24%. In the long term (repeat measurements performed 5.6 +/- 1.9 yr apart), the diagnosis of metabolic syndrome was unstable in 45.5% of cases. CONCLUSIONS: Cutoff-point-based definitions for pediatric metabolic syndrome have substantial instability in the short and long term. The value of making a cutoff-point-based diagnosis of metabolic syndrome during childhood or adolescence remains in question.