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Biomedical subjects

J N Kabalin

Publications and source records attributed to J N Kabalin.

At least 37 records · Page 2Linked to original sources
PubMed1996

Dosimetry studies utilizing the urolase right-angle firing neodymium:YAG laser fiber in the human prostate.

BACKGROUND AND OBJECTIVE: Until recently, little or no objective data have been available to support either the choice of power setting or the timing of laser applications to achieve optimal tissue ablation in the human prostate. The objective of this study was to define quantitative dosimetry curves for the Urolase right angle laser fiber in human prostates. STUDY DESIGN MATERIALS AND METHODS: Transurethral Neodymium:YAG laser application was performed with the Urolase right-angle laser fiber in adult human prostates prior to planned radical surgery. Depth and volume of prostatic tissue coagulation for single, continuous laser applications were measured at variable power settings from 20 to 60 watts while holding total energy delivery constant. Then, holding the power setting constant at 40 watts, the extent of tissue coagulation was measured for variable treatment times from 60 to 120 seconds. RESULTS: Peak tissue coagulation was observed at 40 watts up to a maximum of 14 mm tissue penetration and 4.23 cc volume coagulated following a single spot laser application. The mean depth of tissue coagulation at 40 watts power setting was 13.5 mm, with a mean volume of tissue coagulation of 3.68 cc. The mean depth of tissue penetration at 40 watts was more than 25% greater than that observed at 60 watts, and the mean volume of tissue coagulation was 190% greater than that observed at 60 watts. As treatment time was increased from 60 to 90 seconds, extent of tissue coagulation increased significantly. However, beyond 90 seconds continuous laser application at 40 watts, a plateau in tissue effects was observed, with minimal increase in tissue coagulation between 90 and 120 seconds. Histologic examination of prostates removed acutely showed heat-induced damage to both stromal and glandular epithelial elements in laser-treated areas. At 1 year, the prostatic urethra was lined with a normal transitional epithelium, and mild periurethral fibrosis with focal squamous metaplasia was seen. CONCLUSION: Using the Urolase right-angle laser fiber, this study suggests that 40 watts power setting and 90 seconds continuous application time with a Neodymium:YAG laser source represent optimal treatment parameters to maximize prostatic tissue coagulation.

Adult↗
PubMed1996

Holmium: YAG laser prostatectomy canine feasibility study.

BACKGROUND AND OBJECTIVE: Laser coagulation prostatectomy performed with the Neodymium: Yttrium-Aluminum-Garnet laser has emerged as a viable alternative for the treatment of benign prostatic hyperplasia. Laser vaporization prostatectomy, if feasible, has the potential to reduce postoperative catheterization time and achievement time of maximum voiding outcomes. The objective of this study was to determine the ability of the Holmium: Yttrium-Aluminum-Garnet laser wavelength to vaporize prostatic tissue and create an immediate prostatectomy defect. STUDY DESIGN/MATERIALS AND METHODS: The Holmium: Yttrium-Aluminum-Garnet laser was applied in vivo in a canine prostate model. Laser energy was delivered endoscopically via quartz laser fibers circumferentially to each prostatic fossa. High energies, up to 2.8 joules per pulse and 60 watts total power, were utilized. All prostates were surgically removed immediately following laser applications to determine acute laser effects. RESULTS: Immediate tissue ablation or vaporization with this laser wavelength was found to be both feasible and relatively efficient. The mean transverse dimension of the prostatic defects produced was 19 mm, with a maximum transverse dimension of 27 mm. In one prostate a cavity of 27 (transverse) by 29 (anterior-posterior) by 43 (length) mm was created, with an estimated tissue removal of approximately 20 cc. Hemostasis with the Holmium laser was adequate in this canine prostate model. In addition to the acute tissue cavity created, a 1-2 mm rim of surrounding tissue coagulation was observed in each specimen. CONCLUSION: The Holmium: Yttrium-Aluminum-Garnet laser wavelength is capable of acute prostatic tissue vaporization and deserves ongoing study with potential application in the surgical treatment of benign prostatic hyperplasia in men.

Animals↗
PubMed1996

Neodymium:YAG laser coagulation prostatectomy: 3 years of experience with 227 patients.

PURPOSE: For 3 years we prospectively followed a cumulative cohort of men who underwent neodymium:YAG laser coagulation prostatectomy to relieve bladder outlet obstruction to determine the safety, efficacy and durability of this procedure. MATERIALS AND METHODS: A total of 227 men with symptomatic bladder outlet obstruction was treated with the Urolase side-firing laser fiber between October 15, 1991 and October 15, 1994. Voiding outcomes, including peak urinary flow rates, residual urine volumes and American Urological Association symptom scores, were measured with time, and immediate and long-term complications were assessed. RESULTS: Median patient followup was 26 months (maximum 42). Significant improvement occurred in all measured voiding parameters, including 133% in peak flow rates and 61% in symptom scores 1 year postoperatively. Overall 87% of patients noticed improved quality of life as a result of surgery. Minimum postoperative followup was 6 months in all cases. Complications included prostatitis in 2.6% of patients, urethral stricture in 1.8%, bladder neck contracture in 4.4% and reoperation for residual prostate tissue in 5.3%. CONCLUSIONS: Neodymium:YAG laser coagulation of the prostate represents an efficacious surgical intervention for symptomatic bladder outlet obstruction with minimal associated morbidity. Voiding outcomes are durable through 3 years.

Aged↗
PubMed1996

Extended durability of external metal mirror reflector of side-firing Nd:YAG laser fiber used for prostatic ablation.

A new side-firing neodymium:YAG laser fiber has been developed, incorporating a solid gold external parabolic mirror reflector. Clinical trial of this fiber during actual laser prostatectomy cases demonstrated its extended durability. Mean fiber performance was 5.7 cases, 122.5 min total active laser transmission time, and 294.1 kJ laser energy delivery. Maximum observed fiber lifespan was 9 laser prostatectomy procedures, 207.4 total min, and 497.8 total kJ delivered. The extended durability of the new UroGold fiber allows for greater fiber survivability with less experienced operators, helps to assure maintenance of laser light transmission at therapeutic levels throughout usage, and allows multiple reuse of the fiber if desired. All of these factors can produce a net gain in the cost efficacy of laser prostatectomy.

Equipment Design↗
PubMed1996

Holmium:YAG laser prostatectomy: results of U.S. pilot study.

The holmium:YAG (Ho:YAG) laser wavelength's ability to vaporize and incise soft tissue offers potential advantages for prostatectomy compared with the Nd:YAG laser, which primarily produces tissue coagulation. In this initial U.S. trial, Ho:YAG laser prostatectomy was performed in 20 men, including 2 men treated immediately prior to radical prostatectomy to assess Ho:YAG laser tissue effects in the prostate. A total of 18 men were treated for clinically symptomatic bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH). Estimated excess BPH tissue averaged 24 g (range 5-50 g). A mean of 129 kJ of Ho:YAG laser energy was delivered, combined with a mean of 11 kJ of Nd:YAG energy to provide supplemental coagulation for hemostasis. The mean operative time was 1 hour 34 minutes. No significant intraoperative changes in hematocrit or serum electrolytes were documented. No perioperative or late complications occurred. The mean postoperative catheterization time was 1.4 days. Of the 18 patients, 16 (90%) underwent a successful voiding trial on the first postoperative morning. Immediate improvement in voiding, comparable to that seen after transurethral electrocautery resection of the prostate (TURP), was reported by all patients. Ho:YAG laser resection of the prostate appears to be a useful surgical technique associated with minimal morbidity and immediate improvement in voiding.

Aged↗
PubMed1996

Addition of a second urethral cuff to enhance performance of the artificial urinary sphincter.

PURPOSE: Stress urinary incontinence may persist in approximately 15% of men following implantation of a standard artificial urinary sphincter. The ability of a second urethral cuff to provide satisfactory continence without additional operative complications was investigated. MATERIALS AND METHODS: A second urethral cuff was placed to enhance performance of the artificial urinary sphincter in 5 men with stress urinary incontinence following radical prostatectomy. A stainless steel 3-way tubing connector allowed for addition of a second cuff to the standard artificial urinary sphincter without the kinking problems previously observed with a flexible 3-way connector. In 4 consecutive men a second cuff was added at operative revision of an existing artificial urinary sphincter that had failed to produce satisfactory continence. A double cuff artificial sphincter was placed initially in 1 man. RESULTS: Of 5 men 4 had satisfactory and 1 had improved continence with the double cuff artificial urinary sphincter. The stainless steel 3-way tubing connector eliminated kinking complications. CONCLUSIONS: Implantation of a second urethral cuff can provide satisfactory urinary continence in men with an artificial urinary sphincter and persistent incontinence. Placement of a double cuff artificial urinary sphincter may also represent appropriate initial intervention in men with significant stress urinary incontinence.

Aged↗
PubMed1995

Neodymium: yttrium-aluminum-garnet laser dosimetry for the prolase II side-firing delivery system in the human prostate.

OBJECTIVES: The objective of this study was to define optimal treatment parameters and quantitative dosimetry for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser coagulation prostatectomy utilizing the ProLase II side-firing laser delivery system. METHODS: Transurethral Nd:YAG laser application was performed with the ProLase II side-firing laser fiber in adult human prostates prior to planned radical prostatectomy. Depth and volume of prostatic tissue coagulation for single, continuous laser applications were measured at variable power settings from 40 to 80 W, while holding total energy delivery constant. Holding the power setting constant, the extent of tissue coagulation was similarly measured for variable treatment times from 45 to 90 seconds. RESULTS: Peak tissue coagulation for the ProLase II was observed at 60 W--up to a maximum of 13 mm tissue penetration and 3.92 cc volume coagulation following a single spot laser application. The mean depth of tissue coagulation at 60 W power setting was 12.7 mm, with a mean volume of tissue coagulation of 3.07 cc. Holding the power setting constant at 60 W, and increasing treatment time from 45 to 60 seconds, the extent to tissue coagulation increased significantly. However, beyond 60 seconds continuous laser application at 60 W, a plateau in tissue effects was observed, with minimal increase in tissue coagulation between 60 and 90 seconds. CONCLUSIONS: Using the ProLase II side-firing laser fiber, 60-second Nd:YAG spot laser applications at 60 W power setting represent optimal treatment parameters. The quantitative dosimetry curves produced for the ProLase II fiber are compared with prior dosimetry studies with the Urolase delivery system.

Aged↗
PubMed1995

Insight into mechanism of neodymium: yttrium-aluminum-garnet laser prostatectomy utilizing the high-power contact-free beam technique.

OBJECTIVES: The objective of this study was to define the actual mechanism of neodymium: yttrium-aluminum-garnet (Nd:YAG) laser prostatectomy achieved with the previously described contact-free beam technique using the Ultraline delivery system at high-power settings. METHODS: Transurethral Nd:YAG laser application was performed with the Ultraline side-firing laser fiber in canine and human prostates. Total or radical prostatectomy was performed after laser treatment to examine and measure laser tissue effects produced using the contact-free beam technique. RESULTS: Minimal actual tissue evaporation or vaporization was noted in either the canine or human prostate using this technique. The extent of tissue vaporization achieved was probably insufficient to produce clinically significant voiding outcomes acutely or chronically. However, this technique, using the Nd:YAG laser, produced excellent tissue coagulation and necrosis, similar to other laser delivery systems and reports dealing with laser coagulation prostatectomy. CONCLUSIONS: The primary mechanism accounting for therapeutic efficacy of the contact-free beam technique for Nd:YAG laser prostatectomy utilizing the Ultraline delivery system at high-power settings appears to be tissue coagulation with subsequent necrosis and slough, rather than tissue vaporization. This is consistent with the known tissue effects of the Nd:YAG laser wavelength in other systems.

Animals↗
PubMed1995

Serum prostate-specific antigen and the biologic progression of prostate cancer.

OBJECTIVES: We have previously shown that serum prostate-specific antigen (PSA) is proportional to prostate cancer volume and that progression of prostate cancer is proportional to volume, but other investigators have not found serum PSA to be as useful in predicting pathologic stage at the time of radical prostatectomy. Because our series is the only study to examine prospectively all radical specimens at 3-mm intervals, we have examined the relationship between serum PSA and the morphologic indicators of cancer progression in our first 350 radical prostatectomies. METHODS: Preoperative serum PSA level was tabulated in 350 consecutive patients with prostate adenocarcinoma and compared with morphologic variables in the radical prostatectomy specimen. Morphologic variables included cancer volume, histologic grade, capsular penetration, seminal vesicle invasion, and lymph node metastasis. RESULTS: Serum PSA showed strong correlation with all morphologic variables, which were highly intercorrelated. Serum PSA level was strongly correlated with cancer volume, histologic grade, and frequency of regional spread to lymph nodes. Close intercorrelations found between all variables were translated into a scale relating each level of serum PSA elevation to stage of disease in morphologic terms. Using this scale, serum PSA level can contribute to patient evaluation and treatment decisions in men with prostate cancer. CONCLUSIONS: Serum PSA is primarily determined by prostate cancer volume and secondarily by the percentage of high-grade cancer (Gleason grades 4 and 5) in the prostate. Because of this basic relationship, serum levels of PSA provide a clinically useful estimate of morphologic findings in the prostate. Serial PSA determinations should reflect the growth of the cancer as well as the gradual evolution of more malignant cells with the passage of time. The use of a serum PSA-based rating scale can contribute to patient evaluation and treatment decisions in men with prostate cancer.

Adenocarcinoma↗
PubMed1995

A prospective randomized comparison of transurethral resection to visual laser ablation of the prostate for the treatment of benign prostatic hyperplasia.

OBJECTIVES: Transurethral resection of the prostate (TURP) represents the accepted standard of surgical therapy for the management of symptomatic bladder outlet obstruction due to benign prostatic hyperplasia (BPH). However, this is a major operative procedure associated with significant perioperative morbidity. Visual laser ablation of the prostate (VLAP) utilizing a neodymium:yttrium-aluminum-garnet laser represents a new technologic approach to the surgical management of BPH. We compared the relative safety and efficacy of these two surgical approaches in a prospective, randomized trial. METHODS: At 6 investigational sites in the United States, 115 men with symptomatic BPH more than 50 years of age and not in retention, were randomly assigned to undergo either TURP (59 patients) of VLAP (56 patients). VLAP patients received a mean of 10,200 J of energy delivered in a mean of 5.5 intraprostate laser applications. At preoperative baseline, 3 months, 6 months, and 1 year postoperatively, all patients underwent clinical evaluations, including ultrasonic prostatic volume determination, standardized American Urological Association (AUA)-6 symptom score, peak urine flow, postvoid residual urine volume, and quality-of-life assessment. RESULTS: Compared to TURP, the VLAP procedure required less time (23.4 versus 45.2 minutes; P < 0.01) and shorter hospitalization (1.8 versus 3.1 days, P < 0.01). VLAP was associated with a significantly lower rate of serious treatment-related complications compared to TURP (10.7% versus 35.6%; P < 0.01). Only One (2.2%) patient undergoing VLAP experienced a greater than 2.2 g/dL decrease in hemoglobin compared to 40% of TURP patients (P = 0.01). No patient in the VLAP group required blood transfusion compared with 3.4% of those undergoing TURP. Of the 115 patients, clinical outcomes measured at 1 year showed a mean improvement in AUA-6 symptom scores of -9.0 for VLAP compared with -13.3 for TURP (P < 0.04), mean increase in peak urinary flow rate of 5.3 cc/s for VLAP compared with 7.0 cc/s for TURP (P = 0.27), and mean decrease in postvoid residual urine volume of -55.4 cc for VLAP compared with -138.8 cc for TURP (P < 0.01). At 1 year, 78.2% of patients undergoing VLAP indicated that their quality of life was improved compared with 93.0% of patients undergoing TURP (P = 0.03). When compared with TURP, treatment of BPH with VLAP is associated with less hemoglobin decrease, a lower likelihood of serious complication, and requires less procedure time and a shorter hospital stay. Through a 1-year follow-up, VLAP produced significant improvement over baseline in objective and subjective outcome measures. However, for 1-year improvement in AUA-6 symptom score, postvoid residual urine volume, and quality of life, VLAP was less effective than TURP. CONCLUSIONS: In this initial study in the United States, with relatively low-energy laser applications, VLAP did not result in as complete a removal of prostatic tissue as did TURP. Considering the lower morbidity, shorter procedure and hospitalization times, and the degree of effectiveness that was achieved even at the low-energy doses used in this study, VLAP appears to be a viable and safe alternative to standard TURP.

Aged↗
PubMed1995

Laser coagulation prostatectomy: evolution of clinical practice and treatment parameters.

Laser coagulation prostatectomy has evolved into an accepted option for the management of bladder outlet obstruction secondary to benign prostatic hyperplasia. Clinical results document the safety and efficacy of this operation. Rapidly expanding clinical experience and basic research efforts in recent years have provided a scientific foundation and an improved qualitative understanding of the laser-tissue interactions during Nd:YAG laser coagulation of the prostate. Today, truly quantitative laser dosimetry is becoming available to guide the operative approaches to laser prostatectomy with the increasing variety of Nd:YAG delivery systems. The development of laser coagulation prostatectomy is traced to the present, and accumulated clinical experience and laboratory data are incorporated into a rational approach to operative and perioperative patient management utilizing this technology.

Clinical Trials as Topic↗
PubMed1995

Comparative study of laser versus electrocautery prostatic resection: 18-month followup with complex urodynamic assessment.

A total of 25 patients with symptomatic bladder outlet obstruction due to benign prostatic hyperplasia was entered into a prospective, randomized trial comparing prostatectomy done with the Urolase right angle firing neodymium:YAG laser fiber and standard transurethral electroresection of the prostate. Efficacy of treatment, as assessed by standardized American Urological Association symptom scores, patient assessment of symptom improvement, peak urinary flow rates, post-void residual urine volumes and complex urodynamic evaluation, including assessment of opening pressure and maximum detrusor voiding pressure, was equivalent for the 2 treatment groups through 1 year. Ultrasonic assessment of prostatic volumes at 1 year showed a mean decrease in total volume of 59% for standard electrocautery resection compared to 28% for laser prostatectomy. Symptom scores and peak urinary flow rates remained equivalent for both groups through 18 months.

Aged↗
PubMed1995

[Transurethral laser therapy of benign prostatic hyperplasia].

During the last 4 years, transurethral laser therapy for benign prostatic hyperplasia (BPH) has become an increasingly popular alternative to transurethral resection of the prostate (TURP) for the treatment of obstructive BPH symptoms. Clinical data so far published prove the efficacy of this new therapeutic modality, although the results are up to now possibly inferior to those achieved with TURP. On the other hand, the incidence of severe perioperative complications is significantly lower in patients treated with laser prostatectomy than in those undergoing TURP. Therefore, laser prostatectomy is a reasonable adjunct to the therapeutic spectrum for BPH in high-risk patients. Nevertheless, its role in the treatment of obstructive BPH in low-risk patients cannot be defined until long-term follow-up data are available.

Contraindications↗
PubMed1995

Laser prostatectomy performed with a right-angle firing neodymium:YAG laser fiber at 60 watts power setting.

A total of 50 patients with symptomatic bladder outlet obstruction due to benign prostatic hyperplasia was entered into a prospective trial of laser prostatectomy performed with the right-angle firing neodymium:YAG laser fiber at 60 watts power setting. Mean estimated resectable prostatic weight was 30 gm. with a mean prostatic urethral length of 3.3 cm. Nine patients (18%) were in urinary retention requiring catheterization before treatment. Mean energy delivery was 30,834 joules (range 14,400 to 127,800) with a mean operative time of 31 minutes. Efficacy of treatment was assessed at 3, 6 and 12 months postoperatively by standardized American Urological Association symptom scores, peak urinary flow rates and post-void residual urine volumes. At preoperative baseline the mean symptom score was 20.8, mean peak urinary flow rate 7.6 cc per second, and mean post-void residual urine volume 353 cc. At 1 year postoperatively mean symptom score was 8.4, mean peak urinary flow rate was 18.7 cc per second and mean post-void residual urine volume was 175 cc. Two patients required retreatment for residual tissue. There were 6 complications including 5 bladder neck contractures requiring incision (10%) and 1 case of postoperative prostatitis requiring antibiotic therapy (2%). Of 37 evaluable sexually active patients 31 (84%) reported preservation of antegrade ejaculation postoperatively.

Aged↗