Influence of perioperative oxygen fraction on pulmonary function after abdominal surgery: a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>A high perioperative inspiratory oxygen fraction (FiO₂) may reduce the frequency of surgical site infection. Perioperative atelectasis is caused by absorption, compression and reduced function of surfactant. It is well accepted, that ventilation with 100% oxygen for only a few minutes is associated with significant formation of atelectasis. However, it is still not clear if a longer period of 80% oxygen results in more atelectasis compared to a low FiO₂.</p> <p>Our aim was to assess if a high FiO₂ is associated with impaired oxygenation and decreased pulmonary functional residual capacity (FRC).</p> <p>Methods</p> <p>Thirty-five patients scheduled for laparotomy for ovarian cancer were randomized to receive either 30% oxygen (n = 15) or 80% oxygen (n = 20) during and for 2 h after surgery. The oxygenation index (PaO₂/FiO₂) was measured every 30 min during anesthesia and 90 min after extubation. FRC was measured the day before surgery and 2 h after extubation by a rebreathing method using the inert gas SF₆.</p> <p>Results</p> <p>Five min after intubation, the median PaO₂/FiO₂ was 69 kPa [53-71] in the 30%-group vs. 60 kPa [47-69] in the 80%-group (<it>P</it> = 0.25). At the end of anesthesia, the PaO₂/FiO₂ was 58 kPa [40-70] vs. 57 kPa [46-67] in the 30%- and 80%-group, respectively (<it>P</it> = 0.10). The median FRC was 1993 mL [1610-2240] vs. 1875 mL [1545-2048] at baseline and 1615 mL [1375-2318] vs. 1633 mL [1343-1948] postoperatively in the 30%- and 80%-group, respectively (<it>P</it> = 0.70).</p> <p>Conclusion</p> <p>We found no significant difference in oxygenation index or functional residual capacity between patients given 80% and 30% oxygen for a period of approximately 5 hours.</p> <p>Trial registration</p> <p>ClinicalTrials.gov Identifier: NCT00637936.</p