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Trial registered on ANZCTR

Trial ID
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
A Prospective Randomised Trial of Two Tidal Volume Ventilator Strategies in Patients Undergoing Major Surgery
Scientific title
A prospective randomised trial of intraoperative tidal volume ventilation with 6ml/kg (Ideal Body weight) and positive end expiratory pressure (PEEP) of 5 cm H2O versus 10ml/kg (Ideal Body weight) and PEEP of 5 cm H2O, in adult patients undergoing major surgery.
Secondary ID [1] 285016 0
Universal Trial Number (UTN)
Trial acronym
Not applicable
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Effects of ventilation in patients undergoing major surgery 292530 0
Condition category
Condition code
Anaesthesiology 292834 292834 0 0
Surgery 292835 292835 0 0
Other surgery
Respiratory 292836 292836 0 0
Other respiratory disorders / diseases

Study type
Description of intervention(s) / exposure
In patients undergoing major surgery who mechanical ventilation patients with an endotracheal tube, the ventilation strategy will be randomised to compare either a 6ml/kg or 10ml/kg tidal volume strategy in combination with PEEP.
Intervention code [1] 289850 0
Treatment: Devices
Comparator / control treatment
Both group will receive the intervention; the ventilation strategy will either a 6ml/kg or 10ml/kg tidal volume in combination with PEEP.
Control group
Dose comparison

Primary outcome [1] 292701 0
The number of patients with a postoperative pulmonary complication. Pulmonary complications include pneumonia, bronchospasm, atelectasis, pulmonary congestion, pulmonary embolism, respiratory failure and requirements for mechanical ventilation.
Timepoint [1] 292701 0
Duration of hospital stay
Secondary outcome [1] 309520 0
Requirements for post-operative Intensive Care
Timepoint [1] 309520 0
Duration of hospital stay
Secondary outcome [2] 309521 0
Number of hours in ICU
Timepoint [2] 309521 0
Duration of ICU stay
Secondary outcome [3] 309522 0
Length of hospital stay
Timepoint [3] 309522 0
Duration of hospital stay
Secondary outcome [4] 309523 0
30 day mortality
Timepoint [4] 309523 0
30 days postoperatively

Key inclusion criteria
Patients will be eligible to participate in this study if:
1. The patient is aged 40 years or older
2. The treating anaesthetist expects that the patient will remain intubated for a period of equal to or greater than two hours
3. The patient will have an arterial line inserted for routine monitoring of blood pressure during the surgical procedure
Minimum age
40 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Patients will be ineligible for participation if:
1. The patient is pregnant and/or lactating
2. The patient has planned thoracic surgery
3. The patient has planned cardiac surgery
4. The patient has planned intracranial neurosurgery
5. Previously enrolment in this Trial

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
All adult patients scheduled to undergoing a major surgical procedure and require mechanical ventilation in the operating suite of the Austin Hospital will be screened for eligibility. Once informed consent has been obtained, randomisation will be by means of sealed opaque envelopes with permuted blocks of variable size. Each envelope will contain a study arm allocation with the tidal volume target as well as a copy of a simplified study protocol.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Permuted block randomisation will be used using computer generated software.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
There are two study groups associated with this trial:
1. Volume control ventilation with a tidal volume 6ml/kg of Ideal Body Weight and PEEP of 5cm H2O.
2. Volume control ventilation with tidal volume 10ml/kg of Ideal Body Weight and PEEP of 5cm H2O.

Calculation of tidal volume & use of PEEP.
Tidal volume for each participant will be calculated base on a) the patient’s gender and b) the patient’s ideal body weight (IBW). IBW will be calculated by the treating anaesthetist using the following standard formula.
For males: 50 + 0.91 (centimetres in height – 152.4)
For females 45.5 + 0.91 (centimetres in height – 152.4)

Immediately after randomisation, the tidal volume will be set on the ventilator for either a target of 6ml/kg or 10 ml/kg based on ideal body weight and gender. This allocated tidal volume target will be maintained for the duration of the surgical procedure. At the end of the surgical procedure the patient will have their anaesthesia reversed and will be woken and weaned from mechanical ventilation according to standard hospital protocol. There is no change to the type of anaesthesia provide or any oxygenation or ventilation management of enrolled patients during the surgical procedures.
Phase 4
Type of endpoint(s)
Statistical methods / analysis
This is a prospective randomised trial comparing two tidal volume targets in patients undergoing major surgery. Data will be analysed on an intention-to-treat basis. Comparisons will be made using t-test and ANOVA for repeated-measures or Wilcoxon rank-signed test and Kruskall-Wallis according to the underlying distribution for continuous data and Chi-square for categorical data. A Kaplan-Meier curve with log-rank test will be performed to further compare in-hospital mortality and rate of discharge home where appropriate. Logistic regression analysis will also be performed to adjust for baseline imbalances.

Recruitment status
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] 2753 0
Austin Health - Austin Hospital - Heidelberg
Recruitment postcode(s) [1] 8452 0
3084 - Heidelberg

Funding & Sponsors
Funding source category [1] 289628 0
Name [1] 289628 0
Departments of Intensive Care and Anaesthesia, Austin Hospital
Address [1] 289628 0
Studley Road, Heidelberg, Victoria, 3084, Australia
Country [1] 289628 0
Primary sponsor type
Departments of Intensive Care and Anaesthesia, Austin Hospital
Studley Road, Heidelberg, Victoria, 3084, Australia
Secondary sponsor category [1] 288315 0
Name [1] 288315 0
Address [1] 288315 0
Country [1] 288315 0

Ethics approval
Ethics application status
Ethics committee name [1] 291369 0
Research Ethics Unit Austin Health
Ethics committee address [1] 291369 0
Studley Road, Heidelberg, Victoria, 3084, Australia
Ethics committee country [1] 291369 0
Date submitted for ethics approval [1] 291369 0
Approval date [1] 291369 0
Ethics approval number [1] 291369 0

Brief summary
There is no good evidence to guide the choice of breath size (tidal volume) delivered by the breathing machine during anaesthesia. In a recent multi-centre study, we found that anaesthetists deliver a variable tidal volumes with some patients receiving low-tidal volumes (6-7 ml/kg) and others receiving high-tidal volumes (9-10 ml/Kg) according to clinician preference. We also found that they typically positive end expiratory pressure (PEEP) (pressure to keep lung when breathing out has been completed) at an average modest value of 5.0 cmH2O. Thus, in Victoria and the Austin hospital in patients under general anaesthesia administered tidal volume can be variably high or low and PEEP is often applied at modest levels. Because of such variability and the possibility that one approach or another may be better at avoiding lung complications after anaesthesia, we wish to perform prospective randomised trial to evaluate the impact and outcome of two different tidal volume strategies during anaesthesia.

Specifically, we wish to conduct a pilot single-centre prospective randomised trial comparing a low tidal volume (6 ml/kg) to a higher tidal volume (10 ml/kg) tidal volume strategy in combination with PEEP at 5 cm H2O for patients undergoing major surgery. The anticipated sample size is 900 participants over a 18 month period. Patients will be randomly allocated to either low or control tidal volume ventilation for the period of their surgical procedure to test the hypothesis that one of these two approaches in superior at decreasing post-surgical lung complications.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 50066 0
Dr Laurence Weinberg
Address 50066 0
Department of Anaesthesia
Austin Hospital, Studley Road, Heidelberg, 3084, Victoria
Country 50066 0
Phone 50066 0
+61 3 94965000
Fax 50066 0
+61 3 94596421
Email 50066 0
Contact person for public queries
Name 50067 0
Dr Laurence Weinberg
Address 50067 0
Department of Anaesthesia
Austin Hospital, Studley Road, Heidelberg, 3084, Victoria
Country 50067 0
Phone 50067 0
+61 3 94965000
Fax 50067 0
+61 3 94596421
Email 50067 0
Contact person for scientific queries
Name 50068 0
Dr Laurence Weinberg
Address 50068 0
Department of Anaesthesia
Austin Hospital, Studley Road, Heidelberg, 3084, Victoria
Country 50068 0
Phone 50068 0
+61 3 94965000
Fax 50068 0
+61 3 94596421
Email 50068 0