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Expiratory Flow Limitation in Non Obstructed Obese Patients FREE TO VIEW

Thomas S. Kaleekal, MBBS*; Tilottama Majumdar, MBBS; Elizabeth Guy, MD; Amir Sharafkhaneh, MD
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Baylor College of Medicine, Houston, TX


Chest. 2004;126(4_MeetingAbstracts):798S-c-799S. doi:10.1378/chest.126.4_MeetingAbstracts.798S-c
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PURPOSE:  Obesity alters the functional relationship between the lung, chest wall and diaphragm resulting in abnormal pulmonary function. We have noted a flow volume loop pattern {tidal flow volume loop (tFVL) touches or cuts across the forced expiratory flow-volume loop (fvcFVL)} suggestive of expiratory flow limitation in non-obstructed obese patients. We wished to study the relationship between this abnormal flow volume pattern with pulmonary function data obtained from obese and normal weight individuals.

METHODS:  A retrospective review of pulmonary function test (PFT) data of 420 consecutive patients over a four-month period was done. Exclusion criteria were Age≤18, Fev1/VC<70 or incomplete data. PFT data on 152 patients was analyzed. Two groups of patients were identified, those patients in whom the tFVL touched or cut the fvcFVL (Group1) and those in whom it did not (Group2). Unpaired t tests were used to look for differences between the two groups.

RESULTS:  Age and Body Mass Index (BMI) were significantly higher in Group 1. Forced Vital Capacity (FVC), Forced expiratory volume 1(FEV1), Fev1/FVC, Forced expiratory flow 25-75% (FEF25-75%) were significantly lower in Group 1. Peak Expiratory Flow (PEF) and Peak Inspiratory Flow (PIF), Total Lung Capacity (TLC), Vital Capacity (VC), Inspiratory Capacity (IC) and Functional Residual Capacity (FRC) showed no significant difference. Expiratory reserve volume (ERV) was significantly lower while Residual Volume (RV) and RV/TLC were increased in Group 1 and approached significant values. Logistic regression analysis with abnormal flow volume loop as the dependent variable correlated significantly with age, BMI and ERV. A multivariate regression analysis with ERV as the continuous dependent variable strongly correlated with flow volume loop pattern, age and BMI.

CONCLUSION:  Obesity (BMI > 30) is independently associated with significant expiratory flow limitation due to subtle small airway dysfunction, detected by an abnormal flow volume loop pattern (tFVL touching or cutting across the fvcFVL) in the absence of clinical obstruction.

CLINICAL IMPLICATIONS:  This abnormal flow volume loop pattern may indicate ventilatory limitation in clinically non-obstructed obese patients.

DISCLOSURE:  T.S. Kaleekal, None.

Wednesday, October 27, 2004

12:30 PM - 2:00 PM




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