Table 1 Entry and exclusionary criteria

Adequate gas exchange as indicated by a P_aO₂ above 60 mmHg while breathing with an F_IO₂ of 0.50 or less

Be medically stable and ready to be weaned from the ventilator as determined by the attending physician

Hemodynamically stable for 24 hours prior to participation or requiring only minimal intravenous pressor agents (dobutamine or dopamine ≤ 5 mcg/kg/min, phenyleprine ≤ 1 mcg/kg/min)

Be able to follow simple verbal directions related to inspiratory muscle strength testing and training

Receiving assist control or SIMV or pressure support ventilation via a tracheostomy, with SIMV ≤ 6 breaths/min, pressure support ventilation ≤ 15 cm H₂O and PEEP ≤ 10 cmH₂O

Unable to sustain unsupported breathing for at least 72 consecutive hours following resolution of factor(s) precipitating respiratory failure

Demonstrate normal hemidiaphragm positions on X-ray

Not have any progressive neuromuscular disease such as amyotrophic lateral sclerosis, muscular dystrophy, multiple sclerosis, myasthenia gravis, or any other neuromuscular disorder that would interfere with responding to inspiratory muscle training

Have an anticipated life expectancy of at least 12 months

Have a core temperature between ≥36.5°C and ≤ 38.5°C

Not have a spinal cord injury above T8

Not have any skeletal pathology (scoliosis, flail chest, spinal instrumentation) that would seriously impair the movement of the chest wall and ribs

Not using any type of home MV support prior to hospitalization

Body mass index < 40 kg/m²

Not require continuous sedative or analgesic agents that will depress respiratory drive or the ability to follow commands

No excessive secretions (requiring suctioning more than once every hour)

Not being considering for transfer to another hospital in the next

28 days