Baseline measurements of pulmonary function included standard lung volumes, flow rates, diffusion, measurements of maximal inspiratory and expiratory pressure, and ABG determinations measured with the patient breathing room air. antibiotics levaquin
Inspiratory muscle endurance was measured by pressure threshold loading, a technique first described by Nickerson and Keens among healthy volunteers and subsequently reported to be useful in assessing inspiratory muscle function among patients with chronic respiratory disease. A weighted plunger serves as an inspiratory valve and the inspiratory pressure load is determined by the amount of weight applied to the valve. Inspiratory muscle endurance was measured as the endurance time (TUM) during which the subject could maintain inspiration against 45 percent of maximum inspiratory pressure (MIP) at residual volume (RV). Subjects inspired against a weighted plunger housed in a valve; air flow occurred when the pressure generated at the airway opening was sufficient to lift the plunger. This threshold pressure had to be sustained throughout inspiration to prevent valve closure. Subjects were given maximal encouragement throughout this test to comply with the following ventilatory controls: (1) duty cycle (T/TJ) at 0.5; (2) respiratory rate (/b) at resting level; and (3) tidal volume (Vt) at 125 percent of the previously measured resting value.