Heat production, nerve function, and morphology following nerve close dissection with surgical instruments

Area of Science:

• Surgical Technology
• Neuroscience
• Biomedical Engineering

Background:

• Comparing heat production, nerve function, and morphology of ultrasonically activated (US) shears, monopolar electrosurgery (ES), and bipolar ES.
• Assessing in vivo application of these surgical tools near the sciatic nerve.

Purpose of the Study:

• To evaluate and compare the thermal effects and potential nerve damage caused by US shears versus monopolar and bipolar ES.
• To determine the impact of different surgical energy devices on nerve integrity and function.

Main Methods:

• Standardized longitudinal cuts adjacent to the rat sciatic nerve using US shears, monopolar ES knife, or bipolar ES scissors.
• Continuous temperature recording with thermoelectric microsensors at varying distances from the activation site.
• Functional assessment via electromyography (EMG) and histopathological examination for morphological damage grading.

Main Results:

• Bipolar ES generated significantly higher maximum temperatures and thermal doses compared to US shears, with greater result variability.
• US shears demonstrated less variation in temperature and thermal dose.
• While not statistically significant, functional loss was least common with US shears. Moderate to severe morphological damage was significantly less frequent with US compared to monopolar ES.

Conclusions:

• Temperature elevation is highly dependent on the distance from the activated instrument.
• Bipolar ES scissors produced higher maximum temperatures and thermal doses with greater variability than US.
• Functional loss and severe morphological nerve damage were infrequent across all tested energy modalities.