Novel Quantum Molecular Resonance Energy Source for Laparoscopic Bipolar Vessel Sealer: An Experimental Study in Animal Model

Abstract

This study is to evaluate a novel Quantum Molecular Resonance energy device as a laparoscopic bipolar vessel sealer. The majority of conventional bipolar energy-based vessel sealing devices utilize energy at frequencies between 300 kHz and 500 kHz. The use of such frequencies has disadvantages including unintended damage to surrounding tissues and excessive surgical smoke production. Here, we developed a bipolar energy source using Quantum Molecular Resonance (QMR) energy of 4–64 MHz and combined this into a laparoscopic vessel sealer. We investigate the microscopic tissue effect and surgeon’s experiences of the laparoscopic bipolar vessel sealer using a novel QMR energy source through animal experiments. QMR energy sources showed higher sealing success rates (100% vs. 66.7%) and a higher burst pressure (963 mmHg vs. 802 mmHg) of the sealed vessels compared to LigaSure™. Histological analysis showed less vessel wall injury in the QMR energy source (55.0% vs. 73.9%). In the laparoscopic setting experiments, compared to LigaSure™, QMR energy sources showed statistically significantly less smoke formation (p = 0.014), less tissue carbonization (p = 0.013), and less stickiness (p = 0.044) during sealing tissues. A novel QMR energy source for a laparoscopic bipolar vessel sealer could produce a better sealing performance and less surrounding tissue damage.

1. Introduction

The introduction of energy-based vessel sealing technology has facilitated laparoscopic surgery reducing the complexity of surgical procedures. These devices have also enabled the rapid sealing and reliable hemostasis and cutting of blood vessels and tissues during laparoscopic surgery [1].

The majority of conventional bipolar energy-based vessel sealing devices utilize energy at frequencies between 300 kHz and 500 kHz. The use of such frequencies has the disadvantage of a possible energy transfer to a wide area causing unintended damage to surrounding tissues [2]. In the laparoscopic surgical environment, unnecessary energy transference also inevitably produces surgical smoke that compromises the visibility of surgeons and generates sticky binding between the instrument and tissue [3,4].

Strategies using high-frequencies (4–64 MHz) of quantum molecular resonance (QMR) electrical energy have been studied to compensate for these drawbacks. Theoretically, QMR produces energy quanta that are able to break molecular bonds without raising the kinetic energy of the affected molecules. Using these higher frequencies could result in minimizing the gradient of deposited energy, allowing the applied energy to concentrate at the surgeon’s intended sites. By this principle, the QMR energy generator could minimize surrounding tissue damage and maximize tissue ligation. These advantages have already been shown in the use of monopolar instruments in open surgery [5], but have not yet been applied to laparoscopic devices.

Strategies using high frequencies (4–64 MHz) of quantum molecular resonance (QMR) electrical energy have been studied to compensate for these drawbacks. Theoretically, QMR produces energy quanta that are able to break molecular bonds without raising the kinetic energy of the affected molecules. Using these higher frequencies could result in minimizing the gradient of deposited energy, allowing the applied energy to concentrate at the surgeon’s intended sites. By this principle, the QMR energy generator could minimize the surrounding tissue damage and maximize tissue ligation. These advantages have already been shown in the use of monopolar instruments in open surgery [5], but have not yet been applied to laparoscopic devices.

2. Materials and Methods

The two bipolar energy generators, LigaSure™ V Lap System (Valleylab, Boulder, CO, USA) and QMR electrical energy generator, were tested in this study. The laparoscopic jaw of LigaSure™ was used by switching between the two energy generators. The ligation performances, microscopic tissue effects, and surgeon experiences in the laparoscopic environment of each device were evaluated.

2.1. QMR Energy Generator

The carrier frequency of the QMR energy generator was 4 MHz, and the output was composed of a push–pull converter. The output waveform contained the component of the 4 MHz carrier frequency and its harmonic waves. Compared to the spectrum of the 4 MHz component, the intensities of the spectrum of the 8 MHz, 16 MHz, 32 MHz, and 64 MHz components were attenuated by −6 dB, −12 dB, −18 dB, and −24 dB, respectively. The power spectrum of the components higher than 64 MHz was also included, but the intensities were negligibly low.

2.2. Open Surgery Experiment

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Animals and procedures

A total of three abdominal aortas from three adult male rabbits were used. All the rabbits were New Zealand white rabbits (Oryctolagus cuniculus) and all weighed 3.6 kg. Anesthesia was performed using an intramuscular injection of glycopyrrolate (0.01 mg/kg) and intravascular injection of propofol (1.5 mg/kg). Animals were positioned in dorsal recumbency and prepared for aseptic surgery. The abdomen was incised to expose the abdominal aorta. Vascular ligation was performed by applying LigaSure™ or QMR device to the abdominal aortas of the anesthetized rabbits in the distal and proximal directions. A total of 11 ligations was conducted, six times using LigaSure™ and five times using the QMR energy generator.

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Measurements

The outer diameters of the aortas were measured before the ligations. During the ligations, duration to seal and peak temperature of surrounding tissue were measured. While applying energy, all the procedures were recorded using a thermal imaging camera (FLIR-T62101, FLIR Systems, USA), then the stored images were analyzed using a temperature analysis program (FLIR R & D software 3.3, FLIR Systems, Wilsonville, OR, USA). After the ligations, the abdominal aortas of anesthetized rabbits were extracted and subjected to a burst pressure measurement and a histological analysis. Among the three rabbits, burst pressures were measured using the aortas of two rabbits and the other aorta was histologically analyzed. The burst pressure was measured by instilling normal saline into both ends of the vessel lumen. Using a previously described technique [6], pressure was slowly increased until the vessel leaked. Histological analyses were performed on both proximal and distal portions of the sealing site (Figure 1) with an optical microscope (Bx 50, Olympus, Tokyo, Japan). Each sealed vessel was processed for staining with Masson trichrome stain and hematoxylin and eosin stain. Histological analysis was performed on the following items (Figure 2): seal width (width of ligation site), adventitial collagen denaturation (length of denatured collagen in the total collagen surrounding the vascular outer membrane of both ligature sites), wall layer cleavage (portion of the whole blood vessel walls on both sides of the ligation site where layer separation occurred, as indicated by qualitative evaluation), and wall injury (ligation site including the length of the entire vessel wall length of damaged blood vessels, expressed as numerical qualitative value).

2.3. Laparoscopic Surgery: Surgeons’ Experience

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Animals and Laparoscopic simple nephrectomy

Two female pigs (conventional farm pigs weighing 40 kg) were used and underwent bilateral laparoscopic simple nephrectomy. Pigs were pretreated by intramuscular injection of rompun (2 mg/kg) and zoletil (10 mg/kg), intubated, and maintained under general anesthesia using 2.5% enflurane and 100% O₂. Animals were first placed in a left lateral decubitus position, and CO₂ was injected to form a pneumoperitoneum through Veress needle at the umbilical level. A 12 mm camera port was inserted and two 5 mm ports were inserted between the umbilical region below the lateral rib of the camera port and the outside of the anterior superior iliac spine, respectively. CO₂ was injected into the abdominal cavity at a rate of 3–5 L/min, and the intraperitoneal pressure was maintained at 12 mmHg during surgery. After placement of the port, the abdominal organs and fascia were incised, as in conventional procedures of simple nephrectomy, exposing the kidney and renal vessels. Then vascular ligation was performed using randomly selected laparoscopic energy-based device. By dissecting into the pelvic cavity along the lateral part of the colon, the peritoneum and ureters were dissected and ligated with the devices. After left-side laparoscopic nephrectomies, we reversed the position of the pigs and the right side laparoscopic nephrectomies were performed in same manner.

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Measurements

All laparoscopic surgical procedures were recorded and divided into video clips of ligation of three types of tissue (peritoneum, renal vein, and ureter). Six urologic surgeons watched randomly mixed video clips in a single-blind setting and scored each clip according to the evaluation criteria. The surgeons’ experiences of surgical smoke, carbonization, and stickiness of tissue to the device were measured according to the established criteria (

Table 1. Criteria in the surgeon’s experience during laparoscopic surgery.

1. Amount of surgical smoke formation
Grade	Evaluation criteria
0	No smoke formation
1	Mild smoke formation but no visual interference
2	Moderate smoke formation, must be removed to increase visibility
3	Severe smoke formation, difficult to proceed with surgery
2. Tissue carbonization
Grade	Evaluation criteria
0	No carbonization
1	Mild carbonization, brown-colored tissue observed
2	Moderate carbonization, blackened tissue observed
3	Severe carbonization, all tissue is black
3. Stickiness
Grade	Evaluation criteria
1	No stickiness
2	Stick a little but falls off by itself
3	Must be removed by holding the tissue with the opposite hand but involves no tissue damage
4	Sticking caused damage tissue but no bleeding
5	Sticking is severe and produces tissue damage and bleeding when removing the instrument

).

2.4. Statistical Analysis

The groups were compared using Fisher’s exact test for the sealing success rate in open surgery experiments and chi-square test for histological analysis. Student’s t-test for reported grades of the surgeon’s experience (surgical smoke formation, tissue carbonization, and tissue stickiness). Statistical analyses were performed using SPSS^® (version 21.0, SPSS Inc., Chicago, IL, USA). All p-values were two-sided, and p < 0.05 was considered statistically significant.

3. Results

In the open surgical experiments, the parameters measured in the experiment did not show statistically significant differences between the two devices (

Table 2. Evaluated parameters and histological analysis for ligated aortas.

	LigaSure™	QMR Energy Source	p
Vessel width (mm)	3.08 ± 0.20	2.90 ± 0.37	0.657
Time to seal (s)	4.00 ± 0.45	5.00 ± 0.00	0.076
Sealing success rate	66.7% (4/6)	100.0% (5/5)	0.455
Temperature (°C)	73.68 ± 1.28	79.30 ± 3.92	0.174
Burst pressure (mmHg)	802.00 ± 0.00	963.00 ± 3.00	-
Seal width (mm)	1.92 ± 0.07	1.98 ± 0.25	0.593
Collagen denaturation (mm)	1.60 ± 0.47	1.36 ± 0.16	0.264
Wall layer cleavage (%)	30.00 ± 22.80	20.00 ± 15.49	0.395
Wall injury (%)	73.87 ± 16.93	54.98 ± 16.16	0.076

). The success rate of the ligation of the rabbit aorta was 100% in QMR energy generators and 66.67% in LigaSure™. The LigaSure™ demonstrated a mean temperature of the surrounding tissue which was about five degrees lower (73.68 °C) compared to the QMR energy generator (79.30 °C). In comparing the estimated sealing stability using burst pressure, the QMR energy generator showed a higher burst pressure (963 mmHg) than LigaSure™ (802 mmHg). The mean sealing width of the ligated vessels using the LigaSure™ and QMR energy generator was 1.92 mm and 1.98 mm, respectively. In microscopic analysis, less collagen denaturation and wall layer cleavage was noted when using a QMR energy generator compared to LigaSure™ (1.36 mm vs. 1.60 mm, 20.0% vs. 30.0%, respectively). Additionally, less wall injury was identified when using a QMR energy generator compared to LigaSure™ (54.98% vs. 73.87%).

In the laparoscopic surgical experiments, a total of 26 video clips that contain the sealing moments of the peritoneum, vessel (renal vein), and ureter was obtained. Regarding the formation of surgical smoke (

Table 3. Evaluated Parameters in the surgeon’s experience of Laparoscopic nephrectomy.

	Peritoneum			Vessel			Ureter
	LigaSure™ (n = 42)	QMR (n = 42)	p	LigaSure™ (n = 24)	QMR (n = 18)	p	LigaSure™ (n = 18)	QMR (n = 12)	p
Surgical smoke formation	1.29 ± 0.60	0.98 ± 0.64	0.025	1.83 ± 0.64	1.28 ± 0.75	0.013	1.11 ± 0.58	1.00 ± 0.00	0.430
Tissue carbonization	1.45 ± 0.63	1.17 ± 0.38	0.014	2.00 ± 0.89	1.56 ± 0.92	0.121	1.72 ± 0.75	1.33 ± 0.78	0.182
Stickiness	2.21 ± 0.93	1.83 ± 0.70	0.036	2.38 ± 1.17	1.78 ± 0.88	0.078	3.28 ± 1.45	2.25 ± 1.06	0.044

), the surgeons reported significantly less surgical smoke production when using the QMR energy generator to the peritoneum and vessels compared to LigaSure™ (p = 0.025 and p = 0.013, respectively). In the tissue carbonization parameter, the QMR energy generator showed a significantly favorable outcome when dissecting the peritoneum (p = 0.014). The use of the QMR energy generator to seal and cut the peritoneum and ureter showed that it was significantly less likely to stick to the instrument compared to LigaSure™ (p = 0.036 and p = 0.044, respectively).

4. Discussion

The use of electrosurgical instruments in laparoscopic surgeries facilitates the reliable and rapid sealing of blood vessels and tissues [7]. Previously, laparoscopic energy-based devices with various sealing mechanisms, including bipolar electric current (e.g., LigaSure™), ultrasonic energy (e.g., Harmonic Scalpel™), and nanotechnology (e.g., EnSeal PTC™) have been studied. It has been reported that devices using bipolar electric current have the highest burst pressure and shortest sealing time [6]. Bipolar electrical energy melts collagen and elastin within the tissue bundles, forming a durable seal. Unlike the circuits of a monopolar surgical system, the advantage of the bipolar energy system is a more controlled spread of energy since it is only transmitted between the jaws of an instrument [8]. However, current technologies still present limitations, such as collateral tissue damage and surgical smoke generation [3,4,9].

A previous report of the application of a QMR energy generator into monopolar surgical devices demonstrated favorable tissue effects in both short-term and long-term animal studies [5]. The studies suggested that when using QMR, specific wave forms at high-frequencies (4–64 MHz) transmitted to the tissue into the quanta, which disrupts the molecular bonds of the tissue without causing damage to the surrounding tissue [10,11]. Further research in molecular cell biological effects of QMR has been conducted in more recent studies as well. Researchers reported the upregulation of vascular endothelial growth factor expression in chronic wounds treated by QMR technology [12]. Another study suggested that the QMR stimulation could trigger the angiogenesis and tissue regeneration of human mesenchymal stromal cells [13].

In this present study, we combined the QMR energy generator with the bipolar laparoscopic instrument and developed a novel laparoscopic sealing energy generator using a frequency of 4 MHz, which is 10 times higher than that of conventional instruments. As for the relationship between the output power and impedance of our QMR energy generator, the estimated impedance to the bipolar electrode before applying energy was approximately 100 ohm, and as the application of energy increased, the impedance increased to 200 to 300 ohm. Impedance appears different depending on the type of tissue, and the degree of coagulation appears different even when the same energy is applied. It was difficult to access the degree of coagulation based on the impedance value alone, therefore, experiments in various tissues were required.

Our animal experiments successfully demonstrated that a laparoscopic bipolar vessel sealer using a QMR energy generator showed both more favorable histological change and better surgeon’s experience in a real laparoscopic environment compared to a conventional laparoscopic bipolar device (LigaSure™). In our open surgical experiment with aortas of living rabbits, although the parameters measured in the experiment did not show a statistically significant difference between the two instruments, the QMR energy generator showed more favorable results for all parameters except for the temperature of the surrounding tissue. During laparoscopic nephrectomies with an actual laparoscopic setting in pigs, the QMR energy generator produced an effective performance with a more favorable surgeon experience in the investigated parameters of surgical smoke, the carbonization of tissue, and stickiness to the instruments. The smoother coagulation and cutting of tissues were not a measurement criteria in this study, however, the surgeons who performed the operations had smoother experiences in the above two process with the QMR energy generator compared to the conventional device. For this characteristic, it is considered that clinical studies involving more surgeons are needed in the future.

There were several limitations to our study. First, our results were based on experiments using two species of animal. Thus, though the surgical environment was the same as in human surgery, the results may not be directly transferable to humans. Second, in the laparoscopic experiment, we used the jaw of the LigaSure™ connected to the QMR energy generator. The feedback-controlled response system of LigaSure™, which automatically discontinues the energy delivery when the seal cycle is complete, has not been applied to the QMR energy generator. However, the use of the same jaw as a controlled variable has enabled the objective comparison of the two energy generators. Furthermore, the QMR energy generator results have shown a more favorable performance without a feedback-controlled system in this study. This suggests that utilizing a novel QMR may demonstrate the excellence of the energy generator.

5. Conclusions

Novel bipolar QMR energy generators for laparoscopic surgery could produce at least an equivalent or better sealing performance and less surrounding tissue damage than LigaSure™. Laparoscopic surgery using QMR energy generators show significantly improved surgeon experience in terms of surgical smoke formation, tissue carbonization, and stickiness in animal experiment.