Comparison of ferromagnetic induction and bipolar electrosurgery and suction in corticotomies in pig cerebrum.

INTRODUCTION: The effects of newer energy-based surgical dissection and coagulation modalities on cerebral tissue have not been investigated. Several instruments have been developed to address the limitations of traditional electrosurgical instruments in the nervous system. We compared the effects of standard bipolar electrocautery and suction (BPS) with those of a new ferromagnetic induction (FMI) device in corticotomies of pig cerebral tissue as assessed by magnetic resonance imaging (MRI) and histological analysis. METHODS: Three adult pigs underwent bilateral corticotomies (3 cm long×1 cm deep) using both FMI and BPS. The acute cerebral tissue edema created by each method was measured on coronal volumetric T2-weighted MRI sequences immediately after surgery. A lateral thermal "damage index" was calculated by dividing the width of the visible T2 tissue edema by the measured depth. The radiographic damage indices with each method were compared statistically. Histological analysis of each incision was conducted to compare the extent of tissue damage. RESULTS: MRI showed that the mean radiographic damage index of each corticotomy was significantly lower with the FMI (0.30 ± 0.02 (0.28-0.32)) than with the BPS method (0.54 ± 0.11 (0.42-0.64)) (p = 0.02). Histological analysis suggested a correlation with the radiographic findings as the FMI tissue samples demonstrated less adjacent tissue damage than BPS. CONCLUSIONS: FMI appeared to cause less adjacent tissue damage than the BPS method in pig cerebral tissue based on quantitative radiographic and qualitative histological analysis. Future studies are needed to investigate the clinical implications of energy-based surgical dissection on cerebral tissue.

Comparison of tissue effects in rabbit muscle of surgical dissection devices.

While some energy-based surgical dissection and coagulation modalities may offer excellent cutting and coagulation abilities, the impact on healing may differ among devices. We compared the tissue effects of three of these modalities with those of the standard surgical scalpel in rabbit muscle at 24 h and 14 days after surgery by evaluating radiographic and histological data. Linear incisions were made with each device in the dorsal lumbar musculature of rabbits using monopolar electrocautery in cut mode (MPE-Cut) and coagulation mode (MPE-Coag), a ferromagnetic induction loop (FMI), and a traditional scalpel. Magnetic resonance imaging scans and histological sampling were done at 24 h and 14 days. Subjective cutting and coagulation characteristics for each device were also recorded during surgery. The scalpel and FMI appeared to cause the least tissue damage adjacent to the incisions in rabbit dorsal lumbar musculature. The scalpel showed the best healing, while the FMI and MPE-Cut demonstrated good healing. The MPE-Coag showed the worst tissue healing. The scalpel, FMI, and MPE-Cut all exhibited favorable subjective characteristics during surgery. It appears that the FMI may be a better choice for surgical dissection and coagulation in muscle tissue than the MPE coagulation mode because it shows less tissue damage and offers better tissue healing.

Comparison of the effects of surgical dissection devices on the rabbit liver.

PURPOSE: Multiple energy-based surgical dissection and coagulation modalities are available to facilitate surgical dissection and hemostasis, but there is limited information regarding the acute tissue effects of these devices. Our objective was to compare the functional characteristics and tissue effects of four energy-based surgical dissection and coagulation modalities on the rabbit liver. METHODS: Linear incisions were created in the rabbit liver using monopolar electrocautery, a harmonic scalpel, a PlasmaBlade and a new ferromagnetic induction loop device. Subjective cutting and coagulation characteristics for each device were recorded, and the histological tissue effects were evaluated. RESULTS: Each of the modalities successfully incised the liver tissue. The PlasmaBlade and the ferromagnetic induction loop exhibited significantly less perceived tissue drag during the incision, significantly less collateral tissue damage and significantly better margin uniformity than the monopolar electrocautery device. Each device showed comparable subjective hemostasis. The harmonic scalpel did not demonstrate a significant difference compared with any of the other devices in any of the parameters examined. The histological analysis revealed that the least lateral thermal damage resulted when the PlasmaBlade, harmonic scalpel and ferromagnetic induction loop were used, and the most damage occurred with the use of monopolar electrocautery. CONCLUSIONS: Each of the newer energy-based surgical tools showed improvement over monopolar electrocautery with regard to lateral thermal injury, and the ferromagnetic induction device and the PlasmaBlade demonstrated superior surgical tissue handling characteristics to the monopolar electrocautery device.

Conceptus elongation in ruminants: roles of progesterone, prostaglandin, interferon tau and cortisol.

The majority of pregnancy loss in ruminants occurs during the first three weeks after conception, particularly during the period of conceptus elongation that occurs prior to pregnancy recognition and implantation. This review integrates established and new information on the biological role of ovarian progesterone (P4), prostaglandins (PGs), interferon tau (IFNT) and cortisol in endometrial function and conceptus elongation. Progesterone is secreted by the ovarian corpus luteum (CL) and is the unequivocal hormone of pregnancy. Prostaglandins (PGs) and cortisol are produced by both the epithelial cells of the endometrium and the trophectoderm of the elongating conceptus. In contrast, IFNT is produced solely by the conceptus trophectoderm and is the maternal recognition of pregnancy signal that inhibits production of luteolytic pulses of PGF2α by the endometrium to maintain the CL and thus production of P4. Available results in sheep support the idea that the individual, interactive, and coordinated actions of P4, PGs, IFNT and cortisol regulate conceptus elongation and implantation by controlling expression of genes in the endometrium and/or trophectoderm. An increased knowledge of conceptus-endometrial interactions during early pregnancy in ruminants is necessary to understand and elucidate the causes of infertility and recurrent early pregnancy loss and provide new strategies to improve fertility and thus reproductive efficiency.