Randomized-controlled Trial of Preoperative Inspiratory Muscle Training on Postoperative Complications

Postoperative complications measured by the comprehensive complication index (CCI) Com-prehensive Complication Index (CCI) 90 days after surgery. The CCI expresses postoperative morbidity on a continuous numeric scale from 0 (no complication) to 100 (death) by weighing all postoperative complications according to the validated Clavien-Dindo classification for their respective severity. It is measured at the end-of hospitalization and 90 days after surgery to include cases in which a readmission was necessary. Postoperative complications are gold standard in evaluation of quality of surgery as they directly reflect the procedures out-come and are most relevant for the patients.

Secondary endpoints are the postoperative morbidity along the classification of Clavien-Dindo at the end of hospitalization as well as 90 days +/- 2 weeks after surgery. This classification consists of five (1-5) severity grades. Grade 1 reflects minor complications, while grade 5 re-flects death. The classification is widely accepted and validated to report postoperative compli-cations.

Length of postoperative hospital stay

Readmission rate as reflection of postoperative outcome.

Mortality as reflection of postoperative outcome.

MIP is the most commonly used measure to evaluate inspiratory muscle strength. Very sensitive in detecting early respiratory muscle dysfunction, it allows for the assessment of ventilatory failure, restrictive lung disease and respirato-ry muscle strength and therefore represents a clinically meaningful trial endpoint.

Load (cmH20) (LOAD) is a measure of resistance to inhalation, and represents the pressure generated in the airways due to the force of the inspiratory muscles during a training session. As the training load decays with increasing lung volume (in order to match the length tension characteristics of the inspiratory muscles), the load displayed corresponds to the resistance at the start of inhalation (i.e. at RV). A higher load result means that the patient is training their inspiratory muscles hard-er, leading to stronger muscles. Stronger inspiratory muscles will need to work less hard to cope with the demands of breathing, leading to reduced breathlessness

POWER is a measure of muscle performance which combines strength and speed of move-ment (Pressure x Flow). More powerful muscles will be more resistant to fatigue at a given level of work and therefore, breathlessness will be reduced. The value displayed is the average power for all breaths in a training session.

During the sit-to-stand test, the quantity [n] how often a patient can sit down on a chair and stand up during 60 seconds is noted. These values are evaluated at admission to hospital for surgery and 5 days after surgery.

Breathing Energy) is a measure of the mechanical work (or effort) of breathing during your breathing training session. It is a result which combines the force exerted by your inspiratory muscles and the volume of air inhaled. The higher the value of breathing energy you attain, the longer and harder you have worked your inspiratory muscles.

Lung volume refers to the volume of gas the lungs and it represents the functions of the respiratory muscles and the mechanics of the lung and chest .