Ventilatory Muscle Training in Stroke

The purpose of the present study is to determine the utility and effectiveness of Expiratory Muscle Training in improving respiratory muscle strength in patients with chronic stroke, when combined with Inspiratory Muscle Training.

20 participants will be recruited from one site (Rehabilitation Institute of Chicago). All participants will give written informed consent before the enrollment in the study. Participants will be compensated for their participation.

Participants will participate in the study for one month. Maximum inspiratory and expiratory pressures will be measured in the seated position. Pulmonary function testing will also be performed in the seated position using a spirometer. Dyspnea will be assessed by the Medical Research Council (MRC) dyspnea scale.

The initial evaluation will consist of recording demographic information and conducting a comprehensive medical history, including: age, gender, race, marital status, education, employment, smoking history, ischemic stroke etiology, stroke severity with NIH Stroke Scale, and stroke location. This information may also be obtained from the RIC electronic medical record. Each subject will undergo a thorough neurologic assessment.

Study participants will be randomly assigned to one of two groups: the experimental group with high resistance EMT and the control group with low resistance EMT. The participants will be randomized to the two groups by an independent staff member at the time of enrollment based on the medical record number. Both groups will undergo IMT because IMT has been found to be effective improving MIP as well as FEV1 and FVC. The patients and those reading the pulmonary function tests will be blinded to the group assignment of each participant.

Upon enrollment in the study, respiratory muscle training will be completed twice daily for 5 days a week for 4 weeks. Training will be provided with the Threshold IMT (Respironics, Murrysville, PA) for inspiratory training and Threshold PEP (Respironics, Murrysville, PA) for expiratory training. The Threshold respiratory trainers are commercially available devices with a spring-loaded valve that provided resistance. The pressure loads can be adjusted at 2 cm H2O intervals for the Threshold IMT, up to 41 cm H2O, and 1 cm H2O intervals for the Threshold PEP, up to 20 cm H2O. EMT training loads in the experimental group will be set to 30% of maximal expiratory pressure while the control group EMT will be set to 5 cm H2O, the lowest setting on the device. IMT training loads will be set to 30% of maximal inspiratory pressure for both groups. The patient will be blinded to the valve titration. Each training session will include one set of 10 repetitions with IMT followed by one set of 10 repetitions with high resistance EMT or low resistance EMT. Patients will be instructed to maintain a respiratory rate of 15-20 breaths/min without rest between repetitions. Participants will be monitored daily by phone and by self-reported log for completion of each training. At two weeks, participants will have a follow-up office visit to monitor progress and those that have completed 80% of their training sessions will increase their training to 40% of maximum inspiratory and expiratory pressures as tolerated.

Each participant will undergo baseline measurement of maximal inspiratory and expiratory pressure and baseline pulmonary function tests as well as after 4 weeks of training. Three trials will be performed with the highest result of the three trials recorded.

Inclusion criteria

• History of Ischemic stroke
• Stroke impairment 8 months or more
• Hemiparesis in upper and/or lower limb
• Ability to give informed consent
• Ability to follow instructions for study procedures
• Completed a standard multidisciplinary inpatient stroke rehabilitation program consisting of physical, occupational, and speech therapy sessions for at least 3 hours a day for 5 days a week for at least 2 weeks

Exclusion criteria

• Neurological conditions other than stroke
• Active concurrent exacerbation of cardiopulmonary disease
• Presence of a tracheostomy