Negative Venous Line Pressure in a Miniaturised Cardiopulmonary Bypass Circuit (CPB)

Study Overview
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Brief Summary
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Study to measure the ability of a 'fenestrated' venous line cannula to reduce the negative line pressure seen with kinetic-assist active venous drainage (KAVD) in a standard miniaturised cardiopulmonary bypass circuit and thereby increase the flow characteristics of the bypass pump.

Detailed Description
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To investigate whether a new venous drainage pipe (cannula) which has three sets of drainage holes (three-stage) compared with the standard two-stage cannula, or a three-stage which also has additional windows (fenestrations), can improve the drainage of blood into the circuit, reducing the negative pressure produced and increase the blood flow delivered to the patient. Patients who consent to participate will be randomly assigned to one of three types of venous cannula: Standard venous cannulation with a two-stage venous cannula The three-stage cannula (91437C, Medtronic) The fenestrated three-stage cannula (MC2X, Medtronic)

Official Title
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Negative Venous Line Pressure in a Miniaturised Cardiopulmonary Bypass Circuit - the Influence of a Fenestrated Venous Cannula and Its Effect on Pump Flow

Conditions
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Heart Surgery

Intervention / Treatment
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* Device: Conventional 2-stage venous cannula
* Device: Conventional 3-stage venous cannula
* Device: Fenestrated 3-stage venous cannula


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients over the age of 18 years of age scheduled to undergo isolated Coronary Artery Bypass Grafting (CABG) or isolated Aortic Valve Replacement (AVR), who are able and willing to consent. Consultant surgeon willing to operate using either Mini-CPB for CABG or AVR surgery. Exclusion Criteria: Re-operation and emergency surgery Patients refusing or unable to provide informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Sequential Assignment
Interventional Model Description: A single centre, prospective, randomised, double-blind trial
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Conventional 2-stage venous cannulation<br>The two-stage venous cannula 36Fr and 51Fr (size) for each of the two stages (91251C, Medtronic) | Device: Conventional 2-stage venous cannula<br>* venous cannula<br>|
| Active Comparator: Conventional 3-stage venous cannula<br>The standard three-stage cannula (91437C, Medtronic) is 29Fr, 46Fr and 37Fr for each of the three stages. | Device: Conventional 3-stage venous cannula<br>* venous cannula<br>|
| Experimental: Fenestrated 3-stage venous cannula<br>The fenestrated three-stage cannula (MC2X, Medtronic) is 29Fr, 29Fr and 29Fr for each of the three stages. | Device: Fenestrated 3-stage venous cannula<br>* venous cannula<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Average blood flow | Average blood flow measured in litres per minute per body surface area meter (squared). | duration of surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Negative pressure readings | The duration and depth of negative pressure readings from the venous line during cardiopulmonary bypass (CPB) are made in negative pressure readings in mmHg. | duration of surgery | 
| Number of microbubbles | Measured as total count (n). | duration of surgery | 
| Size of microbubbles | Measured as total volume (ml). | duration of surgery | 
| Haemolysis | Differences in the rate of haemolysis associated with the cannula is measured by the relative increase in plasma alanine aminotransferase (ALT) concentration U/l, as a percentage change from baseline at each of 3 later timepoints. | duration of surgery |