Respiratory Strength Training in Cardiac Surgical Patients

Enrolled research participants will undergo baseline assessments of pulmonary function: maximum expiratory pressure (MEP), maximum inspiratory pressure (MIP), cough function (voluntary PEF and cough spirometry), and will complete self-reported dyspnea using the validated London Chest Activity of Daily Living (LCADL) scale. Following baseline testing, participants will complete a respiratory strength training program (RST) in the home via telehealth with one in-person home therapy session conducted at each participant's midpoint to reassess MEP and MIP and to recalibrate the respiratory strength trainer devices. After the prescribed RST program, participants will complete a second post-RST preoperative assessment. All pulmonary function measures will be performed by a research SLP in accordance with standardized protocols and guidelines from the American Thoracic Society 12-14 with research participants in an upright seated position with nose clips in place. A swallowing examination (FEES) will be completed both pre and post surgery to assess any impact on swallowing safety.

Respiratory Assessment:

MEP and MIP measurements will be obtained using a MicroRPM handheld menometry device (MicroDirect). For MEP testing, research participants will be instructed to take a deep breath in, place their mouth around the mouthpiece, and blow out as forcefully as possible. As needed, the research SLP will assist with lip seal by holding the sides of participant's cheeks to prevent air leakage. For MIP testing, research participants will be instructed to expel all the air out of their lungs, place their mouth around the mouthpiece, and breathe in as forcefully as possible. Each participant will perform 3 MEP and MIP trials. Average MEP and MIP values will be used to calibrate expiratory and inspiratory devices and for subsequent analyses.

Respiratory Strength Training (RST) Program:

The RST program consists of expiratory muscle strength training (EMST) and inspiratory muscle strength training (IMST) using the EMST-75 Lite or the EMST-150 and the IA-150 devices (Aspire Products), respectively. Trainer devices will be calibrated to a 50% load of individualized MEP and MIP values. The CS patients will perform 25 repetitions each (5 sets of 5 repetitions) of the expiratory and inspiratory exercises, 5 days/week leading up to their surgical procedure. The patients will be given training logs to track completion of the RST exercises to measure adherence.

Telehealth sessions:

Telehealth sessions will be conducted by a research speech-language pathologist (SLP) at least once per week via a secure version of Zoom. During telehealth sessions, the research SLP will ensure that participants performed the prescribed exercises with correct form, completed a safety and adverse event check, answered participant questions, assisted with adherence issues, monitored adverse events, and aided participants in adjusting the resistance of the expiratory and inspiratory training devices based on participant exertion ratings using the Borg Category Ratio 10 Scale.11 During the adverse event check, the research SLP will ask research participants if they were experiencing any pain, fatigue, discomfort, or other adverse events related to the RST protocol. Attendance for telehealth sessions will be tracked.

Home Visits:

In addition to weekly telehealth sessions, a home visit will be conducted by a research SLP midway through the RST program. During the home visit, the research SLP will perform check-ins similar to telehealth sessions, retest MEP and MIP, and recalibrate the training devices to meet the 50% training load target.

Fiberoptic Endoscopic Evaluation of Swallowing (FEES):

Participants will undergo a FEES exam in a dedicated room in the preoperative clinic or the ARC lab before and after completing the RST program using an Olympus flexible video HD Rhino Laryngoscope connected to a portable video processor and light source. To ensure patient comfort, a water-soluble lubricant and, per participant preference, a topical numbing-agent (i.e., lidocaine) will be applied to the naris, and the laryngoscope will be passed trans-nasally through the nasopharynx and hypopharynx until an optimal position is obtained. A standardized FEES protocol will be used that includes a combination of voicing and swallowing tasks. At the completion of the swallowing trials, the laryngoscope will be carefully removed. Blinded analysis of the swallowing exam will be performed.

Statistical Analysis:

Demographic information and pulmonary and cough function data will be exported directly from our secure online database, REDCap, into JMP version 16.1.020 and Prism version 9.4.1 (GraphPad Software) for statistical analyses. Descriptive statistics will be used to summarize demographic information and pulmonary and cough function data. Intraclass correlation coefficients (ICCs) with 95%confidence intervals (CI) will be used to calculate inter-rater and intrarater reliability for voluntary cough spirometry metrics. Mean differences with 95% CIs will be calculated, and the Wilcoxon signed-rank test will be performed to assess pre-RST to post-RST changes in pulmonary and cough function.