Donna L. Korvick

Electromagnetic Energy Sources in Surgery

The biophysics, mechanism of actions, applications, benefits and complications of electromagnetic (EM) energy-based surgical instruments, and their current use are reviewed. Understanding the mechanism of action, tissue effects, and appropriate applications of EM devices is critical to achieving an optimal surgical outcome. Although a more diverse range of EM devices are used in human medicine, current use in veterinary medicine is limited to conventional electrosurgery and CO(2) lasers.

Ultrasonic incisions produce less inflammatory mediator response during early healing than electrosurgical incisions.

As the use of laparoscopic surgery has become more widespread in recent years, the need has increased for minimally-invasive surgical devices that effectively cut and coagulate tissue with reduced tissue trauma. Although electrosurgery (ES) has been used for many generations, newly-developed ultrasonic devices (HARMONIC® Blade, HB) have been shown at a macroscopic level to offer better coagulation with less thermally-induced tissue damage. We sought to understand the differences between ES and HB at a microscopic level by comparing mRNA transcript and protein responses at the 3-day timepoint to incisions made by the devices in subcutaneous fat tissue in a porcine model. Samples were also assessed via histological examination. ES-incised tissue had more than twice as many differentially-expressed genes as HB (2,548 vs 1,264 respectively), and more differentially-expressed proteins (508 vs 432) compared to control (untreated) tissue. Evaluation of molecular functions using Gene Ontology showed that gene expression changes for the energized devices reflected the start of wound healing, including immune response and inflammation, while protein expression showed a slightly earlier stage, with some remnants of hemostasis. For both transcripts and proteins, ES exhibited a greater response than HB, especially in inflammatory mediators. These findings were in qualitative agreement with histological results. This study has shown that transcriptomics and proteomics can monitor the wound healing response following surgery and can differentiate between surgical devices. In agreement with clinical observations, electrosurgery was shown to incur a greater inflammatory immune response than an ultrasonic device during initial iatrogenic wound healing.

Can Harmonic Focus Curved Shear Effectively Seal the Pancreatic Ducts and Prevent Pancreatic Leak? Feasibility Evaluation and Testing in Ex Vivo and In Vivo Porcine Models

BACKGROUND The purpose of this study was to evaluate the ability of Harmonic energy technology to transect and seal the pancreatic duct compared with the standard monopolar electrosurgery transection and oversew technique in a porcine distal pancreatectomy survival model. Harmonic energy technology is as effective as standard oversew technique for preventing pancreatic leak after distal pancreatectomy. METHODS The animal protocol used for this study was approved by the Institutional Animal Care and Use Committee (IACUC) prior to the conduct of the study. Spleen-preserving distal pancreatectomy was performed in seven pigs (80-100 lb) by the same surgeon. In four animals, the pancreas was divided with the Harmonic Focus Curved Shears (test group) with no additional suturing for control of hemostasis or leak. In three animals, the pancreas was divided using monopolar electrosurgery (30 W coagulation) and the cut end of the pancreas was oversewn with a locking suture (control group). A previously worked out standard operative technique was used in all procedures. Operating end points included surgery time and blood loss. Animals were euthanized and necropsied at 7 to 8 d following surgery. Survival endpoints included clinical response to surgery, serum chemistry profiles before surgery and at necropsy, and histology of the pancreas transection site. RESULTS Mean operative time for pancreatic resection was 15min in the control group and 10min in the test group. No significant blood loss was noted in either group. The median size of the resected pancreas was 4.3 cm. Three animals in the control group and three in the test group completed the study without complications. One animal in the test group failed to eat, appeared dehydrated, and was taken off study on POD#2. In this animal, there was a doubling of serum lipase at euthanasia and gross evidence of ileus, which was attributed to a pancreatic leak. Histologic examination of the residual pancreas in both groups at necropsy revealed a 2-5 mm band of necrotic tissue associated with neutrophilic infiltration in the control group, and less than a 1mm band of necrotic tissue in the test group. CONCLUSION The Harmonic Focus Curved Shears, using Harmonic energy technology, appears to seal the pancreatic ducts and prevent pancreatic leak at 75% (3/4) efficiency in this survival model. However, the survival leak rate, 25% (1/4) was higher in the Harmonic Focus Curved Shears test group compared with the control oversewn group 0% (0/3). This feasibility study shows potential for Harmonic technology to be used to seal the pancreatic ducts, but additional testing and optimization of surgical techniques are needed.

Perpendicular Blood Vessel Seals Are Stronger Than Those Made at an Angle

Vessel sealing devices effectively produce hemostatic seals with minimal thermal damage, but the strength of seals decreases as vessel diameter increases. Because vessels sealed at an angle to the vessel require a greater functional seal diameter than those sealed perpendicularly to the vessel, it was hypothesized that perpendicular seals would have comparably higher burst pressures. Ex vivo, porcine carotid arteries of nominal diameters of 5, 6, and 7 mm were sealed perpendicularly to and at a 45° angle to the longitudinal axis of the vessels, and burst pressures of the sealed vessels were measured. Overall burst pressures were 51% greater for perpendicular seals than for angled seals (P<.001). Mean burst pressures for the 5-mm angled and 7-mm perpendicular groups, which have similar seal lengths, were not significantly different (P=.959). Analysis using the functional diameter as a covariate indicated that the seal length is the primary variable in determining burst pressure, and not some other inherent characteristic of angled versus perpendicular sealing. These results suggest that at least for vessels ≥5 mm in diameter, surgeons should approach vessels perpendicularly and not at an angle, for the highest possible seal strength. The development of articulated sealing and cutting devices would provide greater seal strength, in addition to improved maneuverability, especially in laparoscopic surgery, where angles of approach may be limited by the fixed location of surface cannulas.

Mycoplasma suis infection in pigs after splenectomy.

(jclymer@its.jnj.com). The pigs were used in a study to evaluate the intraoperative hemostatic efficacy of advanced bipolar vessel-sealing devices. Pigs were pre-anesthetized with 0.5 mg acepromazine and 0.01 mg glycopyrrolate per kg body weight administered intramuscularly (i.m.). Anesthesia was induced with 20 mg ketamine and 2 mg xylazine per kg body weight administered i.m. and maintained with isoflurane at 1.5–2.0%. Blood pressure was monitored directly through a femoral arterial catheter. If systolic blood pressure fell below 80 mm Hg, a solution of phenylephrine was administered intravenously (i.v.) to effect as a pressor support. We sealed and transected several blood vessels, including a carotid artery, the gastroepiploic artery and vein and the splenic and short gastric arteries and veins, through splenectomy. Post-operatively, we placed a 100 μg per h fentanyl patch (Butler Schein Animal Health, Dublin, OH) and administered 5 mg per kg body weight ceftiofur (Excede, Zoetis, Madison, NJ) i.m. and 22 mg per kg body weight cefazolin (SteriPharma, Syracuse, NY) i.v. We carefully monitored the pigs during their recovery, which is typically uneventful following such treatments. For the management of pain and inflammation, we administered 4 mg per kg body weight carprofen (Rimadyl, Zoetis) orally to the pigs once daily for 3 d.