The arterial blood pressure is thought to affect the ratio between filtration and reabsorption of fluids in the circulating blood volume and thereby the plasma volume. During induction of anesthesia blood pressure, hemoglobin level and hematocrits decreases and the plasma volume increases. The aim of the study is to evaluate weather a maintained blood pressure with norepinephrine during anesthesia induction reduces the increase in 125 iodine-labeled human serum albumine (125I-HSA) measured plasma volume.
24 patients scheduled for coronary artery bypass surgery will be included and randomized to receive either norepinephrine in the dose needed to maintain pre-anesthesia blood pressure or to a control group and receive norepinephrine only if mean arterial pressure decreases below 60 mmHg. Equal anesthesia in both groups will be monitored. No fluids will be infused. Changes in vascular resistance and cardiac output will be measured with thermodilution and changes in plasma volume will be measured with 125I-HSA. Endothelial cell function will be evaluated by measuring leakage of 125I-HSA and the plasma concentration of endothelial cell markers. Hormonal effects will be evaluated by measuring the plasma concentration of atrial natriuretic peptide (ANP). Shedding of glycocalyx will be evaluated by measuring heparan sulphate. The level of fibrinogen and platelet function will be evaluated by thromboelastography/multiplate.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
24
Ordinary anaesthesia and maintained preanesthetic blood pressure by norepinephrine infusion
Norepinephrine therapy to maintain preanesthesia blood pressure
Sahlgrenska University Hospital
Gothenburg, Sweden
The change of plasma volume measured by 125I-HSA before anesthesia induction until 50 minutes after anesthesia induction.
To assess if the increase in plasma volume measured by 125I-HSA can be reduced by maintaining the blood pressure with vasopressor infusion.
Time frame: 50 minutes from anesthesia induction
Difference in 125I-HSA leakage
To assess if there is a difference in 125I-HSA leakage in between the control and intervention groups before and after anaesthesia induction
Time frame: 50 minutes from anesthesia induction
ANP, heparan sulphate, thrombomodulin, fibrinogen, ROTEM
To assess if there is a difference in the plasma concentration of ANP, heparan sulphate, thrombomodulin, fibrinogen and ROTEM before and after anaesthesia induction in the intervention group compared to the control group
Time frame: 50 minutes from anesthesia induction
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