Acute and subacute effects of the ultrasonic blade and electrosurgery on nerve physiology.

Ultrasonic blades have been shown to cause less acute electrophysiological damage when applied near nerves than monopolar electrosurgery (ES). This study was performed to determine whether the acute nerve damage observed for ES, as well as the relative lack of damage observed for ultrasonic dissection, extends through a subacute timeframe. Muscle incisions were made in rat with the Harmonic(®) Blade (HB) and ES at a distance of 2 mm from the sciatic nerve. Sham surgery was also performed which consisted of similar exposure of the sciatic nerve without use of an energized device. Electrophysiological function was assessed acutely over a 3-h period, and subacutely after a 7-day survival, by monitoring the sciatic nerve compound action potential (CAP), conduction velocity (CV), von Frey hair (VFH) stimulation force, leukocyte infiltration, and impaired axonal transport via ß-amyloid precursor protein (ß-APP) immunocytochemistry. During the acute period, ES produced significantly lower CAP and CV, and higher levels of leukocytes and ß-APP than sham, whereas the ultrasonic blade was not significantly different from sham, and had significantly lower VFH force than ES. After the subacute survival, ES continued to display significantly lower CAP and CV, and higher levels of leukocytes and ß-APP than sham, whereas ultrasonic blade had higher CAP and CV than sham, and lower VFH than ES. This study confirms that incisions made with an ultrasonic blade cause less acute nerve damage than monopolar ES, and are comparable to sham surgery at a distance of 2 mm from the sciatic nerve. The negative effects of electrosurgery extend through at least a 7-day survival period, whereas subacute recovery after application of the ultrasonic blade was comparable to that of sham surgery. For surgical procedures in the vicinity of vital nerves, use of the ultrasonic blade represents a lower risk than ES for both acute and subacute neural trauma.

Tissue effects in vessel sealing and transection from an ultrasonic device with more intelligent control of energy delivery.

BACKGROUND: Ultrasonic surgical devices have been demonstrated to provide excellent hemostasis, efficient transection, minimal lateral thermal damage, low smoke generation, and no risk of electrical current passage to the patient. These benefits originate from the inherent characteristics of the ultrasonic mechanism, but further improvements were thought possible through optimization of the energy delivery during application. The study reported here compared a new ultrasonic device, Harmonic ACE®+ Shears with Adaptive Tissue Technology, with a commercial predicate device, Harmonic ACE® Shears (both Ethicon Endo-Surgery, Inc., Cincinnati, OH, USA). METHODS: Devices were evaluated in an in vivo porcine model intraoperatively and after a 30-day survival period. Both devices were used to seal a variety of vessels 1-5 mm in diameter, and compared for hemostasis, histological thermal damage, and adhesion formation. Sealed vessels were evaluated ex vivo for burst pressure, and visual obstruction caused by plumage from device application was assessed quantitatively. RESULTS: ACE+ produced significantly less thermal damage, had fewer adhesions, offered faster transection, involved less visual obstruction, and had higher burst pressures than the predicate device. All vessel seals, evaluated over the course of a 30-day survival period in pigs, remained intact. CONCLUSION: The new Adaptive Tissue Technology algorithm assists the surgeon in achieving better control of energy delivery to the tissue, sealing vessels with supra-physiological burst pressures, and low thermal damage. These preclinical results with Harmonic ACE+ may translate into meaningful clinical benefits, providing greater precision along with more efficient and effective cutting and coagulation in open or laparoscopic procedures.

Hemostatic effectiveness of Fibrin pad after partial nephrectomy in swine.

BACKGROUND: Current management of severe surgical or traumatic bleeding is often achieved by manual tamponade or occlusion using devices such as tourniquets or ligatures. There are some clinical scenarios where these options are either marginally effective or impractical. The present study evaluates a new combination device (Fibrin pad) consisting of biologically active components (human thrombin and fibrinogen) delivered to the targeted site by an absorbable synthetic matrix (oxidized regenerated cellulose and polyglactin 910) in a swine severe bleeding model. In this model, severe bleeding can be managed by concurrent use of several currently available treatments, or a more convenient option that offers performance and safety advantages. MATERIALS AND METHODS: Partial nephrectomies were performed on swine and treated with either Fibrin pad (FP) or conventional therapy (CTR)-temporary occlusion of renal artery, electrocautery, SURGIFLO, EVITHROM, SURGICEL NU-KNIT, and PDS II suture). After intraoperative hemostasis was confirmed, the animals were closed and recovered, then survived for 2, 14, or 56 d. RESULTS: Hemostasis was achieved at surgery and maintained in all FP and CTR treated animals. FP was as effective as CTR at establishing durable hemostasis. Treatment with FP did not require temporary occlusion of the renal artery and decreased the total treatment time by half. No animals in either group had complications related to postoperative bleeding at any time during the study. There was no evidence of pulmonary thrombi or evidence of thrombotic complications. No biologically significant adverse local tissue response was present in association with the Fibrin pad at any study interval, and no biologically relevant or consistent changes in blood parameters were identified. CONCLUSIONS: Fibrin pad was as effective as CTR for the primary management of severe bleeding without occlusion of the renal artery and a shorter surgical time. No evidence of a systemic or local adverse response was identified due to exposure to the Fibrin pad.