Probing penile hemodynamics by using photoplethysmography as objective indicators for male erection quality and sexual function

Yuan-Hung Pong,Yu-Chuan Lu,Men-Tzung Lo,Ching-En Hsu,Yi-Kai Chang,Po-Cheng Chen,Hong-Chiang Chang,Chen Lin,Vincent F S Tsai

doi:10.1038/s41598-021-91582-9

Yuan-Hung Pong, Yu-Chuan Lu + Show 7 more

Open Access

https://doi.org/10.1038/s41598-021-91582-9

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Abstract

Erectile dysfunction (ED) is mostly due to the lack of blood flow into the penis. In the past 20 years, near-infrared spectroscopy (NIRS) was used in measuring the concentrations and temporal dynamics of different hemoglobin types. However, the dynamics of the light absorption (photoplethysmography; PPG) have not been applied to survey penile hemodynamics and erection quality. This paper compared the use of photoplethysmography (PPG) to study vascular ED with standard penile Doppler ultrasonography. Men diagnosed with vascular ED for at least 6 months and nominated for penile ultrasonography were included. PPG signals were collected during the ultrasound examination. All beat-to-beat PPG waveforms were aligned with the peak and averaged to one representative template waveform for feature analysis, including amplitude differences (APD) index, reflection time index (RTI), augmentation index (AI), and perfusion index (PI). An inverse correlation was found between end-erection amplitude and both erection hardness score (EHS) and resistive index (RI). APD index and EHS as well as the international index of erectile function-5 (IIEF) and RI were positively correlated. RTI and AI were inversely correlated to IIEF and RI. PI was positively correlated to RI. PPG may therefore be useful as a noninvasive, convenient, technique for sexual function evaluation.

Highlights

Erectile dysfunction (ED) is mostly due to the lack of blood flow into the penis
Significant differences exist in the amplitude differences (APD) index, reflection time index (RTI), augmentation index (AI), and resistive index (RI) when patients were grouped by ED severity (Table 2)
This study analyzed the dynamics of arterial PPG monitored via near-infrared spectroscopy (NIRS) and derived several waveform characteristics

Summary

Introduction

Erectile dysfunction (ED) is mostly due to the lack of blood flow into the penis. In the past 20 years, near-infrared spectroscopy (NIRS) was used in measuring the concentrations and temporal dynamics of different hemoglobin types. The dynamics of the light absorption (photoplethysmography; PPG) have not been applied to survey penile hemodynamics and erection quality. In the last 20 years, NIRS has been used in urological examinations, including the measurement of testicular and renal cortex oxygenation, bladder functional studies, and penile hemodynamics[6,7,8,9,10]. The dynamics of arterial light absorption measured in a finger were used as an alternative to noninvasive hemodynamic parameters in assessing vascular stiffness and continuous blood pressure in many studies[12,13]. Cavernous arteries due to high pressure inside the penis during erection causes a relatively lesser blood volume pumped into the penis and induces a decrease in PPG amplitude, representing the degree of hardness of penile erection. This study was undertaken to investigate penile hemodynamics and penile erection quality using PPG

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