RESUMEN
Objective: Warm water immeresion (WWI) has been customary in Japan as useful thermal therapy. However, a comprehensive investigation of the effects of WWI on internal organs has never been undertaken. The purpose of this study was to examine the effects of single WWI on indocyanine green (ICG) excretion in healthy humans. Subjects: 23 healthy males. (32.6±1.9 [mean±SEM] years) Methods: 1CG was administered intravenously (0.5mg/kg) to calculate excretion rate (ER). ICG injection was given before and after WWI (10min at 41°C). Sublingual temperature (ST), blood pressure (BP), heart rate (HR), and cardiac output (CO) were simultaneously measured by noninvasive methods. Results: Significant changes were observed after WWI. These included an increase in ST, HR, and CO and a decrease in systolic BP (p<0.01). ER significantly decreased from 0.210±0.015 to 0.168±0.009 (p<0.01). Front-back ratio of ICG-ER which was calculated in order to evaluate the effect of aging increased significantly with age (R=0.582, p<0.0001). Conclusion: These results indicate that although CO increased due to the vasodilating effects of WWI, hepatic blood flow decreased after WWI and its response reduced with age even in before middle age.