REVIEW

 

Lasers in Urology

 

Vicente-Rodríguez J*, Fernández-González I**, Hernández-Fernández C***, Santos García-Vaquero I****, Rosales-Bordes A*

 

* Puigvert Foundation (Barcelona), ** Princesa Hospital (Madrid), *** Gregorio Marañón Hospital (Madrid), **** Carlos Haya Hospital (Málaga). Spain

 

Actas Urol Esp. 2006;30(9):879-895

 

 

The purpose of this “opinion paper” is to report the text, concepts and iconography presented on occasion of the round table: “Lasers in Urology today”, held on January 18, 2006, in El Escorial, in the course of the 28^th Meeting of the Group on Lithiasis, Endoscopy and Laparoscopy. A subject - laser therapy - common to the three sections of the Working Group, guided the round table and is contemplated in the present article: Introduction (and conclusions) on Lasers in Urology Yesterday, summarized by the coordinator: J. Vicente; Usefulness of the holmium laser in lithiasis, tumors and stenoses in Urology: I. Fernández-González; Innovations in the laser treatment of benign prostate hyperplasia: KTP (green laser) by C. Hernández and holmium laser by I. Santos; and Role of the laser in laparoscopic surgery: A. Rosales.

In the course of the round table, and also in the present article, a presentation has been made of the prevalently accepted critical concepts and current criteria in relation to the practical usefulness of lasers in urological practice.

 

LASERS IN UROLOGY YESTERDAY

Lasers and lithotripsy

J. Vicente

In situ lithotripsy proved a priority consideration both before and after the introduction of extracorporeal shockwave lithotripsy (ESWL). The indications and techniques have varied in parallel to development of the endoscopic instrumentation and energy sources.

Electrohydraulic lithotripsy, effective but aggressive, was surpassed by ultrasound lithotripsy with synergic lithotripsic - aspiration capacity, of use in application to soft or semihard ureterorenal stones. Pneumatic lithotripsy, as well as the summative techniques: electrokinetic lithotripsy and the Lithoclast Master, have afforded excellent results (with success rates in the order of 90%), in application to most calculi, regardless of their hardness or location¹.

All these in situ lithotripsy procedures are carried out with conventional endoscopic equipment. The introduction of laser lithotripsy, using very subtle fibers (200-600 nm i) facilitated the following:

- The development of reduced caliber and semirigid or flexible instruments (miniscope, miniper, etc.).

- Reduction of the incidence of parietal lesions and iatrogenic stenoses.

- Access to, and the solution of, calculi in difficult locations (caliceal, lumbar ureter, etc.).

The essential characteristics of the different lasers are shown in Table 1. Lasertripsy with the Nd-YAG laser, involving complex equipment and easy alteration of the laser fiber, was displaced by the more compact monitorized alexandrite laser, though the latter system was characterized by poorer transmission and easy fiber wear. We obtained satisfactory results and minimum complications with the Candela Dye Laser, though maintenance of the system proved delicate and expensive². All these forms of lasertripsy have been surpassed and replaced by the holmium (Ho or HoL) laser, of which mention will be made later on.

 

Table 1

Lasers and lithotripsy.

 

Laser in urological tumors

With the exception of the recently applied holmium laser, the laser treatment of urological tumors has fundamentally been carried out with the Nd-YAG laser (photocoagulation).

Such treatment in application to bladder tumors initially generated considerable enthusiasm, in the late 1980s (Beislan, Holfstetter, Malloy etc.). However, in the 1990s, both our group and other authors showed that photocoagulation (Nd-YAG laser) offers no clinical advantages in terms of disease relapse, or histological advantages in terms of bladder wall damage, when compared with conventional transurethral resection (TUR) (Vicente. Arch Esp Urol 1990)³.

Although involving fewer cases, a similar approach has been followed in the case of upper urinary tract tumors. Despite advantages in the treatment of ureteral tumors (smaller caliber ureteroscope, lesser risk of iatrogenic stenosis), photocoagulation as treatment for upper urinary tract tumors has not gained predominant acceptance within the urological community⁴.

Due to its affinity for hemoglobin, the Nd-YAG laser is very useful in application to intensely vascularized tumors or lesions: bladder hemangioma (Vicente. Urología 1990), bladder endometriosis (Vicente. Arch Esp Urol 1991), or interstitial/radical cystopathy (Vicente. Act Urol Esp 1990), etc.

 

Laser in stenotic disease

As can be seen in Table 2, neither photocoagulation with the Nd-YAG laser nor incision with the KTP or contact laser has significantly improved the results obtained with the traditional methods: the sole exception in this sense appears to be the holmium laser, which will be evaluated below.

 

Table 2

Lasers and urological stenoses.

 

In the late 1980s and early 1990s, a number of authors (Smith, Dixon, Hubert, etc.) advocated the association of urethrotomy to photocoagulation of the urethrotomy area. Despite the good initial results, both our group⁵ and other authors (Gurdal. J Endourol 2003) confirmed that there were no differences in results with respect to isolated urethrotomy. Similar results were obtained on comparing cold incision versus KTP-532⁶.

In ureteral stenoses, balloon dilatation is only indicated in application to stenoses of under 2 cm, and in post-renal transplant stenoses - affording a success rate of 30-60%.

Incision (cold section, electric, Acucise) is indicated in benign ureteral stenoses (e.g., postsurgical stenoses), in those measuring over 2 cm, in cases where vascular impairment is suspected, and in most ureterointestinal stenoses - since in such situations the success rate is improved and maintained (50-70%).Incision with the contact or KTP-532 laser slightly improves these results (55‑70%), though without significant differences, and without sufficient studies to allow the drawing of firm conclusions.

 

Lasers in benign prostate hyperplasia

Following the greatest literature projection and media diffusion, the greatest disappointment in urological practice has been the use of lasers as an alternative to prostate gland surgery. Nevertheless, at present, hope is again focusing on the new lasers (KTP-80 W, holmium), of which more will be commented later on.

Important cumulative efforts, with scientific rigor and critical evaluation^7-9, have shown the following (summarized in Tables 3 and 4):

 

Table 3

TURP and lasers: Results and durability.

 

 

Table 4

TURP and lasers: Morbidity.

 

- The lasers (VLAP, CL and Int L) afford a subjective response in the form of lessened symptoms, similar to that obtained with TUR.

- The objective response, i.e., a postoperative increase in urinary flow (Q max), is almost twice as great with TUR versus the lasers.

- The need for retreatment is twice as great (VLAP), more than twice as great (contact laser), and three times as great (interstitial laser) as in the case of TUR.

- Irritative symptoms are generally more accentuated with lasers, and are the cause of abandonment of the VLAP in clinical practice.

- The duration of postoperative urethral catheterization is 3-4 times longer than with endoscopic surgery, except in the case of the contact laser.

- Regional or general anesthesia, and hospital admission, are necessary, in the same way as with TUR.

- The most relevant complications: bleeding (need for transfusion), postoperative urethral stenosis, urinary incontinence and retrograde ejaculation are all more common with endoscopic surgery (TUR) than with any of the laser techniques.

Therefore, and as will be seen later on with the KTP and holmium lasers, the surgical management of benign prostate hyperplasia (BPH) tends to seek procedures that afford results in line with TURP, but with the limited complications afforded by lasers.

 

Lasers in laparoscopy

The “Yesterday” of lasers in urological laparoscopic surgery has been very brief, and its “Today” will be developed in the future.

In effect, the results of lasers in application to such surgery have been based on experimental studies, rather than on clinical experience.

- Lasers have been used as a complement to laparoscopy. In cases of stenosis of the pyeloureteral ostium (where the success rate reaches 89%), when the presence of a polar vessel is confirmed or suspected preoperatively, the ideal solution has been and remains laparoscopic surgery¹⁰. In the absence of a polar vessel, however, retrograde incision with laser is a competitive option with respect to the other endoscopic techniques.

- Laser as a “welding” instrument: this has been explored mainly in the experimental setting, with scant application to clinical practice, in partial nephrectomy and tumor resection combining the diode laser and albumin, and the argon laser with fibrin glue as tissue welding option¹¹.

- Laser as a “hemostatic” instrument in laparoscopy: coagulation with the interstitial laser or incision with the holmium laser causes lesser bleeding¹².

 

LASERS IN ENDOUROLOGY TODAY

Holmium lasers and lithotripsy

Dr. Inmaculada Fernández-González

 

The holmium-YAG laser is the gold standard in laser lithotripsy. This is a solid, pulsed laser operating at a wavelength of 2120 nm, with 170-1000 µm fibers. The system fragments stones through a chemical-photothermal effect (Fig. 1). The laser generates weak photoacoustic effects due to low-amplitude pressure waves, as a result of which the mechanical damage inflicted upon the ureter and kidney is negligible. Moreover, these characteristics make the device safe in patients receiving anticoagulation therapy, since the risk of bleeding is low. On the other hand, the photothermal effect is circumscribed to an area of less than 1 mm; as a result, when the laser is directly triggered in the kidney parenchyma, the damage is limited to only a small volume of tissue.

 

FIGURE 1. The holmium-YAG laser is a solid, pulsed contact laser that exerts a chemical-photothermal effect.

 

The erbium-YAG laser produces greater stone ablation, though with lesser coagulative properties. This system is more effective than the holmium-YAG laser in application to lithotripsy, since experimental studies have shown that it produces deeper craters in the stone, secondary to increased energy absorption as a result of its longer operating wavelength (2940 nm) - in contraposition to the craters produced by the holmium-YAG laser, which are less deep, wider and irregular. The problem is that its endoscopic application is still limited by the non-availability of fibers transmitting in the mid-infrared zone and meeting the requirements of biocompatibility, flexibility and tolerance of the intense laser-stone interaction at the tip of the fiber¹³.

In a retrospective study, Lee y Bagley¹⁴ investigated the effect of the holmium-YAG laser during intracorporeal lithotripsy in ureteroscopy (URS) within the glomerular filtration range (GFR) - the inclusion criterion being the presence of renal failure. They showed this to be a safe technique, with no risk for kidney function. Moreover, the changes in GFR were not correlated to the size of the stone, its location or composition.

The complication rate associated with the laser is less than 1%. These complications can be avoided by triggering the laser only when the optic fiber tip is visualized, and moreover examining it before use, to identify light “leakages” along the fiber, indicating the risk of transmitting laser energy to the ureteroscope or operating room.

In addition, the system has been shown to be effective in treating renoureteral lithiasis, since the resulting stone-free range is 98% in the pelvic ureter, 100% in the sacral ureter, 97% in the lumbar ureter, and 84% in the kidney - fragmentation being incomplete in only 6% of cases.

Due to miniaturization of the ureteroscopes used and the degree of stone fragmentation afforded, two questions have been raised: on one hand whether intramural ureter dilatation is required, and whether the placement of a double-J catheter is needed after the procedure¹⁵

 (Fig. 2).

 

FIGURE 2. The holmium-YAG laser produces very fine stone fragmentation.

 

Although the retropulsion effect on ureteral stones is less pronounced than in the case of other short-pulse lasers, it can be avoided in different ways:

- Placing the patient in the anti-Trendelenburg position.

- Using different devices to avoid fragment migration.

- Application of the laser with longer pulses of 700 μsec. rather than 350 μsec., without this measure affecting the fragmentation capacity.

- Ensuring a standby flexible ureteroscope in case the stone migrates to the kidney, to facilitate treatment.

When compared with pneumatic lithotripsy (CalCUTRIPT; Karl Storz, Kennesaw, Georgia, USA) for the treatment of ureteral stones, it is seen that the success rate for the holmium-YAG laser in a single procedure is 96% versus 70% - with a shorter operating time and fewer complications¹⁶.

In turn, when compared with extracorporeal lithotripsy using the HM-3 Dornier lithotriptor for the treatment of distal ureteral lithiasis (the latter system being considered the gold standard in such situations), patient satisfaction questionnaires show that patients prefer extracorporeal lithotripsy - the urologist considering URS only in cases of stones presumed to be hard for fragmentation or difficult to visualize in patients with allergy to iodine contrast media¹⁷.

The treatment of intrarenal lithiasis with flexible URS and lasertripsy is indicated in the case of stones measuring under 2 cm in size where extracorporeal lithotripsy has either failed or is contraindicated, or where the urologist considers that the chances of success with this technique are small - the resulting success rate being close to 100%. The stone-free range is inversely associated to the size and number of stones. Therefore, in stones smaller than 2 cm, the procedure would be indicated in the event of failure of extracorporeal lithotripsy and percutaneous nephrolithotomy (PCNL), in patients with bleeding disorders, in morbid obesity, or when preferred by the adequately informed patient - the success rate being 76-91%.

The Lower Pole Stone Study Group recommends extracorporeal lithotripsy in the case of stones measuring less than 10 mm in size and located in the lower calix, regardless of the anatomy of the latter, since the stone-free range is 63%. URS or PCNL is in turn advocated if extracorporeal lithotripsy fails. The development of flexible, small-caliber ureteroscopes with an active double deflection mechanism at the distal tip, together with the introduction of 200 µm holmium-YAG optic fibers, allows lower calix stone treatment. The stone-free range when the stone is smaller than 10 mm is 82%, versus 72% for stones measuring 10-20 mm, and only 65% in the case of stones larger than 20 mm¹⁸.

The indications of Chan and Jarret¹⁹ for the treatment of kidney stones using a minipercutaneous access are:

- Lower caliceal lithiasis associated to an unfavorable infundibular-pyelic angle for extracorporeal lithotripsy or URS.

- Stone volume between 1-2 cm².

- Failure of extracorporeal lithotripsy or URS.

- Cystine stones measuring under 2 cm².

- Anatomical anomalies contraindicating extracorporeal lithotripsy or URS.

- Second step intervention for treating residual fragments after conventional PCNL.

In the adult, different percutaneous access calibers have been used, ranging from 13-20 Fr, in the same way as different endoscopes and lithofragmentation sources for treating small kidney stones. The percentage conversion to standard PCNL is 5-11.7%, with a stone-free range of 89-100%. Clinically, different studies have demonstrated lesser blood loss with minipercutaneous PCNL when compared with conventional PCNL, though it must be remembered that such treatment has been applied to small stones. Minipercutaneous PCNL poses a series of problems. Firstly, it is not accessible for most urologists, due to the instrumentation required and its high cost. In addition, the use of miniaturized instruments requires finer fragmentation of the stone - with the resulting risk of prolonging the operating time and the number of residual fragments²⁰.

 

Lasers in urological tumors

The vaporization of surface bladder tumors is rapid, safe, easy to perform and easy to learn. The procedure is carried out using a flexible cystoscope and a holmium-YAG laser, without the need for spinal anesthesia or hospital admission. Although the initial cost of the flexible cystoscope and laser system is considerable, the investment is compensated after only a few treated cases, when compared with conventional TUR²¹. The greatest treatment difficulty corresponds to patients with tumors located in the bladder dome and very close to the bladder neck. With the new laser bladder tumor resection techniques it is also possible to secure an adequate histopathological study.

Many series have demonstrated the safety and efficacy of URS in treating upper urinary tract transitional cell carcinomas (UT-TCC). The general recurrence rate is 35%, and the risk of bladder recurrence is 41%; nephroureterectomy is only performed in 12% of cases due to recurrence or progression of the disease. The impossibility of fully treating the tumor is recorded in 32% of cases. The lowest recurrence rates correspond to low grade tumors measuring under 1.5 cm in size, with single presentations and a negative pre-treatment urine cytological study. Tumor location exerts no influence (Fig. 3). Specific cancer survival is not impaired by treatment with URS or by local recurrence after this treatment^22-23. The neodymium-YAG laser was the first laser used to treat UT-TCC; its fiber is positioned close to the tumor, and the laser is triggered at 20-30 W, moving the tip over the surface of the lesion to ensure coagulation to a depth of 5-6 mm. More recently, use is being made of the holmium-YAG laser, fundamentally in application to small lesions, since its tissue penetration is limited to 1 mm. It is therefore particularly useful in ureteral tumors, affording fewer ureteral stenoses. The fiber is placed in contact with the tumor, and the laser is triggered at an energy rating of 0.6-1.2 J and a frequency of 8-10 Hz.

 

FIGURE 3. Endoscopic view of a low grade urothelial tumor in the renal pelvis.

 

Lasers and urological stenoses

The principles of retrograde endopyelotomy are the same as those of anterograde endopyelotomy, though without the need for creating a nephrostomy trajectory. First described in 1986, Meretik et al.²⁴ in 1992 reported a 21% ureteral stenosis rate, though at present this figure has decreased thanks to the use of smaller-caliber ureteroscopes. Generally, the different authors use endoluminal ultrasound to identify polar vessels. A section is made of all layers to the periureteral fatty tissue, using the holmium laser at a rating of 1-1.5 J, with a high success rate similar to that afforded by endopyelotomy with the Acucise catheter²⁵.

Stenosis of ureterointestinal anastomosis occurs in 3-10% of the patients subjected to urinary bypass. Access to the stenosis through the bypass is often impossible, while the generally associated hydronephrosis makes anterograde access an attractive option. An incision though all layers is made using the holmium-YAG laser at a rating of 0.6-2 J and a frequency of 8-15 Hz. The long-term success rate is 57-71%, with better results in the case of right-side ureteral stenosis versus left stenosis (83% versus 38%)^26-27 (Fig. 4).

 

FIGURE 4. Anterograde endoscopic view of a ureteroileal stenosis.

 

In the treatment of ureteral stenosis based on the conventional Sachse-type urethrotomy technique, the long-term success rate is 35-60%, with improved results in those cases involving single short stenoses (less than 1 cm in length), treated for the first time. Other influencing factors are the location of the lesion, its etiology and duration. Urethrotomy performed with the holmium-YAG laser affords an increased success rate, since in addition to sectioning, the technique vaporizes the scar tissue with peripheral thermal damage extending a mere 300-400 μm²⁸.

 

Laser in the surgical treatment of benign prostate hyperplasia

The KTP laser (green laser) in BPH

Dr. Carlos Hernández

 

Introduction

The KTP laser has been in use in urological practice since 1986 for the treatment of urothelial tumors, bladder neck sclerosis, condylomas, urethral stenosis, etc. However, its potential application to benign prostate hyperplasia (BPH) was fundamentally postulated only once greater power ratings were achieved.

 

What is the KTP laser?

The KTP laser is a neodymium-YAG laser in which the light passes through a Potassium (K), Titanyl (T) and phosphate (P) crystal. The system affords up to 80 W of power and operates at a wavelength of 532 nm. This makes it visible in the green part of the spectrum - hence the term “green laser”, by which the instrument is also known.

 

What is the KTP laser able to do?

This system allows selective prostate tissue vaporization, penetrating the tissue to a depth of only 0.8 mm.

The laser beam is very poorly absorbed by water, but is very well absorbed by hemoglobin.

 

Advantages

Only minimal bleeding is produced, and there is practically no fluid reabsorption into the bloodstream.

Early bladder removal is possible, after within 12 to 24 hours.

The learning curve for this system is very brief for any urologist with experience in transurethral resection (TUR).

 

Inconveniences

Surgical time is longer than in the case of TUR, which makes the technique tedious when dealing with voluminous prostate glands.

No sampling for histopathological study is possible, as a result of which small prostate tumors may go undetected.

In using instrumentation of lesser caliber than in the case of TUR, vision may be somewhat limited.

The technique is expensive, particularly in the case of large prostate glands, where more than one probe can be used.

 

Number of systems in Spain

At present there are 36 KTP laser systems in Spain - Madrid, Barcelona and Valencia being the cities where most such laser are found (with 5, 4 and 3 systems, respectively).

 

Number of patients treated

Up until December 2005, i.e., the time when this review was conducted, a total of 1946 patients had been treated - the cases registered in Madrid and Barcelona accounting for 50% of the total.

 

Scientific evidence. Safety

Articles fundamentally published in 2005 show that there are few short- and middle-term postoperative complications (Table 5)^29,30, the most relevant being summarized below:

 

Table 5

Scientific evidence. Safety.

 

- Transient hematuria is observed in 2-9% of cases, and usually poses no hemodynamic problems.

- Bladder neck sclerosis is seen in 2-3% of cases.

- Transient incontinence is recorded in 1-2% of patients.

 

Scientific evidence. Efficacy

Efficacy as evaluated by the International Prostate Symptoms Score (IPSS) and flowmetry reveals very significant symptoms improvement, with an IPSS reduction of over 50% and a two- to three-fold increase in maximum (peak) flow (Table 6)^31-33.

 

Table 6

Scientific evidence. Efficacy.

 

Holmium laser in benign prostate hyperplasia

Dr. I. Santos

 

Treatment for patients with lower urinary tract symptoms diagnosed as corresponding to benign prostate hyperplasia (BPH) classically includes medical management in the form of phytotherapy, alpha-blockers or 5-phosphodiesterase inhibitors, or surgery in the form of transurethral resection (TUR) or prostatectomy.

The surgical management of BPH has been dominated by TUR, which is known to be safe and effective. The main operative problems are the need for blood transfusions and the post-TUR absorption syndrome. Only in the case of large prostate glands in excess of 100 g is prostatectomy advisable. With the purpose of improving the results of TUR in terms of the transfusion requirements, absorption syndrome and the duration of hospital stay, new treatment modalities such as TUNA (transurethral needle ablation), bipolar energy resection and lasers have been introduced. The laser options in turn comprise the interstitial laser, the KTP laser (“green laser"), and the holmium laser.

 

Use of the holmium laser in Urology

The holmium laser is effective for incision and ablation of the prostate gland (HOLAP), since it affords excellent hemostasia and uses saline solution for irrigation. The high-power holmium laser (60-100 W) has been used for incision, resection (HOLRP), ablation (HOLAP) and enucleation of the prostate gland (HOLEP). Laser resection of the prostate (HOLRP) has been shown to be as effective as TUR³⁴. The latest advances in laser resection comprise enucleation of the prostate gland through dissection of the adenoma, in the same way as in classical digital prostatectomy, displacing the prostate lobes to the bladder, to then posteriorly aspirating them with the morcelator. This technique allows us to deal with larger glands that were only amenable to classical prostatectomy in the past.

 

Equipment required

At present, we use the following equipment for prostate gland enucleation:

- Endoscopic optics (30º)

- Endoscopic camera with video system

- VersaPulse PowerSuite (Lumenis Corpora­tion), 100 W, with a DuoTome Side­Lite fiber (550 μm) (Fig. 5).

 

FIGURE 5

 

- Continuous flow resectoscope, 26 Fr

- Adaptor link for the laser fiber, with an operating canal of over 7.5 Fr

- Ureteral catheter (6 Fr) through which the laser fiber is inserted

- Adaptor silicone membrane

- Nephroscope (27 Fr) through which the morcelator is inserted (Versacut Tissue Morcelator)

 

What parameters are used?

The Versapulse Powersuite can be programmed at different frequencies and with different energy ratings to ensure a given power (Table 7). To perform prostate enucleation, the pulse frequency should be 50 Hz with an energy of 2 J, to yield a power rating of 100 W.

 

Table 7

 

Prostate enucleation technique

As has been commented, prostate lobe enucleation is prevailing over prostate gland resection or ablation. This is because enucleation affords superior improvement in flow and symptoms, with a lesser percentage of retreatments, and the possibility of treating larger glands.

The surgical steps are summarized below:

Step 1: Incision at the 5 and 7 o’clock positions: Two classical myocapsulotomies are performed, starting 1 cm from the ureteral orifice and working to the lateral zone of the veru montanum. Incision is to extend to the prostate capsule; upon reaching the latter, small lateral movements are applied to start detachment of the lateral lobes and middle lobe. If the incisions are symmetrical, they will merge ahead of the veru montanum. We then section the middle lobe, raising it and deflecting it towards the bladder (Fig. 6a).

Step 2: Incision close to the veru montanum. This is one of the most important steps. The incision is to be made between the apical zone of the adenoma and the striate sphincter. We must clearly reach the prostate capsule layer, which is identified by its different texture and more pearly appearance. A common technical error in this step is penetration of the adenoma, without finding the dissection plane (Fig. 6b).

Step 3: Incision of the anterior commissure. The resector is turned 180º, performing incision of the anterior commissure in the same way as in classical prostatectomy, from the bladder neck to the height of the veru montanum, as during the myocapsulotomy. We must reach the capsule and apply small lateral displacements of the laser fiber, to separate the adenoma from the prostate capsule and facilitate the subsequent steps. The incision is to be of adequate length, because if made too long it can damage the striate sphincter, while if left too short we will be unable to join this plane with that of the lateral lobe (Fig. 6c).

 

FIGURE 6

 

Step 4: Joining of the anterior incision with the lateral incisions. This is probably the most complicated step. We surround the lobes laterally from bottom to top, and displace the prostate lobe towards the bladder. At a certain point the lateral plane being created must merge with the plane created in step 3. Finally, the lobes are displaced towards the bladder, leaving the prostate space free.

Step 5: Regularization and coagulation of the prostate space.

Step 6: Extraction of the adenoma with the morcelator (Fig. 7). Since aspiration and morcelation of the adenomatous tissue implies the aspiration of large amounts of saline solution from the bladder, the risk exists of totally aspirating the bladder and of sectioning bladder mucosa. Consequently, during this phase we introduce saline through the two irrigation valves, to ensure correct bladder filling at all times.

 

FIGURE 7

 

Advantages of HOLEP over TUR: The main advantages are^35-36:

- Coagulation while sectioning

- Minimization of bleeding

- Catheterization for under 16 hours

- Lesser need for transfusion

- Shorter hospital stay

- Irrigation with saline solution

- Fewer irritative symptoms

- Applicable to large prostate glands

However, despite these improvements, the procedure has not quite become the standard treatment option. This is because of the current high cost of the equipment, and the fact that learning is not easy - the corresponding learning curve requiring the performance of 20-30 cases. Moreover, there are still few centers that perform this technique on a routine basis or teach other centers where the procedure is being introduced. Furthermore, the most important reason is probably that TUR continues to offer excellent results.

 

Lasers in urological laparoscopic surgery

Dr. A. Rosales

 

Introduction

In the past 20 years there have been a series of technical innovations that are changing classical surgical concepts. Among these innovations, lasers have introduced a change in different areas of Urology, applied to both resective and reconstructive operations. A review is provided of the use of laser technology in urological laparoscopic surgery.

 

Physical principles

Laser (Light Amplification by Stimulated Emission of Radiation) is a monochromatic light beam with one same wavelength. The components of laser center on three elements. The first is the medium where the monochromatic and coherent light beam is generated. The second component is the energy source, and the third is represented by the mirrors that facilitate general light beam collimation.

 

Laser light exerts three tissue effects:

1) Thermal action: This heat effect occurs when the laser beam is reflected upon a tissue at under 60ºC, resulting in a tissue temperature rise from which the different tissue effects derive. Between 60-70ºC, laser light induces denaturalization of the proteins within the interstitial space of the tissues (particularly collagen and elastin), inducing anarchical intermingling of the fibers and producing a sealing effect in the tissue exposed to the beam. If the temperature reaches 70-100ºC, tissue necrosis and vascular thrombosis result, favoring hemostasia. In turn, tissue vaporization results when the temperature reaches over 100ºC.

 

2) Photochemical action: It has been seen that the interaction of laser light with photosensitizing agents facilitates certain biochemical effects upon the treated tissues - thus giving rise to photodynamic therapy. Following administration, the photosensitizing substance is taken up by the reticuloendothelial system of certain solid organs. Malignant cells are able to retain these substances, thus favoring the action of lasers that show affinity, e.g., for hematoporphyrin and its derivatives. The result is a photochemical reaction that releases free radicals at intracellular level, resulting in cell death. This effect has been used for the treatment of in situ carcinoma, and in application to superficial bladder tumors, though the results to date have not been satisfactory.

3) Photoacoustic or mechanical action: This effect is based on the conversion of the energy of the different types of laser into shock waves that constitute the mechanism underlying laser lithotripsy - the latter being considered very useful in urological practice (Table 8).

 

Table 8

Tissue effects of laser energy.

 

The different lasers used in urological clinical practice are divided into three major groups according to the active medium used to generate the coherent light beam. The systems using a gaseous medium are the CO₂ and argon lasers. A liquid medium is used in the case of the rhodamine b and coumarin green laser systems. The most numerous group is composed of lasers that generate the light beam in a solid medium such as neodymium, potassium-Titanyl-phosphate (KTP), or diode laser (Table 9).

 

Table 9

Physical characteristics of lasers.

 

Lasers in laparoscopic surgery

The use of laser in laparoscopic surgery is presently limited, and most of the published experience is based on experimental surgery - though there are cases of laparoscopic partial nephrectomies, ureterorraphies, and pyeloplasties.

Experience with lasers, taking advantage of their hemostatic effect to perform partial nephrectomies in experimental surgery, has been based on canine, feline and porcine models. The lasers used have been the CO₂ and Nd: YAG lasers, and the Holmium laser with and without renal hilum control. Lotan performed three partial nephrectomies without vascular control; kidney resection was achieved, though oxycellulose and fibrin were required to prevent bleeding. Other authors compared laser sectioning with cold scissors - no significant differences being observed between the two approaches, since in both instances sutures were required to control bleeding. Thus, lasers in renal surgery alone are unable to ensure hemostasia without using substances that facilitate coagulation or seal the opened urinary tract. Among the disadvantages cited in the literature are the lack of urinary tract sealing, the important production of smoke that can blind the optics, and the occasional need for two insufflators to perform the technique, due to the great carbon dioxide losses implied by working permanently with several open trocar valves; this results in important intracavitary gas exchange (Table 10).

 

Table 10

Applications of laser in tissue welding.