Improvement of restrictive and obstructive pulmonary mechanics following laparoscopic bariatric surgery

Surg Endosc. 2009 Apr;23(4):808-12. doi: 10.1007/s00464-008-0084-9. Epub 2008 Sep 20.


Background: Morbidly obese patients often have impaired respiratory mechanics leading to restrictive and obstructive lung diseases. Weight loss after bariatric surgery has been shown to improve or resolve many obesity-related comorbidities. However, few studies have examined long-term changes in pulmonary mechanics after bariatric surgery. We hypothesize that pulmonary function improves after surgically induced weight loss.

Methods: We examined the pulmonary function of 104 morbidly obese patients who underwent laparoscopic gastric bypass or gastric banding. Pulmonary studies, including forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), peak expiratory flow (PEF), and forced expiratory volume at midexpiratory phase (FEV(25-75%)) were measured preoperatively and at 3-month intervals. All results are expressed as a percentage of the baseline values.

Results: There were 80 females and 24 males with a mean age of 41 years. The mean body mass index was 48 kg/m(2). The mean percentage of excess body weight loss at 12 months was 54%. At 12 months postoperatively, restrictive pulmonary mechanics significantly improved as demonstrated by an increase in the FEV(1) to 112% of baseline value, increase in the FVC to 109% of baseline value, increase in the PEF to 115% of baseline value, and increase in the FEV(25-75%) to 130% of baseline value. Additionally, the percentage of patients with obstructive lung pattern (FEV(1)/FVC ratio less than 0.8) decreased from 9.6% preoperatively to 1.9% postoperatively (p=0.03).

Conclusions: Weight loss after laparoscopic gastric bypass significantly improves restrictive and obstructive respiratory mechanics. The improvements were observed as early as 3 months postoperatively.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Female
  • Follow-Up Studies
  • Forced Expiratory Volume / physiology
  • Gastric Bypass / adverse effects*
  • Humans
  • Laparoscopy*
  • Lung / physiology*
  • Lung Diseases, Obstructive / etiology
  • Lung Diseases, Obstructive / physiopathology*
  • Male
  • Obesity, Morbid / surgery*
  • Postoperative Complications
  • Recovery of Function / physiology*
  • Respiratory Mechanics / physiology*
  • Time Factors
  • Treatment Outcome
  • Vital Capacity / physiology
  • Weight Loss / physiology