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

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

Randomized-controlled Trial of Spirometry-Assisted Preoperative INSPIRAtory Muscle Training on Postoperative Complications in Abdominal Surgery in a Single Tertiary Referral Centre

Rehabilitation strategies after abdominal surgery enhance recovery and improve outcome. A cornerstone of rehabilitation is respiratory physiotherapy with inspiratory muscle training to enhance pulmonary function. Prehabilitation is the process of enhancing functional capacity before surgery in order to compensate for the stress of surgery and postoperative recovery. There is growing interest in deploying pre-habilitation interventions prior to surgery. The aim of this study is to assess the impact of preoperative inspiratory muscle training on postoperative overall morbidity. The question is, whether inspiratory muscle training prior to elective abdominal surgery reduces the number of postoperative complications and their severity grade.

INSPIRA is a prospective randomized-controlled single-center trial, non-blinded The aim of this study is to assess the impact of preoperative inspiratory muscle training on postoperative overall morbidity. The question is, whether inspiratory muscle training prior to elective abdominal surgery reduces the number of post-operative complications and their severity grade. Furthermore, the impact of preoperative inspiratory muscle training on postoperative physiotherapeutic performance as surrogate of convalescence is assessed, too. Patients will be instructed by physiotherapists to perform inspiratory muscle training containing of 30 breaths twice a day for 14-18 days before surgery using Power®Breathe KHP2. Primary outcome is Comprehensive Complication Index (CCI) at 90 days after surgery. The CCI expresses morbidity on a con-tinuous numeric scale from 0 (no complication) to 100 (death) by weighing all postoperative complications according to the Clavien-Dindo classification for their respective severity.

inspiratory muscle training, CCI, postoperative complications, prehabilitation, preoperative respiratory training

Patients perform inspiratory muscle training containing of 30 breaths twice a day for 14-18 days before surgery.

Physiotherapists will measure the maximal inspiration pressure (MIP) with the POWER®breathe device of each single patient. Patients will then be instructed to perform inspiratory muscle training at the level of 60% of their individual MIP. Patients are instructed to perform the training containing of 30 breaths twice a day for 14-18 days before surgery. The devices are able to register the performance of each single training session and training results are monitored.

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.

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 .

Inclusion Criteria: Informed Consent as documented by signature (Appendix Patient Informed Consent Form) Planned abdominal surgery with planned duration >2hours (disease localization: upper vs. lower gastro intestinal, HPB, hernia, others) Planned surgery at least two weeks after inclusion at outpatient clinic Male and female patient over 18 years Exclusion Criteria: Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, of the participant Known or suspected non-compliance, drug or alcohol abuse, Previous enrolment into the current study Participation in another study with inspiratory muscle training within 30 days preceding or during this study

Birrer DL, Kuemmerli C, Obwegeser A, Liebi M, von Felten S, Pettersson K, Horisberger K. INSPIRA: study protocol for a randomized-controlled trial about the effect of spirometry-assisted preoperative inspiratory muscle training on postoperative complications in abdominal surgery. Trials. 2022 Jun 7;23(1):473. doi: 10.1186/s13063-022-06254-4.