Laparoscopy

Laparoscopy

Introduction

In recent years, laparoscopic surgery has been increasingly applied to complex intra-abdominal procedures such as bariatric surgery and surgery for gastrointestinal malignancy. The increased complexity of laparoscopic surgery requires much longer operation time. For example, the operation time required for the laparoscopic colorectal cancer surgery is as long as 120-275 min. In laparoscopic pancreatodudenectomy, the operation time is even longer.

Prolonged laparoscopic surgery requires long duration and large volume gas insufflations, which raises concerns about the adverse effects of prolonged gas insufflations. It is well known that carbon dioxide (CO2) is the most commonly used gas for laparoscopic insufflations. However, the standard CO2 used in current laparoscopic practice is cold-dry CO2 (20-21C and 0.0002% relative humidity), which is not physiological to the normal condition of the peritoneal cavity (36°C and virtually 100% relative humidity) [9]. Experimental and clinical studies of short-duration laparoscopic insufflation (<3 h) have demonstrated that cold-dry CO2 insufflations can cause peritoneal alterations and result in numerous detrimental outcomes, including hypothermia, increased postoperative pain and narcotics usage, as well as prolonged recovery Therefore, it is speculated that prolonged cold-dry CO2 insufflations may result in more intense peritoneal alterations and expose patients to increased risk of its detrimental effects. Recently, there has been accumulating evidence that insufflation with heated-humidified CO2 (37°C and 95% relative humidity, physiological condition) can eliminate or greatly alleviate the detrimental effects of cold-dry CO2 insufflation. The benefits of heated-humidified CO2 insufflations have been reported to include less hypothermia, less postoperative pains, shortened recovery room stay, better convalescence, and less tumor spread and growth. Accordingly, it is speculated that heated-humidified CO2 may be able to prevent the adverse effects of prolonged cold-dry CO2 insufflations during complex laparoscopic surgery.The purpose of this study was to evaluate the detrimental effects of prolonged cold-dry CO2 insufflations (>3 h) and the effectiveness of heated-humidified CO2 in preventing those adverse effects in a rat model. Two commonly concerned areas of the detrimental effects, hypothermia and peritoneal injury, were selected for evaluation. Intra-abdominal adhesion formation, as one of the consequences of peritoneal injury, was also assessed.

Light Microscopy

After the rats were sacrificed, the abdominal wall was immediately opened by a midline incision. Peritoneum and underlying muscles of the anterior and upper abdomen were immediately resected and fixed in 10% formalin. Then the specimens were embedded in paraffin and sectioned with microtome. The sections (5 µm) were stained with hematoxylin and eosin. Images were obtained using Olympus IX71 light microscope (Olympus, Japan) with digital camera output (Nikon Digital Sight DS-U1, Nikon, Tokyo, Japan). All of the peritoneal specimens were analyzed by an independent observer who was blind to the experimental design. Structural changes, cellular damages, and inflammatory response were assessed and compared between groups.

Scanning Electron Microscopy

Peritoneal samples of anterior and upper abdomen were obtained as described above. After resection, the specimens were immediately fixed in 2.5% glutaraldehyde in 0.1 M phosphate-buffered saline (pH 7.4) for 6 h. After fixation, the specimens were rinsed with 0.1 M phosphate-buffered saline (pH 7.3) for 30 min. Then they were postfixed in 1% OsO4 in ...