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The study aims to examine how noradrenaline in combination with venous return influences the energy transmission from heart to central circulation and arteries - also called arterio-ventricular coupling.
After being informed about the study 40 elective CABG patients with written informed consent will undergo assessment of their arterio-ventricular coupling postoperatively after coronary bypass graft surgery. Whilst still in deep general anesthesia on the CT ICU the study population will be assessed by echocardiographic examination (transthoracic and transesophageal), blood pressure tracing by arterial line, respiratory data and ECG in 4 different situations.
Initially the individual patient is either considered fluid responsive (SVV >13%) og non- responsive (SVV<13%) by using stroke volume variation assessed by echocardiography.
In case of fluid responsiveness a fluid bolus of 4ml/kg of crystalloid fluid is given until SVV drops below 13% and the patient can be considered as fluid NON responder.
Right afterwards the study patient is stabilized with a baseline dose of noradrenaline (NA) intravenously in a supine position (situation 1). Situation 2 will be a slight increase in NA dose stabilizing mean arterial pressure in a "baseline + 20mmHg" state. After reversing the NA dose back to base line level the patient is allowed a short period of rest to wean of drug effect (4-5 x t1/2, appr. 12min). Subsequently the patient is to be placed in a 20% semi upright position (Anti-Trendelenburg) causing an increase in fluid responsiveness (situation 3). Following a phase of equilibration the dose of NA is again titrated up to obtain a 20mmHg increase in mean arterial pressure (situation 4).
There will be logging of arterial pressure curve and VTI-tracing I LVOT simultaneously (ultrapower, uPWR) as well as calculation of energy delivery, cardiac power, oscillatory power and -fraction and both arterial and ventricular elastance in every of those 4 situations.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Noradrenalin | Experimental | treatment with 2 different NA concentrations in 2 different states of fluid responsiveness |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Noradrenalin | Procedure | Norepinephrine challenge (concentration 'A' ) in fluid responsive position |
|
| Measure | Description | Time Frame |
|---|---|---|
| Change in Cardiac Power | Change in Cardiac Power in reaction to both different noradrenaline doses and states of fluid responsiveness. By logging invasive BP curve and tracing left ventricular outflow tract Velocity Time Integral (by echocardiography) simultaneously Total and Mean Cardiac Power (Watt) can be determined. Examining the response to different NA doses relative to fluid responsiveness the effect of NA on arterio-ventricular coupling can be examined. | within 30 minutes after having been stabilised on the cardiothoracic ICU after performed CABG surgery |
| Change in Oscillatory Power Fraction | Change in Oscillatory Power Fraction (OPF) in reaction to both different noradrenaline doses and states of fluid responsiveness. By logging invasive BP curve and tracing left ventricular outflow tract Velocity Time Integral (by echocardiography) simultaneously Total Cardiac Power (TCP, Watt) and Cardiac Power Output (CPO, Watt) can be determined. By subtracting CPO from TCP, OPF (in %) can be calculated. Examining the response to different NA doses relative to fluid responsiveness the effect of NA on arterio-ventricular coupling can be examined. | within 30 minutes after having been stabilised on the cardiothoracic ICU after performed CABG surgery |
| Measure | Description | Time Frame |
|---|---|---|
| Change in single beat ventricular elastance | Change in single beat ventricular elastance in reaction to both different noradrenaline doses and states of fluid responsiveness. Ventricular elastance (Ees) can be determined on the bedside by using a single beat measurement of left ventricular ejection fraction, stroke volume, preejection time and ejection time. | within 30 minutes after having been stabilised on the cardiothoracic ICU after performed CABG surgery |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Hilde Pleym (Head of Department), md, PhD | St. Olavs Hospital | Study Director |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| St Olavs Hospital, Dep. for Anesthesia & Intensive care. Section of cardiothoracic Anesthesia and -intensive Care. | Trondheim | 7006 | Norway |
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| ID | Term |
|---|---|
| D006331 | Heart Diseases |
| ID | Term |
|---|---|
| D002318 | Cardiovascular Diseases |
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| ID | Term |
|---|---|
| D016683 | Supine Position |
| ID | Term |
|---|---|
| D011187 | Posture |
| D009142 | Musculoskeletal Physiological Phenomena |
| D055687 | Musculoskeletal and Neural Physiological Phenomena |
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| Noradrenalin | Procedure | Norepinephrine challenge (concentration 'A') in non-fluid responsive position |
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| Noradrenalin | Procedure | Norepinephrine challenge (concentration 'B') in fluid responsive position |
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| Noradrenalin | Procedure | Norepinephrine challenge (concentration 'B') in non-fluid responsive position |
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| Change in single beat arterial elastance | Change in single beat arterial elastance in reaction to both different noradrenaline doses and states of fluid responsiveness. Using an estimative formula Ea can be calculated (Ea=SBPx0.9/SV) and Ea/Ees as a marker of arterio-ventricular coupling can be evaluated. | within 30 minutes after having been stabilised on the cardiothoracic ICU after performed CABG surgery |