Bipolar vessel sealing: instrument contamination and wear have little effect on seal quality and success in a porcine in vitro model

"In Vitro" Evaluation of Energy-Based Sealing of Graft Side Branches in Bypass Surgery

INTRODUCTION

Our objective was to compare the in vitro efficacy of electrothermal bipolar [EB] vessel sealing and ultrasonic harmonic scalpel [HS] versus mechanical interruption, with conventional ties or surgical clips (SC), in sealing saphenous vein (SV) collaterals, during its eventual preparation for bypass surgery.

METHODS

Experimental in vitro study on 30 segments of SV. Each fragment included two collaterals at least 2 mm in diameter. One of them was sealed by ligation with 3/0 silk ties (control) and the other one with EB (n = 10), HS (n = 10) or medium-6 mm SC (n = 10). After incorporation in a closed circuit with pulsatile flow, the pressure was progressively increased until causing rupture. Collateral diameter, burst pressure, leak point, and histological study were recorded.

RESULTS

Burst pressure was higher for SC (1320.20 ± 373.847 mmHg) as compared with EB (942.2 ± 344.9 mmHg, p = 0.065), and especially with HS (637.00 ± 320.61 mmHg, p = 0.0001). No statistically significant difference between EB and HS was found, and bursting always happened at supraphysiological pressures. The leak point for HS was always detected in the sealing zone (10/10), while for EB and SC, it occurred in the sealing zone only in 6/10(60%) and 4/10(40%), respectively (p = 0.015).

CONCLUSIONS

Energy delivery devices showed similar efficacy and safety in sealing of SV side branches. Although bursting pressure was lower than with tie ligature or SC, non-inferiority efficacy was shown at the range of physiological pressures in both, EB and HS. Due to their speed and easy handling, they may be useful in the preparation of the venous graft during revascularization surgery. However, remaining questions about healing process, potential spread of tissue damage and sealing durability, will require further analysis.

Laser coagulation and hemostasis of large diameter blood vessels: effect of shear stress and flow velocity

Photocoagulation of blood vessels offers unambiguous advantages to current radiofrequency approaches considering the high specificity of blood absorption at available laser wavelengths (e.g., 532 nm and 1.064 µm). Successful treatment of pediatric vascular lesions, such as port-wine stains requiring microvascular hemostasis, has been documented. Although laser treatments have been successful in smaller diameter blood vessels, photocoagulation of larger sized vessels is less effective. The hypothesis for this study is that a primary limitation in laser coagulation of large diameter blood vessels (500-1000 µm) originates from shear stress gradients associated with higher flow velocities along with temperature-dependent viscosity changes. Laser (1.07 µm) coagulation of blood vessels was tested in the chicken chorio-allantoic membrane (CAM). A finite element model is developed that includes hypothetical limitations in laser coagulation during irradiation. A protocol to specify laser dosimetry is derived from OCT imaging and angiography observations as well as finite element model results. Laser dosimetry is applied in the CAM model to test the experimental hypothesis that blood shear stress and flow velocity are important parameters for laser coagulation and hemostasis of large diameter blood vessels (500-1000 µm). Our experimental results suggest that shear stress and flow velocity are fundamental in the coagulation of large diameter blood vessels (500-1000 µm). Laser dosimetry is proposed and demonstrated for successful coagulation and hemostasis of large diameter CAM blood vessels.

Evaluation of the performance of an endoscopic 3-mm electrothermal bipolar vessel sealing device intended for single use after multiple use-and-resterilization cycles

OBJECTIVE

To evaluate the performance of an endoscopic 3-mm electrothermal bipolar vessel sealing device (EBVS) intended for single use after multiple use-and-resterilization cycles.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Eight 3-mm EBVS handpieces.

METHODS

Handpieces were subjected to a maximum of 15 cycles of testing, including simulated surgery, sealing and burst pressure testing of porcine carotid arteries, reprocessing, and hydrogen peroxide plasma resterilization. Failure was defined as two sequential vascular seal leakage events occurring at <250 mm Hg. Histological evaluation, maximum external temperature of the jaws, sealing time, tissue adherence, jaw surface characterization, and mechanical deterioration were studied. Failure rate was analyzed by using a Kaplan-Meier curve. Linear and ordinal logistic mixed models were used to analyze sealing time, handpiece jaw temperature, and adherence score.

RESULTS

Mean ± SD diameter of arteries was 3.22 ± 0.35 mm. Failure was observed starting at cycle 10 and going up to cycle 13 in 37.5% (3/8) of the handpieces. Tissue adherence increased after each cycle (P < .001). Maximum external temperature (79.8°C ± 13.9°C) and sealing time (1.8 ± 0.5 seconds) were not significantly different throughout cycles up to failure. A flatter surface and large scratches were observed microscopically throughout the jaw surface after repeated use and resterilization.

CONCLUSION

The 3-mm EBVS handpiece evaluated in this study can be considered safe to use for up to nine reuse-and-resterilization cycles.

CLINICAL SIGNIFICANCE

These data provide the basis for establishing preliminary guidelines for the reuse and hydrogen peroxide plasma resterilization of an endoscopic 3-mm EBVS handpiece.

Performance and microbiological safety testing after multiple use cycles and hydrogen peroxide sterilization of a 5-mm vessel-sealing device

OBJECTIVE

To evaluate the functional and microbiological safety of a single-use laparoscopic vessel-sealing device in a multiuse setting.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Twelve 5-mm LigaSure Maryland jaw devices.

METHODS

Handsets underwent repeated test cycles until failure. The handset packaging was opened, and handsets were agitated in phosphate-buffered saline (PBS). The PBS was removed, centrifuged, and submitted for culture. Canine ovariectomy was simulated on cadaveric tissue, after which vascular seal quality was evaluated by pressure testing of sealed porcine carotid arteries. The handsets were cleaned and sterilized with hydrogen peroxide gas and repackaged.

RESULTS

Mean ± SD cycles to failure was 7.7 ± 2.8, with a minimum of 4 and a maximum of 12 use cycles achieved. Eleven of the 12 handsets failed by failure of handset activation after depression of the activation trigger. Only 1 handset failed to hold an adequate vascular seal under 300 mm Hg of pressure. No handset exhibited positive bacterial culture at any cycle.

CONCLUSION

The sterilization method used in this study resulted in an excellent microbiological safety profile. Most of the handsets failed by activation button failure.

CLINICAL SIGNIFICANCE

Under the conditions of this study, hydrogen peroxide sterilization achieved microbiological safety. Handsets can successfully be reused until activation button failure without negative effects on the vascular seal or increased risk of infection to the patient.