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Trial registered on ANZCTR


Registration number
ACTRN12616000146493
Ethics application status
Approved
Date submitted
4/02/2016
Date registered
8/02/2016
Date last updated
10/01/2017
Type of registration
Prospectively registered

Titles & IDs
Public title
Ventilation strategies in anaesthetised cardiac surgical patients.
Scientific title
A prospective single centre randomised controlled clinical trial comparing the physiology of apnoeic oxygenation vs. low tidal volume ventilation in anaesthetised cardiac surgical patients.
Secondary ID [1] 288475 0
None
Universal Trial Number (UTN)
U1111-1179-1553
Trial acronym
None
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Cardiac surgery 297513 0
Mechanical ventilation 297514 0
Condition category
Condition code
Surgery 297711 297711 0 0
Other surgery
Anaesthesiology 297712 297712 0 0
Anaesthetics
Cardiovascular 297713 297713 0 0
Coronary heart disease

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
In patients undergoing coronary artery bypass surgery who require harvesting of the left internal mammary artery; the intervention arm will be low tidal volume ventilation during the first 15 minutes of the surgical harvest of the left internal mammary artery. The low tidal volume ventilation will be at 2.5mL/kg of ideal body weight with 100% oxygen. There will be no additional requirements of the participant or deviation from standard surgical and anaesthesia care except for the additional sampling of 8mL (approximately two teaspoons) of blood from an artery in the wrist. This will allow for the additional measurements of oxygen and carbon dioxide.
Intervention code [1] 293813 0
Treatment: Other
Comparator / control treatment
In patients undergoing coronary artery bypass surgery who require harvesting of the left internal mammary artery; the comparator arm will be apnoeic oxygenation (ie no ventilation) during the first 15 minutes of the surgical harvest of the left internal mammary artery. There will be no additional requirements of the participant or deviation from standard surgical and anaesthesia care except for the additional sampling of 8mL (approximately two teaspoons) of blood from an artery in the wrist. This will allow for the additional measurements of oxygen and carbon dioxide.
Control group
Active

Outcomes
Primary outcome [1] 297251 0
Arterial partial pressure of carbon dioxide

This variable will be measured via an ABL Blood Gas Analyzer.
Timepoint [1] 297251 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [1] 320466 0
Pulmonary artery pressure

This variable will be measured via the pulmonary artery catheter device that will be inserted prior to the start of the trial.
Timepoint [1] 320466 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [2] 320467 0
Cardiac Index

This variable will be measured via the pulmonary artery catheter device that will be inserted prior to the start of the trial.
Timepoint [2] 320467 0
At baseline and at 15 minutes whilst the surgeons are harvesting the left internal mammary artery.
Secondary outcome [3] 320468 0
Cardiac Output

This variable will be measured via the pulmonary artery catheter device that will be inserted prior to the start of the trial.
Timepoint [3] 320468 0
At baseline and at 15 minutes whilst the surgeons are harvesting the left internal mammary artery...
Secondary outcome [4] 320469 0
Mean arterial pressure

This variable will be measured via the pulmonary artery catheter device that will be inserted prior to the start of the trial.
Timepoint [4] 320469 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [5] 320470 0
Blood pressure (systolic and diastolic)

This variable will be measured via the pulmonary artery catheter device that will be inserted prior to the start of the trial.
Timepoint [5] 320470 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [6] 320471 0
Heart rate

This variable will be measured using an electrocardiogram..
Timepoint [6] 320471 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [7] 320472 0
Central venous pressure

This variable will be measure via a central venous catheter device inserted prior to the start of the trial.
Timepoint [7] 320472 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [8] 320473 0
Transoesophageal echocardiography to assess right ventricular function

This variable will be measured using a Phillips E33 TOR machine using two standard right ventricular function views.
1 - Ejection phase myocardial velocities measure by tissue doppler imaging
2 - Pulmonary artery or right ventricular outflow tract acceleration time

Timepoint [8] 320473 0
At baseline and at 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [9] 320477 0
Oxygen saturation

This variable will be measured via a pulse oximeter.
Timepoint [9] 320477 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [10] 320478 0
Arterial partial pressure of oxygen

This variable will be measured via an ABL Blood Gas Analyzer.
Timepoint [10] 320478 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [11] 320479 0
Arterial pH

This variable will be measured via an ABL Blood Gas Analyzer.
Timepoint [11] 320479 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [12] 320480 0
Arterial bicarbonate

This variable will be measured via an ABL Blood Gas Analyzer.
Timepoint [12] 320480 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..
Secondary outcome [13] 320481 0
Arterial base excess

This variable will be measured via an ABL Blood Gas Analyzer.
Timepoint [13] 320481 0
At baseline, then 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes whilst the surgeons are harvesting the left internal mammary artery..

Eligibility
Key inclusion criteria
Patients will be eligible to participate in this study if:
1. The patient is aged 18 years or older
2. The patient is undergoing elective coronary artery bypass surgery requiring harvesting of the left internal mammary artery as part of standard of care
3. The patient will have an arterial line inserted for routine monitoring of blood pressure during the surgical procedure
4. The patient will have transoesophageal echocardiography as routine standard of care.
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Patients will be ineligible for participation if:
1. The patient is less than 18 years
2. The patient is undergoing emergency coronary artery bypass surgery
3. The patient is undergoing a non-coronary artery bypass surgery
4. The patient has chronic lung disease (KCO/TLCO/FEV1 <50% predicted)
5. The patient has moderate pulmonary hypertension (MPA >40mmHg)
6. The patient has super obesity (BMI>50kg/m2)
7. The patient is pregnant.
8. The patient has an ASA (American Society of Anesthesiologists) physical status V

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
All adult patients scheduled to be undergoing coronary artery bypass surgery and require harvesting of the left internal mammary artery 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
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Statistical analysis will be performed using computerised software (SPSS for Windows version 12.0). For data that is non-normally distributed a Mann–Whitney test will be used and normally distributed data will be compared using the Student T test. Ordinal and nominal data will be compared using Chi square analysis. A p-value <0.05 will be considered significant. Correlation coefficients will be used to measure how strong the relationship is between changes in PaCO2/PaO2 and pulmonary artery pressures. Repeated measures ANOVA will be used to examine changes in mean PaCO2, PaO2, and pulmonary artery pressures over the allocated time points.

Sample size calculations for this study are based on arterial blood gas data from 9 patients undergoing cardiac surgery with apnoeic oxygenation at Austin Hospital this year. Summary data from 9 patients undergoing cardiac surgery requiring apnoeic oxygenation during dissection of the LIMA demonstrated that after 15 minutes of apnoeic oxygenation the mean PaCO2 was 74 mmHg with standard deviation of 7 mmHg.

Sample size calculations used inferences for means and comparing two independent samples (http://www.stat.ubc.ca/~rollin/stats/ssize/n2.html). Using a low tidal volume ventilation strategy we consider a 15% reduction in PaCO2 i.e. an 11.1 mmHg decrease in PaCO2 at 15 minutes will be clinically important. Therefore, assuming a mean PaCO2 of 74 mm PaCO2 at 15 minutes in the apnoeic oxygenation group (mu1: mean of control group), and an 11.1 mmHg decrease in PaCO2 at 15-minutes in the low tidal volume ventilation group (mu2: mean of apnoeic oxygenation group), and sigma/common standard deviation of 7 mmHg, with an a-value of (type I error rate) of 0.05, and a desired power of 90%, 9 participants will be required in each group.

To allow for any breaches in protocol and patients exclusions, we will randomise 12 subjects in each group. A total of 24 participants will be included.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
10/02/2016
Actual
10/02/2016
Date of last participant enrolment
Anticipated
29/04/2016
Actual
29/04/2016
Date of last data collection
Anticipated
Actual
10/05/2016
Sample size
Target
24
Accrual to date
Final
24
Recruitment in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 5232 0
Austin Health - Austin Hospital - Heidelberg
Recruitment postcode(s) [1] 12703 0
3084 - Heidelberg

Funding & Sponsors
Funding source category [1] 292823 0
Hospital
Name [1] 292823 0
Departments of Intensive Care and Anaesthesia, Austin Hospital
Country [1] 292823 0
Australia
Primary sponsor type
Hospital
Name
Departments of Intensive Care and Anaesthesia, Austin Hospital
Address
Studley Road, Heidelberg, Victoria, 3084, Australia
Country
Australia
Secondary sponsor category [1] 291566 0
None
Name [1] 291566 0
Address [1] 291566 0
Country [1] 291566 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 294330 0
Austin Health Human Research Ethics Commitee
Ethics committee address [1] 294330 0
Studley Road, Heidelberg, Victoria, 3084, Australia
Ethics committee country [1] 294330 0
Australia
Date submitted for ethics approval [1] 294330 0
29/09/2015
Approval date [1] 294330 0
07/12/2015
Ethics approval number [1] 294330 0
HREC/15/Austin/412

Summary
Brief summary
Apnoeic oxygenation is the delivery of oxygen to the lungs without causing the lungs to inflate. Whereas, low tidal volume ventilation is the delivery of oxygen to the lungs that causes the lungs to partially inflate and deflate. Both are established anaesthetic techniques that have been used for over fifty years and are used routinely in many surgical procedures to allow easier access to different structures in the chest.

During cardiac artery bypass graft surgery (open heart surgery to bypass blocked arteries of the heart), the most common artery used to bypass blocked arteries is the left internal mammary artery (LIMA). This artery is has been proven to be the best option for short and long term survival after cardiac surgery. This artery is 15-26cm long and runs straight down the left side of the breastbone. The use of apnoeic oxygenation and low tidal volume ventilation are used as routine techniques to allow safe surgical access of the LIMA.

Currently, there are no studies comparing apnoeic oxygenation to a low tidal volume strategy in a cardiac setting. It is unknown what the effects of these techniques are on levels of oxygenation and carbon dioxide on the vessels in the lungs, or on the function of the heart. In this study, we aim to compare the usefulness and safety of apnoeic oxygenation to a low tidal volume ventilation technique during dissection of the left internal mammary artery.

There will be no additional requirements of the participant or deviation from standard surgical and anaesthesia care except for the additional sampling of 8mL (approximately two teaspoons) of blood from an artery in the wrist. This will allow for the additional measurements of oxygen and carbon dioxide.

This study will help us determine if one technique (apnoeic oxygenation or low tidal volume ventilation) is better than the other. If so, that technique could be adopted as standard of care in this setting for all patients.

A total of 24 subjects will be included at the Austin Hospital.
Trial website
Nil
Trial related presentations / publications
Nil
Public notes
Nil

Contacts
Principal investigator
Name 63298 0
A/Prof Laurence Weinberg
Address 63298 0
Department of Anaesthesia
Austin Hospital, Studley Road, Heidelberg, 3084, Victoria
Country 63298 0
Australia
Phone 63298 0
+61 3 94965000
Fax 63298 0
+61 3 94596421
Email 63298 0
[email protected]
Contact person for public queries
Name 63299 0
Laurence Weinberg
Address 63299 0
Department of Anaesthesia
Austin Hospital, Studley Road, Heidelberg, 3084, Victoria
Country 63299 0
Australia
Phone 63299 0
+61 3 94965000
Fax 63299 0
+61 3 94596421
Email 63299 0
[email protected]
Contact person for scientific queries
Name 63300 0
Laurence Weinberg
Address 63300 0
Department of Anaesthesia
Austin Hospital, Studley Road, Heidelberg, 3084, Victoria
Country 63300 0
Australia
Phone 63300 0
+61 3 94965000
Fax 63300 0
+61 3 94596421
Email 63300 0
[email protected]

No information has been provided regarding IPD availability


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
SourceTitleYear of PublicationDOI
EmbaseRelationship between acute hypercarbia and hyperkalaemia during surgery.2019https://dx.doi.org/10.12998/wjcc.v7.i22.3711
N.B. These documents automatically identified may not have been verified by the study sponsor.