Endothelial dysfunction is associated with increased cardiovascular mortality and morbidity; however, this dysfunction may be ameliorated by several therapies. For example, it has been reported that heat‐induced increases in blood flow and shear stress enhance endothelium‐mediated vasodilator function. Under these backgrounds, we expect that carbon dioxide (CO 2)‐rich water‐induced increase in skin blood flow improves endothelium‐mediated vasodilation with less heat stress. To test our hypothesis, we measured flow‐mediated dilation (FMD) before and after acute immersion of the lower legs and feet in mild warm (38°C) normal or CO 2‐rich tap water (1000 ppm) for 20 min in 12 subjects. Acute immersion of the lower legs and feet in mild warm CO 2‐rich water increased FMD (P < 0.01) despite the lack of change in this parameter upon mild warm normal water immersion. In addition, FMD was positively correlated with change in skin blood flow regardless of conditions (P < 0.01), indicating that an increase in skin blood flow improves endothelial‐mediated vasodilator function. Importantly, the temperature of normal tap water must reach approximately 43°C to achieve the same skin blood flow level as that obtained during mild warm CO 2‐rich water immersion (38°C). These findings suggest that CO 2‐rich water‐induced large increases in skin blood flow may improve endothelial‐mediated vasodilator function while causing less heat stress.

No abstract

BackgroundDuring endotracheal intubation training, only providing verbal guidance to students may result in inadequate recognition of the inner larynx and cause delays in mastering endotracheal intubation. Therefore, we introduced a deliberate practice approach to the education of residents in endotracheal intubation. For this purpose, a video laryngoscope was used to give the residents detailed feedback of the anesthesiology faculty. We hypothesized that if the anesthesiology faculty could provide sufficient and precise feedback of the larynx through the video monitor, the residents’ intubation skills would be retained for a more extended period.MethodsThis cluster randomized controlled study enrolled first-year residents who completed a two-month rotation at our department. Each rotation group (2–4 residents) was assigned to the Macintosh laryngoscope (ML) group or the McGRATH MAC video laryngoscope (MML) group. Endotracheal intubation skills were evaluated on a simulated mannequin immediately after the rotation, three months later, and six months later. The primary endpoint was the time required for intubation. The secondary endpoint was the percentage of glottic opening (POGO) score.ResultsForty-six residents participated in this study and were assigned to the ML group (n = 23) or the MML group (n = 23). The time required for intubation was significantly shorter in the MML group than in the ML group. The POGO score did not show any significant differences between the two groups; however, the POGO score of the MML group had a relatively narrower confidence interval than the ML group.ConclusionsWhen comparing endotracheal intubation training using the Macintosh laryngoscope and video laryngoscope, the McGRATH MAC video laryngoscope shortened the intubation procedure and facilitated long-term skill retention.Trial registrationClinical registry and trial number, URL: https://www.umin.ac.jp, UMIN000036643 date of registration: 2019/05/03, This study was retrospectively registered.