UPDATE ON TECHNOLOGY: VESSEL-SEALING DEVICES
This overview of vessel-sealing devices for laparoscopic procedures should help you select a system that meets the particular needs of your practice
IN THIS ARTICLE
When Harry Reich performed the first laparoscopically assisted vaginal hysterectomy in 1989, he advocated the use of sutures for control of the uterine vessels. Monopolar, bipolar, and laser instruments available at that time were inherently risky to use along the pelvic sidewall because of their potential for 1) considerable thermal energy spread beyond the area of treatment (bipolar, NG:YAG laser, monopolar) and 2) unreliable hemostasis (CO2 laser).
Minimally invasive surgical practice has driven meaningful advances in instrumentation and technique over the past 20 years. The constraints inherent in laparoscopic surgery, although somewhat mitigated by robotics, have generated a proliferation of technologies to obtain reliable hemostasis. Every device now on the market claims to “seal” vessels. In this article, I review the mechanism of action of these instruments and compare their strengths and weaknesses, based on high-quality scientific evidence.
Two studies highlight vessel ligation
Newcomb WL, Hope WW, Schmeizer TM, et al. Comparison of blood vessel sealing among new electrosurgical and ultrasonic devices. Surg Endosc. 2009;23:90–96.
Lamberton GR, Hsi RS, Jin DH, et al. Prospective comparison of four laparoscopic vessel ligation devices. J Endourol. 2008;22:2307–2312.
Many energy-delivery systems are available for the gynecologic surgeon; any of them can be used effectively and safely under most circumstances. Before we can make an informed choice about which system is best for our own practice, however, we need to be aware of the strengths and limitations of the systems overall ( TABLE ).
These two studies focus on the following devices:
- Gyrus PK Tissue Management System, PKS Cutting Forceps, and Plasma Trissector (all from Gyrus Medical). These are bipolar electrosurgical devices designed to deliver high current and very low voltage to tissue. Tissue impedance is continuously monitored between the jaws of the instrument, and energy delivery is adjusted accordingly. These systems deliver electrosurgical energy through a series of rapid pulses, thereby allowing the tissue to cool briefly and limiting the heating of adjacent tissue. Protein in the vessel walls is denatured and forms a coagulum, which occludes the lumen.
- Harmonic Scalpel (Ethicon EndoSurgery). This device uses a high-frequency ultrasonic transducer (55,000 cycles/second) to create mechanical vibration of one of the two jaws. The device can be used to vaporize tissue (cut) or achieve hemostasis by coagulation. As with the other devices, protein is denatured and vessels are occluded by formation of a coagulum.
- Ligamax 5 Endoscopic Multiple Clip Applier (Ethicon). This device is a sterile, single-patient-use, 5-mm, endoscopic, multiple-clip applicator that delivers 15 medium or large titanium clips that close to 8.8 mm, the same clip size as the 10-mm applicator. Ligamax 5 has long, thin angled jaws (8.4 mm) that extend beyond vessels and ducts to improve visibility. It includes a long, 33-cm shaft for additional reach, and an anti-clip drop-ratchet mechanism for control over clip closure.
- EnSeal Tissue Sealing and Hemostasis System and EnSeal PTC (SurgRx). EnSeal utilizes nanotechnology to control the energy at the electrode–tissue interface. The jaws contain a temperature-sensitive matrix with embedded conductive carbon spherules designed to “sense” tissue characteristics. It uses extremely high jaw compression to create uniform tissue effects. It does not require a dedicated electrosurgical unit for use; an adapter can be purchased that permits use with most generators.
- LigaSure V (Valleylab). LigaSure is a bipolar electrosurgical device designed to deliver high current and very low voltage to tissue. It monitors tissue impedance between the jaws of the instrument and continuously adjusts the delivery of energy.
Rating vessel-sealing devices: 5 measures of success
Safety: Minimal thermal spread
Reliability: Efficacy on vessels ≤7 mm
Efficiency: Treatment time
Consistency: Independent of user
Utility: Multiple uses
These ratings were devised by the author based on data from independent studies in living tissue models.
FIGURE How energy-based vessel-sealing works
(A) When the carotid artery of an animal model was sealed using a standard bipolar forceps, the lumen remained open and a proximal thrombus developed. (B) When LigaSure was used, the artery was fused and the lumen obliterated with one 5-second application. (C and D) When a renal artery was sealed with LigaSure, the lumen of the vessel walls fused completely.
What the studies found
Newcomb and associates compared blood-vessel-sealing ability of the following devices:
- Gyrus 5-mm PKS Cutting Forceps
- Gyrus Plasma Trissector
- Harmonic Scalpel
- EnSeal Tissue Sealing and Hemostasis System
- LigaSure V, using the LigaSure Generator (Valleylab)
- LigaSure V, using the Force Triad Generator (Valleylab)
- Ligamax 5 Endoscopic Multiple Clip Applier.
The authors assessed mean seal times and burst pressures. Used on medium and large vessels, the Harmonic Scalpel and Gyrus products had significant failure rates: 8% to 22% for the Harmonic Scalpel and 41% to 92% for the pulsed, bipolar Gyrus systems.
The shortest sealing times for medium to large vessels were achieved with the LigaSure V using the Force Triad Generator. The Gyrus systems were the fastest devices when vessels were 2 to 3 mm in diameter.
There were no seal failures with the Ligamax, EnSeal, or LigaSure products.
Second study involved repeated applications
Lamberton and colleagues tested 5-mm laparoscopic devices under controlled temperature and humidity using a laparoscopic simulator, focusing on the following systems:
- LigaSure V
- Gyrus PK
- Harmonic Scalpel
- EnSeal Tissue Sealing and Hemostasis System.
The authors used 5-mm bovine arteries to assess sealing time, burst pressure, lateral thermal spread, and smoke production, as well as both subjective and objective effects on visibility.
Each device was used 10 times to determine burst pressure, lateral thermal spread, visibility, and smoke production. The devices were applied 20 times to measure time to seal, based on the devices’ preprogrammed endpoints.
The Harmonic Scalpel produced the lowest thermal spread and least smoke, but also had the lowest mean burst pressure.
The Gyrus PK generated the most smoke and had variable burst pressure. Although it had the fastest sealing times, in three of 10 trials there was a completely open arterial lumen following transection. In addition, 50% of applications involved burst pressures below 50 mm Hg.
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Maximum temperatures 2 mm from the device were 49.9°C for the Harmonic Scalpel, 55.5°C for LigaSure, 58.9°C for EnSeal, and 64.5°C for Gyrus PK.
LigaSure was the highest-rated device overall, with the highest burst pressure and fastest sealing time.
EnSeal was the slowest and had variable burst pressures.
Clinical implications of the trials
These studies—neither of which was industry-sponsored—suggest that larger vessels cannot be controlled consistently and effectively using the Harmonic Scalpel or Gyrus systems. The Harmonic Scalpel is most user-dependent.
So what’s the bottom line? In the end, according to Andrew Brill, MD, past president of AAGL, “it’s not the wand, it’s the magician.”
Experts talk about how they choose an energy source
for laparoscopic surgery
When OBG Management surveyed a number of laparoscopic experts and members of our Virtual Board of Editors about their preferred energy sources for laparoscopic surgery, the responses were strikingly similar. The consensus? The best device depends on the case at hand, the skill of the surgeon, economic concerns, and other variables.
As Keith Isaacson, MD, put it, “Because tissue may be thick or thin, moist or desiccated, vascular or avascular, the ideal instrument to achieve a pure cut varies. Because a vessel may be large or small, contain a large amount of collagen or very little collagen, or be on tension or relaxed, the ideal instrument for vessel sealing also varies, depending on the surgical situation.”
All of the devices are roughly equivalent, he added. “Fortunately, almost all of the commercially available energy sources that utilize bipolar radiofrequency or ultrasonic energy will perform our desired function if the surgeon understands the technology and utilizes the instruments properly.”
Here is a summary of recommendations made by the experts we interviewed.
Andrew I. Brill, MD
Director of Minimally Invasive Gynecology,
California Pacific Medical Center,
San Francisco, Calif
Having been actively engaged in advanced laparoscopic surgical training for more than 20 years, I have extensive experience with all of these novel devices. I critically assess any new energy-based device for its ergonomic handedness, propensity for sticking to tissue and production of plume, ability to manipulate and dissect tissue, efficiency in desiccated or fatty tissues, discoloration of tissue by carbon, response to tissue tension, and reliability for hemostasis. Because no device is perfectly suited to all procedures, I customarily rely upon several devices to satisfy my technical needs.
All advanced bipolar energy devices—LigaSure, PK Cutting Forceps, and EnSeal—can be safely used to coagulate and cut all vascular pedicles during hysterectomy and salpingo-oophorectomy. These devices perform best when tissue tension is reduced to maximize vessel sealing. Despite the fact that these devices provide audible feedback to signal the electrosurgical endpoint, I also gauge tissue color, retraction, and the emission of steam before advancing the cutting blade.
The tapered-tip design of the PK Cutting Forceps offers some comparative advantage for fine tissue dissection, but I find that hemostasis is more consistently achieved with less thermal spread using the EnSeal or LigaSure device.
I commonly utilize the Harmonic Scalpel in lieu of any electrosurgical device, understanding that it requires more finesse to achieve equivalent results.
When I anticipate that I will need to manipulate uterine pedicles during a difficult laparoscopic hysterectomy, I employ electrosurgery using the EnSeal device for its superior tissue sealing. A 3-mm curved device by EnSeal, akin to a Pean clamp, works as an exceptionally agile instrument for hysterectomy without sacrificing hemostasis.
Only the LigaSure Advance provides both coaptive coagulation and spark cutting via an electrode on the tip of one blade; therefore, an adjunctive mechanical or energy-based device must be employed to perform culdotomy during total laparoscopic hysterectomy when EnSeal or the PK Cutting Forceps is used.
The ability to efficiently and hemostatically cut through tissue of variable mass with minimal plume, predictable thermal margins, and the retention of tissue color make the Harmonic Scalpel my first choice for laparoscopic resection of endometriosis, extensive adhesiolysis, myomectomy, cervical amputation during supracervical hysterectomy, and culdotomy during total hysterectomy. Although I have similarly utilized the unique capacity of the spatula, J-hook, and needle electrodes by Plasmacision (Gyrus) to cut tissue using bipolar electrosurgery, all have afforded less technical control, not as much hemostasis, and wider thermal margins.
Use of any energy-based device does not preclude the need for skill. Before adding any of these devices to your surgical armamentarium, appropriate training should be acquired in a skills lab using living tissue or with a laparoscopic trainer using a tissue surrogate.
Dr. Brill reports no financial relationships relevant to this review.
Jon I. Einarsson, MD, MPH
Director of Minimally Invasive Gynecologic Surgery,
Brigham and Women’s Hospital,
Assistant Professor of Obstetrics,
Gynecology, and Reproductive Biology,