Anssi Petas

Biodegradable self-reinforced polyglycolic acid spiral stent in prevention of postoperative urinary retention after visual laser ablation of the prostate-laser prostatectomy

PURPOSE The efficacy and safety of a new biodegradable (self-reinforced polyglycolic acid) spiral stent in securing free voiding despite edema after visual laser ablation of the prostate were studied. MATERIALS AND METHODS A biodegradable spiral stent was inserted into the prostatic urethra in 22 patients immediately after visual laser ablation of the prostate. Uroflowmetry, measurement of residual urine volume, urine culture, cystoscopy and assessment of symptomatic improvement were done before, and 1, 3 and 6 months after visual laser ablation of the prostate. RESULTS All 22 patients voided freely on day 1 or 2 after visual laser ablation of the prostate. However, 4 patients later had urinary retention due to a short spiral or too rapid spiral degradation. Half of the patients experienced a transient decrease in flow with some obstructive symptoms at 3 weeks that lasted 1 to 2 weeks. At 4 weeks all spirals were degraded and 3 patients had a positive urine culture. The maximum flow rate increased and the residual urine volume decreased significantly concomitantly with significant symptomatic improvement. CONCLUSIONS The self-reinforced polyglycolic acid spiral stent can effectively and safely prevent postoperative urinary retention after visual laser ablation of the prostate.

A Randomized Study to Compare Biodegradable Self-reinforced Polyglycolic Acid Spiral Stents to Suprapubic and Indwelling Catheters After Visual Laser Ablation of the Prostate

PURPOSE A randomized controlled study was done to evaluate the efficacy of the self-reinforced polyglycolic acid spiral stent compared to a suprapubic catheter, and combined suprapubic and indwelling catheters in the prevention of urinary retention after visual laser ablation of the prostate. MATERIALS AND METHODS We studied 72 men with benign prostatic hyperplasia who underwent placement of a suprapubic catheter and visual laser ablation of the prostate. In 27 men in group 1 the self-reinforced polyglycolic acid spiral stent was inserted into the prostatic urethra after visual laser ablation of the prostate, while 23 in group 2 received no other devices. In 22 men in group 3 an indwelling catheter was left in situ for an average of 6.5 days. RESULTS Voiding began 1 or 2 days postoperatively in 20 of 27 patients (median 1 day) in group 1, and 8 of 23 (median 6 days) in group 2. In 16 of 22 men in group 3 voiding began 1 or 2 days (median 6) after removal of the indwelling catheter. Improvements in patient weighted symptom score, mean peak urinary flow rate and post-void residual volume were significant (p < 0.001) at 6 months of followup in all groups. The overall infection rate was 30%. CONCLUSIONS The self-reinforced polyglycolic acid spiral stent is superior to the suprapubic catheter alone, and to combined indwelling and suprapubic catheters for the treatment of postoperative urinary retention after laser therapy, offering possibilities for shorter catheterization time.

A randomised study to evaluate the efficacy of a biodegradable stent in the prevention of postoperative urinary retention after interstitial laser coagulation of the prostate.

Objective: Interstitial laser coagulation (ILC) of the prostate induces necrosis, oedema and increased risk for postoperative urinary retention. The present randomized study was carried out to investigate the feasibility and efficacy of a biodegradable self-reinforced polyglycolic acid (SR-PGA) stent in preventing postoperative urinary retention and the need for prolonged catheterization after ILC treatment. Material and methods: 35 males with benign prostatic enlargement (BPE) entered the study: 21 in the ILC + stent group and 14 in the ILC group without a stent. A suprapubic catheter was inserted for all patients and ILC was performed. The SR-PGA stent was inserted immediately after laser therapy in the stent group and kept open until the next morning when it was closed and the patient started trying to void. The suprapubic catheter was removed after voiding had started and the urinary bladder emptied adequately. Results: In the ILC + stent group voiding started on the first postoperative day in 17 patients and on the second day in 2 patients. Voiding was delayed in 2 cases: in 1 case due to inadequate length of the stent and in the other as a result of the stent placement being too proximal. There was 1 case of urinary retention due to early degradation of the stent. In the ILC-only group voiding started on average 6.1 days postoperatively. At 1 month follow-up, the mean peak urinary flow rate had increased significantly in the ILC + stent group (p < 0.05) but not in the ILC-only group (p = 0.26). Improvements in symptom scores were significant in both groups (p < 0.005) but in terms of the mean peak urinary flow rates at 6 months follow-up the improvement was significant only in the stent group (p < 0.05). Conclusions: The use of a SR-PGA stent enabled early voiding and is safe and effective in the treatment of postoperative urinary retention after ILC. The 3-4 week degradation time of the SR-PGA stent was too short for some patients. There is still a need for further development work to improve the stents and larger controlled studies to show the true value of biodegradable stents in the treatment of BPE.

Bacterial adherence to self-reinforced polyglycolic acid and self-reinforced polylactic acid 96 urological spiral stents in vitro

The aim of this study was to evaluate the bacterial adherence to biodegradable self-reinforced polyglycolic acid (SR-PGA) and self-reinforced poly-DL-lactic acid (SR-PLA 96) spiral stents in vitro. They are used as temporary urethral stents in urology. Gold-plated metal wire, polyurethane and latex were used as controls. Materials were incubated up to 28 days in artificial urine, after which a bacterial suspension was added. After detaching by sonication the adhesive bacteria were analysed as colony forming units (CFUs) and by scanning electron microscopy (SEM) analysis. Adhesion was more significantly correlated to stent bacterial type than to the tested material in both assays. No encrustation was seen on SR-PGA or SR-PLA 96. SR-PGA and SR-PLA 96 had no effect on the bacterial growth. In conclusion, the bacterial properties are equally or more important than the material properties in the adhesion process.

Viscoelastic memory and self-expansion of self-reinforced bioabsorbable stents

The possibility to decide the speed and rate of expansion of stents is of great clinical importance by reason of the varying requirements for different indications to use stents. Self-reinforced bioabsorbable stents can be made self-expanding owing to the viscoelastic memory of the material. Stents are stable at room temperature and expansion occurs at body temperature. The level at which the expansion stops depends on the material, crystallinity, initial diameter of spira and annealing temperature. The expansion rate can be estimated by logarithmic equation, if material, draw ratio and diameter of stent wire are constant. This is, however, possible only if processing parameters are constant. Based on the present results annealing temperature and expansion time were seen to be directly proportional to the expansion rate of the stent.

Dabigatran for thromboprophylaxis after robotic assisted laparoscopic prostatectomy: Retrospective analysis of safety profile and effect on blood coagulation

Abstract Objective. The aims of this study were to analyse the efficacy and safety of orally administered dabigatran in prostate cancer patients who have undergone robotic assisted laparoscopic prostatectomy (RALP) and to analyse the effects of RALP on selected markers of coagulation activity. Material and methods. Data were collected prospectively on the first 400 patients who underwent RALP at Helsinki University Central Hospital between 2009 and 2011. As thromboprophylaxis, intermittent compression devices were used in association with anaesthesia. Dalteparin sodium at 2500 IU was administered on the preoperative evening and at 5000 IU daily until discharge. Then patients were prescribed 220 mg dabigatran etexilate once daily for the next 15 days. Bleeding and thromboembolic complications were recorded. A set of routine coagulation analyses was undertaken in 61 patients preoperatively, on the first, second and eight postoperative days. Results. One patient with obesity- and cancer-related risk factors developed venous thromboembolism 18 days after the operation. Nine patients (2.3%) had postoperative blood loss or bleeds, eight patients required blood transfusions and three underwent reoperation before dabigatran administration. Increased fibrinogen, factor VIII, d-dimer and thrombocytosis were observed postoperatively, reflecting coagulation activity. Conclusions. RALP activates coagulation, and thromboprophylaxis for high-risk patients even after minimally invasive surgery may be beneficial. Orally administered dabigatran after discharge from hospital appears safe for venous thromboembolism prophylaxis after RALP.

Performance of transrectal prostate biopsies in detecting tumours and implications for focal therapy

Abstract Objective. The aim of this study was to investigate the performance of transrectal biopsies in predicting pathological outcomes after radical prostatectomy (RP) and in estimating possible candidates for focal therapies. Material and methods. The study was a retrospective analysis of 96 prostate cancer patients treated by robot-assisted laparoscopic RP at Helsinki University Central Hospital in 2009–2010. Data from diagnostic biopsies were compared with data from reassessment of RP slides. At reanalysis, an index tumour was chosen for all patients and was determined as being the most dedifferentiated tumour or the largest tumour with Gleason pattern 3 in case Gleason patterns 4 or 5 were absent. The performance of prostate biopsies in predicting cancer laterality, tumour size and tumour location was analysed. Statistical methods included Spearman’s correlation, linear regression analysis and Pearson’s chi-squared test. Suitability for focal therapies was assessed based on tumour morphology and laterality. Results. The extent of cancer in biopsies correlated with tumour size in the apex and middle of the prostate [standard coefficients in linear regression for the apex 2.479–2.553, 95% confidence interval (CI) 1.952–3.056, p < 0.001–0.007; and for the middle 1.936–2.388, 95% CI 1.504–2.861, p < 0.001]. Prostate biopsies performed moderately in predicting tumour location in RP slides (positive predictive value 34.1–90.9%). Thirty-six patients (37.5%) would possibly have been candidates for focal therapy and thirty-nine (40.6%) patients for hemiablation. Conclusions. Contemporary transrectal prostate biopsies are a suboptimal tool for predicting pathological findings at RP. Approximately 40% of patients would possibly have been suitable candidates for focal or hemiablative therapies.

Initiation of robot-assisted radical prostatectomies in Finland: Impact on centralization and quality of care

Abstract Objective The aim of this study was to analyze the impact of introduction of robot-assisted prostate surgery and its quality measures in Finland from 2008 to 2012. Materials and methods Registry data were collected for time trends and national distribution of prostate cancer surgery in Finland, while preoperative, operative and follow-up data were collected for quality measures. Results The number and proportion of robot-assisted laparoscopic radical prostatectomies (RALPs) increased rapidly and they accounted for 68% of all radical prostatectomies in 2012. The number of centers performing prostatectomies diminished from 25 to 20 at the expense of low-volume centers. In total, 1996 patients were operated on in the four RALP centers in 2008–2012. As anticipated, the learning curve was uniform between the centers, as were mean blood loss (212 ml), hospitalization (1.8 days) and catheterization times (10.6 days). At 3 and 12 months, 49.4% and 71.2% of patients, respectively, were totally continent (no pads). After unilateral nerve-sparing surgery, 9.9% and 5.1% had partial or normal erection at 3 months postoperatively and 14.8% and 20.4% at 12 months, respectively. If bilateral nerve sparing was done, the figures were 13.0% and 13.5% at 3 months and 14.6% and 34.9% at 12 months. Clavien–Dindo grade 3, 4 or 5 complications were seen in 0.3%, 0.3% and 0.1% of patients, respectively. Limitations of the study include non-standardized collection of outcome parameters. Conclusions This report shows that the main impact of adoption of RALP on a national level was rapid spontaneous centralization of prostate cancer surgery. The main advantages of minimally invasive prostatectomy, i.e. low blood loss and short hospitalization, are easily achieved, while continuous effort is necessary for improvements in surgical outcomes.