RESUMEN
Twenty-four-hour rhythms in physiology and behaviour are shaped by circadian clocks, environmental rhythms, and feedback of behavioural rhythms onto physiology. In space, 24 h signals such as those associated with the light-dark cycle and changes in posture, are weaker, potentially reducing the robustness of rhythms. Head down tilt (HDT) bed rest is commonly used to simulate effects of microgravity but how HDT affects rhythms in physiology has not been extensively investigated. Here we report effects of -6° HDT during a 90-day protocol on 24 h rhythmicity in 20 men. During HDT, amplitude of light, motor activity, and wrist-temperature rhythms were reduced, evening melatonin was elevated, while cortisol was not affected during HDT, but was higher in the morning during recovery when compared to last session of HDT. During recovery from HDT, time in Slow-Wave Sleep increased. EEG activity in alpha and beta frequencies increased during NREM and REM sleep. These results highlight the profound effects of head-down-tilt-bed-rest on 24 h rhythmicity.
RESUMEN
INTRODUCTION: Different types of remote expeditions often require an expedition crew to conduct medical emergency assessments without prior medical training. Modern technology offers new devices that support diagnosis with a simple guided user instructions interface. It is not yet clear how quickly medically untrained individuals can acquire the required skills with such a device. This study investigated the time and quality of obtained outcomes, as well as the mental workload when using a vital signs monitor and its guided procedure interface during a simulation of a medical emergency event.METHODS: There were 50 individuals (25 medically inexperienced, 25 medically trained) who participated in this study. In a randomized order subjects measured electrocardiography, noninvasive blood pressure, pulse oximetry, and body temperature. The procedure was repeated after a 20-min break. Completion time, data validity, and mental workload were analyzed.RESULTS: Average times to obtain stable and reliable signals of all recorded vital signs were significantly shorter for both groups during the second attempt and for medically experienced individuals in comparison to medically inexperienced individuals. The number of errors did not change between attempts for both groups. The mental workload was higher during the first attempt in both groups for most vital sign acquisitions.DISCUSSION: Automated devices could be easily and quickly used by members of a given expedition, even if the crew lacks advanced medical training. With relatively little training provided by a built-in guidance system, medically untrained individuals can achieve a basic level of proficiency in reliably obtaining valid vital signs.Huerta R, Kaduk SI, Fatai L, Rusch H, Weber T, Sammito S. A built-in guidance system to monitor vital signs in space and on Earth. Aerosp Med Hum Perform. 2024; 95(3):139-146.