Effects of CO2 Pneumoperitoneum and Enteric Disturbance on B-endorphin in SD Rats

Abstract

Carbon dioxide (CO2) pneumoperitoneum, abdominal incision and especially enteric disturbance are very important stressful stimuli of abdominal surgery including laparoscopy. Surgery is a stressful stimulus that elicits inflammatory, endocrine and metabolic responses as represented by increased levels of stress hormones, leading to substrate mobilization. These changes together constitute the stress response. The stress response caused by surgery is conditioned by several factors such as anxiety, incision size, enteric disturbance (enteric exposure and drawing), exposure of abdominal organs to air, temperature change, operation duration, pain, hemorrhage, and infection. To obtain excellent exposure in laparotomy, it is necessary to incise the abdomen and pull the intestine. Avoidance of enteric disturbance, less hemorrhage, smaller incisional size and shorter operation duration contribute to lowering stress responses in laparoscopic surgery. Laparoscopic surgery and induction of pneumoperitoneum cause minimal activation of stress hormones, resulting in a lower stress response on the part of the patient, and possibly a shorter recovery time. Serum β-endorphin (β-EP) and cortisol levels are often elevated in animals and humans under major stress conditions including perioperative procedures. Increased generation of β-EP and cortisol contributes to trauma-related acute phase reaction and hypermetabolic response. Secretion of β-EP and cortisol plays a central role in mediating metabolic responses to stress, and there is a linear correlation between cortisol values and the severity of injury. As β-EP is positively correlated with cortisol, and both hormones are the result of corticotropin-releasing hormone (CRH) activation, increased circulating β-EP seems to be part of the response to stress. In this experimental study, the effect of enteric disturbance and carbon dioxide (CO2) pneumoperitoneum on stress response was studied in a rat model. Serum β-EP of SPF-grade male SD rats was measured at different time points after initiation of surgery under the experimental condition of CO2 pneumoperitoneum at 1.0 kPa, a 5 cm abdominal incision without enteric distrubance, or a 5 cm abdominal incision with enteric disturbance to see whether intestinal disturbance as an important factor increased the degree of stress response, and whether reducing intraoperative traction on the intestine reduced the extent and shortened the duration of perioperative stress response, thus reducing trauma and promoting patient rehabilitation. Abstract