[Duration of preoxygenation in patients with normal and impaired lung function (author's transl)]

We determined the time required for the O2-filling of the lung, which is important for reasons of preoxygenation prior to intubation during apnoea and apnoeic oxygenation. 97 patients were examined. A multiple breath nitrogen washout method, the Hewlett-Packard lung function analyser HP 47402 A, was used. Complete O2-saturation of the lung in three different groups of patients took a mean time of 2 min 55 s, 4 min 20 s and 7 min 17 s. The differences were attributed to varying qualities of ventilatory gas distribution. Total O2-filling of the lung is necessary for apnoeic oxygenation. After breathing air, there is a mean decrease of PaO2 from 97 to 54 mm of mercury in 2 min of apnoea. For purposes of intubation, a 90% O2-filling of the lung takes not more than 1 and a half minutes even in patients with seriously impaired lung function. The gain of apnoeic tolerance time is approximately 4 min.