Temperature and Pressure Effects on Tissue Sealing and Protein Denaturation

Abstract

Tissue sealing is an attractive method for tissue sealing in laparoscopic (minimally in-vasive) surgeries as it does not leave any materials in a patient’s body. Most of the re-search for tissue sealing has been concerned on the end-goal results of burst pressure, and not as much time has been spent investigating the more fundamental properties of tissue sealing which include temperature, pressure, time, vessel composition, disease state, and sealing modality (i.e., thermal, radiofrequency, and ultrasonic). This work in-vestigates temperature and pressure by studying how these parameters affect collagen denaturation and burst pressure. Ethicon provided carotid arteries that were sealed under controlled temperature and pressure with a constructed Thermal Jig. Additionally, dena-turation of collagen was studied with the use of carotid arteries and rat tail tendons with the use of FTIR spectroscopy under temperature and pressure control from an ATR ac-cessory. From the research, it was determined that the burst pressure was highest with the temperature of 140ºC. Changing the weight from 20lb to 50lb did not yield any sig-nificant difference. The results for burst pressure from the treatments of 100ºC;80psi;30s, 100ºC;330psi;30s, 140ºC;80psi;30s, and 140ºC;330psi;30s were 188.4 ± 55.3mm Hg, 439.9 ± 232.6mm Hg, 647.3 ± 241.3mm Hg, and 678.1 ± 153.7mm Hg, respectively. Denaturation onset was observed to be delayed with the application of pressure. For rat tail tendon, denaturation onset was observed to be 58.0 ± 2.5ºC and 60.1 ± 4.9ºC for loads of 0N and 2N, respectively. For carotid artery, the denaturation onset was observed to be 59.8 ± 0.7ºC, 59.8 ± 1.9ºC, 79.1 ± 4.3ºC, indeterminable, and indeterminable for loads of 0N, 2N, 10N, 20N, and 50N, respectively. To form an effec-tive seal one must increase the temperature above 100ºC. Additionally, the denaturation was delayed significantly as the load was increased. This mechanical pressure correlates with results from osmotic pressure that also cause a delay in protein denaturation. Fu-ture work should investigate protein denaturation to higher temperature and tissue fu-sion by varying disease state of arteries, tissue composition (i.e., collagen and elastin content), and sealing time.