Objective Current perception threshold (CPT) measurement is a noninvasive, easy, and semi‐objective method for determining sensory function using transcutaneous electrical stimulation. Previous studies have shown that CPT is determined by physical characteristics, such as sex, age, physical sites, and presence of neuropathy. Although the CPT reported in males is clearly higher than that in females, the reason for this difference remains unclear. This study investigates the cause of sex‐based differences in CPT and suggests an adjustment method, which may suppress the sex difference in CPT. Materials and Methods Electrical stimulation was applied with PainVision® via five sizes of circular surface electrodes. Seventy healthy participants were examined thrice under each electrode. The relationship among body water percentage, body fat percentage, and CPT was then analyzed. Results CPT values are higher in males than that in females, with statistically significant sex differences with each electrode pairs (EL 1: p < 0.001; EL 2: p = 0.006; EL 3: p < 0.001; EL 4: p < 0.001; EL 5: p < 0.001). By adjusting for body fat percentage or body water percentage, the log‐transformation values (CPT values) no longer exhibit sex differences with any electrode pairs (body fat: p = 0.09; body water: p = 0.08). Conclusion We conclude that sensitivity for perceiving electrical stimulation can be influenced by the subjects' characteristics, such as body fat or body water percentages.

Sweating, the intermittent secretion of uid from the sweat glands, is an indispensable mechanism for the regulation of body temperature. The methods used to measure the sweat rate include an iodine starch test, a weight assay, and an ion electric conductivity method. The ventilation capsule method is another method for quanti cation of sweat rate. However, this method has a problem in that the subject s physical activity is restricted by the rmly attached measurement probes. SNT-200, a wearable sweat meter developed by Rousette Strategy Inc., is already commercially available. This sweat meter contains silica gel that serves as an absorbent for sudoriferous steam and uses a temperature-humidity sensor to detect humidity changes in the device caused by sweating. However, the accuracy of the measurement has not yet been suf ciently investigated. This study was designed to provide evidence to validate the underlying measurement principle and accuracy of the device. We simulated various sweating conditions and performed simulated sweating measurements using SNT-200. In the rst experiment, continuous sweating over a wide body surface was simulated. The calculated absorbed steam volume was 1.84 times greater than the real transpiration rate. In the second experiment, sweating was simulated in the form of water drops, and the sweat meter absorbed the generated steam. In the second experiment, the data obtained using SNT-200 was in good accord with the volume dispensed by a micropipette. These experiments provided convincing evidence that the total area of four steam holes (A1, in the equation for calculating the sweat rate) required correction. We therefore modeled the effective absorption area of the sweat meter as one circle encompassing the four holes (8 mm in diameter; 52 mm 2) instead of a summation of the areas of four steam holes. De ning the effective absorption area by this method modi ed the value calculated in the rst experiment, which agreed with the transpiration rate. In addition, the modi ed moisture absorption volume in the sweat meter converged within ± 20% error of the actual measurement, except at 30 C.

中村淳史 1) ・木暮英輝 1) ・井上 将 2) 桑名克之 2) 電気的測定法による静脈リザーバレベル測定の検討 要 旨 人工心肺において静脈リザーバ(venous reservoir：VR)内の血液レベルは連続的に測定するべき重要な項目 である。本研究では VR の材質であるポリカーボネートの電気的特性を利用して静電容量(Cs)値から VR の血液 レベルを測定する方法を考案し、測定周波数、ヘマトクリット(Ht) 、血液量の Cs 値への影響について検討した。 実験 1 は VR 壁面に電極を 2 枚貼り各液面レベルにおける電極間の静電容量 Cs［F］を周波数 100kHz ～ 1MHz で測定した。VR には生理食塩液と牛血(Ht 20％、25％、30％)をそれぞれ充填した。実験 2 では円筒状容器に 電極を貼り生理食塩水を充填させ周波数 1MHz で Cs 値を測定した。 実験 1 の結果は液面レベルが高くなると Cs 値が増加し、周波数 1MHz では 1.30pF/cm(生理食塩液) 、1.26pF/ cm(Ht 20％) 、1.28pF/cm(Ht 25％) 、1.13pF/cm(Ht 30％)の増加となった。実験 2 では 1.41pF/cm となった。 周波数 800kHz ～ 1MHz が血液の影響は少なく安定した測定が可能であり、様々な形状をした VR において血液レ ベルを連続的に測定が可能であることが示唆された。 索引用語：人工心肺、静脈リザーバ、レベルセンサ、貯血量、自動化 Investigation of a method for the electrical measurement of venous reservoir blood volume Atsushi Nakamura 1) ，Eiki Kogure 1) ，Masaru Inoue 2) ，Katsuyuki Kuwana 2)

Objective This study aimed to measure the current perception threshold (CPT) of five fingertips of the left hand in healthy subjects and analyze whether sex differences in perception thresholds are suppressed when adjusting for fingertip size among males and females. Results For fingertips from the thumb to the little finger, the males’ CPT values were 1.03, 0.83, 0.86, 0.86, and 0.88 mA; the females’ results were 0.63, 0.55, 0.54, 0.51, and 0.50 mA. The CPTs were higher in males than in females for every fingertip. Upon adjusting for fingertip length, the log-transformed CPT values were found to have sex differences, except for the index finger: thumb, t(20.05) = 3.493, p = 0.002; middle finger, U(30) = 44.50, p = 0.005; ring finger, t(30) = 55.50, p = 0.018; little finger, U(30) = 30.00, p = 0.001. Similarly, the CPT values, transformed into log values when adjusting for the fingertip area, were found to have sex differences for three fingertips: thumb, t(18) = 2.649, p = 0.016; middle finger, U(20) = 12.00, p = 0.004; ring finger, t(18) = 2.206, p = 0.041. According to this study, sex differences in CPTs were not completely abolished by adjusting for fingertip length or area.