L’effet de faible puissance sur l’énucléation de la prostate par laser holmium (HoLEP); Une étude comparative avec 12 mois de suivi

25 octobre 2020

Auteurs : E. Gazel, E. Kaya, S. Yalc?n, T. Tokas, H.C. Aybal, S. Y?lmaz, T.B. Aydogan, L. Tunc
Référence : Prog Urol, 2020, 12, 30, 632-638




 




Introduction


In the last two decades, a plethora of innovative transurethral procedures challenged the supremacy of the two, formerly standard, surgical options (monopolar transurethral resection of the prostate (TUR-P) and open prostatectomy [1]. To date, laser enucleation of the prostate has abrogated the indications of the open technique for large prostate glands. Holmium Laser Enucleation of the Prostate (HoLEP) has been established as a distinguished method between the different surgical treatment modalities, can be applied to all prostate sizes [2, 3, 4, 5] and shows similar effectivity with the Thulium laser [6, 7, 8]. when compared to TUR-P, the HoLEP provides better hemostasis, shorter catheterization and hospitalization times, and nullifies the rates of the TURP syndrome [4, 9].


The Holmium laser system allows the prostatic tissue to be enucleated from the capsule while providing simultaneous coagulation [10]. Depending on technological developments, laser technology has also made progress. Nonetheless, despite evolution of instrumentation and surgical technique, stress urinary incontinence (SUI) remains a great challenge. The new Holmium YAG laser device, with 120W laser energy, contains a dual foot pedal. This feature allows the surgeon to use two different settings. The low power energy is used for hemostasis and dissection of the prostatic apex, while the high-power energy is used for enucleation [11]. Various results have been reported in the international literature, by using different laser energy settings [11, 12, 13]. The initial installations of the Lumenis laser device are usually set at 50Hz-2J(100W) and 20Hz-1J (20W). In this work, we used low-power energy settings during the whole procedure, except near the bladder neck, where high-power settings can be used to facilitate enucleation. The aim of this study is to compare the effectiveness and safety of the Holmium laser, using two different low-energy settings, during enucleation and hemostasis (20W and 37.5W) in order to set a slightly higher energy threshold (37.5W) in order to increase enucleation efficiency and not compromising patient safety, mainly not increasing SUI rates.


Materials and methods


The study was designed retrospectively and was approved by the Scientific Research Ethics Committee of Gazi University (protocol no. 2017-297). Data were collected from 160 patients who underwent a HoLEP procedure for Benign Prostate Hyperplasia (BPH), between June 2015 and July 2017. Written informed consents were collected from all participants. The patients were divided into two groups, based on the Holmium laser 120-W holmium: YAG (yttrium aluminum garnet) energy settings. In Group 1 (20W), enucleation and hemostasis were performed in a setting of 20Hz and 1J. In Group 2 (37.5W) the settings were 25Hz and 1.5J. In both groups, the prostate tissue in the bladder neck and the enucleated tissue far away from the apex, as subjectively judged by the surgeon, were cut with a setting of 50Hz and 2J (100W). Pulse duration was long for low energy setting as hemostasis mode and short pulse duration was used for high energy setting as enucleation mode. All procedures were performed by a single expert surgeon. All patients underwent a 3-lobe technique as previously described [14]. The main clinical endpoint of our work is the enucleation efficacy parameters (translated in increase of Qmax and Qave) of the different laser settings, with secondary endpoints being the postoperative outcomes, QoL and complication rates. The inclusion criteria were as follows: inadequate response to medical therapy, peak urinary flow rate (Qmax) of <15mL/s, gross hematuria due to BPH, recurrent urinary tract infection, postvoid residual (PVR) volume of >150mL, or acute urinary retention. Patients with neurogenic bladder, prostate cancer, diabetes mellitus, anticoagulation therapy, bladder cancer, urethral stricture, and previous prostate surgeries, larger prostates (>120cc) as well as cases with missing data were excluded.


Patient characteristics included age, prostate-specific antigen (PSA) and prostate size. The prostate volume was evaluated by transrectal ultrasonography. Improvement of symptoms were evaluated by uroflowmetry parameters and symptom scores. International prostate symptom score (IPSS), quality of life (QoL), maximum flow rate (Qmax), average urinary flow rate (Qave), post voiding residual volume (PVR), voiding time (VT), time to maximum of voiding (MVT) were recorded pre- and postoperatively (at the time of discharge and at one, 3, and 12 months). Enucleation rates (ERs) were calculated by the ratio of the amount of tissue removed to the transitional zone size. Additional information, like enucleation time (ET), morcellation time (MT), total operation time (TOT), total laser energy (TLE), efficiency of laser (EL-joule/gram), efficiency of enucleation (EE-gram/min), decrease in hemoglobin, enucleated tissue weight (ETW), complication rate (CR), hospitalization time (HT), catheterization removal time (CRT) was recorded. Intraoperative, perioperative and late complications (in 3th and 12th months) were also recorded. For continence status, patients filled International Consultation on Incontinence Questionnaire short form.


Equipment


All procedures were performed using a 120-W holmium: YAG (yttrium aluminum garnet) laser (Versapulse, Lumenis Inc., Santa Clara, CA, USA), and a 550-nm end-firing fiber (SlimLineTM 550, Lumenis Inc.). The energy settings for each pedal were entered separately to the main computer prior to surgery. A continuous-flow 26F resectoscope (Karl Storz, Tubingen, Germany), a rigid nephroscope with a 5-mm working channel (Karl Storz), and a Versacut tissue morcellator (Lumenis Inc.) were also utilized. The power settings were, for the right pedal, 20 Watt (1J energy, 20Hz frequency) in Group 1, and 37.5 Watt (1.5J energy, 25Hz frequency) in Group 2. In both groups, power settings were set at 100 Watt (2J energy, 50Hz frequency, and short-500μs pulse width combination) in the left pedal.


Statistical analysis


The Statistical Package for Social Sciences 20.0 software (SPSS 20.0, Chicago, IL, USA) was utilized. The Kolmogorov-Smirnov, Kurtosis, and Skewness Tests were used to assess the normality of the data. Descriptive statistics of nominal samples were expressed with numbers and percentiles. Descriptive statistics of scale samples were expressed as mean±standard deviation. The continuous variables were compared using independent samples t -test or Mann-Whitney U-test. Categorical data were compared using the Chi2 or Fisher's Exact test. Spearman correlation coefficient was used to explore the relationship between the continuous variables including the energy settings and the EE, ER, ET, TLE and EL. P <0.05 value was considered statistically significant.


Results


Two groups of 80 patients each were demonstrated (Table 1). Their mean age was 63±7.97 years in group 1 and 62±7.07 years in group 2. There was no significant difference between most characteristics of the two groups, including PSA, prostate volume, IPSS scores, and uroflowmetry parameters. Nevertheless, PVR was lower in Group 1 (102 vs. 173ml-P :0.01). In both groups, postoperative IPSS, QoL, PVR, MVT, and VT significantly decreased while Qmax and Qave significantly increased postoperatively in comparison to their preoperative status (Table 2). This improvement could be recorded in all follow up periods (discharge, 1st, 3rd and 12th month). Nonetheless, by comparing the different groups, QoL was significantly better in the 2nd (37.5W) group (p: 0.015), beginning direct postoperatively. Additionally, IPSS was also significantly better in the 2nd group, beginning 1 month postoperatively (p :0.001)


By comparing the mean CRT (27 vs. 42hrs-P :0.008) and Hb decrease (0.5 vs. 0.6g/dl-P :0.019) a statistically significant difference in favor of group 2 could be recorded. There were no significant differences regarding hospitalization time (Table 3). The mean EE was significantly higher (P :0.001) in group 2 (1.2g/min) compared with group 1 (0.78g/min). The mean ER and EL were significantly higher (P :0.001 and P :0.003) in group 2 (0.88% and 2.12 joule/g) than in group 1 (0.64% and 2.07joule/g). Additionally, the mean of ER, TLE, EL, EE and ET were significantly different with Pearson correlation test (P :0.001) (Figure 1). In the spearman analysis, two groups positively correlated with EE (rho=0.248, P =0.04), ER (rho=0.394, P =0.001), TLE (rho=0.235, P =0.004), LE (rho=0.251, P =0.002), No correlations were identified between the laser energy settings and ET. Finally, the ET was shorter in Group 2 than in Group 1 (54 vs. 75.5 mins-P :0.002). In terms of ETW, MT, TOT, TLE, there were no significant differences (Table 4). Finally, there was no significant difference between the groups according to the Clavien-Dindo Complication Classification (Table 5).


Figure 1
Figure 1. 

Correlations of the enucleation parameters, total laser energy and efficiency of laser between groups.





Discussion


Since the first pioneering studies [15, 16], the HoLEP procedure has evolved alongside other advances in urological technology [2, 3, 4, 5]. Most existing studies recommend a high laser energy (>80W) during the whole procedure, applied by utilizing a single pedal [12, 17, 18]. However, although, in that way, a fast enucleation can be achieved, irritative symptoms frequently remain, also after 12 months [17]. The first work about the safety and efficacy of a 50W holmium laser was presented by Rassweiller et al in 2008 [19]. The authors recruited two groups of patients treated at power settings of 25W and 40W, and recorded comparable enucleation efficiency with our cohort. However, their transfusion rate was relatively high, reaching 8%. Following studies proved the feasibility of the low energy power set (30-40W), presenting excellent enucleation and minimal complication rates [12, 13]. Our preoperative, postoperative results, and complication rates are comparable with the aforementioned studies.


One recent improvement in in HoLEP surgery is the use of a 120W laser (Lumenis Pulse; Lumenis Ltd) [14]. It allows the user to change between two different setups by utilizing a dual pedal without the need for a manual changeover [2]. The low energy setting is usually preferred for hemostasis and dissecting near the apex of the prostate, while the high energy setting is used for enucleation [2]. In this patient cohort, the high energy setting was applied to cut the prostatic tissue at the bladder neck level. The rest of the enucleation, as well as the hemostasis, were processed by using the low energy settings. In this way, we could achieve comparable enucleation efficiency and procedure times with the already published ones [13, 20], and at the same time preserve optimal hemostasis and minimize complications, including irritative symptoms and stress urinary incontinence (SUI). By slightly increasing energy to 37.5W, we could achieve improved enucleation efficiency not compromizing patient safety. Gong and colleagues [21] used an energy of 30W for the apical incision and presented a mean IPSS score decrease from 21.9 to 4.3, three months after the procedures. At the same time, their Qmax increased from 4.7ml/sec to 23.4ml/sec and their PVR dropped from 146.3ml to 28.1ml. Their mean operative time was 54.7minutes and mean enucleation time 36.5minutes. Our study demonstrates comparable outcomes and goes one step further regarding apical dissection energy, by comparing two different low-power enucleation settings (20W vs. 37.5W). The majority of our patients had a prostate volume range of 60-80mL, an IPSS score range of 22-25, a Qmax range of 8.47-10.1mL/s, and a PVR range of 102-173mL. Our results emphasize that better hemostasis can be accomplished at frequencies above 20Hz.


In both groups, voiding parameters including Qmax, Qave, IPSS, QoL, VT, MVT significantly improved starting direct postoperatively. There was a significant difference in favor of the 2nd group when assessing postoperative QoL and IPSS. Furthermore, decrease in hemoglobin was lower, and CRT was shorter in group 2. Our postoperative outcomes appear to be better than the results of a study using the 100W holmium laser [22]. Another cohort of 231 patients demonstrated similar results with our group, in terms of IPSS, Qmax, PVR, HT and CRT [23]. Stern el al reported HoLEP procedures utilizing a 120W laser platform. Their laser settings were 80W for enucleation and 45W for apex dissection and hemostasis. The authors reported a higher decrease of Hb compared with our study. On the other hand, EE was 0,84g per minute which is slightly lower (1,2g per minute) than the one presented by our group [11]. According to our results, the use of 37W setting seems to provide a lower hemoglobin decrease and a shorter removal of the urethral catheter. According to enucleation parameters, the results of Group 2 were better than Group 1. Although ETW was similar between the groups, EE, ER, ET were higher in Group 2. Thus, enucleation and hemostasis can be performed more effectively and rapidly by applying the 1.5J and 25Hz energy settings. TLE and EL were more efficient in Group 2. We report higher enucleation and laser efficiency, as well as increased enucleation rates when using the 37.5W, compared to the 20W setting.


In comparison with already published works, a lower perioperative and postoperative complication rate could be reported. No transfusions were necessary for both groups. One of the challenging complications of the HoLEP procedure is the postoperative stress urinary incontinence (SIU), ranging 2-15% and being, however, often a temporary condition [24, 25, 26]. This situation is based on two factors; excessive urethral sphincter traction during the procedure and tissue damage caused by laser energy near the apex of the prostate. The low energy use for the adenoma near the urethral sphincter can reduce likelihood SIU. Our postoperative SIU rates were similar in both 20W and 37.5W energy settings and compatible with the international literature (3.7% and 2.5%). Additionally, bladder neck contracture, urethral stricture and meatal stenosis rates were also similar between the two groups.


Our study is not without limitations, namely its retrospective character and the lack of a control group. Moreover larger prostates (>120cc) were not included. An additional confounder could be the subjective switch to the high-power setting when enucleating away from the apex. However, our results presented strong evidence regarding a HoLEP dual-energy mode that provides efficient and fast enucleation, and, at the same time, optimal hemostasis and significant improvement of symptoms related to prostatic hyperplasia.


Conclusion


The new 120 H Holmium laser can be used efficiently utilizing the 100 W-37.5W settings. With the use of 37. 5W, both enucleation and hemostasis can be performed successfully, while the use of 100W in the bladder neck shortens the duration of the procedure. The use of laser energy with>35W may be recommended in HoLEP procedure.


Funding


No funding was received for this study.



Acknowledgement


All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the Helsinki declaration and comparable ethical standards.

Disclosure of interest

The authors declare that they have no competing interest.




Table 1 - Patients' baseline characteristics and preoperative data.
Variable  Group 1 (N:80)  Group 2 (N: 80)  P -Value 
Patient age(year)  63±7.97  62±7.07  0.28 
PSA (ng/mL)  3.22±5.02  1.27±0.17  0.84 
Hb level (g/dL)a  14.65±1.04  14.25±0.21  0.12 
Prostate Volume (mL)  79±35.71  68.5±47.37  0.32 
IPSS  25.68±5.77  21.08±5.27  0.33 
QoL  4±1.09  4 4±0.57  0.81 
Qmax(ml/s)a  10.39±4.21  9.05±5.71  0.07 
Qave(ml/s)  4.4±1.86  3.2±2.38  0.08 
PVR (ml)  105±51.12  154±124.3  0.001 
VT (sec)  128±77.15  82.65±55.16  0.63 
MVT (sec)  72±35.16  11.5±10.95 



Légende :
N: number of patients; PSA: Prostate Specific Antigen; Hb: Hemoglobin; IPSS: International Prostate Symptom Score; OoL: Quality of Life; Qmax: Maximum flow rate; Qave: Average urinary flow rate; PVR: Post Voiding Residual Volume; VT: voiding time; MVT: Time to maximum of voiding Sec: second

[a] 
Statistically analyzed with Independent Samples t -test; Others analyzed with Mann-Whitney U test.


Table 2 - Baseline and follow up datas.
Parameters 
Mean±SD 
  IPSS  QoL  Qmax(ml/s)  Qave(ml/s)  PVR (ml)  VT (sec)  MVT (sec) 
Preoperative               
Group 1  25.68±5.77a  4±1.09  10.39±4.21a  4.4±1.86  105±51.12  128±77.15  72±35.16 
Group 2  21.08±5.27a  4±0.57  9.05±5.71a  3.2±2.38  154±124.3  82.65±55.16  11.5±10.95 
P -value  0.33  0.81  0.07  0.08  0.001  0.63 
Discharge               
Group 1  15±3.52b  4±0.99b  13±4.81b  9±3.32b  35±22.59b  35.1±29.96b  28±14.32b 
Group 2  14±3.4b  4±0.92b  14±9.08b  10±5.72b  32±27.54b  44±30.35b  24±18.71b 
P -value  0.08  0.015  0.65  0.15  0.23  0.65  0.39 
1th month               
Group 1  12.5±2.77b  2±0.58b  20±7.11b  14±5.09b  27±17.04b  32±23.49b  25±13.17b 
Group 2  11±2,59b  2±0.6b  22.5±11.99b  16±7.76b  24±23.48b  44±30.35b  22±19.81b 
P -value  0.001  0.04  0.25  0.26  0.09  0.19  0.37 
3th month               
Group 1  3±0.86b  1±0.55b  27.09±7.28a,b, tblfn0015  10.85±4.57b  24±23.38b  28.5±9.62b  10.3±4.03b 
Group 2  1±0,99b  1±0.48b  28.09±7.22a,b, tblfn0015  13.6±4.18b  12±11.02b  30±18.63b  4.88b 
P -value  0.001  0.03  0.46  0.02  0.34  0.4  0.79 
12th month               
Group 1  3±0.67b  1±0.5b  27±7.25b  17±4.88b  22±21.05b  25±8.62b  11±4.1b 
Group 2  1±0,96b  1±0.44b  28±6.65b  17±5.6b  20±19.02b  25±14.77b  5.19b 
P -value  0.001  0.06  0.74  0.18  0.29  0.65  0.96 



Légende :
N: number of patients; IPSS: International Prostate Symptom Score; OoL: Quality of Life; Qmax: Maximum flow rate; Qave: Average urinary flow rate; PVR: Post Voiding Residual Volume; VT: Voiding time; MVT: Time to maximum of voiding; Sec: Second.

[a] 
Statistically analyzed with Paired Samples t-test; Others analyzed with Wilcoxon test.
[b] 
P <0.01 compared to baseline.


Table 3 - Patients'comparison of postoperative outcomes.
  Group 1 (N :80)  Group 2 (N :80)  P -value 
Hb decrease (g/dl) Catheterization removal  0.6±0.39  0.5±0.1  0.019 
Time (hour)  42±27.74  27±14.38  0.008 
Hospitalization time (hour)  28±6.06  33±8.03  0.16 



Légende :
* Statistically analyzed with Mann-Whitney U-test. N: number of patients.



Table 4 - Comparison of perioperative outcomes between groups.
  Group 1 (N : 80)  Group 2 (N : 80)  P -Value 
Enuclated tissue weight (g)a  54,16±43,56  58,3 ±57,33  0,49 
Efficiency of enucleation (g/min)  0.78±0.35  1.2±0.56  0.032 
Enucleation rate (%)  0.64±0.27  0.88±0.5  0.001 
Enucleation time (min)  75.5±35  54±29.73  0.002 
Morcelation time (min)  8±5.68  7.5±6.88  0,07 
Total operation time (min  78±38.17  66±35.15  0.09 
Total laser energy (joule)  57.12±47.14  74.2±44.88  0.004 
Efficiency of laser (joule/g)  1.78±0.62  2.23±1.28  0.003 



Légende :
N: number of patients; g: gram; min: minute.

[a] 
Statistically analyzed with Independent Samples t-test; Others analyzed with Mann-Whitney U-test.


Table 5 - Detailed analysis of complications.
Intraoperative and perioperative complications  Group 1 n (%)  Group 2 n (%)  P -value 
Bleeding   
Bladder mucosal injury  1(1.25)  1(1.25) 
Capsular perforation 
Conversion to TUR-P   
Transfusion   
TUR syndrome   
Recatheterisation  3(3.7)  2(2.5)  0.97 
Clot retention  2(2.5)  1(1.25)  0.99 
Secondary haemorrhage   
Urosepsis   
Urinary tract infection  2(2.5)  3(3.7)  0.97 
Fever  2(2.5)  3(3.7)  0.97 
Late postoperative complications (3th/12th mo)       
Stress Urinary Incontinence  3(3.7)/1(1.2)  2(2.5)/0  0.97/0.95 
Bladder neck contracture  3(3.7)/2(2.5)  4(5)/2(2.5)  0.97/1 
Urethral stricture  4(5)/0  4(5)/1(1.2)  1/0.95 
Meatal stenosis  3(3.7)/0  4(5)/0  0.07/1 
Reoperation for residual adenoma  0/0  0/0 




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