Bipolar transurethral resection of the prostate: a valid innovation

Despite all alternative techniques, transurethral resection of the prostate (TURP) remains the reference standard in the surgical management of male LUTS. During the last decade, TURP has undergone significant technical improvement with a major impact on the incidence of intra- and postoperative complications. Recently, different manufacturers introduced bipolar TURP. Early studies addressed some advantages regarding the improved safety of the bipolar devices, because they allow the use of physiological sodium chloride as irrigant. On the other hand, bipolar technology is still criticised by well-experienced advocates of monopolar TURP emphasising a higher rate of strictures in comparative studies.

Therefore, the European Society of Urotechnology (ESUT), invited experts from all relevant faculties (i.e. electrophysics, experimental and clinical urology, anaesthesiology) as well as representatives of the involved industry (Erbe, Fresenius-Kabi, Gyrus, Olympus, Storz) to discuss the actual situation (see photo). De La Rosette (Amsterdam), Faul (Memmingen) and Rassweiler (Heilbronn) chaired the meeting. Fastenmeier (Munich) and Farin (Tuebingen) focused on the basics of high frequent electrosurgery for TUR, emphasising the importance of high temperatures around the loop to create a plasma or light-arc, which facilitates the cutting through tissue. Significant progress has been made by down-regulation of the electrical output once the light-bow has been created. Earlier measurements of the heat distribution versus neutral electrode during mono- and (quasi)bipolar resection showed significant differences (i.e. with a more focused field of bipolar TURP).

However, due to the significant and better conductivity of sodium chloride than Purisole (resistance 40 vs. 800 Ohms) a higher energy input is necessary (i.e. 480 vs. 230 W) for plasma formation around the loop. Technically, all different bipolar modifications enable TUR in irrigation fluids with high conductivity (NaCl, Ringer`s lactate) by approximation of the neutral electrode close to the loop (Table 1). Since, the current does not flow exclusively between two electrodes (i.e. definition of bipolar electrosurgery), these modifications should be better called ìquasi-bipolarî. Due to the same reason, for both (mono-, and bipolar) the use of lubricants with high conductivity (i.e. more than 4 mmho/cm = conductivity of muscle) is very important to minimise the risk of conductive trauma of the urethra. Hahn (Stockholm) reviewed the current incidence of fluid absorption during TURP with the risk of minor and major side effects for the patient (i.e. if more than 1L) even with delayed manifestation. Serum natrium cannot be used as indicator, if sodium chloride represents the irrigant. It was emphasised, that fluid overload with sodium chloride (i.e. following capsular perforation) may have deleterious consequences. Interestingly in animal studies, Ringer`s lactate proved to be superior over sodium chloride as high conductive solution. Modern methods for detection of fluid absorption still include the injection of ethanol, but also of nitrid oxide (NO) in the irrigation fluid.

Table 1: Handling of different bipolar devices compared to monopolar TURP

Criteria

TURP monopolar

Olympus

Gyrus plasmakinetic

Storz
bipolar

Size (F) of
resectoscope

24-26

24-26

26

24-26

Active Loop

Normal size

Smaller

Two sizes

Smaller

Neutral Electrode

At skin

Resection sheath

Proximal to loop

Opposite to loop

Life-time of loop

Resterilisable (100-200g)

Resterilisable (100-200g)

Disposable (one case)

Resterilisable (60-80g)

View during resection

+++

+++

+++

+++

Hagg (T¸bingen) and Leyh (Garmisch-Partenkirchen) presented recent improvements of (quasi) bipolar and monopolar TURP. Whereas, recent bipolar systems have tried to minimise the energy for plasma formation (i.e. warmed sodium chloride, modified generators), new monopolar HF-generators combined intervals of cutting and coagulating current (i.e. cocut, dry-cut) to reduce the degree of bleeding during TURP. With both techniques, the speed of the loop may also be used to vary the degree of simultaneous coagulation.

Hoffmann (Marburg) reviewed the actual techniques of TURP, emphasising the need of a structured standardised procedure (i.e. Mauermeyer, Nesbit), whereas there is no evidence in the literature, that one technique is superior over another. The role of low-pressure systems with continuous irrigation was recommended especially for larger glands (i.e. >50 gs). Also, novices should at least be trained to perform a video-TUR. With the introduction of the new monopolar generators, the role of vaporisation techniques (i.e. TVP; Rotoresect) or broad loops diminished significantly.  

Michel (Mannheim) summarised the existing experimental studies with four different bipolar devices in comparison to monopolar systems. Most experiments used an ex-vivo study of a blood perfused porcine kidney. The initiation of the cut was slower with all devices (i.e. most pronounced with ACMI/VISTA), but on higher output powers bleeding was less compared to monopolar technology. More importantly, however, the coagulation depth was significantly reduced (141 vs. 287 micron), which could be reconfirmed by pathological studies after TURP (Rassler). Overall, the energy input during bipolar was higher compared to monopolar. The Olympussystem was tested in an ex-vivo study using porcine vagina and bladder wall. Thereafter, the impact on nerve-stimulation (i.e. obturator nerve) was examined in vivo showing significantly less limb contraction compared to monopolar resection. That may favour the bipolar technology for other indications such as TUR of bladder tumours.  

Patel (London), Janetschek (Linz), Rassler (Leipzig) and Rassweiler (Heilbronn) presented an overview of the actual modifications of the bipolar devices of Olympus, Gyrus and Karl Storz (Table 1,2): Due to the longest time of development the Gyrus technology was considered as most matured; more than 900 patients have been already enrolled in phase IIIstudies. Unfortunately, however, most of the studies have only a small number of patients in every arm. Olympus is still working on enhancing the system to improve the ignition of plasma formation with minimal energy input and the safe conduction of the current via the shaft. Storz focuses on the life-time of the loop, which theoretically represents the safe modification. In contrast to Gyrus, the loop is resterilisable, but actually provides a relatively short life-time (60-80 g of resection weight).  

Table 2: Definition, advantages and possible  disadvantages of bipolar TURP

Definition of bipolar electrode

An electrode whereby two active electrodes are attached to a single support and having a structure that allows high frequency electric current to pass through these two electrodes when electrified (International Electrotechnical Commission 1998).

Advantages of bipolar technology

• Less conductive trauma (i.e. resulting to a lower rate of bladder neck stenosis or urethral strictures)
• Elimination of TUR-syndrome (i.e. hyponatremia) 
• Lower risk of capsular lesion (i.e. decreased stimulation of pelvic floor)
• Better visual orientation (i.e. reduced coagulation depth)
• Self-cleaning of the loop (i.e. by high energy level at plasma ignition)

Potential disadvantages of bipolar technology

• Higher risk of conductive trauma if current is  deviated (i.e. via sheath) due to higher energy  levels for ignition of plasma (i.e. insufficient lubrication). 
• Fluid absorption still possible, but serum natrium cannot be used as early indicator. Inferior quality of loops (fine resection, durability).
• Risk of recurrent bleeding due to smaller coagulation zone.

Madersbacher (Vienna) prepared an overview of Phase III-studies comparing bipolar and monopolar TURP: There are advantages for bipolar technology concerning the rate of TUR-syndrome / fluid absorption, bleeding, catheter time, whereas the resection speed was similar. In two studies using two different devices (Gyrus, Olympus) a higher rate of urethral strictures was detected
(Table 3).

Table 3: Bipolar versus monopolar in phase III-studies


a) Comparison of irrigation and fluid absorption

Authors

N

Peroperative
Irrigation (L)

Postoperat.
Irrigat. (L)

Fluid
absorpt.(ml)

Change in Na (mEq/L)

- TURP

30   

17.3

9.8

191.1

-4.6

- bipolar (Vista)

30   

19.6

9.9

133.3

-1.2

Tefekli 2005

96

- TURP    

47

18.3

7.8

n.a.

n.a.

- bipolar (Gyrus)    

49

11.4

6.9

n.a.

n.a.

Hon 2006

160

- TURP    

79

n.a.

28.3

334

-2.2

- bipolar (Gyrus)+    

81

n.a.

20.4

305

-2.0

de Sio 2006

70

- TURP    

35

n.a.

52 hrs

n.a.

-0.9

- bipolar (Gyrus)    

35

n.a.

30 hrs

n.a.

-0.6

Ho 2006

100

- TURP    

52

n.a.

n.a.

n.a.

-10.7

- bipolar (Olympus)   

48

n.a.

n.a.

n.a.

-3.2

n.a. = not available; *present study; + plasmakinetic vaporisation

b) Perioperative results after bipolar and monopolar TURP

 

Authors

N
Rate (%)

Bleeding
drome (%)

TUR-syn
time (d)

Catheter
stricture (%)

Urethral

Singh 2005

60

- TURP    

30

3.3

0.0

3.4

0.0

- bipolar (Vista)    

30

0.0

0.0

2.5

3.3

Tefekli 2005

96

- TURP    

47

2.1

0.0

3.8

2.1

- bipolar (Gyrus)    

49

2.0

0.0

2.3

6.1

Starkman 2005

43

- TURP    

18

11.0

0.0

3.2

5.5

- bipolar (Gyrus)    

25

0.0

6.6

1.8

6.6

Hon 2006

160

- TURP    

79

5.3

0.0

2.4

1.2

- bipolar (Gyrus)+    

81

1.2

0.0

2.0

0.0

de Sio 2006

70

- TURP

35

11.4

0.0

4.1

2.8

- bipolar (Gyrus)      

35

5.7

0.0

3.0

2.8

Patankar 2006

104

- TURP    

51

3.9

3.9

1.8

n.a.

- bipolar (Gyrus)

53

0.0

0.0

0.8

n.a.

Ho 2006

100

- TURP    

52

3.8

3.8

n.a

6.3

- bipolar (Olympus)    

48

6.3

0.0

2.0

1.9

n.a. = not available; *present study; $ fluid absorption; + plasmakinetic vaporisation;

At the end of the ESUT-expert meeting, the conclusion was that TURP still represents the standard in the surgical management of male LUTS, particularly with recent developments. Bipolar technology has proven to be safe and effective. It may offer some advantages with respect to the reduction of TUR-syndrome, less conductive trauma (i.e. tissue charring), cheaper irrigation solution, and a shorter catheter time. However, larger randomised multi-institutional trials have to substantiate these advantages. Further indication may include TUR of bladder tumours. Future experimental studies should focus on the improvement of the electrical efficacy of quasi-bipolar devices, including the development of special irrigation fluids, modification of the loops, and temperature measurements to evaluate the risk of any conductive trauma of the urethra. A consensus paper is currently being prepared.

Figure 3: Technical modification of (quasi)bipolar resectoscopes


a) Gyrus with neutral electrode proximal to loop



b) Storz with neutral electrod opposite to loop

c) Olympus using the sheath as neutral electrode

By Prof. Jens Rassweiler & Prof.Dr. Jean De La Rosette


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