Study of Inhaling Carbon Monoxide to Treat Patients With Intestinal Paralysis After Colon Surgery.

Inhaled Carbon Monoxide in Patients With Post-Operative Ileus Following Colon Resection.

Post operative ileus (POI), a temporary paralysis of the intestines, is a serious health care problem. It normally occurs in all patients after surgery to the abdomen but in some cases can result in serious complications. The objective of this study is to determine if inhaling very low doses of carbon monoxide (CO) before and after colon surgery will shorten the duration of normal POI and/or prevent the development of POI complications in patients undergoing colon surgery.

A preliminary study will be conducted in six healthy volunteers to monitor for blood levels and adverse effects that occur at 3 different doses of inhaled CO to establish a safe dose for patients in the main trial. For the main trial, patients requiring surgery to their colon will be assigned randomly to receive one hour treatments of either CO or oxygen by face mask before and after their operation. Length of normal POI and occurrence of POI complications will be compared between the two groups. Side effects that occur from inhaling CO or oxygen will also be recorded.

We hypothesize that inhaling CO before and after colon surgery will shorten the length of normal POI and decrease the occurrence of POI complications with minimal side effects.

Inclusion Criteria:

• Men and women, age > 18 years.
• Women must be using acceptable contraceptives, post-menopausal or surgically sterile.
• No prior smoking history.
• BMI between 16 and 30 inclusive.
• No significant abnormalities on history, physical examination or laboratory parameters.

Exclusion Criteria:

• Exposure to any carbon monoxide source during the 48 hours prior to the study day or occupational exposure to CO.
• Significant disease or disorder (as explained in Study B).
• Complete bowel obstruction.
• Intra-abdominal inflammation (diverticulitis, inflammatory bowel disease, colitis).
• Retroperitoneal hematomas.
• Known GI motility disorder.
• Underlying lung disease such as pneumonia, asthma or COPD.
• Sepsis.
• Planned pregnancy, already pregnant or breastfeeding.
• Electrolyte disturbance (hypokalemia, hypomagnesemia, hyponatremia).
• Significant opioid and laxative use 4 weeks prior to surgery.
• Anti-inflammatory use 2 days prior to surgery.
• Drugs such as antacids, Coumadin, amitriptyline, chlorpromazine.
• Baseline oxygen saturation <92% on room air.
• Baseline blood level of COHb >2%.
• Baseline hemoglobin <90 g/dL.
• Participation in another clinical trial within 2 months prior to study.