Impact of pressure and gas type on adhesion formation and biomaterial integration in laparoscopy

Abstract

Laparoscopic mesh repair of inguinal and incisional hernias has been widely adopted. Nevertheless, knowledge about the impact of pneumoperitoneum on mesh integration is rare. The present study investigates pressure and gas-dependent effects of pneumoperitoneum on adhesion formation and biomaterial integration in a standardized animal model. Laparoscopic intraperitoneal onlay mesh implantation (IPOM) was performed in 32 female chinchilla rabbits using CO(2) or helium for pneumoperitoneum. Intra-abdominal pressures were 3 or 6 mmHg. Animals were killed after 21 days, and the abdominal wall was explanted for subsequent histopathological examinations. Adhesions were assessed qualitatively with a scoring system, and the adhesion surface was analyzed semiquantitatively by planimetry. Infiltration of macrophages (CD68), expression of matrix metalloproteinase 13 (MMP-13), and cell proliferation (Ki67) were analyzed at the mesh to host interface by immunohistochemistry. The collagen type I/III ratio was analyzed by cross-polarization microscopy to determine the quality of mesh integration. After 21 days, perifilamental infiltration with macrophages (CD68) and percentage of proliferating cells (Ki67) were highest after 6 mmHg of CO(2) pneumoperitoneum. The extent of adhesions, as well as the expression of MMP-13 and the collagen type I/III ratio, were similar between groups. Our experiments showed no pressure or gas-dependent alterations of adhesion formation and only minor effects on biomaterial integration. Altogether, there is no evidence for a clinically negative effect of CO(2) pneumoperitoneum.