BACKGROUND: To develop human space exploration, it is necessary to study the effects of an isolated and confined environment, as well as a microgravity environment, on cerebral circulation. However, no studies on cerebral circulation in an isolated and confined environment have been reported. Therefore, we investigated the effects of a 14-day period of confinement in an isolated environment on dynamic cerebral autoregulation. METHODS: We participated in an isolation and confinement experiment conducted by the Japan Aerospace Exploration Agency in 2016. Eight healthy males were isolated and confined in a facility for 14 days. Data were collected on the days immediately before and after confinement. Arterial blood pressure waveforms were obtained using a finger blood pressure monitor, and cerebral blood flow velocity waveforms in the middle cerebral artery were obtained using transcranial Doppler ultrasonography for 6 min during quiet rest in a supine position. Dynamic cerebral autoregulation was evaluated by transfer function analysis between spontaneous variability of beat-to-beat mean arterial blood pressure and mean cerebral blood flow velocity. RESULTS: Transfer function gain in the low- and high-frequency ranges increased significantly (0.54 ± 0.07 to 0.69 ± 0.09 cm/s/mmHg and 0.80 ± 0.05 to 0.92 ± 0.09 cm/s/mmHg, respectively) after the confinement. CONCLUSION: The increases observed in transfer function gain may be interpreted as indicating less suppressive capability against transmission from arterial blood pressure oscillation to cerebral blood flow velocity fluctuation. These results suggest that confinement in an isolated environment for 14 days may impair dynamic cerebral autoregulation. TRIAL REGISTRATION UMIN000020703 , Registered 2016/01/22.
Adult ; Cerebrovascular Circulation ; physiology ; Confined Spaces ; Homeostasis ; physiology ; Humans ; Male ; Middle Aged ; Space Flight ; Young Adult

Background: Patients with malignant brain tumors are often accompanied by progressive loss of consciousness, aphasia, and paralysis, and often miss the time to make decisions on their own. Methods: In an acute neurosurgical unit, a multidisciplinary conference was held to support decision-making, and a brain tumor-specific advance care planning (ACP) leaflet was created and operated. The attainment rate of the five steps of ACP and the number of times the ACP process was repeated during hospitalization were evaluated for 79 inpatients before and after the introduction of the leaflet. Results: Forty-eight patients received decision-making support with the leaflet, while 31 did not. The rate of achievement of the discussion (38.7% vs 89.6%, p<0.001) and writing down (6.5% vs 33.3%, p=0.006) in ACP significantly increased after the introduction of the leaflet. Conclusion: The newly developed brain tumor-specific ACP leaflet was useful in promoting ACP for patients with brain tumors and providing decision support. In addition, a multidisciplinary ACP support framework for brain tumor patients has been established through ACP conferences.