Proximity injury by the ultrasonically activated scalpel during dissection

Development and evaluation of a titanium-based planar ultrasonic scalpel for precision surgery

This paper introduces a titanium-based planar ultrasonic microscalpel. The concept of silicon-based planar ultrasonic transducers has already been proven, but they are not yet suitable for clinical use due to material failure. The main objective of this work was to develop a smaller, lighter, and more cost-effective ultrasonic scalpel that could be used as an alternative or supplementary device to current surgical instruments. Various prototypes were fabricated and characterized, differing in bonding by three epoxy adhesives and two solder pastes as well as three variations in tip design. The instruments were designed to operate in the frequency range of commercial instruments and to generate a longitudinal displacement amplitude. The electro-mechanical characterization through impedance analysis and vibration measurements was complemented by an in vitro cutting trial and an acute in vivo animal experiment in comparison to commercial ultrasonic and electrosurgical devices. The operating frequency was around 40 kHz and 48 kHz depending on whether matched or unmatched operation was used. Unmatched operation turned out to be more suitable, achieving displacement amplitudes of 25.3 μm and associated velocity amplitudes of up to 7.9 m/s at an electrical power of 10.2 W. The cutting ability was demonstrated in vivo by successful dissection even under anticoagulation. The geometry of the instrument tip was found to have a major influence on cutting performance by affecting the resonance behaviour and tissue penetration.

Learning by doing: an observational study of the learning curve for ultrasonic fundus-first dissection in elective cholecystectomy

BACKGROUND

Surgical safety and patient-related outcomes are important considerations when introducing new surgical techniques. Studies about the learning curves for different surgical procedures are sparse. The aim of this observational study was to evaluate the learning curve for ultrasonic fundus-first (FF) dissection in elective laparoscopic cholecystectomy (LC).

METHODS

The study was conducted at eight hospitals in Sweden between 2017 and 2019. The primary endpoint was dissection time, with secondary endpoints being intra- and postoperative complication rates and the surgeon's self-assessed performance level. Participating surgeons (n = 16) were residents or specialists who performed LC individually but who had no previous experience in ultrasonic FF dissection. Each surgeon performed fifteen procedures. Video recordings from five of the procedures were analysed by two external surgeons. Patient characteristics and data on complications were retrieved from the Swedish Registry of Gallstone Surgery and Endoscopic Retrograde Cholangiopancreatography (GallRiks).

RESULTS

Dissection time decreased as experience increased (p = 0.001). Surgeons with limited experience showed more rapid progress. The overall complication rate was 14 (5.8%), including 3 (1.3%) potentially technique-related complications. Video assessment scores showed no correlation with the number of procedures performed. The self-assessed performance level was rated lower when the operation was more complicated (p < 0.001).

CONCLUSIONS

Our results show that dissection time decreased with increasing experience. Most surgeons identified both favourable and unfavourable aspects of the ultrasonic FF technique. The ultrasonic device is considered well suited for gallbladder surgery, but most participating surgeons preferred to dissect the gallbladder the traditional way, beginning in the triangle of Calot. Nevertheless, LC with ultrasonic FF dissection can be considered easy to learn with a low complication rate during the initial learning curve, for both residents and specialists.

Repeated partial tissue bite with inadequate cooling time for an energy device may cause thermal injury

BACKGROUND

Over the past three decades, the use of ultrasonically activated device (USAD) and advanced bipolar device (ABD) has grown in minimally invasive surgeries. However, the thermal profile differences during repeated dissection with different grasping ranges of energy devices, which provide valuable information for preventing thermal injury by energy devices, remain unclear.

METHODS

We developed an ex vivo benchtop model to examine the temperature profile of the blade and jaws of two USADs (HARMONIC® ACE + and Sonicision™) and a ABD (Ligasure™ Maryland) with different grasping ranges (partial tissue and full tissue bite) in repeated dissection with minimum cooling time. The maximum temperature, time required for completion to dissection of 10 cm of porcine muscle, thermal spread, and cooling time to reach 60 °C were continuously measured using video thermography. In addition, to evaluate one more grasping range "no tissue", we performed a stress test that activated the USAD without tissue intervention to assess the effects of excessive load on the blade and jaw.

RESULTS

Repeated dissection of energy devices with minimal cooling time results in high blade and jaw temperatures proportional to the incision distance. In particular, the USADs with partial tissue bite showed a significantly higher temperatures at the blade and jaw, longer cooling times, and higher lateral thermal spread than those with a full tissue bite and the ABD. The stress test with a USAD showed an extremely high blade temperature exceeding 400 °C, with the tissue pad melting only 13.2 s after activation.

CONCLUSION

Although USAD with partial tissue bite help ensure precise dissection, repeated long activation with inadequate cooling time may increase the risk of thermal injury during surgery. These results suggest that surgeons should use energy devices properly while understanding the risks of adjacent organ damage that could result from abuse of the device.

Ultrasonic versus monopolar energy-based surgical devices in terms of surgical smoke and lateral thermal damage (ULMOST): a randomized controlled trial

BACKGROUND

The purpose of this study was to compare the degree of surgical smoke or vapor and lateral thermal damage caused by two different energy-based surgical devices (ESDs) used in colpotomy during total laparoscopic hysterectomy.

METHODS

Patients undergoing laparoscopic hysterectomy were randomly assigned to an ultrasonic ESD group (n = 20) or monopolar ESD group (n = 20). Colpotomy was performed using the assigned ESD. The degree of surgical smoke or vapor obstructing the laparoscopic view was assessed by two independent reviewers using a 5-point Likert scale, in which a higher score indicates worse visibility. The degree of the lateral thermal damage was measured as the width from the point of instrument application to the margins of the unchanged nearby tissue using a light microscope.

RESULTS

The baseline characteristics did not statistically differ between the two groups. The degree of surgical smoke or vapor obstructing vision was 1.2 ± 0.8 points in the ultrasonic group and 3.9 ± 0.7 points in the monopolar groups (p < 0.001). The lateral thermal damage was significantly increased in the monopolar group compared to in the ultrasound group (1500 µm [1200-2500 µm] vs. 950 µm [650-1725 µm], p = 0.037).

CONCLUSION

Ultrasonic ESD had better laparoscopic visibility and caused less lateral thermal damage during colpotomy compared to monopolar device.

Surgical Efficacy Among Laparoscopic Ultrasonic Dissectors: Are We Advancing Safely? A Review of Literature

The specialty of laparoscopy has evolved with the advent of new technologies over the last few years. Energy-based devices and Ultrasonic dissectors are used with a lot of factors in play-including ergonomics and economics during surgery. Here an attempt is based to review the surgical efficacy and safety of these dissectors with importance to plume production and lateral thermal damage. The factors contributing to adversities to the dissectors are also to be noted. The strategy adopted was aimed at finding relevant studies from PubMed from 1995 to 2014. The basic principle of plume production and thermal damage are studied in this review. Factors contributing to the same that can lead to adversities during laparoscopic surgeries are identified. Summarizing key points that increase lateral thermal damage and plume production amongst different ultrasonic shears and suggesting a technique to identify the right balance between the existing dissectors was possible. The RF Device and USS are both useful and widely used and are more safer than monopolar devices. RF Device is considerably slower than USS, as it cannot achieve coagulation and cutting at the same time. Although USS definitely improvises dissection and has less thermal injury than RF Device, the clinical implications in balancing dissection efficacy with hemostasis need to be investigated further. The ideal haemostatic energy-based shear device would be one with excellent hemostatic results and visual acuity while allowing none or minimal thermal energy escape at the point of application. In our current setting, a combined use of both RF and USS device usage as applied in the particular situations has potential.

Ultrasonic dissection versus conventional electrocautery during gastrectomy for gastric cancer: a meta-analysis of randomized controlled trials

OBJECTIVE

Use of ultrasonic surgical instrument is gaining popularity for dissection and coagulation in open surgery. However, there is still no consensus on the efficacy and safety of its use compared with conventional surgical technique in open gastrectomy for gastric cancer. The aim of this meta-analysis was to evaluate the role and surgical outcomes of ultrasonic dissection (UD) compared with conventional electrocautery (EC).

METHODS

A systematic literature search was performed to identify all studies comparing UD and EC in gastric cancer surgery. Intraoperative and postoperative outcomes were compared using weighted mean differences (WMDs) and odds ratios (ORs).

RESULTS

Five studies were included in this meta-analysis, comprising 489 patients. Meta-analysis results showed that compared with EC, UD was associated with significantly shorter operation time (P = 0.03), less intraoperative blood loss (P = 0.002), lower morbidity (P = 0.02), and reduced postoperative hospital stay (P = 0.03). However, there was no significant difference between the two surgical techniques with regards to postoperative abdominal drainage (P = 0.17), and total cost in hospital (P = 0.59).

CONCLUSIONS

Compared to EC, the use of UD during open gastrectomy can provide several improved outcomes for operation time, intraoperative blood loss, overall morbidity, and postoperative hospital stay. It appears that UD can be used instead of conventional EC in open gastric cancer surgery, although more larger trials with long follow-up should be performed.

Evaluation of emissivity and temperature profile of laparoscopic ultrasonic devices (blades and passive jaws)

OBJECTIVES

We examined the emissivity and temperature profile of passive and active jaws of various laparoscopic ultrasonic devices during cutting, coagulation, and cooling time.

METHODS

The Harmonic ACE™ (ACE), Covidien Sonicision™ (SNC), and Olympus SonoSurg™ (SS) were applied using pre-set factory cutting and coagulation settings to Bovine mesentery and Lamb renal veins, respectively. The maximum temperature and cooling time to reach 60 °C were recorded using an infrared Fluke Ti55 thermal imager. Histological examination was evaluated after application of energy.

RESULTS

The ACE, Sonicision, and SonoSurg had emissivity measurements of 0.49 ± 0.01, 0.40 ± 0.00, and 0.39 ± 0.01, respectively. Maximum cutting temperatures were: ACE = 191.1°, SNC = 227.1°, and SNS 184.8° * (*p < 0.001). Maximum coagulation temperatures did not differ significantly among devices (p = 0.490). The cooling time to reach 60 °C after activation were 35.7 s (ACE), 38.7 s (SNC), and 27.4 s* (SS) (*p < 0.001). The cooling time of passive jaws to reach 60 °C after activation were 25.4 s* (ACE), 5.7 s (SNC), and 15.4 s (SS) (*p < 0.001).

CONCLUSION

Laparoscopic ultrasonic instruments obtain the same cutting and coagulation objectives but in different manners. The Sonicision improves cutting by getting the blade hotter while the SonoSurg has more precise coagulation effects by heating slower. Emissivity values varied among instruments, providing equally varied results. Depending on the purpose of the devices, a certain device may be more appropriate. Based on emissivity, more studies are needed to identify the ideal material that can predictably and effectively perform in clinical settings. Although different blade geometry is apparent between instruments, the jaws are also designed differently between the generations of instruments.

Common uses and cited complications of energy in surgery

BACKGROUND

Instruments that apply energy to cut, coagulate, and dissect tissue with minimal bleeding facilitate surgery. The improper use of energy devices may increase patient morbidity and mortality. The current article reviews various energy sources in terms of their common uses and safe practices.

METHODS

For the purpose of this review, a general search was conducted through NCBI, SpringerLink, and Google. Articles describing laparoscopic or minimally invasive surgeries using single or multiple energy sources are considered, as are articles comparing various commercial energy devices in laboratory settings. Keywords, such as laparoscopy, energy, laser, electrosurgery, monopolar, bipolar, harmonic, ultrasonic, cryosurgery, argon beam, laser, complications, and death were used in the search.

RESULTS

A review of the literature shows that the performance of the energy devices depends upon the type of procedure. There is no consensus as to which device is optimal for a given procedure. The technical skill level of the surgeon and the knowledge about the devices are both important factors in deciding safe outcomes.

CONCLUSIONS

As new energy devices enter the market increases, surgeons should be aware of their indicated use in laparoscopic, endoscopic, and open surgery.

Comparison of lateral thermal damage of the human peritoneum using monopolar diathermy, Harmonic scalpel and LigaSure

BACKGROUND

New hemostatic technologies are often employed in open and laparoscopic surgery to reduce duration of surgery and complications. Monopolar diathermy, Harmonic scalpel and LigaSure are routinely used in open and laparoscopic surgery for tissue cutting and hemostasis. We compared lateral thermal damage following in vivo application of 3 commonly used instruments.

METHODS

We used monopolar diathermy, Harmonic scalpel and LigaSure to coagulate and divide the peritoneum of patients who underwent median laparotomy. After anesthesia, median supraumbilical laparotomy was performed, and the peritoneum of each patient was coagulated using different devices. Using light microscopy and morphometric imaging analysis, the width of tissue lateral thermal damage was measured from the point of the peritoneal incision.

RESULTS

We included 100 patients in our study. After a peritoneal incision, the mean lateral thermal damage of monopolar diathermy, Harmonic scalpel (output power 3), Harmonic scalpel (output power 5) and LigaSure were 215.79 μm, 90.42 μm, 127.48 μm and 144.18 μm, respectively.

CONCLUSION

The degree of lateral thermal spread varied by instrument type, power setting and application time. LigaSure and Harmonic scalpel were the safest and most efficient methods of tissue coagulation. Monopolar diathermy resulted in the greatest degree of thermal damage in tissues.

The effects of ultrasonic and electrosurgery devices on nerve physiology

BACKGROUND

While the risks associated with the use of electrosurgery near nerves are well known, few studies have examined the neurophysiologic effects of application of the Harmonic Blade, an ultrasonic scalpel, in the vicinity of nerve fibres. This study sought to compare the sub-acute neurophysiologic effects of the Harmonic Blade and electrosurgery after incisions close to the sciatic nerve.

METHODS

Incisions were made in rats with the Harmonic Blade and electrosurgery at distances of 1, 2, 3 and 4 mm from the sciatic nerve. Sham surgery was also performed. The compound action potential, conduction velocity and calibrated nylon filament (von Frey hair, VFH) stimulating force were monitored for up to 3 hours after surgery. The sciatic nerve was assessed for inflammation via H&E staining and impaired axonal transport by β-APP immunohistochemistry.

RESULTS

Electrosurgery incisions produced a significantly greater decrease in compound action potential and conduction velocity, and increase in the VFH force than the Harmonic Blade over all time points and distances from the sciatic nerve. The Harmonic Blade was similar to sham surgery for the compound action potential and VFH force. Electrosurgery yielded significantly greater leukocyte infiltration than the Harmonic Blade and produced the highest levels of β-APP immunoreactive swellings.

CONCLUSIONS

Incisions with electrosurgery in the range of 1-4 mm of the sciatic nerve caused substantial changes in neurophysiologic functioning and inflammation. In contrast, the Harmonic Blade was similar to sham surgery in the vicinity of the nerve, producing little observable acute trauma.

Tissue damage with different surgical techniques in a porcine model of liver resection: implications for living-donor liver transplantation?

Background/purpose

For living-donor liver transplantation (LDLT) it is of paramount importance to preserve as much viable liver tissue as possible to avoid postoperative complications in the donor and recipient. The depth of tissue damage caused by common surgical techniques for liver resection has not been studied so far.

Methods

Here we compared the depth of tissue damage and the immunohistochemical expression of heat shock protein (HSP) 70, a marker for tissue damage, in a porcine model of liver resection, to assess the effect of different surgical techniques, i.e., blunt dissection (BD), and dissection with an ultrasound aspirator (UA), an ultrasound scalpel (US), or a water-jet (WJ).

Results

Analysis with linear mixed effects models (LME) showed significantly less tissue damage with BD and UA than with US and WJ (joint p value <0.001). Damage also increased within 6 h after surgery (p value = 0.004). Semiquantitative evaluation of HSP 70 showed increased expression after resection with US compared to all other resection methods (p value <0.001), indicating increased tissue damage with this method.

Conclusion

We suggest that in cases of liver resection for LDLT surgeons should reevaluate using US and WJ because of possible excessive tissue damage compared to BD and UA. Overall we advocate the use of BD as it requires no special equipment and, hence, has considerably higher cost-effectiveness without compromising tissue preservation and clinical outcome and is readily available even in low-tech environments.

Safe use of ultrasonically activated devices based on current studies

Ultrasonically activated devices (USADs) are a widely used alternative to suture ligation and clips in open and laparoscopic surgery because of their fast and easy control of bleeding without significant complications. By inducing protein denaturation and forming coaptive coagulation to seal vessels for cutting tissue, USADs result in reduced operating time, blood loss and hospital stay. Recently, various other types of vessel sealers have become available. In this article, we summarize the mechanism, efficacy and the advantages and disadvantages of USADs for appropriate use in surgery.

An animal model for assessment of heat distribution and neural damage around the endo shears coagulation device-applications for laparoscopic nerve-sparing surgery

BACKGROUND AND PURPOSE

Current urologic laparoscopic procedures include preservation of locoregional nerve fibers. The use of electrical coagulation is limited because of tissue conductance of current and heat production. While ultrasonic coagulation does not use electricity, heat is still produced. We designed an animal model to characterize the heat spread around ultrasonic devices and assess whether it is neurodestructive.

MATERIALS AND METHODS

10 rats were anesthetized; their skin was reflected, exposing the muscles. An ultrasonic probe was introduced into the tissue, and coagulation was performed for 10 seconds. Tissue temperature was measured using four thermocouples, at distances of 4, 8, 12, and 16 mm from the probes and in a circumferential manner. Thermal mapping of the probes was performed with an infrared camera. Further, four rats were anesthetized; the skin above their inner thighs was reflected bilaterally exposing the "nervus ischiadicus." Coagulation was performed in varying distances from the nerve on one side while the other served as control. One week later, the animals were sacrificed, and the nerves were obtained. Silver staining was used to assess the vitality of the axons.

RESULTS

In distances of 4 to 8 mm from the device, temperatures as high as 81°C were recorded, and silver staining showed severe axonal damage.

CONCLUSIONS

Although ultrasonic coagulation is efficient, local heat production may reach neurodestructive levels with a typical tissue distribution pattern. These features should be addressed during laparoscopic dissection and when considering nerve-sparing procedures.

Ureteral injury due to a Harmonic scalpel during laparoscopic salpingo-oophorectomy

This report highlights the need for vigilance when using laparoscopic energy sources and suggests surgeons who use the Harmonic scalpel pay close attention to application times during tissue dissection.

We present an unusual complication of a ureteral injury occurring during a bilateral laparoscopic salpingo-oophorectomy with the Harmonic scalpel (HS). The case illustrates in the same patient the versatility of the HS as a laparoscopic surgical instrument and energy source while at the same time demonstrating the potential for adverse, unexpected complications.

Pancreatic injury response is different depending on the method of resecting the parenchyma

OBJECTIVES

The present study was performed to compare the pancreatic injury response on the parenchymal resection either with ultrasonic scissors, electrocautery, or surgical scalpel.

METHODS

A 1 x 0.5 cm piece of rat pancreas was resected from side of the pancreas either with ultrasonic scissors (Harmonic Scalpel; UltraCision, Ethicon Endosurgery Inc., Cincinnati, OH) or electrocautery (Force FX; Valleylab, Tyco Healthcare Group LP, Boulder, CO) at two power levels, 1 and 3; 8W and 25W, respectively, or with surgical scalpel. Hemostasis was provided after surgical scalpel either with cellulose patch (Interceed; Johnson and Johnson Medical, Inc., New Brunswick, NJ), three stitches of 6-0 polydioxanone at tightness of 0.6N or fibrin glue (Tisseel Duo Quick; Baxter AG, Wien, Austria). Blood sample and pancreas specimens, both at the resection site and far away, were taken 1, 7, and 21 days postoperatively from exposed animals, sham operated animals (n = 18 in each) and from unexposed baseline animals (n = 5). Necrosis, edema, leukocyte infiltration, hemorrhage, vacuolization, and fibrosis were histologically assessed separately.

RESULTS

Each resection and sham operation induced similar increase in the amylase activity on day 1 with normalization by day 7. Resection with ultrasonic scissors and electrocautery induced more tissue injury to the pancreas than resection with surgical scalpel independent of the method for hemostasis. The injury, although somewhat milder in intensity, was also observed in parts of the pancreas located far away from the site of resection.

CONCLUSIONS

Of the compared methods, surgical scalpel resection plus cellulose patch or fibrin glue hemostasis induced the least histological changes in the pancreatic parenchyma. This injury response spread over the pancreas.

Temperature safety profile of laparoscopic devices: Harmonic ACE (ACE), Ligasure V (LV), and plasma trisector (PT)

BACKGROUND

Reports of iatrogenic thermal injuries during laparoscopic surgery using new generation vessel-sealing devices, as well as anecdotal reports of hand burn injuries during hand-assisted surgeries, have evoked questions about the temperature safety profile and the cooling properties of these instruments.

METHODS

This study involved video recording of temperatures generated by different instruments (Harmonic ACE [ACE], Ligasure V [LV], and plasma trisector [PT]) applied according the manufacturers' pre-set settings (ACE setting 3; LV 3 bars, and the PT TR2 50W). The video camera used was the infrared Flex Cam Pro directed to three different types of swine tissue: (1) peritoneum (P), (2) mesenteric vessels (MV), and (3) liver (L). Activation and cooling temperature and time were measured for each instrument.

RESULTS

The ACE device produced the highest temperatures (195.9 degrees +/- 14.5 degrees C) when applied against the peritoneum, and they were significantly higher than the other instruments (LV = 96.4 degrees +/- 4.1 degrees C, and PT = 87 degrees +/- 2.2 degrees C). The LV and PT consistently yielded temperatures that were < 100 degrees C independent of type of tissue or "on"/ "off" mode. Conversely, the ACE reached temperatures higher than 200 degrees C, with a surprising surge after the instrument was deactivated. Moreover, temperatures were lower when the ACE was applied against thicker tissue (liver). The LV and PT cooling times were virtually equivalent, but the ACE required almost twice as long to cool.

CONCLUSIONS

The ACE increased the peak temperature after deactivation when applied against thick tissue (liver), and the other instruments inconsistently increased peak temperatures after they were turned off, requiring few seconds to cool down. Moreover, the ACE generated very high temperatures (234.5 degrees C) that could harm adjacent tissue or the surgeon's hand on contact immediately after deactivation. With judicious use, burn injury from these instruments can be prevented during laparoscopic procedures. Because of the high temperatures generated by the ACE device, particular care should be taken when it is used during laparoscopy.

Laparoscopic lymphadenectomy for gynecologic malignancies using ultrasonically activated shears: analysis of first 100 cases

OBJECTIVE

To evaluate the feasibility, safety and utility of the ultrasonic shears for laparoscopic pelvic and para-aortic lymph node retrieval in the treatment of gynecologic cancers.

METHODS

Data on laparoscopic lymphadenectomy performed for gynecologic malignancies using ultrasonic shears over a 5-year period were collected and analyzed prospectively.

RESULTS

Laparoscopic lymphadenectomy using ultrasonic shears was performed on 100 patients with a median age of 58 (17-87) years. The types of malignancies included cervical (n = 29), endometrial (n = 48), ovarian (n = 15), fallopian tube (n = 2), malignant mixed mesodermal tumor (n = 2), vaginal (n = 2) and synchronous ovarian and endometrial cancers (n = 2). Sites of lymphadenectomy included pelvic (n = 49), para-aortic (n = 30) or both pelvic and para-aortic (n = 21). The median nodal yield was 22 (0-87). 66/100 were complete lymphadenectomies with a median nodal yield of 28 (2-71). The median length of hospital stay was 2 (1-13) days and the average blood loss was 148 (0-500) ml. Overall complication rate was 13%. There were 3 intra-operative complications, which were all managed laparoscopically. There were no unplanned conversions to laparotomy. There were 10 post-operative complications including port-site metastasis in a patient with positive nodes (n = 1), trocar-site hernia requiring a second laparoscopy (n = 1), deep leg vein thrombosis (n = 1), and a small bowel obstruction (n = 1).

CONCLUSIONS

This is the largest series to date demonstrating the safety and efficacy of ultrasonic shears in laparoscopic lymphadenectomy for gynecologic malignancies. In addition to the potential for lowering the risk for tissue damage, ultrasonic shears offer multifunctionality which allows for a simpler technique with the use of fewer instruments.

Determination of temperature elevation in tissue during the application of the harmonic scalpel

The temperature elevation in tissue during the application of the harmonic scalpel (UltraCision, operating frequency 55 kHz; Ethicon Endo-Surgery, Norderstedt, Germany) was determined using thermocouples of a specific design. In experiments with and without perfusion, two different scalpel blades were applied to three different kinds of pig tissue (lung parenchyma, tongue, parotid gland) in various configurations. Temperature elevations by more than 40 degrees C were found at 1 mm distance from the blade, whereas at distances of more than 5 mm, perfusion removed the heat very efficiently. The differences in the heating potential of the two blades were small and, at a distance of 2 mm, the temperature elevation did not exceed 6 degrees C at all. In histological investigations, the damaged area between blade and parenchyma was determined. No morphologic indications of thermal damage were found at a distance of more than 2 mm. It is concluded that, during application of the harmonic scalpel, a safety margin of 3 mm from sensitive structures should be kept.

How safe is high-power ultrasonic dissection?

OBJECTIVE

To evaluate the safety of ultrasonic dissection.

SUMMARY BACKGROUND DATA

High-power ultrasonic dissection is in widespread use for both open and laparoscopic operations and is generally perceived to carry a low risk of collateral damage, but there is no published evidence for this.

METHODS

Under controlled experimental conditions, ultrasonic dissections were performed in pigs using Ultracision (Ethicon) or Autosonix (Tyco/USSC) at the three power settings (3, 4, and 5) in random fashion to mobilize the cardia and fundus, bile duct, hepatic artery, portal vein, aorta from the inferior vena cava, renal vessels, colon, and ureters. The dissections (open and laparoscopic) were carried out on pigs at each power setting with each device. Thermal mapping of the tissues during dissection was performed with an infrared thermal camera and associated software. The animals were killed at the end of each experiment and specimens were harvested for quantitative histology.

RESULTS

Extreme and equivalent temperature gradients were generated by ultrasonic dissection with both systems. Heat production was directly proportional to the power setting and the activation time. The core body temperature of the animals after completion of the laparoscopic dissections rose by an average of 2.3 degrees C. The zone around the jaws that exceeded 60 degrees C with continuous ultrasonic dissection for 10 to 15 seconds at level 5 measured 25.3 and 25.7 mm for Ultracision and Autosonix, respectively. At this power setting and an activation time of 15 seconds, the temperature 1.0 cm away from the tips of the instrument exceeded 140 degrees C. Although there was no discernible macroscopic damage, these thermal changes were accompanied by significant histologic injury that extended to the media of large vessels and caused partial- to full-thickness mural damage of the cardia, ureter, and bile duct. Collateral damage was absent or insignificant after dissections at power level 3 with both systems and an activation time not exceeding 5 seconds.

CONCLUSIONS

High-power ultrasonic dissections at level 5 and to a lesser extent level 4 result in considerable heat production that causes proximity collateral damage to adjacent tissues when the continuous activation time exceeds 10 seconds. Ultrasonic dissections near important structures should be conducted at level 3. At power levels of 4 and 5, the ultrasonic energy bursts to the tissue should not exceed 5 seconds at any one time.

How safe is high-power ultrasonic dissection?

OBJECTIVE

To evaluate the safety of ultrasonic dissection.

SUMMARY BACKGROUND DATA

High-power ultrasonic dissection is in widespread use for both open and laparoscopic operations and is generally perceived to carry a low risk of collateral damage, but there is no published evidence for this.

METHODS

Under controlled experimental conditions, ultrasonic dissections were performed in pigs using Ultracision (Ethicon) or Autosonix (Tyco/USSC) at the three power settings (3, 4, and 5) in random fashion to mobilize the cardia and fundus, bile duct, hepatic artery, portal vein, aorta from the inferior vena cava, renal vessels, colon, and ureters. The dissections (open and laparoscopic) were carried out on pigs at each power setting with each device. Thermal mapping of the tissues during dissection was performed with an infrared thermal camera and associated software. The animals were killed at the end of each experiment and specimens were harvested for quantitative histology.

RESULTS

Extreme and equivalent temperature gradients were generated by ultrasonic dissection with both systems. Heat production was directly proportional to the power setting and the activation time. The core body temperature of the animals after completion of the laparoscopic dissections rose by an average of 2.3 degrees C. The zone around the jaws that exceeded 60 degrees C with continuous ultrasonic dissection for 10 to 15 seconds at level 5 measured 25.3 and 25.7 mm for Ultracision and Autosonix, respectively. At this power setting and an activation time of 15 seconds, the temperature 1.0 cm away from the tips of the instrument exceeded 140 degrees C. Although there was no discernible macroscopic damage, these thermal changes were accompanied by significant histologic injury that extended to the media of large vessels and caused partial- to full-thickness mural damage of the cardia, ureter, and bile duct. Collateral damage was absent or insignificant after dissections at power level 3 with both systems and an activation time not exceeding 5 seconds.

CONCLUSIONS

High-power ultrasonic dissections at level 5 and to a lesser extent level 4 result in considerable heat production that causes proximity collateral damage to adjacent tissues when the continuous activation time exceeds 10 seconds. Ultrasonic dissections near important structures should be conducted at level 3. At power levels of 4 and 5, the ultrasonic energy bursts to the tissue should not exceed 5 seconds at any one time.

Early results of coronary grafting using ultrasonically skeletonized internal thoracic arteries

BACKGROUND

We have developed an ultrasonic complete skeletonization technique for obtaining internal thoracic artery (ITA) grafts and have used this method clinically since January 1998. In this report, we discuss the early results of bilateral ITA grafts obtained with our method.

METHODS

We studied 200 consecutive patients who underwent coronary artery bypass grafting using ITAs obtained by this technique. Angiography of the grafts was performed in 188 patients (94%) within 1 month after coronary artery bypass grafting.

RESULTS

The ITA grafts were about 4 cm longer than pedicled ITA grafts. The free flow through the grafts was at least 30% higher than through pedicled ITAs. The early patency rate determined by postoperative angiography of the grafts was 99.7% for left ITAs and 100% for right ITAs. No patient required postoperative intervention or repeated surgery.

CONCLUSIONS

Ultrasonic complete skeletonization increases the effective length of ITA bypasses, improves free flow through the bypasses, and it is less invasive than conventional pedicled harvesting. These excellent early results indicate that this technique is a straightforward, safe, less invasive, and optimal method for obtaining ITA bypass grafts.

LAPAROSCOPIC WEDGE BIOPSY OF THE LIVER WITH USE OF AN ULTRASONICALLY ACTIVATED SCALPEL

Background: Wedge biopsy of the liver yields more accurate diagnosis of liver diseases than does needle biopsy, but is usually more invasive. We have designed a new method for laparoscopic wedge biopsy under local anesthesia with use of an ultrasonically activated scalpel.

Methods: We performed wedge biopsy in seven patients with liver diseases. Under local anesthesia, two trocars punctured the abdomen and the edge of the liver was dissected with the scalpel. We evaluated the differences in operating time, grade of pain during/after the biopsy, changes of laboratory data and changes of body temperature, between seven wedge and 18 needle biopsies.

Results: No differences were found in all factors between wedge and needle biopsies.

Conclusions: This new method of laparoscopic wedge biopsy under local anesthesia was safe and more useful than needle biopsy. It was also no more invasive than needle biopsy.

Histologic and physiologic evaluation of skeletonized internal thoracic artery harvesting with an ultrasonic scalpel

OBJECTIVES

The safety and reliability of a method of skeletonized internal thoracic artery harvesting with an ultrasonic scalpel (Harmonic Scalpel; Ethicon Endo-Surgery, CVG, Cincinnati, Ohio) were evaluated.

METHODS

The mural branches of the internal thoracic artery were cut by means of 3 methods, differentiated by distance from the site of application of the Harmonic Scalpel blade to the internal thoracic artery. A total of 15 branches were cut from the internal thoracic artery at (0 mm) the origin (group I) or at 1 mm (group II) or 2 mm (group III) distal to the origin. Tissue preparations were examined for successful vessel closure and severity of tissue damage. The length of stump (L) and the length of tissue damage from the stump (D) were determined by a computer image analysis system, and pressure testing was performed to evaluate the physical strength of vessel closure.

RESULTS

In group I, 8 of the 15 branches exhibited discontinuity of the vascular wall structure, probably because of insufficient sealing of the divided section, and 12 of the 15 branches exhibited tissue denaturation on the internal thoracic artery wall adjacent to areas of origin, which was probably caused by the heat transferred from the branches during the process of coagulation. In groups II and III, continuity of wall structure of stumps suggestive of stable closure of branches was confirmed. The lengths of tissue damage from the stump (D) were 0.96, 0.58, and 0.63 mm in groups I, II, and III, respectively, and the lengths of intact area (L - D) in the corresponding groups were -0.78, 0.61, and 1.51 mm. The negative figure in group I indicates the presence of tissue damage in the internal thoracic artery itself. By contrast, in groups II and III the internal thoracic arteries were intact, with a safety margin of greater than 0.5 mm. On physiologic evaluation of vessel closure, 2 of the 24 (8.3%) branches burst under a pressure lower than 350 mm Hg because of insufficient vessel coagulation, but the remaining 22 branches (91.7%) remained intact under pressures up to 350 mm Hg.

CONCLUSION

The internal thoracic artery skeletonization method with an ultrasonic scalpel (Harmonic Scalpel: output level 2) appears to be a safe and reliable method of skeletonized internal thoracic artery harvesting when branches are sectioned at least 1 mm distal to their origin at a sufficiently slow speed.

Ultracision: the harmonic scalpel and its possible uses in maxillofacial surgery

We report on the potential uses and benefits of a new development in incisive technology. The harmonic scalpel uses high-frequency mechanical energy to offer the surgeon controlled and precise incision and haemostasis. Vessels up to 2 mm in diameter may be sealed by coaptation with the blade before division. No special training or precautions are required before using this self-cleaning device. It produces considerably less smoke or smell than either diathermy or laser, which reduces the need for instrument exchanges and smoke evacuation. We think that it will be useful for tongue resections and possibly for neck dissections.