Thermal effects of monopolar electrosurgery detected by real-time infrared thermography: an experimental appendectomy study

Abstract

Background Monopolar energy (ME) is routinely used in appendectomy. This study aimed to investigate the degree of lateral thermal spread generated by ME and to evaluate the thermal injury sustained by the close-lying tissues. Methods Appendectomy with a monopolar Maryland dissector was performed in 8 rabbits (at 30 and 60 W power settings). A high-resolution infrared camera was used to record tissue heating during the intervention. After autopsy macroscopic changes were evaluated and tissue samples were subjected to myeloperoxidase (MPO) assay and histological examination. Results No significant differences in the extent of thermal spread, MPO activity and histological signs of inflammation were observed between groups. Regardless of the power settings, the heat spread exceeded 2 cm laterally along the mesoappendix when application time exceeded 3 s. The spread of heat through tubular structures in both groups caused a significant temperature rise in the nearby intestinal loop, resulting in perforation (n = 3) and necrosis (n = 1). Conclusions Application time is critical in thermal spread during appendectomy aided by ME. Tubular anatomic structures can enhance thermal injury on distant tissues. The observed effects of ME bear clinical relevance that need further investigation.

Thermal Processes in Bile Ducts During Laparoscopic Cholecystectomy with Monopolar Instruments. Experimental Study Using Real-Time Intraluminal and Surface Thermography

“…The pedicle effect reported in our previous publication 18 and also observed in this study might be one of the underlying causes of thermal injury to the bile duct at the site of its confluence with the cystic duct, 8 especially when the cystic duct is transected with a monopolar coagulation instrument. 24 Another possible contributor is current “channeling” toward tubular structures, which occurs because electrical current always takes the path of least resistance (ie, of the highest conductivity).…”

“…However, in our previous in vivo experiment conducted on rabbits, the cooling effect was very localized and did not spread beyond the arteries. 18 We did not use any chilling techniques aimed at maintaining a constant temperature in the bile ducts 42 and thus allowing simulation of uninterrupted bile flow. We do not know what effect the chilling approach might have had on the local thermal spread in our case, but given the slow rate of bile flow, we hypothesize that it would have been insignificant.…”

“…During LC, most manipulations are carried out in the vicinity of high-conductivity tubular structures, which act as channels for electrical current flow, posing a risk of greater thermal spread to distant tissues. 16-18 There are reports of other specific LC complications, including the pedicle effect, which appears to an instance of “current channeling.” 8 A thermal injury to the extrahepatic bile duct (EBD) wall can result in the formation of benign EBD strictures that manifest themselves weeks or even months after surgery. 19 It is estimated that about 80% of patients with benign EBD strictures underwent LC in the past.…”

Temperature profile and residual heat of monopolar laparoscopic and endoscopic dissection instruments

“…Preliminary studies showed that an increased power level and longer cutting time are also associated with increased temperature [ 25 ]. However, the temperature of the whole instruments including the shaft were not analyzed [ 26 ]. Furthermore, the tissue is not only touched with the tip of the instrument but -often accidentally- also with parts of the shaft.…”

Carbon dioxide laser transconjunctival lower blepharoplasty: an objective and quantitative comparison to monopolar electrosurgery

“…12 During monopolar electrosurgery, inadvertent harm and delayed injury to the surrounding tissue can occur because of the lateral spread of thermal energy. 13 In contrast, there is almost no lateral thermal damage inflicted to adjacent tissues during carbon dioxide laser blepharoplasty. 14…”