Morphological characterization of particles emitted from monopolar electrosurgical pencils

Abstract

Monopolar electrosurgical pencils are used extensively in surgical operations. With such pencils, electric current passes to the tissue, and as such, electrosurgical pencil operation generates a significant amount of thermal energy, which in turn leads to the generation of electrosurgical smoke (ES). The health risks of ES are dependent on the size distributions as well as the morphologies of the produced particles. To better characterize such particles, in this study we utilized (1) differential mobility analysis with a condensation particle counter (DMA-CPC), (2) an aerodynamic particle spectrometer (APS), (3) DMA-transmission electron microscopy analysis (DMA-TEM), and (4) DMA-aerosol particle mass analysis (DMA-APM) to examine the size distribution and morphologies of particles produced during simulated operation of an electrosurgical pencil (Neptune E-SEP, Stryker Corporation) on bovine, porcine, and ovine tissue. We find that under a variety of operating conditions, ES particles are broadly distributed, with a mode mobility diameter in the 150–200 nm size range, and concentrations well above background levels in the 50 nm–5 μm size range. We also find that the “cut” mode of monopolar electrosurgical pencil operation generates higher particle concentrations than the “coagulate” mode, and that increasing the maximum applied power from 20 W to 50 W also increases ES particle concentrations. TEM images of mobility selected particles reveal both spherical particles and fractal-like agglomerates in ES; these different particle types are produced under the same operation conditions leading to an externally-mixed, morphologically-complex aerosol. Quantitative analysis of the agglomerate images revealed that agglomerates have an average fractal dimension near 1.93 and that they are structurally similar to agglomerates expected from a diffusion limited cluster aggregation growth mechanism. Despite the presence of both spheres and agglomerates, DMA-APM analysis reveals that all particles have effective densities in the 1000–2000 kg m−3 range, suggesting that they likely contain inorganic components. Finally, we determined that the collection efficiency of the ES capture suction unit attached to the electrosurgical pencil was >95% for particles in the 50–400 nm mobility diameter range.