Feasibility, acceptability and change in inspiratory muscle strength in patients performing supervised breathing strengthening exercises using an inspiratory muscle trainer (IMT) device while waiting in hospital to have urgent cardiac surgery.

The intervention is Inspiratory Muscle Training (IMT). This training is supervised by the research physiotherapist and is done with participant in the intervention group at a mutually convenient time on the ward where the participant is located until surgery. IMT is done by inspiring against resistance from an IMT device. The device used in this study is an electronic Powerbreathe. This is a portable TGA approved device that provides resistance to inspiration that can be modified to suit individual people and training load. The research physiotherapists in this study have all had greater than 8 years clinical experience and are experienced in research and in IMT and no specific training is required. The research physiotherapist will supervise all IMT sessions and monitor safety by review of the medical record and observation chart, general observations, and monitoring of SpO2 and HR during and immediately after for 5 minutes post training using a portable oximeter. Blood pressure and respiratory rate will be measured pre and post training. Participants will be suitable for IMT if there is a minimum of 2 days training available pre-surgery and they therefore can receive a minimum of 4 training sessions. The participant’s Maximal Inspiratory Pressure (MIP) will be used to determine the appropriate training load. This is the highest inspiratory pressure generated by the participant as measured by the Powerbreathe. The research physiotherapist will prescribe a training intensity of at least 50% of MIP, and from there will titrate the highest tolerable intensity (up to maximum 80% of MIP) that allows the participant to just complete the 6th breath in a set of 6 breaths. The BORG rate of perceived exertion scale will be used to ensure intensity of training is sufficient. This will aim to be the equivalent of 14-16 on the BORG scale, and this scale will be measured at each session. The intensity will be increased by the research physiotherapist across the training period and across training sessions to ensure adequate training stimulus. Training will be performed twice daily on weekdays (morning and afternoon), with the research physiotherapist assisting the participant to perform 5 sets of 6 breaths each session. Weekend IMT will not be done due to potential poor performance with unsupervised sessions and limited physiotherapy staff. Between sets, participants are allowed a rest period as required, and there will be at least 4 hours between sessions. Each training session is expected to take approximately 20 minutes, and training will continue until the day of surgery. Training will occur no closer than 1 hour after a meal. Before and after each training session, participants will be asked to report any current symptoms of pain on a 0-10 scale, and other symptoms. The research physiotherapist will monitor for any adverse events and respond accordingly to ensure safety. The intervention group also receive usual care. Usual care is standard physiotherapy pre-operative education. This is what is normally delivered to all patients having cardiothoracic surgery at this hospital, and involves watching video education, an opportunity to ask questions and written information in a booklet. This is delivered generally between 12-24 hours prior to surgery. The booklet and video are standard resources used at TPCH. The booklet called "Your guide to Cardiac Surgery" , and the video education (available on hospital TV loop and TPCH website) were developed by TPCH staff prior to this study and are standard practice.