The effects of CO2 pneumoperitoneum at different temperature and humidity on hemodynamic and respiratory parameters and postoperative pain for gynecologic laparoscopic surgery: A Prospective Randomized Study

Laparoscopy surgery has been associated with less postoperative pain, less systemic immunological depression, less wound infection, shorter hospital stays and earlier return to normal activities. However, the hemodynamic changes caused by pneumoperitoneum, patient's position and hypercarbia have always been a concern for surgeon and anesthesiologists. Hypercarbia and increased intraabdominal pressure affect cardiac output, central venous pressure, heart rate (HR), mean blood pressure (MBP) and systemic vascular resistance through various mechanisms in laparoscopic surgery. The hemodynamic effects of mild hypercarbia are less serious than the mechanical effects of increased intraperitoneal pressure, although moderate and severe hypercarbia lead to significant hemodynamic changes, both directly by the cardiovascular system and indirectly by the autonomic system. Its effects on the sympathetic nervous system cause increased blood pressure, heart rate and risk of arrhythmia. Especially, patients with cardiac or pulmonary diseases are at increased risk because of reduced cardiac output, increased central venous pressure, respiratory pressure and acidosis [1-4]. Standard carbon dioxide (CO2) is often preferred at room temperature (20–25°C) and dry (at 0-5% relative humidity) in laparoscopic surgery [5,6]. Recent years have witnessed devices that provide heat (35-37°C) and humidity (95-98%) to prevent postoperative pain and intraoperative hypothermia. However, the number of studies on the effects of heated CO2 on hemodynamic and respiratory parameters is limited [7-9], and these studies do not include humidified CO2. We aimed to test whether heated (37°C)-humidified (95%) CO2 would diffuse more easily into the blood from the abdomen and cause more hypercarbia compared to standard CO2 in cases with constant intraabdominal pressure and whether it would affect hemodynamic, given the vasodilation that could occur, and respiratory parameters. Although laparoscopy surgery is known to cause less systemic inflammation, some studies have reported that the use of standard CO2 during laparoscopy led to a higher local or systemic inflammatory response compared to heated-humidified CO2. This response has been stated to be particularly due to drying and damage in the peritoneum and has been associated with postoperative pain [4,5,10]. The second aim of this study was to examine simple indicators of inflammation, i.e., leukocyte and their subtype (neutrophil and lymphocyte counts) and neutrophil-lymphocyte ratios (NLRs) [11-14] in standard CO2 and heated-humidified CO2 and to evaluate their correlation with postoperative pain., and to evaluate their correlation with postoperative pain