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.