Peripheral arterial tonometry (PAT) is a useful method to assess endothelial function. Analysis of pulse wave amplitude with PAT during reactive hyperemia can be used to study peripheral vascular endothelial function very well. We had injected a specific nitric oxide (NO) synthesize inhibitor intra-arterially into five adult male rats to verify the validation of our proposed photoplethysmograpy (PPG) system for endothelial function assessment. However, the reproducibility was not good for the system applied for measuring fingertip peripheral arteries. Therefore, an air-pressure sensing system with the high reproducibility was developed for peripheral vascular endothelial function assessment. This study showed that the vasodilatation index measured with air-pressure sensing system correlated very well with that measured using peripheral arterial tonometry. In addition, only few minutes are needed for conducting a self endothelial function assessment at home. And, early self-monitoring of cardiovascular dysfunction and arterial stiffness can be easily and effectively achieved.

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Although current technique of photoplethysmography (PPG) is a popular noninvasive method of waveform contour analysis in assessing arterial stiffness, data obtained are frequently affected by various environmental and physiological factors. We proposed an easily operable air pressure sensing system (APSS) for radial arterial signal capturing. Totally, 108 subjects (young, the aged with or without diabetes) were recruited from July 2009 to May 2010. Arterial waveform signals from the wrist were obtained and analyzed using Hilbert-Huang transformation (HHT). Through ensemble empirical mode decomposition (EEMD), the signals were decomposed into eight intrinsic mode functions (IMF1-8) of which IMF5 was found to be the desired signal with a discernible diastolic peak. The results showed significant differences in reflection index (RI) and stiffness index (SI) from the young subjects and those from the aged participants with or without diabetes. Significant differences in RI and SI were also noted between subjects with well-controlled diabetes and those without. Good reproducibility and correlation were demonstrated. In conclusion, the present study proposed the application of radial arterial signal capturing subsystem and HHT in acquiring more reliable data on RI and SI compared with the conventional PPG method.

Introduction High prevalence of erectile dysfunction in young adults has raised much concern regarding early identification of risk factors for timely intervention. Aim This study aimed at identifying young males at risk through a novel penile arterial waveform analyzing system. Methods Between July 2009 and December 2010, 30 young adult volunteers of age 18 to 29 without known history of vascular diseases or erectile dysfunction were recruited. Main Outcome Measures Basic demographic and anthropometric characteristics (i.e., age, body weight, body height, body mass index, waist circumference) were recorded. Blood samples were obtained for determining levels of testosterone, glycosylated hemoglobin, triglyceride, fasting sugar, low- and high-density lipoproteins (HDL). Data obtained from visual sexual stimulation (VSS) RigiScan and the penile arterial waveform amplitude (PAWA) ratios were compared in terms of their correlations with anthropometric and serum biochemical parameters using Pearson’s correlation analysis. Results PAWA ratios were found to correlate with Rigidity (tip and base) (r = 0.425, P = 0.019 and r = 0.664, P < 0.001, respectively). Significant associations of PAWA ratios were noted not only with serum testosterone level but also with risk factors for metabolic and cardiovascular diseases including total triglyceride, HDL, age, waist circumference, body mass index, and diastolic blood pressure. However, VSS RigiScan failed in identifying significant correlations with HDL, age, and diastolic blood pressure. Conclusions Not only could the penile waveform analyzing system assess penile endothelial function in young adults, but the results also showed significant associations with their serum testosterone levels and metabolic parameters. The findings suggest that PAWA ratio may serve as an indicator for early identification and treatment of young adults at risk of erectile dysfunction.

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