Thermocoagulation effect of diode laser radiation in the human prostate: acute and chronic study

Safety During Ureteroscopy: Radiation, Eyes, and Ergonomics

It is known that urologic surgeons are at risk of work-place injury due to the physical requirements of operating and exposure to hazards. These hazards include radiation, exposure to body fluids, use of laser energy, and orthopedic injury due to the physical nature of operating. The risks that these hazards present can be mitigated by implementing several evidence-based safety measures. The methods to protect against radiation exposure include keeping radiation usage in the operating room as low as reasonably achievable, donning lead aprons, and wearing protective glasses. Additionally, protective glasses decrease the risk of eye injury from laser injury and exposure to body fluids. Finally, practicing sound surgical ergonomics is essential to minimize the risk of orthopedic injury and promote career longevity. The interventions discussed herein are simple and easy to implement in one's daily practice of urology.

Phenomenological evolution equations for heat-induced shrinkage of a collagenous tissue

Optimization of clinical heat treatments for various pathologies requires accurate numerical modeling of the heat transfer, evolution of thermal damage, and associated changes in the material properties of the tissues. This paper presents two phenomenological equations that quantify time-dependent thermal damage in a uniaxial collagenous tissue. Specifically, an empirical rule-of-mixtures model is shown to describe well heat-induced axial shrinkage (a measure of underlying denaturation) in chordae tendineae which results from a spectrum of thermomechanical loading histories. Likewise an exponential decay model is shown to describe well the partial recovery (e.g., renaturation) of chordae when it is returned to body temperature following heating. Together these models provide the first quantitative descriptors of the evolution of heat-induced damage and subsequent recovery in collagen. Such descriptors are fundamental to numerical analyses of many heat treatments because of the prevalence of collagen in many tissues and organs.

Mechanism of healing of the human prostatic urethra following thermal injury

OBJECTIVES

To characterize histopathologically the healing response of the prostatic urethra after laser thermal coagulation and standard transurethral resection of the prostate (TURP).

METHODS

The study included 31 patients who underwent radical prostatectomy because of malignancy. Twenty-two (first group) had laser radiation either at the time of surgery (18 patients) or from 1 to 12 weeks prior to prostatectomy (4 patients). Nine patients (second group) had TURP from 6 to 96 weeks prior to prostatectomy.

RESULTS

Coagulation necrosis followed by sloughing was observed during the first 10 weeks after laser radiation. After the first 10 weeks, the healing response was otherwise stereotypical and comparable for both groups of patients. Re-epithelialization was prominent and resulted from migration of proliferating epithelial cells from the remaining acinar and ductal epithelium. Squamous metaplasia was conspicuous and present indefinitely. Development of inflammatory reaction followed by granulation tissue and well-organized fibroblastic stroma were sequentially recognized, but less prominent. Complete re-epithelialization and wound sealing was not observed before the first 12 weeks of healing.

CONCLUSIONS

Our study suggests that laser thermal coagulation and TURP are partial-thickness injuries. Because of the abundant germinal epithelium in the remaining prostatic glands and ducts, the healing response of the prostatic urethra is relatively unimpeded and free of contractures, analogous to second-degree skin burns.

Healing response of the canine prostate to Nd:YAG laser radiation

The objective of the study was to characterize the healing response of the canine prostate to laser thermal injury. The study included 20 canine prostates that underwent transurethral laser radiation. The prostates were retrieved 1 hr after laser radiation in 7 dogs (acute group), and from 3 days to 9 weeks in 13 dogs (chronic group). Two distinct features were observed. First, reepithelialization of the prostate urethra resulted from mobilization of proliferating epithelial cells from acinar and ductal prostatic epithelium into the cavity surface, and not from the edges of the wound at the bladder neck. Squamous cell metaplasia was a prominent feature of reepithelialization. Second, the healing process in the canine prostate was relatively unimpeded. The large glandular component provided abundant germinal epithelial growth, and the absence of stromal elements allowed for complete sloughing of necrotic tissue without residual eschars. Further, the lesions in the chronic group had a tendency to be larger than those in the acute group, suggesting that extended delayed necrosis may occur at deep prostatic tissue layers.