Effect of tripod position on objective parameters of respiratory function in stable chronic obstructive pulmonary disease.

OBJECTIVE To examine changes in respiratory dynamics in patients with chronic obstructive pulmonary disease (COPD) sitting leaning forward with hands supported on the knees (tripod position), a posture frequently assumed by patients in respiratory distress. METHODS Spirometry, maximal inspiratory and expiratory pressures (MIP and MEP) generated at the mouth, and diaphragmatic excursion during tidal and vital capacity maneuver breathing measured by B-mode ultrasonography were studied in 13 patients with stable COPD in sitting, supine and tripod positions. RESULTS Mean +/- SD age of patients was 52.2 +/- 6.8 years. Median disease duration was three years. There was no statistically significant difference in spirometry for sitting, supine and tripod positions (FEV1: 1.11 +/- 0.4L, 1.14 +/- 0.5L and 1.11 +/- 0.4L; p = 0.99), respectively, (FEV1/FVC: 49.2 +/- 11.0, 53.7 +/- 8.5 and 48.5 +/- 11.3, p = 0.37), mouth pressures (MIP: 102.9 +/- 28.9, 90.6 +/- 29.1 and 99.2 +/- 32.9 cm H2O, p = 0.61 and MEP: 100.8 +/- 29.9, 100.4 +/- 34.4 and 90.6 +/- 32.6 cm H2O, p = 0.74) and diaphragmatic movements during tidal (16.1 +/- 5.9, 20.1 +/- 6.8 and 16.6 +/- 6.2 mm, p = 0.22) and forced breathing (33.9 +/- 11.0, 43.1 +/- 19.6 and 37.4 +/- 17.1 mm, p = 0.35). CONCLUSION Commonly measured indices of respiratory function were not different in the tripod compared to sitting and supine positions.