title: Preoxygenation: comparison of maximal breathing and tidal volume breathing techniques.
abstract: BACKGROUND
  Preoxygenation with tidal volume breathing for 3-5 min is recommended by Hamilton and Eastwood. This report compares tidal volume preoxygenation technique with deep breathing techniques for 30-60 s.
  
  
  METHODS
  The study was conducted in two parts on patients undergoing elective coronary bypass grafting. In the first group (n = 32), each patient underwent all of the following preoxygenation techniques: the traditional technique 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, and 20 l/min; and eight deep breaths within 60 s at an oxygen flow of 10 l/min. The mean arterial oxygen tensions after each technique were measured and compared. In the second group (n = 24), patients underwent one of the following techniques of preoxygenation: the traditional technique (n = 8), four deep breaths (n = 8), and eight deep breaths (n = 8). Apnea was then induced, and the mean times of hemoglobin desaturation from 100 to 99, 98, 97, 96, and 95% were determined.
  
  
  RESULTS
  In the first group of patients, the mean arterial oxygen tension following the tidal breathing technique was 392+/-72 mm Hg. This was significantly higher (P<0.05) than the values obtained following the four deep breath technique at oxygen flows of 5 l/min (256+/-73 mm Hg), 10 l/min (286+/-69 mm Hg), and 20 l/min (316+/-67 mm Hg). In contrast, the technique of eight deep breaths resulted in a mean arterial oxygen tension of 369+/-69 mm Hg, which was not significantly different from the value achieved by the traditional technique. In the second group of patients, apnea following different techniques of preoxygenation was associated with a slower hemoglobin desaturation in the eight-deep-breaths technique as compared with both the traditional and the four-deep-breaths techniques.
  
  
  CONCLUSIONS
  Rapid preoxygenation with the eight deep breaths within 60 s can be used as an alternative to the traditional 3-min technique.
authors.affiliation: Department of Anesthesiology, American University of Beirut, Lebanon. abaraka@aub.edu.lb
authors.forename: A S
authors.initials: AS
authors.lastname: Baraka
authors.forename: S K
authors.initials: SK
authors.lastname: Taha
authors.forename: M T
authors.initials: MT
authors.lastname: Aouad
authors.forename: M F
authors.initials: MF
authors.lastname: El-Khatib
authors.forename: N I
authors.initials: NI
authors.lastname: Kawkabani
mesh_terms: D000758:Anesthesia; D005260:Female; D006801:Humans; D008297:Male; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D012119:Respiration; D013990:Tidal Volume
chemical_list: D010100:Oxygen