title: Compensatory exercise hyperventilation is restored in the morbidly obese after bariatric surgery.
abstract: BACKGROUND
  Morbidly obese individuals may have poor compensatory hyperventilation during exercise. The objective was to examine pulmonary gas exchange and the compensatory hyperventilatory response during exercise pre- and post-weight reduction surgery in obese subjects.
  
  
  METHODS
  Fifteen patients (age=39+/-8 years, body mass index=47+/-6 kg/m2), with an excess weight of 69+/-17 kg, were recruited. Pulmonary function at rest was assessed and arterial-blood gases were sampled at rest and all levels of exercise pre- and 10+/-3 weeks postsurgery.
  
  
  RESULTS
  There was a loss of excess weight 21+/-6 kg (p<0.01). Waist and hip circumference decreased by 13+/-9 and 8+/-7 cm, respectively (p<0.01). Prior to surgery, there was no compensatory hyperventilation between rest and peak exercise as arterial PCO2 (PaCO2) remained unchanged (37+/-3 mm Hg). However, postsurgery, there was compensatory hyperventilation as PaCO2 decreased to 33+/-2 mm Hg at peak exercise (p<0.01), with no change in peak oxygen consumption (VO2peak in L/min). Multiple linear regression revealed that the restored ventilatory response to exercise was most strongly associated with the reduction in overall fat mass (adjusted r2=0.25; p=0.03). Total weight loss of 21 kg induces adequate compensatory hyperventilation that begins to show at about 50% of VO2peak, resulting in improved gas exchange at moderate to peak exercise intensities.
  
  
  CONCLUSIONS
  Improvement in compensatory hyperventilation is most closely related to loss in overall fat mass.
authors: Department of Obstetrics, Gynecology and Women's Health, School of Medicine, Saint Mary's Health Center, Saint Louis University, 6420 Clayton Road, Room 290, Saint Louis, MO 63117, USA. zavorsky@slu.edu
authors: Gerald S
authors: GS
authors: Zavorsky
authors: Do Jun
authors: DJ
authors: Kim
authors: Nicolas V
authors: NV
authors: Christou
mesh_terms: D000328:Adult; D001823:Body Composition; D015897:Comorbidity; D015444:Exercise / Q000502:physiology*; D006801:Humans; D006985:Hyperventilation; D008875:Middle Aged; D009767:Obesity, Morbid / Q000453:epidemiology / Q000503:physiopathology* / Q000601:surgery; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000378:metabolism; D011184:Postoperative Period; D011659:Pulmonary Gas Exchange; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology; D013147:Spirometry
chemical_list: D010108:Oxyhemoglobins