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Detailed prostatic interstitial thermal mapping during transurethral grooved rollerball electrovaporization and loop
T R Larson1, W M Religo, J M Collins
1Department of Urology, Mayo Clinic, Scottsdale, Arizona, USA.
Objectives:
To determine the detailed pattern of prostatic interstitial temperature change during rollerball electrovaporization and loop electrosurgery in patients with benign prostatic hyperplasia (BPH).
Methods:
Four patients with symptomatic BPH necessitating prostate surgery were subjected to rollerball electrovaporization on one side of their prostate glands, as well as contralateral loop electrosurgery. Continuous temperature readings were recorded from 20 to 24 interstitially implanted fiber-optic thermosensors using a novel stereotactic thermal mapping technique. Ultrasound and video endoscopic visualization were used to evaluate and quantify the spatial relationship between the thermosensors and the rollerball or loop.
Results:
The patterns of temperature change during rollerbal electrovaporization and loop electrosurgery were substantially similar. Temperatures decreased steeply and significantly with increasing distance from both the rollerball (P < 0.001) and loop (P < 0.001). Marked mean temperature increases occurred at 1 to 2 mm from both the rollerball (30.8 degrees C, 95% confidence interval [CI] 27.8 to 33.8 degrees C) and loop (34.8 degrees C, 95% CI 24.0 to 45.6 degrees C), and temperatures at this distance were significantly higher than those at greater distances (P < 0.05). At 3 to 5 mm, the mean temperature increases declined by 58% for the rollerball and 68% for the loop. Further declines of 68% and 63%, respectively, were observed at 6 to 10 mm, and at distances exceeding 10 mm the temperature changes were minimal (0.5 degree C [95% CI 0.3 to 0.8 degree C] for the rollerball and 0.5 degree C [95% CI 0.1 to 0.8 degree C] for the loop). There was no change in temperature at any of the thermosensors near the neurovascular bundles and rectum.
Conclusions:
The patterns of temperature change with rollerball electrovaporization and loop electrosurgery are closely similar. Interstitial temperature changes during use of the rollerball and loop are transient and highly localized, posing minimal risk of unintended thermal damage to adjacent tissues, including the neurovascular bundles and rectum.