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The benefits of electrothermal tissue sealing systems in urological surgery


27 July, 2010  

Surgery has come far since the use of branding irons to cauterise wounds. The latest electrothermal devices have been shown to reduce blood loss, speed recovery and lower the rate of debilitating side-effects in urological surgery

Daniel Eberli
MD PhD
Department of Urology
University Hospital
Zurich
daniel.eberli@usz.ch

Mathias Tremp

MD

Lukas Hefermehl

MD

Tullio Sulser

MD

Hartmut Knönagel

MD

Basic heat-mediated haemostasis was practised as early as 3000 BC using boiled oils and tools heated in the fire. Further innovations in the 19th century by the French physicist Becquerel and later D’Arsonoval eventually led to the  introduction of the first electrocautery instruments by Cushing and Bovie in 1926 – combining the ability to cut and coagulate.[1] Haemostasis is fundamental in cancer surgery.
High perioperative blood transfusion rates have traditionally been associated with poorer prognosis in patients undergoing surgery for solid tumours.[2]
Several techniques have been described to reduce intraoperative blood loss,[3–5] including clips, sutures and ultrasonic coagulation, as well as both monopolar and bipolar coagulation. Each method offers benefits and also has its limitations.
Clips are easily placed, but they can be expensive and may shift and remain in the body after surgery. Sutures, on the other hand, can be a tedious and time-consuming option. The next developmental stage in electrical haemostasis were vessel-sealing devices (VSD) which use a combination of tissue compression and bipolar energy. Some offer continuous impedance measurement and employ active feedback to optimise the power output.[6] The VSDs were designed to seal vessels up to 7mm in diameter effectively. In this review we will address monopolar, bipolar and vessel-sealing devices in regard to efficacy of haemostasis and collateral damage.

Monopolar coagulation
Classically represented by the Bovie pencil, the active electrode in monopolar coagulation is located at the surgical site and the larger return electrode is located elsewhere on the patient’s body. While current flows through the patient, a return electrode is necessary to complete the circuit and disperse the electrical current and prevent alternate burn sites.[7–8] Through modification of its waveform, the clinical effects of cutting, fulguration and desiccation are possible. Examples of monopolar instruments are loops, needles and balls. This procedure has a number of well-known drawbacks. Among others, the amount of current required to establish the circuit between active and inactive poles through the resistance of the
human body is considerable. Also, such crossing involves the possibility of adverse effects on tissues and organs outside the operative field. As an added danger, serious burns can be produced by defective contact or grounding of the patient’s body, the negative electrode or the conductors.

Bipolar coagulation
In comparison to monopolar, with bipolar electrosurgery, both active and return electrodes are located at the site of surgery, typically within the tip of the instrument. The classic example is the two tines of forceps which are the active and return electrode and represent the entire circuit. In this case, only minimal current flows through the patient. Only the tissue held between the two tines is included in the circuit and is the site of tissue effect. This technique refined the area of coagulation and minimised damage to surrounding tissue when compared to monopolar electrosurgery. [1–9] Most bipolar units use a lower voltage waveform to achieve haemostasis and avoid collateral tissue damage.10 Since the return electrode is included in the circuit at the site of surgery, the dispersive patient return electrode pad is unnecessary.[7,11]
As a result of the way bipolar electrosurgery is designed, many of the problems seen with its monopolar counterpart are avoided. Disadvantages of bipolar electrosurgery include increased time needed for coagulation compared to monopolar electrosurgery caused by the lower power setting, charring and adherence to tissue with incidental tearing of adjacent blood vessels.[12]

Vessel-sealing system
In the last ten years, enormous effort was made in the development of novel vessel-sealing devices (VSD), using more sophisticated devices with highly sensitive electric generators that employ active feedback to optimise power output. This allows continuous impedance measurement for the application of a steady electric current. Companies are now suggesting that the use of these modern vessel-sealing devices is safer because they have a reduced lateral temperature spread. A study by Kennedy at al compared the Liga- Sure vessel-sealing system with ultrasonic coagulation, bipolar coagulation, surgical clips and sutures.[13] In this study, 210 freshly excised porcine
renal arteries ranging from 3–7mm in diameter were occluded using the LigaSure VSD System, ultrasonic coagulator, bipolar forceps, mechanical clips or standard silk ties. The vessels were then cannulated and pressurised with saline using a syringe pump until the occlusion burst. Pressure was recorded when the occluded or normal vessel wall burst, or when the measurement system reached its maximum pressure of 900mmHg. The study results demonstrated that the Liga- Sure VSD System creates seals that are stronger than other energy-based ligation methods (ultrasonic coagulation and standard bipolar coagulation), and comparable in strength to mechanical ligation techniques such as clips and sutures.[14]
Seals created by the LigaSure System were shown to withstand a minimum of three times normal systolic pressure.[15] Shorter operations and decreased blood loss compared to conventional ligation are the major advantages using VSD.[16]

[[HHET23]]

Bipolar versus monopolar transurethral resection of the prostate
Despite the major impact of significant technical improvements during the past 15 years which reduced intraoperative and postoperative adverse events after transurethral resection of the prostate (TURP), there are still concerns on complications such as bleeding, urethral strictures and transurethral resection (TUR) syndrome, a metabolic disturbance due to a hypervolemic state after influx of irrigation fluid into the venous system.[17] However, notwithstanding its flaws, TURP remains the ‘gold standard’ for the operative management of benign prostate hyperplasia (BPH).[18] Reich et al’s prospective multicentre study on 10,654 BPH patients treated with TURP suggests a decrease in mortality (0.1%), but morbidity, although reduced, continues to be high (11.1%).[19]
The introduction of bipolar technology in TURP seems to be a promising technical modification offering possible benefits both for the patient[20] and for training purposes.[21] It shares similar clinical efficacy with monopolar transurethral resection of the prostate, durable in time with low long-term complications rates. It has minimised bleeding risks and eliminated transurethral resection syndrome by using normal saline as irrigation fluid. The evidence derived from randomised clinical trials does not show a statistically significant difference of urethral strictures when bipolar energy is compared with monopolar.[22]

Vessel-sealing devices in urological applications
There are many steps during a radical cystectomy and urinary diversion where the use of an efficient VSD would have significant advantages. The laparoscopic and standard handsets of a VSD can be used for the lymphadenectomy, thus eliminating the use of clips. The LigaSure device, which includes a cutting blade, also saves time when dividing the mesentery for the small or large bowel to be used for the anastomosis.[23] Daskalopoulos et al evaluated the use of an electrothermal bipolar coagulator (LigaSure device) in major urologic procedures, including open radical prostatectomies and radical cystectomies. [16] Fifty-eight patients aged 56-74 years (mean: 65 years) underwent open radical prostatectomy and open radical cystectomy performed by the same surgeon, employing either conventional ligation in the control group (radical prostatectomy, n=15; radical cystectomy, n = 9) or the LigaSure device in the study group (radical prostatectomy, n = 24; radical cystectomy n=10) to ensure blood vessel patency.
Effectiveness and postoperative outcomes were evaluated. The mean operation time was significantly shorter in the LigaSure group compared to the control group for both the prostatectomy (125 minutes vs 144 minutes p <0.001) and the cystectomy procedures (253 minutes vs 281 minutes p <0.001). In addition, the mean intraoperative blood loss was significantly lower in the LigaSure group compared to the control group for both prostatectomy (569 ml vs 685 ml p = 0.04) and cystectomy procedures (637 ml vs 744 ml p = 0.02). There were no serious intraoperative or postoperative complications related to the use of the device. The authors concluded that radical prostatectomy and radical cystectomy using a VSD are safe, and significantly decrease both the operation time and the blood loss when compared to the conventional ligation method. These parameters are appealing to any surgeon but they are particularly important when surgery involves high-risk patients.
Sengupta et al evaluated the application of LigaSure in open urological surgery.[24] The VSD device was used in 32 consecutive open surgical cases, including 25 radical prostatectomies, five radical nephrectomies, one partial nephrectomy and one nephro-ureterectomy. The LigaSure device was used in pelvic lymphatics and prostatic, adrenal, gonadal and aberrant obturator vessels, as well as vessels associated with the ureter, vasa, seminal vesicles, peri-renal fat, peritoneum and peri-adrenal tissue. Vessels >7mm in diameter, such as the renal artery, were ligated. No additional clips or sutures were required to secure any vessels <7mm in diameter. During three nephrectomies the renal vessels were successfully sealed and divided using the LigaSure device, but were subsequently ligated following the manufacturer's recommendations. The authors reported a significant reduction in intraoperative blood loss and operation time with LigaSure in open radical prostatectomy.[24]
Postoperatively, there were no instances of haemorrhage, lymph leakage or lymphocele formation. The authors concluded that the VSD is safe and easy to use in major urological procedures. They also reported that some structures (e.g. the vas and the seminal vesicle) are difficult to control using clips because of their friability and poor access. The LigaSure device allowed them to seal these structures with much greater ease. Given the limited lateral thermal damage, they successfully used the device next to the iliac veins and the inferior vena cava. The device performed well even in the presence of blood or urine, as distinct from conventional diathermy. Leonardo et al compared the effectiveness of the LigaSure Atlas system with earlier methods in 30 patients affected by clinically localised renalcell carcinoma who underwent transperitoneal laparoscopic radical nephrectomy with a threetrocar technique. They found no conversion in
either group. Statistically significant differences were observed between conventional and LigaSure nephrectomy regarding mean intraoperative blood loss (485 vs 100ml, respectively; p <0.005) and mean operative time (164 vs 68 minutes, respectively; p <0.05). No statistical difference was observed in the postoperative discharge time25 and no evidence of collateral tissue injury or injuries to the intestinal tract were found.
Kennedy et al used the LigaSure device on the spermatic cord structures and vas while performing a unilateral inguinal orchiectomy.[26] Once  the spermatic cord was identified and dissected free from the vas, it was divided. The spermatic cord and the vas were successfully ligated using the LigaSure Max handset.[26]

Vessel-sealing devices and the preservation of erectile function
The major age and stage shift over the past ten years [27] is confronting urologists with younger patients and lower tumour stages. Still today, radical prostatectomy is accompanied by a high incidence of urinary incontinence (14%) and erectile dysfunction (73%).[28] In younger patients,  erectile dysfunction leads to a significant reduction of quality of life. Hence, the preservation of erectile function and urinary continence are of great medical interest. Multiple surgical approaches have been described to preserve the nerve bundles.[16,29–31] Lateral temperature spread is the major concern using vessel-sealing devices, especially when it comes to operations where nerve sparing is a crucial part of the procedure. Some studies have been published showing that the use of bipolar cautery devices in nerve-sparing radical  prostatectomy (nsRPE) is followed by a higher rate of erectile dysfunction.[32,33] On the other hand, lower blood transfusion rates for nsRPE were reported when modern vessel-sealing devices were used.[34]  Therefore, the use of vessel-sealing devices for nerve-sparing radical prostatectomies is still under debate. Recently, we investigated the lateral thermal spread and the corresponding injury caused by vessel-sealing devices (LigaSure Impact and LigaSure Axs) with regard to radical prostatectomies. To evaluate the precise lateral temperature spread along the musculofascial tissues, we
used an infrared camera, continuous temperature measurement, and histology in an in vitro model. We demonstrated that both vessel-sealing devices have a significant thermal spread of 2.5mm. Our findings suggested that the use of modern vessel-sealing devices for nerve-sparing radical prostatectomy is basically feasible and safe if a distance of 2.5 mm to the nerve is respected. Furthermore, we recommend protecting the nerve-vessel bundle by placing a clamp laterally to the device.[35]

Conclusion
Monopolar, bipolar and vessel-sealing devices are routinely used during many urologic procedures. The newest generation of electrothermal systems, the VSD, shows some significant advantages: it produces a more consistent, permanent seal of veins, arteries and tissue bundles by fusing the collagen in vessel walls. By reducing sutures and the number of instrument exchanges during surgeries, the VSD is a cost-effective tool that can reduce blood loss and save time in surgery. If the surgeon respects the lateral thermal spread, these instruments can be used in proximity to sensitive structures, including nerves.

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