title: Physiologic correlates of dyspnea in patients with morbid obesity.
abstract: OBJECTIVE
  Mechanisms of dyspnea in obesity remain unclear. This study was undertaken to determine the relationships between dyspnea and pulmonary function including inspiratory muscle endurance (IME) in morbidly obese patients before bariatric surgery.
  
  
  METHODS
  Fifty-five patients with a mean+/-s.d. body mass index (BMI) of 49.4+/-7.0 kg/m(2) were included. Dyspnea was evaluated by the Baseline Dyspnea Index (BDI; 0-12, 0=maximal dyspnea). Pulmonary function tests included a plethysmography, maximal inspiratory pressure (PImax) and IME was assessed by the incremental threshold loading test, determining the maximal pressure sustained for 2 min (Plim(2)) and Plim(2)/PImax ratio. Patients were classified according to their BMI in two groups: BMI < or =49 (n=27) and >49 kg/m(2) (n=28).
  
  
  RESULTS
  Breathlessness was higher in the BMI >49 kg/m(2) group compared to the BMI < or =49 kg/m(2) group (BDI score at 6.9+/-2.2 in the BMI >49 kg/m(2) group vs 8.9+/-2.5 in the BMI < or =49 kg/m(2) group, P<0.01). Patients with BMI >49 kg/m(2) had significantly higher PaCO(2) level and significantly lower vital capacity, inspiratory capacity and PImax values compared with the BMI < or =49 kg/m(2) group. Correlations between BDI and lung function were moderate: forced expiratory volume in 1 s (FEV(1))% pred: Rho=0.27; P=0.05; vital capacity % pred: Rho=0.40; P=0.004; and Plim(2)/PImax: Rho=0.40; P=0.003. Higher correlations with dyspnea were found in the BMI < or =49 kg/m(2) group: FEV(1)% pred: Rho=0.38; P=0.05; and Plim(2)/PImax: Rho=0.49; P=0.01.
  
  
  CONCLUSIONS
  Inspiratory muscle performance is moderately reduced in morbid obesity. Dyspnea in these patients remains moderately related to lung function and inspiratory muscle performance. However, inspiratory muscles performance correlates more significantly with dyspnea in patients with a BMI < or =49 kg/m(2).
authors.affiliation: Lung Function Department, Calmette Hospital, Lille University, France.
authors.forename: F
authors.initials: F
authors.lastname: Collet
authors.forename: A
authors.initials: A
authors.lastname: Mallart
authors.forename: J F
authors.initials: JF
authors.lastname: Bervar
authors.forename: N
authors.initials: N
authors.lastname: Bautin
authors.forename: R
authors.initials: R
authors.lastname: Matran
authors.forename: F
authors.initials: F
authors.lastname: Pattou
authors.forename: M
authors.initials: M
authors.lastname: Romon
authors.forename: T
authors.initials: T
authors.lastname: Perez
mesh_terms: D000328:Adult; D015992:Body Mass Index; D004417:Dyspnea / Q000150:complications / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D009767:Obesity, Morbid / Q000150:complications / Q000503:physiopathology*; D010807:Physical Endurance / Q000502:physiology; D012129:Respiratory Function Tests / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology; D012132:Respiratory Muscles / Q000503:physiopathology; D014797:Vital Capacity / Q000502:physiology