Article

Effect of obesity on respiratory function

The American review of respiratory disease (Impact Factor: 10.19). 10/1983; 128(3):501-6.
Source: PubMed

ABSTRACT Obesity, because it alters the relationship between the lungs, chest wall, and diaphragm, has been expected to alter respiratory function. We studied 43 massively obese but otherwise normal, nonsmoking, young adults with spirometry, lung volume measurement by nitrogen washout, and single-breath diffusing capacity for carbon monoxide (DLCO). Changes in respiratory function were of two types, those that changed in proportion to degree of obesity--expiratory reserve volume (ERV) and DLCO--and those that changed only with extreme obesity--vital capacity, total lung capacity, and maximal voluntary ventilation. When compared with commonly used predicting equations, we found that mean values of subjects grouped by degree of obesity were very close to predicted values, except in those with extreme obesity in whom weight (kg)/height (cm) exceeded 1.0. In 29 subjects who lost a mean of 56 kg, significant increases in vital capacity, ERV, and maximal voluntary ventilation were found, along with a significant decrease in DLCO. Because most subjects fell within the generally accepted 95% confidence limits for the predicted values, we concluded that obesity does not usually preclude use of usual predictors. An abnormal pulmonary function test value should be considered as caused by intrinsic lung disease and not by obesity, except in those with extreme obesity.

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    • "RV/TLC may be increased in obesity reflecting air trapping secondary to increased volume-dependent airway closure [9] [41] [51], although Jones and Nzekwu found no significant difference in this ratio between BMI groups [9]. Vital capacity (VC) may decline as BMI increases but generally into the lower normal range [9] [48] [50] [52]. However, the inspiratory capacity (IC) and the IC/TLC ratio increase with increasing the BMI reflecting the relative preservation of TLC in the presence of decreased EELV [9] [53]. "
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    • "reduced resting arterial PO 2 and increased alveolar-to-arterial PO 2 difference (Fritts et al., 1959; Dempsey et al., 1966a, 1966b; Holley et al., 1967; Barrera et al., 1969, 1973; Ray et al., 1983; Babb et al., 1989, 2002, 2008b; Thomas et al., 1989; Rubinstein et al., 1990; Pelosi et al., 1996, 1997, 1998, 1999; Pankow et al., 1998; Weiner et al., 1998; Kress et al., 1999; Eichenberger et al., 2002; Aaron et al., 2004; Chlif et al., 2005, 2007; DeLorey et al., 2005; Watson and Pride, 2005; Jones and Nzekwu, 2006; Collet et al., 2007; Ofir et al., 2007; Salome et al., 2007; Sutherland et al., 2008; Zavorsky and Hoffman, 2008). "
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