Inspiratory Muscle Training in Patients With Duchenne Muscular Dystrophy: Training Apparatus
For this study, a special training apparatus was constructed to enable the patient to actually adhere to the prescribed training intensity. In addition, the number of correctly and incorrectly performed exercises was stored by the apparatus to give the physician the possibility to control the training of the patient.
The training apparatus enabled the patient to do resistive breathing maneuvers against a variable inspiratory resistance or maximal static inspiratory efforts against the almost occluded resistance. Room air was breathed through a mouthpiece, a twoway non-rebreathing valve of low resistance, a 3-cm-long plastic tube, a pneumotachograph, and a variable alinear inspiratory resistance. Inspiratory flow was measured with the pneumotachograph connected to a differential pressure transducer (Honeywell 163 PC, Freeport, III). The training equipment was kept in a small collapsible case. In the bottom half of the case, the mouthpiece, the two-way valve, and the short plastic tube were kept. The pneumotachograph and the alinear resistor were fixed in this part of the case. In addition, there was a slot for a videogame cassette that could be opened if the training was successful. The possibility to play a videogame as a reward could motivate the patients not to interrupt the training prematurely. mycanadianpharmacy
To provide a visual control of the performance, there were two vertical LED displays fixed to the inside of the upper half of the case. On one display, the patient was shown breath by breath the inspiratory airflow (in arbitrarily chosen units). During the loaded breathing runs, each breath had to reach an exact minimal value. On the other display, the patient would be shown by the indicator if he had achieved the preset minute volume (Ve) while breathing against the inspiratory resistance. Two lights beside the displays served as visible cues for maintaining breathing frequency (fb). During the maximal static inspiratory effort maneuvers against the almost completely occluded resistance, the generated negative pressure was displayed in arbirary units in place of inspiratory airflow. A small leak prevented the patients from using the buccal muscles for generating negative pressures. Pressures were measured with a ± 300 cm H20 differential pressure transducer (model 142 PC, Honeywell, Freeport, 111). On a side wall of the case, there was a switch with which one could select one of the two training programs. The resistance was automatically set at the desired level when the switch was in the “program Iй position. In the “program 2” position, the resistance was almost completely closed.