PURPOSE: To measure changes in respiratory dynamics in patients with chronic obstructive pulmonary disease (COPD) sitting leaning forward with hands supported anteriorly on the knees (tripod position), a posture frequently assumed by patients in respiratory distress.
METHODS: Pulmonary function testing, maximal inspiratory and expiratory pressures 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 (defined as no exacerbations in the preceding 4 weeks) in sitting, supine and tripod positions. Each test was done after the patient had assumed that posture for 5 minutes. Nonparametric Kruskal-Wallis test was used to assess difference between the three groups for all tests. p≤;0.05 was considered significant.
RESULTS: The mean±SD age of the patients was 52.2±6.8 years. Median disease duration was 3 years. Mean±SD six minute walk distance was 417.9±88.5 meters. 9 of the 13 patients were in Global Initiative for Chronic Obstructive Lung Disease stages 3 and 4. There was no statistically significant difference in spirometry (FEV1 1.11±0.4, 1.14±0.5 and 1.11±0.4 L for sitting, supine and tripod positions respectively, p=0.99; FEV1/FVC 49.2±11.0, 53.7±8.5 and 48.5±11.3, p=0.37), maximum pressures generated at the mouth(Maximal inspiratory pressures 102.9±28.9, 90.6±29.1 and 99.2±32.9 cm H2O, p=0.61 and Maximal expiratory pressures 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 and16.6±6.2 mm, p=0.22) and forced vital capacity maneuver (33.9±11.0, 43.1±19.6 and 37.4±17.1 mm, p=0.35) breathing for the three postures.
CONCLUSION: Commonly measured indices of respiratory function were not different in tripod position compared to sitting and supine positions.
CLINICAL IMPLICATIONS: It is clinically difficult to reproduce the respiratory dynamics involved in tripod position assumed by patients in respiratory distress and mechanisms other than those easily measured might be able to explain the perceived benefits of assuming tripod position in some patients.
DISCLOSURE: Surya Bhatt, No Financial Disclosure Information; No Product/Research Disclosure Information