title: Preoperative gender differences in pulmonary gas exchange in morbidly obese subjects.
abstract: BACKGROUND
  Morbidly obese men may have poorer pulmonary gas exchange compared to morbidly obese women (see Zavorsky et al., Chest 131:362-367, 2007). The purpose was to compare pulmonary gas exchange in morbidly obese men and women at rest and throughout exercise.
  
  
  METHODS
  Twenty-five women (age=38+/-10 years, 164+/-7 cm, body mass index or BMI = 51+/-7 kg/m(2), peak oxygen consumption or VO(2peak)=2.0+/-0.4 l/min) and 17 men (age=43+/-9 years, 178+/-7 cm, BMI=50+/-10 kg/m(2), VO(2peak)=2.6+/-0.8 l/min) were recruited to perform a graded exercise test on a cycle ergometer with temperature-corrected arterial blood-gas samples taken at rest and every minute of exercise, including peak exercise.
  
  
  RESULTS
  At rest, women were 98% predicted for pulmonary diffusion compared to 88% predicted in men. At rest, women had better pulmonary gas exchange compared to the men which was related to women having a lower waist-to-hip ratio (WHR; p<0.01). Only 20% of the subjects had an excessive alveolar-to-arterial oxygen partial pressure difference (>or=25 mmHg) at peak exercise, but 75% of the subjects showed inadequate compensatory hyperventilation at peak exercise (arterial carbon dioxide pressure >35 mmHg), and both were not different between genders.
  
  
  CONCLUSIONS
  At rest, morbidly obese men have poorer pulmonary gas exchange and pulmonary diffusion compared to morbidly obese women. The better gas exchange in women is related to the lower WHR in the women. During exercise, few subjects showed disturbances in pulmonary gas exchange despite demonstrating poor compensatory hyperventilation at peak exercise.
authors.affiliation: Department of Obstetrics, Gynecology and Women's Health, School of Medicine, Saint Louis University, Saint Mary's Health Center, 6420 Clayton Road, Suite 290, Saint Louis, MO 63117, USA. zavorsky@slu.edu
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Zavorsky
authors.forename: Nicolas V
authors.initials: NV
authors.lastname: Christou
authors.forename: Do Jun
authors.initials: DJ
authors.lastname: Kim
authors.forename: Franco
authors.initials: F
authors.lastname: Carli
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Mayo
mesh_terms: D000328:Adult; D001823:Body Composition; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery; D010101:Oxygen Consumption; D011653:Pulmonary Diffusing Capacity; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012737:Sex Factors; D049629:Waist-Hip Ratio; D055815:Young Adult