J Gutiérrez-Aceves | PubMed Health

PubMed1997

A pilot study of energy utilization patterns during different transurethral electrosurgical treatments of the prostate.

OBJECTIVES: During a prospective randomized study of prostatic and periprostatic heating during transurethral electrosurgical treatment, energy utilization was studied with respect to electrode configuration and prostate size. METHODS: Patients were stratified for gland volume (transrectal ultrasound [TRUS] 50 cc or less and more than 50 cc) and randomized to treatment either with loop resection (transurethral resection of the prostate [TURP]) or electrovaporization (transurethral electrovaporization [TUEVAP]. VaporTrode-Grooved Bar, CIRCON ACMI). Power was provided by a radiofrequency unit (Force FX, Valleylab) initially set at 150 W. A passive feed-through system was connected to the patient circuit to record current and voltage at 10 Hz during each activation of the cut mode in real time. RESULTS: Patients (6 per group) were well matched for prostate volume (P < 0.57) and operating time (P < 0.33). Power settings were also similar (120 to 190 W). Both total energy utilization (P < 0.025) and energy used per minute of treatment (P < 0.004) were greater for TUEVAP than for TURP. The higher energy deposition per unit time for TUEVAP was not associated with undesirable periprostatic heating. For TURP, more energy was used per unit time for each gram resected in small prostates than in larger glands. Comparing energy consumption per minute per cubic centimeter of prostate, we found a 2:1 ratio between TUEVAP and TURP in large prostates, which increased to 3.4:1 (P < 0.049) in small glands. CONCLUSIONS: For the same panel power settings, more energy is deposited at the tissue interface during TUEVAP than during TURP. This extra energy provides better surface hemostasis without undesirable deep heating and can be explained by the larger contact surface and contact time (slower speed of excursion) of the VaporTrode than a regular loop. The novel observation that more energy is required for small prostates during both treatments suggests that these glands have different electrical properties and higher tissue impedance than larger glands.

Electrosurgery↗

PubMed1997

Prostate heating patterns comparing electrosurgical transurethral resection and vaporization: a prospective randomized study.

PURPOSE: A prospective study was performed to determine if transurethral electrosurgical vaporization of the prostate is associated with unseen heat damage to vital periprostatic structures compared to conventional loop resection. In addition, energy consumption and its relationship to observed tissue temperature at the prostate periphery were evaluated for each treatment. MATERIALS AND METHODS: Patients with moderate to severe symptoms of benign prostatic bladder outflow obstruction and objective evidence of diminished flow or acute urinary retention were randomized to undergo either transurethral loop resection or electrosurgical vaporization after stratification for gland volume. Instrumentation was standardized for both groups except for the monopolar electrode used. The radiofrequency power source in the study was a new computer controlled generator with a constant power delivery feature. Regional tissue heating patterns were evaluated with optical fiber probes in real time. Four stationary sites were chosen for temperature measurements, namely the lateral lobe of the prostate, neurovascular bundle beside the prostatic apex at the level of the external sphincter, and anterior rectal wall at the level of the prostatic base and apex. A pull back technique was used to search for hot points in the long axis of the probe (3-dimensional temperature mapping) in 2 patients from each group. Incident generator panel power settings for the electrosurgical vaporization treatments were equivalent to those commonly used for loop resection (150 watts) and were adjusted up or down as needed. RESULTS: Prostate electrosurgical vaporization was possible at generator panel settings that were nearly equivalent to those for transurethral resection of the prostate (130 to 190 watts). No significant rectal or sphincteric heating was detected with either procedure. Conductive cooling of the neurovascular bundles was observed in 2 patients in each group toward the end of the operation. More energy was used per minute of treatment during electrosurgical vaporization than with regular loop resection (p < 0.004) but this was not associated with unwanted tissue heating. CONCLUSIONS: Neither conventional loop resection nor electrosurgical vaporization of the prostate appeared to be unsafe treatments with respect to unseen deep heating effects to vital periprostatic structures when performed at equivalent low incident power. The extra energy used during electrosurgical vaporization provided the benefit of improved coagulative hemostasis concurrently with shallow tissue vaporization using pure cutting current alone, without compromising treatment safety.

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