Measurement of Penile Hemodynamics with Laser Oximetry in Rabbit Model

Choi, Seong; Rhew, Hyun Yul; Min, Kweon Sik; Goldstein, Irwin

Abstract

PURPOSE: This study was designed to determine the validity and usefulness of laser oximetry in measuring changes in penile hemodynamics for assessment of erectile function.
MATERIALS AND METHODS
Anesthetized male New Zealand White rabbits (3.5~4.0 kg) were divided into two groups and penile hemodynamics were assessed by either laser oximetry (total hemoglobin, oxyhemoglobin, deoxyhemoglobin concentration and oxygen saturation) or intracavernosal pressure (ICP) monitoring before, during and after penile erection induced by pelvic nerve stimulation (PNS) or intracavernosal administration of phentolamine (0.05~1.0 mg/kg), nitroprusside (1~30ng/kg), papaverine (0.1~1.0 mg/kg) or sildenafil (3~150ng/kg). ICP recordings were normalized to systemic systolic arterial pressure.
RESULTS
PNS caused significant frequency-dependent increases in penile ICP. PNS also caused significant increases in penile tissue hemoglobin (total and oxy) concentrations and tissue oxygen saturation in a frequency-dependent manner. These changes were correlated with frequency-dependent increases in ICP. The duration of recorded responses (changes in hemoglobin concentration or ICP) increased with increasing frequency of nerve stimulation. Intracavernosal administration of phentolamine, nitroprusside, papaverine and sildenafil produced significant increases in ICP, tissue hemoglobin, oxygen saturation and duration of response as a function of increasing drug concentration.
CONCLUSIONS
Laser oximetry permits reproducible and valid assessment of changes in penile hemodynamics comparable to classical intracavernosal pressure measurements. Thus, we consider laser oximetry a reliable technique in evaluating penile hemodynamics. Its sensitivity in detecting small changes in oxyhemoglobin concentration and its non-invasive nature makes it advantageous over invasive METHODS such as intracavernosal pressure monitoring and laser Doppler flowmetry.