(HealthDay News) – For patients undergoing abdominal surgery, use of 80 percent oxygen in the perioperative period is associated with an increased risk of long-term mortality, which is statistically significant for cancer patients but not for non-cancer patients, according to a study published in the October issue of Anesthesia & Analgesia.

Christian S. Meyhoff, MD, PhD, from Copenhagen University Hospital in Denmark, and colleagues examined the correlation between long-term mortality and perioperative oxygen fraction in patients undergoing abdominal surgery. A total of 1,386 patients undergoing elective or emergency laparotomy from October 2006–October 2008 were randomly allocated to receive 30 or 80% oxygen during, and for two hours following surgery. Patients were followed through February 2010 and vital status was recorded for 1,382 patients.

After a median follow-up of 2.3 years, the researchers found that, 23.2% of patients died in the 80% oxygen group (159 of 685 patients), compared with 18.3% (128 of 701 patients) in the 30% oxygen group, for a hazard ratio of 1.3 (P=0.03). For patients undergoing cancer surgery, the hazard ratio was significant (1.45; P=0.009), while the hazard ratio was not significant (1.06; P=0.79) for those undergoing non-cancer surgery.

“We conclude that administration of 80% oxygen during, and for two hours after abdominal surgery, compared to 30% oxygen, is associated with a significantly increased long-term all-cause mortality that appears to be statistically significant in patients undergoing cancer surgery but not in non-cancer patients,” the authors write.

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