RT Journal Article
SR Electronic
T1 Imposed Power of Breathing Associated With Use of an Impedance Threshold Device
JF Respiratory Care
FD American Association for Respiratory Care
SP 177
OP 183
VO 52
IS 2
A1 Ahamed H Idris
A1 Victor A Convertino
A1 Duane A Ratliff
A1 Donald F Doerr
A1 Keith G Lurie
A1 Andrea Gabrielli
A1 Michael J Banner
YR 2007
UL http://rc.rcjournal.com/content/52/2/177.abstract
AB OBJECTIVE: To measure the imposed power of breathing (imposed work of breathing per minute) associated with spontaneous breathing through an active impedance threshold device and a sham impedance threshold device. DESIGN: Prospective randomized blinded protocol. SETTING: University medical center. PATIENTS: Nineteen healthy, normotensive volunteers (10 males, 9 females, age range 20–56 y, mean ± SD weight 54.8 ± 7.7 kg for females, 84 ± 8 kg for males). METHODS: The volunteers completed 2 trials of breathing through a face mask fitted with an active impedance threshold device set to open at −7 cm H2O pressure, or with a sham impedance threshold device, which was identical to the active device except that it did not contain an inspiratory threshold pressure valve diaphragm. Spontaneous breathing frequency (f), tidal volume (VT), exhaled minute ventilation, inspiratory pressure, and inspiratory time were measured with a respiratory monitor, and the data were directed to a laptop computer for real-time calculation of the imposed power of breathing. RESULTS: There were no significant differences in heart rate, respiratory rate, tidal volume, and minute ventilation, with and without inspiratory impedance. For the sham and active impedance threshold device groups, respectively, the mean ± SD imposed power of breathing values were 0.92 ± 0.63 J/min and 8.18 ± 4.52 J/min (p < 0.001), the mean ± SD inspiratory times were 1.98 ± 0.86 s and 2.97 ± 1.1 s (p = 0.001), and the mean ± SD inspiratory airway/mouth pressures were −1.1 ± 0.6 cm H2O and −11.7 ± 2.4 cm H2O (p < 0.001). CONCLUSIONS: Breathing through an active impedance threshold device requires significantly more power than breathing through a sham device. All subjects tolerated the respiratory work load and were able to complete the study protocol.