Fig. 2. Intramural oxygen partial pressure in the left colon during colon resection surgery in patients receiving supplemental oxygen (inspired oxygen concentration of 80%) and an end-tidal carbon dioxide partial pressure of 35 mmHg (normocapnia) and patients receiving supplemental oxygen and a carbon dioxide partial pressure of 50 mmHg (mild hypercapnia). The open circles represent the value in each patient. Variance is displayed using box plots (medians, 25th and 75th quartiles, and ranges); the medians differed significantly ( P = 0.020).