The effect of body position on maximum inspiratory and expiratory pressures and forced expiratory flow.
Purpose/Hypothesis: The lungs are free to move within the chest wall and, therefore, susceptible to internal and external forces. For example, the gravitational effects resulting from changes in body position modify the resting alignment of the diaphragm and abdominal contents, alter resistance imposed on muscles, and vary ventilation/perfusion relationships. The purpose of this study was to examine the effect of different body positions on the ability of the lungs to forcefully inhale and exhale. More specifically, the purpose of this study was to compare forced vital capacity (FVC), forced expiratory volume in one second as a percent of forced vital capacity (FEV1/FVC%), maximum inspiratory pressure (MIP), and maximum expiratory pressure (MEP) values obtained during standing, sitting, forward sitting, supine, and prone positions. Number of Subjects: Twenty healthy subjects (8 men and 12 women 25 [+ or -] 2.96 years of age) volunteered to participate in this study. Inclusion criteria consisted of: classification of low to moderate risk according to the American College of Sports Medicine ranking criteria, no history of past or present orthopedic injury or trunk scarring that prevented or limited chest movements, and no known neurological disease. Materials/Methods: Subjects' maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) were measured using a Micro Direct MicroRPM Respiratory Pressure Meter (Lewiston, ME). Forced vital capacity (FVC) and forced expiratory volume in one second as a percent of forced vital capacity (FEV1/FVC%) were measured using the MedGraphics CPFS/DTM USB Spirometer (St. Paul, MN). Measurements were obtained in random order with subjects in standing, sitting, forward sitting, supine, and prone positions. Results: A repeated measures one-way ANOVA revealed no significant effect of position on MIP, MEP, and FEV1/FVC%. However, FVC was affected by position (p [less than or equal to] 0.05). Follow up paired t-tests indicated the forced vital capacity in the supine position was significantly less than in the sitting, forward sitting, and standing positions and forced vital capacity in prone was less than in the sitting and standing positions (p [less than or equal to]0.005). Conclusions: Results indicate body position does not affect the ability to generate inspiratory and expiratory pressures. However, horizontal positions such as supine and prone do result in decreased forced vital capacities. It appears the gravitational effects on thoracic and abdominal structures as well as potential restrictions imposed by contact with the table surface impact this movement. Clinical Relevance: Patients with already decreased lung volumes secondary to pathology may experience increased ventilation problems when in supine and prone positions. Patients and health care workers should be educated and encouraged to utilize more upright positions to improve lung mechanics.
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|Title Annotation:||Poster Presentations|
|Publication:||Cardiopulmonary Physical Therapy Journal|
|Date:||Dec 1, 2009|
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