Reference chart of inspiratory muscle strength: a new tool to monitor the effect of pre-operative training

Objectives
To develop a reference chart to monitor inspiratory muscle strength during pre-operative inspiratory muscle training for patients at high risk of developing postoperative pulmonary complications awaiting coronary artery bypass graft (CABG) surgery.
Design
Secondary data analysis using patients from the intervention arm of a randomised clinical trial.
Setting
University medical centre.
Participants
Patients at high risk of developing postoperative pulmonary complications awaiting CABG surgery.
Interventions
Patients performed inspiratory muscle training seven times per week for at least 2 weeks before surgery.
Main outcome measures
Maximal inspiratory muscle strength.
Results
A new reference chart was produced using a non-linear time trend model with a normal error structure.
Conclusions
The chart is a novel tool for monitoring the progress of inspiratory muscle training for physiotherapy practice. Wider use of this chart is recommended.