We are not performing the study and we don't plan to continue. We do not have support to complete the study.

Laparoscopic surgery (surgery with the use of a camera and small instruments) uses insufflation, which is the standard medical practice where CO2 (carbon dioxide) gas is blown into the abdomen to create space for surgical procedures. The purpose of this study is to investigate whether heating and humidifying surgical CO2 will reduce surgery-related inflammation and postoperative pain.

This is a prospective, randomized controlled trial in which 120 patients undergoing elective laparoscopic colorectal resection will either undergo insufflation of the peritoneum with cold and dry (CD), control or warm and humidified (WH) CO2, experimental. Patients scheduled to undergo elective Laparoscopic Colon Resection (LCR) will be informed about the study and all questions answered. Consenting patients will be randomized (via envelope system) to have either standard cold (19-21°C) and nonhumidified (0%) CO2 or warm (37°C) and humidified (95%) CO2 utilized for their resection. To ensure that similar numbers of rectal resection patients are in each group, a separate envelop randomization will be used for colectomy and rectal resection cases.

The study will be conducted at Mount Sinai West hospital. The ambient operating room temperature will be regulated to 70-72° F. All patients will undergo laparoscopic surgery. During laparoscopic surgery the camera and instruments are inserted into the abdomen via small incisions allowing for the surgeon to explore the whole abdominal cavity without making larger cuts. In order to create space for surgical procedures, insufflation with CO2 is used. Regarding the method of insufflation, subjects will be randomized into 2 groups: i) standard CD CO2 insufflation ii) Lexion Insuflow device providing warmed humidified CO2 insufflation (95° F and 95% relative humidity) The humidification and warming device to be used is the Insuflow Synergy Port (Lexion Company, FDA approved) which is a specialized 5 mm port that delivers warmed (95° F) and humidified (95% relative humidity) CO2, the source of which is a standard CO2 tank or wall source. This study was conceived and designed by the PI who approached Lexion seeking devices for the study. The company will provide no funds for the study and the data and all decision regarding presentation and publications are to be made by Mount Sinai West research team.

Study patients will receive anesthesia according to the following regimen (Mount Sinai West anesthesia department has suggested this regimen and has agreed to abide by it for LCR patients unless there is a contraindication to this approach in a given patient): Induction anesthesia will include IV midazolam, IV fentanyl (3-5 mcg/kg), IV propofol, IV rocuronium, perioperative IV antibiotics, IV ondansetron for nausea prophylaxis, IV dexamethasone (8mg), IV acetaminophen 1000mg, and IV ketorolac 15 mg. Maintenance anesthesia will included IV fentanyl (1-2 mcg/kg/hr), sevoflurane or desflurane inhalational agent, and 100% oxygen. Fentanyl doses can be increased at the discretion of the anesthesiologist. 30-40 minutes before the end of the procedure, the intraoperative narcotics will be discontinued and hydromorphone PCA will be started. Patients will receive hydromorphone in the post anesthesia care unit according to the discretion of the anesthesiologist.

Analysis: Data will be recorded by the Study RN and/or the research resident on a daily basis on Case Report Forms (paper) which will be entered into a HIPPA compliant dedicated study data base with access limited to study personnel and our data manager. The Non-parametric and parametric tests such as Kruskal-Wallis test and Analysis of Variance test shall be used to determine the impact of warm humidified vs cold dry CO2 on postoperative pain medication requirements as well as on other operative and short term clinical outcomes.

Inclusion Criteria:

• Patients undergoing elective laparoscopic colorectal resection (LCR) for all indications (cancer, diverticular disease, benign neoplasm, inflammatory bowel disease, etc)

Exclusion Criteria:

• Patients younger than 18 and older than 85, emergency surgery, reoperation within 30 days, patients who are taking pain medications (either NSAID's or narcotics) on a daily basis preoperatively for whatever reason, patients with a history of narcotics addiction, paraplegic and quadriplegic patients, patients with dementia or altered mental status, and patients on steroids.