165 Near-Infrared Spectroscopy Assessment of Tissue Saturation of Oxygen in Torsed and Healthy Testes

Abstract

Study Objectives: To assess whether testicular torsion is associated with low testicular tissue saturation of oxygen (StO2) as measured by trans-scrotal near-infrared spectroscopy (NIRS), and to compare the differences in NIRS values between testicles of the same patient, both in patients with testicular torsion and in healthy controls. Methods: This was an observational study. Near-infrared spectroscopy measurements were obtained from males less than 30 years old presenting with acute testicular pain, and participants were assigned to the testicular torsion group (TT) based on ultrasonography and operative findings. Healthy controls were males presenting to the emergency department for low acuity, non-genito-urinary conditions. We hypothesized that the absolute difference in trans-scrotal NIRS StO2 between left and right sides for healthy controls would be zero, and that the difference between non-torsed and torsed sides for testicular torsion group would be significantly non-zero. Based on animal data, we powered our study to detect an absolute difference of StO2 of 47%. Using a beta of 0.8 and an alpha of 0.05, this would require at least 5 patients in the testicular torsion group. Results: The mean StO2 for the left and right testicles for healthy controls was 73.6% for each side (95% CI 68.0%-79.1% for left side, 66.9% - 80.4% for right side) (N=17). The absolute difference in NIRS StO2 for left minus right was 3.5% (95% CI 1.8% - 5.4%), which was significantly non-zero (p=0.0007) and refuted the hypothesis that there was no significant difference in StO2 between left and right testes in health. In the testicular torsion group, the torsed side demonstrated mean StO2 of 82.8% (95% CI 68.7% - 96.9%), and the contra-lateral non-torsed testes was 85.8% (95%CI 72.3%-99.3%). The mean StO2 difference, non-torsed minus torsed was 3.0% (range -1% to 9%, 95%CI -2% to 8%) refuting the hypothesis that torsed testes would demonstrate significantly lower values for StO2. Conclusion: While pilot animal investigations support a potential role for trans-scrotal NIRS for the detection of testicular torsion, this first clinical translation of animal findings reveals that the investigated, trans-cutaneous, reflectance geometry NIRS device failed to demonstrate symmetric oxygenation of left and right testes in healthy controls and also failed to demonstrated depressed tissue saturation of oxygen values in patients with confirmed testicular torsion.