Transurethral Bipolar Plasmakinetic Resection Combined with 2 μm Continuous Wave Laser Vaporization: A New Method for the Treatment of Large Volume Benign Prostatic Hyperplasia

Abstract

Objective: The aim of this study was to evaluate the safety and efficiency of transurethral bipolar plasmakinetic resection of the prostate (PKRP) combined with 2 μm laser vaporization in the management of large prostates (>80 mL). Background data: The safety and efficiency of transurethral vaporesection of the prostate with benign prostatic hyperplasia (BPH), using a 2 μm laser system, have been verified. However, this method does still not manage large volume prostates efficiently. Methods: From October 2009 to June 2010, 120 BPH patients with a median prostatic volume of 106.7 (±16.7) mL (range, 82.5–156.8 mL) were randomized for surgical treatment with PKRP combined with 2 μm laser vaporization (n=58) or PKRP only (n=62). All patients were preoperatively assessed with subjective symptoms score. Preoperative and perioperative parameters at 3-, 6-, and 9-month follow-up were also evaluated. All complications were recorded. Results: PKRP combined with 2 μm laser vaporization was significantly superior to PKRP alone in terms of operative time, irrigation time, catheterization time, hospital stay, and hemoglobin decrease. The blood transfusion and urinary tract infection observed in the PKRP combined with 2 μm laser vaporization group was significantly less than that of the groups that received PKRP only. Both groups were similar with respect to resected tissue weight, transient incontinence, urethral stricture and retrograde ejaculation in the postoperative period. Both groups showed a significant improvement from baseline in terms of International Prostate Symptom Score (IPSS), quality of life (QOL), maximum urinary flow rate (Qmax), and pulmonary vascular resistance unit (PVRU) values. However, no significant difference was found between them. Conclusions: PKRP combined with 2 μm laser vaporization, which combines the advantages of both PKRP and 2 μm laser, is superior for its shorter operation time, less bleeding, and better efficiency. It may be a safer and more effective method for the treatment of BPH in large prostates.

Introduction

B enign prostatic hyperplasia (BPH) is a common disease in men >50 years of age,¹ and according to the European Association of Urology (EAU) guidelines, transurethral resection of the prostate (TURP) is still considered the gold standard for surgical treatment of the lower urinary tract symptoms (LUTS) caused by BPH.² However, the efficacy and safety of this procedure was mainly shown on treating small-to-medium prostates. Complications and morbidity related to this procedure, such as blood loss, fluid balance disturbances, excessive fluid absorption, and incontinence, are still significant in patients with larger prostates.³ Although the transurethral plasmakinetic resection of the prostate (PKRP) has been successfully introduced over the past decade and has reduced many of the problems associated with TURP, a higher risk of bleeding and long operative times for large glands still limit the practicality of this technique.^4,5 Additionally, with the rising efficacy of drug therapy, surgical treatment is postponed. More and more patients with larger prostates appear at the point of treatment, and, thus, the new surgical treatment is necessary to meet this challenge.

The 2-μm (thulium) laser is a new surgical laser with a wavelength tunable from 1.75 to 2.22 μm, which can both precisely cut and vaporize biological tissue.⁶ In recent decades, it has been commonly used in transurethral prostate surgery with good hemostasis and without damaging surrounding structures. Several trials have shown that vaporesection of the prostate with BPH using a 2 μm laser system is an effective and safe procedure with encouraging surgical outcomes, and that it is therefore considered to be an alternative to PKRP.^7
–9 However, one criticism is that 50–66% of tissue will be lost for histologic evaluation because of vaporization during this procedure.^10,11 Furthermore, although the application of a 70 W laser has achieved a significant increase in the speed of this procedure,¹² a longer operation time will be still needed with this method compared with electroresection, especially in patients with large volume prostates, which may still require open simple prostatectomy or staged TURP.

Considering the advantages and disadvantages of PKRP and 2 μm laser, we designed a method of transurethral resection of the prostate using PKRP combined with 2 μm continuous wave laser. In our experience, this method can improve resection efficiency and reduce operation time, especially when treating BPH in a large prostate. The aim of the current study was to evaluate the feasibility and efficiency of this method for the treatment of BPH in large prostates (>80 mL), and to compare the results to PKRP alone as reference standards.

Patients and Methods

Patients

From October 2009 to June 2010, 120 BPH patients were randomized to surgical treatment with PKRP (n=62) or PKRP combined with 2 μm continuous wave laser vaporization (n=58).

Inclusion criteria included age <85 years, International Prostate Symptom Score (IPSS) >7, failure to respond to medical therapy, maximum urinary flow rate (Qmax) ≤15 mL/sec and transrectal ultrasound (TRUS) adenoma volume ≥80 mL. Patients with a neurogenic bladder and any urethral, bladder neck, or prostatic surgery were excluded.

After a routine physical examination and digital rectal examination (DRE), all patients were evaluated preoperatively by scoring subjective symptoms with the IPSS and quality of life score (QoLs); laboratory analysis with total serum prostate-specific antigen (PSA); and TRUS measurement of prostate volume, postvoid residual (PVR) urine volume and Qmax. All patients with abnormal PSA levels or DREs or with TRUS abnormalities underwent ultrasound-guided prostatic biopsy using the six-core biopsy protocol, and any cases of prostate cancer were excluded from this series. The study was approved by the hospital Institutional Review Board and all patients gave written, informed consent to participate.

Instruments and surgical techniques

The 2 μm continuous-wave thulium laser (RevoLix) was used for vaporesection with the 2 μm continuous wave as an active ion at a power level of 70 W, incorporating an end-firing optical fiber. The Gyrus Plasmakinetic SuperPulse System (consisting of a PK generator, a PK resectoscope, and a PlasmaSect electrode) with continuous flow irrigation and television monitoring system were used. Normal saline was used for all irrigation at room temperature.

All surgical procedures were completed by experienced surgeons, with the patient under epidural anesthesia and receiving preoperative antibiotics. The patient was placed in a lithotomic position and received a temporarily suprapubic catheter for better irrigation and a clear visual field. After the insertion of a continuous 24 F resectoscope through the urethra into the urinary bladder, the ureteral orifices, the verumontanum, and the prostatic adenoma were visualized. Afterward, three longitudinal grooves were first made deep into the prostatic capsule by the 2 μm continuous wave laser vaporesection of the prostatic tissue at the 5:00, 7:00, and 12:00 positions, from the bladder neck to the level of the verumontanum. As a result, the whole prostate was divided into three independent major parts, the median, the left, and the right. Next, each prostatic subdivision was treated by PKRP, which was performed with the use of a standard tungsten wire loop with a cutting current of 160 W and a coagulating current of 80 W. After resecting the middle lobe of the prostate, the resection of the lateral lobes was continued from the bladder neck to the level of the verumontanum close to the prostatic capsule. Finally, the 2 μm continuous wave laser was used to vaporize the remaining prostate tissue until the prostatic capsule was reached. Because of the good hemostatic properties of the thulium laser, even heavy arterial bleeding was handled easily. The use of normal saline for irrigation excludes the risk of a TUR syndrome.

At the end of both procedures, the resected tissue chips were removed and investigated histologically. A 22 F triple lumen catheter was inserted into the bladder, the balloon was inflated within the bladder according to the estimated sum of resected plus vaporized adenoma tissue, and the irrigation was started until hematuria had sufficiently decreased.

Assessment

Assessed outcomes included the operative time, resected tissue weight (actual weight of tissue retrieved), hemoglobin decrease, blood transfusion rate, postoperative catheterization time, and postoperative hospital day in the two groups. Catheters were removed when hematuria had settled sufficiently. Postoperatively in the two groups, the improvements in IPSS, QoLs, Qmax and PVR volume were evaluated at 3, 6, and 9 months. All perioperative and postoperative complications were recorded.

Statistical analysis

The baseline characteristics and perioperative data were statistically analyzed with the Student t test and presented as the mean±standard deviation (SD). The two-tailed χ² test was used to compare the postoperative adverse events. Statistical analysis was performed with Statistical Package for Social Sciences, version 12.0 for Windows analytical software. Statistical significance was considered at p<0.05 for all analyses.

Results

All procedures were successfully performed with the patient under epidural anesthesia. The baseline characteristics and perioperative results are summarized in Table 1. There were no statistical differences in the preoperative parameters between the two groups. During the operation, the surgical view was clearer in the PKRP + 2 μm laser group. Although the mean resected tissue weight in the PKRP + 2 μm laser group was less than that in the PKRP group (69±15.6 vs. 74±13.1 g), there was no significant difference between them (p=0.06). The average decrease in hemoglobin was significantly lower in the PKRP+2 μm laser group than in the PKRP group (1.4±0. 9 vs. 1.8±0. 7 g/dL, p=0.001). Similarly, significant difference was also found in the mean operative time, irrigation time, catheterization time and total hospital stay.

Table 1.

Summary of Baseline Characteristics and Perioperative Data for the Study Population (Mean±SD)

	PKRP	PKRP+2 μm laser	p Value
No. of patients	62	58
Age (years)	69±9.5	70±8.8	0.55
PSA (ng/mL)	2.2±1.2	2.4±1.6	0.47
TRUS vol (mL)	105.2±17.5	107.3±16.5	0.50
Operative time (min)	92.3±14.2	86.4±13.7	0.02
Resected weight (g)	74±13.1	69±15.6	0.06
Hemoglobin decrease (g/dL)	1.8±0.7	1.4±0. 9	0.01
Irrigation time (days)	3.9±1.3	1.0±0.5	<0.001
Catheterization time (days)	4.1±0.8	1.2±0.6	<0.001
Hospital stay (days)	7.6±2.9	4.2±1.3	<0.001

Results assessed statistically using the Student t test.

PKRP, plasmakinetic resection of the prostate; SD, standard deviation; PSA, prostate-specific antigen; TRUS, transrectal ultrasound.

All 120 patients completed the 9-month assessment. In comparison with baseline, there was highly significant improvement in each parameter at all intervals in each group. At the 3-, 6-, and 9-month follow-ups, we did not find any statistical difference between the two groups in IPSS, QoLs, Qmax, or PVR volume at any time (Table 2).

Table 2.

Follow-Up Data (Mean±SD)

Parameter	Preoperative	3 months postoperative	6 months postoperative	9 months postoperative
IPSS
PKRP+2 μm laser	25±4.7	8.1±3.3	11.4±4.5	5.8±2.9
PKRP	26±5.2	8.4±3.6	12.1±4.3	6.6±2.5
p Value	0.27	0.64	0.22	0.11
QOL
PKRP+2 μm laser	4.9±0.8	3.4±0.8	2.5±1.1	1.9±1.2
PKRP	4.7±1.1	3.3±1.0	2.7±0.9	1.7±1.4
p Value	0.29	0.56	0.28	0.40
Qmax (mL/sec)
PKRP+2 μm laser	6.0±1.9	17.2±3.9	18.5±5.3	17.6±4.2
PKRP	6.6±2.2	16.5±4.3	17.6±4.9	16.8±3.8
p Value	0.11	0.35	0.34	0.28
PVRU (mL)
PKRP+2 μm laser	132±33	23±8.0	28±7.6	22±8.1
PKRP	126±29	24±9.9	30±6.4	23±7.5
p Value	0.29	0.55	0.12	0.48

PKRP, plasmakinetic resection of the prostate; IPSS, International Prostate Symptom Score; QOL, quality of life; Qmax, peak flow rate; PVRU, post void residual urine.

The adverse events are listed in Table 3. Of the patients, no case of transurethral resection syndrome (TURS) was observed in either group. A secondary bleeding was seen in 10 patients (16.1%) in the PKRP group and in 2 patients (3.4%) in the PKRP + 2 μm laser group after removal of the catheters. These patients were treated with a repeat cystoscopy and one of them with PKRP + 2 μm laser required blood transfusion, whereas nine with PKRP did. Postoperatively 13 patients in the PKRP + 2 μm laser group and 20 patients in the PKRP group complained of some degree of urinary incontinence within the following months respectively. Three patients (5.2%) in the PKRP + 2 μm laser group and 11 patients (17.7%) in the PKRP group were diagnosed with urinary tract infection. The irritative symptoms released after the antibiotics were used. Of sexually active patients, retrograde ejaculation postoperatively was reported in 28 of 50 (56.0%) in the PKRP + 2 μm laser group and 35 of 57 (61.4%) in the PKRP group. At the 9-month follow-up, 3.4% patients in the PKRP + 2 μm laser group and 4.8% patients in the PKRP group developed urethral stricture. All these strictures required dilatation in the office without internal urethrotomies.

Table 3.

Number (%) of Patients Presenting with Complications

	PKRP+2 μm laser	PKRP	p Value
Secondary bleeding	2 (3.4%)	10 (16.1%)	0.03
Blood transfusion	1 (1.7%)	9 (14.5%)	0.02
Urinary tract infection	3 (5.2%)	11 (17.7%)	0.04
Transitory urge incontinence	13 (22.4%)	20 (32.3%)	0.31
Retrograde ejaculation	28 (56.0%)	35 (61.4%)	0.38
Urethral stricture	2 (3.4%)	3 (4.8%)	0.98

Results assessed statistically using the two-tailed×2 test.

PKRP, plasmakinetic resection of the prostate.

Discussion

Over the past decade, PKRP have been successfully introduced and widely used for the treatment of BPH. Compared with conventional TURP, PKRP has been accepted as a safer and more effective therapy for the surgical management of symptomatic BPH, and appears to be a new gold standard.^4,5 However, PKRP still has the potential risk of causing major complications. Especially for large prostates, the operation time is inevitably prolonged because of the small operating space and slow ablative properties of this technique, which may lead to a higher risk of bleeding and rising comorbidities.^5,13

Technological alternatives such as laser treatments may further minimize the risks of this procedure. In the past, several laser devices have been developed to treat BPH. Particularly green-light vaporisation (PVP) and holmium laser enucleation (HoLEP) have been studied intensively and represent valid clinical alternatives to PKRP.^14,15 However, both systems have limitations in terms of treatable prostate size or learning curve.^16,17 The 2 μm laser, a new type of surgical laser that appears to solve many of the limitations of both these devices, has been commonly used in recent decades.^6,7,11 First, the center wavelength of the laser is tunable between 1.75 and 2.22 mm, allowing the wavelength to exactly match the 1.92 mm water absorption peak in tissue. The high density of absorbed energy at the tissue surface leads to instant vaporization and limits the penetration depth to 500–2000 μm, a reasonable depth for sufficient homeostasis with minimal thermal injury to surrounding tissue.¹⁸ Unlike HoLEP, which is performed in a pulsed mode, the continuous-wave output of this laser allows smooth incision and vaporization of tissue with much better hemostasis.¹² Second, when compared with the quite popular potassium-titanyl phosphate (KTP) laser, the main advantage of the thulium laser is the retrieval of tissue for histology and a higher cost effectiveness resulting from lower acquisition costs and the repeated use of the laser fibers.¹⁹ Furthermore, the thulium laser is not only suitable for BPH, but also for other applications requiring precision cutting, such as bladder-neck contractures, urethral and ureteral strictures, and, possibly, lithotripsy.^20,21 With rising healthcare expenses throughout the world, the cost effectiveness and versatility of a tool is an important factor when it comes to making decisions about the routine implementation of new technology.

In the last decade, increasingly studies have shown that vaporesection of the prostate with BPH using a 2 μm laser system is an effective and safe procedure, even in patients with complications of refractory urinary retentions or hemorrhagic disorders. However, most of the literature reports only on treating small-to-medium prostates.^7

–10 The main criticism of this technique was the potential limitation to smaller prostatic glands because of the prolonged operation time with larger prostates.²² Although using the maximal output power of 70 W resulted in an approximately 1.5-fold increase in tissue removal compared with the 80 W KTP laser, a longer operation time is still needed by this method compared with PKRP, especially in patients with large prostates.^7,12

To deal with this problem, we developed this technique for resection of the prostate using the PKRP in combination with sparse use of 2 μm continuous wave laser. During this procedure, the 2 μm laser was first used to make three longitudinal grooves because it can give a more precise cutting performance, and coagulation of blood vessels was easily achieved by defocusing the laser beam, which could provide a clear view of the surgical site, allowing the surgeon to operate more freely and quickly.^23,24 Lastlty, resection with PKRP ensures the safety and efficiency of this technique as well as reducing the resection time and operative risk. In the final step, a combination use of the 2 μm continuous wave laser to vaporize the remaining prostate tissue, not only provides excellent hemostasis but also offers the ability to precisely incise and excise prostate tissue without uncontrolled tissue damage. In contrast to PKRP, the laser energy release at the layer of the surgical capsule is reduced to a minimum because of the strong absorption of the 2 μm wavelength in water. At the same time, because of the slightly shorter wavelength, the depth of shallow penetration is decreased to 0.25 mm and thermal coagulation is performed precisely at the area of bleeding vessels, rather than complete coagulation of the capsule being performed during dissection of the adenoma.^8,10,24 Therefore, the surgical capsule is always visible throughout the entire procedure and remains untouched.

In our present study, a shorter operating time was achieved in the PKRP+2 μm laser group. Surprisingly clear visions in the procedure made sure that the adenomatous tissue was precisely dissected off the surgical capsule of the prostate, having almost no adenomatous tissue residual. There was no significant difference in the mean resected tissue weight between both groups, and adequate tissue samples were available for histological examination in this procedure, but we will also note that the mean resected tissue weight in the PKRP+2 μm laser group was really less compared with PKRP and the p-value was 0.06 which is very close to our α level of 0.05. One explanation for these results is that more tissue might be vaporized in the PK+laser group than in pure PK group. As can be seen in our study, there was significant clinical improvement in all variables measured compared with baseline levels in both groups. However, no statistically significant disparities were identified between them in IPSS, QoLs, Qmax, or PVR at any time. These results suggested that this new technique can be performed safely and with similar efficacy to that of PKRP. Postoperatively, retrograde ejaculation was common in both groups and a certain degree of urethral stricture and urge incontinence was also recorded to be similar between them. However, the following reflect the superiority of this novel technique: less blood loss, high safety, and quick recovery. First, the decrease in hemoglobin was significantly lower than that of the group treated with PKRP only. Because the thulium laser wavelength is excellent for controlling bleeding intraoperatively, the secondary bleeding and blood transfusion postoperatively were also less frequent in the PKRP+2 μm laser group. Second, the urine was so clear postoperatively that less bladder irrigation was needed. Also, the catheters were removed 1–2 days postoperatively and the total hospital stay was decreased to 4–6 days. Third, the thulium laser was operating in a continuous wave (CW) mode, which allowed for smoother and more precise cutting. Therefore, it is suspected that there was significantly less urinary tract infection in the PKRP + 2 μm group than in the PKRP group. Fourth, saline irrigation was used intraoperatively, thus decreasing the risk of TURS.

Conclusions

PKRP combined with 2 μm laser vaporization, which has the advantages of both PKRP and 2 μm laser is superior to PKRP alone for its shorter operation time, less bleeding, slight perioperative morbidity and better efficacy. It seems to be a new method that is suited to the endoscopic treatment of BPH in large prostates. Although this technique has no advantages in terms of urethral stricture, retrograde ejaculation, and voiding function, the 9-month follow-up results are still encouraging. Future well-designed, randomized trials with extended follow-up and larger sample sizes may be needed to better define the role of this technique in treating patients with large prostates.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

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