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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Do cardiac surgery patients have weak breathing muscles before surgery? An observational study
Scientific title
Prevalence of inspiratory muscle weakness in pre-operative cardiac surgery patients: an observational study.
Secondary ID [1] 295818 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
cardiac surgery 309266 0
respiratory muscle weakness 309267 0
post-operative pulmonary complications 309268 0
Condition category
Condition code
Respiratory 308140 308140 0 0
Other respiratory disorders / diseases
Cardiovascular 308141 308141 0 0
Other cardiovascular diseases

Study type
Patient registry
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
Inspiratory muscle weakness measured prior to cardiovascular surgery
Presence of post-operative pulmonary complications in the 1 week following cardiac surgery.
Intervention code [1] 312158 0
Early Detection / Screening
Comparator / control treatment
No control group
Control group

Primary outcome [1] 307116 0
Inspiratory muscle weakness measured in cmH2O.

This observational study of elective cardiac surgery patients will involve measuring maximum inspiratory pressure (MIP) at the pre-admission clinic visit. This MIP measurement is a straight-forward procedure that can be completed
by the pre-admission nurse and/ or physiotherapist using a hand-held device (MicroRPM machine and disposable filter). Briefly, the participant will be instructed to exhale to residual volume (they will be instructed to "empty their lungs"), then close their lips around a mouthpiece connected to a respiratory pressure meter, and then maximally inhale for at least 1 second. In accordance with established guidelines for respiratory measurement, they will repeat this manoeuvre 3 times, and best result will be recorded as their MIP. This allows for any learning effects or fatigue effects which may affect measurement. The total duration of testing will take less than 5 minutes. The researchers have extensive experience with this technique.
Timepoint [1] 307116 0
Pre-operative appointment prior to elective cardiac surgery, usually between 2 and 6 weeks prior to surgery date.
Secondary outcome [1] 350737 0
Prevalence of post-operative pulmonary complications (PPCs) as defined by the Melbourne Group Criteria.

PPCs include atelectasis , pneumonia, pleural effusion, pulmonary oedema, respiratory failure, pneumothorax and others.

We will scrutinise the patients' medical records to determine whether PPCs have occurred. This will involve a manual trawl of medical records at the hospital, and categorisation of PPCs according to the predefined criteria of the Melbourne Group Scale (Version 2):
Diagnosis will be confirmed when four or more of the following are present:
• Chest radiograph report of consolidation/collapse
• Raised temperature >38 ?C on two or more consecutive days
• SpO2 <90% on room air on two consecutive days
• Production of yellow or green sputum which is different to pre-operative assessment
• An otherwise unexplained white cell count >11 × 109 L-1 or prescription of an antibiotic specific for respiratory infection
• Physician diagnosis of chest infection
• Presence of infection on sputum culture report
• Abnormal breath sounds on auscultation which differ from pre-operative assessment
Timepoint [1] 350737 0
1 week following elective cardiac surgery

Key inclusion criteria
Patients presenting at the pre-admission clinic for assessment prior to elective cardiac surgery (e.g. coronary artery bypass grafting, valve replacements, or any other major open cardiac surgery via sternotomy).

Must be able to follow instructions and provide informed written consent.
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Patients will be excluded if they cannot provide informed written consent (eg due to physical or intellectual disability).
Patients with recent lung surgery, a known pneumothorax, or an inability to maintain a lip seal on the assessment device will also be excluded.

Study design
Convenience sample
Statistical methods / analysis
Data will be stored securely on a password protected computer throughout the project, and then stored at the University of Canberra for the required five-year period after which it will be destroyed according to university protocols. Data will be identifiable in the collection phase only, using hospital medical record numbers to ensure
accuracy and avoid duplication. Once data collection is complete, the data will be stored in a deidentified manner only, using study numbers instead of medical record numbers.

Demographic and inspiratory muscle strength (MIP) data will be analysed descriptively. We will then use regression analysis to determine whether any pre-operative factors were associated with prevalence of PPCs, and in particular whether MIP was
associated with PPCs in any way.

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 11676 0
National Capital Private Hospital - Garran
Recruitment postcode(s) [1] 23723 0
2605 - Garran

Funding & Sponsors
Funding source category [1] 300410 0
Name [1] 300410 0
University of Canberra
Address [1] 300410 0
University Drive
Bruce ACT 2617
Country [1] 300410 0
Primary sponsor type
University of Canberra
University Drive
Bruce ACT 2617
Secondary sponsor category [1] 299868 0
Name [1] 299868 0
Address [1] 299868 0
Country [1] 299868 0

Ethics approval
Ethics application status
Ethics committee name [1] 301215 0
University of Canberra Human Research Ethics Committee
Ethics committee address [1] 301215 0
University Drive
Bruce ACT 2617
Ethics committee country [1] 301215 0
Date submitted for ethics approval [1] 301215 0
Approval date [1] 301215 0
Ethics approval number [1] 301215 0

Brief summary
Emerging evidence indicates that elective cardiac surgery patients may benefit from inspiratory muscle training (targeted strengthening of the respiratory muscles) to reduce the incidence of post-operative pulmonary complications (PPCs). However, little is known about the baseline (pre-operative) inspiratory muscle strength of patients undergoing elective cardiac surgery. It is unlikely that every patient requires inspiratory muscle training,and it would be helpful to clarify the proportion of patients who are likely to benefit from such training. This can be easily done through measuring their inspiratory muscle strength pre-operatively as part of their preparation for surgery. However, such measurement is not yet standard practice.

We hypothesise that the prevalence of inspiratory muscle weakness may be 30% or greater in a cohort of patients preparing for elective cardiac surgery.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 86254 0
Dr Bernie Bissett
Address 86254 0
12D44 University of Canberra
University Drive, Bruce ACT 2617
Country 86254 0
Phone 86254 0
+61 404319234
Fax 86254 0
Email 86254 0
Contact person for public queries
Name 86255 0
Dr Bernie Bissett
Address 86255 0
12D44 University of Canberra
University Drive, Bruce ACT 2617
Country 86255 0
Phone 86255 0
+61 404319234
Fax 86255 0
Email 86255 0
Contact person for scientific queries
Name 86256 0
Dr Bernie Bissett
Address 86256 0
12D44 University of Canberra
University Drive, Bruce ACT 2617
Country 86256 0
Phone 86256 0
+61 404319234
Fax 86256 0
Email 86256 0

No information has been provided regarding IPD availability
Summary results
No Results