Preoxygenation - Comparison of maximal breathing and tidal volume breathing techniques

Background: Preoxygenation with tidal volume breathing for 3-5 min is recom mended by Hamilton and Eastwood. This report compares tidal volume preoxyge nation technique with deep breathing techniques for 30-60 s. Methods: The study was conducted in two parts on patients undergoing electi ve coronary bypass grafting. In the first group (n = 32), each patient unde rwent all of the following preoxygenation techniques: the traditional techn ique consisting of 3 min of tidal volume breathing at an oxygen flow of 5 l /min; four deep breaths within 30 s at oxygen flows of 5 l/min, 10 l/min, a nd 20 l/min; and eight deep breaths within 60 s at an oxygen now of 10 l/mi n. The mean arterial oxygen tensions after each technique were measured and compared. In the second group (n = 24), patients underwent one of the foll owing techniques of preoxygenation: the traditional technique (n = 8), four deep breaths (n = 8), and eight deep breaths (n = 8). Apnea was then induc ed, and the mean times of hemoglobin desaturation from 100 to 99, 98, 97, 9 6, and 95% were determined. Results In the first group of patients, the mean arterial oxygen tension fo llowing the tidal breathing technique was 392 +/- 72 mmHg. This was signifi cantly higher (P < 0.05) than the values obtained following the four deep b reath technique at oxygen flows of 5 l/min (256 +/- 73 mmHg), 10 l/min (286 +/- 69 mmHg), and 20 l/min (316 +/- 67 mmHg). In contrast, the technique o f eight deep breaths resulted in a mean arterial oxygen tension of 369 +/- 69 mmHg, which was not significantly different from the value achieved by t he traditional technique. In the second group of patients, apnea following different techniques of preoxygenation was associated with a slower hemoglo bin desaturation in the eight-deep breaths technique as compared with both the traditional and the four-deep-breaths techniques. Conclusion: Rapid preoxygenation with the eight deep breaths within 60 s ca n be used as an alternative to the traditional 3-min technique.