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

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.

Study Overview

• Status: Completed
• Conditions: Postoperative Complications; Preoperative Period; Breathing Exercises
• Intervention / Treatment: Behavioral: preoperative inspiratory muscle training

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 134
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Zurich, Switzerland
    • University Hospital Zurich

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Training arm; Patients perform inspiratory muscle training containing of 30 breaths twice a day for 14-18 days before surgery.	Behavioral: preoperative inspiratory muscle training; 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.
No Intervention: Control arm; No preoperative inspiratory muscle training

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	90 days postoperative

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative morbidity	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.	At the end of hospitalization and 90 days +/- 2 weeks postoperative
Length of hospital stay (LOS)	Length of postoperative hospital stay	90 days postoperative
Readmission rate	Readmission rate as reflection of postoperative outcome.	90 days postoperative
Mortality	Mortality as reflection of postoperative outcome.	90 days postoperative
Maximum inspiratory pressure (MIP)	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.	5 days after surgery
Load	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	5 days after surgery
Power (Watt)	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.	5 days after surgery
Sit-to-stand test	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.	5 days after surgery
Energy (Joule)	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.	5 days after surgery
Volume (l)	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 .	5 days after surgery

Collaborators and Investigators

• Sponsor: University of Zurich
• Collaborators: Lunge Zuerich
• Investigators: Principal Investigator: Dominique Lisa Birrer, MD, Universitätsspital Zürich (USZ)

Publications and helpful links

General Publications

• 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.

Helpful Links

• Related Info

Study record dates

Study Major Dates

• Study Start (Actual): August 13, 2021
• Primary Completion (Actual): October 8, 2025
• Study Completion (Actual): October 8, 2025

Study Registration Dates

• First Submitted: September 15, 2020
• First Submitted That Met QC Criteria: September 15, 2020
• First Posted (Actual): September 22, 2020

Study Record Updates

• Last Update Posted (Estimated): January 7, 2026
• Last Update Submitted That Met QC Criteria: January 4, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: prehabilitation; inspiratory muscle training; postoperative complications; CCI; preoperative respiratory training
• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Postoperative Complications
• Other Study ID Numbers: 2020-PreopInsp

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No