Pressure-dependent Changes in Hematocrit and Plasma Volume During Anesthesia

Study Overview
=================
Brief Summary
-----------------
The arterial blood pressure affects the ratio between filtration and reabsorption of fluids in the circulating blood volume and thereby the hematocrit. During induction of anesthesia blood pressure, hemoglobin level and hematocrit decreases. The aim of the study is to evaluate weather a maintained blood pressure with norepinephrine during anesthesia induction reduces the decrease in hematocrit.

Detailed Description
-----------------
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. Arterial blood gas will be analysed every ten minutes. Equal anesthesia in both groups will be monitored. No fluids will be infused. Noninvasive continuous hemoglobin measurement (SpHb) will be measured.

Official Title
-----------------
Pressure-dependent Changes in Hematocrit and Plasma Volume During Anesthesia

Conditions
-----------------
Blood Pressure, Hematocrit Change, Anesthesia

Intervention / Treatment
-----------------
* Procedure: Maintained blood pressure
* Drug: Norepinephrine


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Elective coronary artery surgery patients Exclusion Criteria: Age under 18 years untreated hypertension a reduced left ventricular systolic ejection fraction of 45 % or less diabetes mellitus former stroke and/or a known carotid artery stenosis.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: control<br>Ordinary anesthesia, mean arterial pressure allowed to decrease to 60 mmHg. If it is lower the patients will receive a norepinephrine infusion in order to raise the mean arterial pressure to 60 mmHg. | |
| Active Comparator: Maintained blood pressure<br>Ordinary anaesthesia and maintained preanesthetic blood pressure by norepinephrine infusion | Procedure: Maintained blood pressure<br>* Norepinephrine therapy to maintain preanesthesia blood pressure<br>Drug: Norepinephrine<br>* Norepinephrine therapy to maintain preanesthesia blood pressure<br>* Other names: Vasopressor;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The magnitude and dynamics of the decrease in hematocrit during anesthesia induction |  | 70 minutes from anesthesia induction | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reduced hematocrit decrease by vasopressor infusion maintained blood pressure | To assess if the decrease in hematocrit can be reduced, by maintaining the blood pressure with vasopressor infusion | 70 minutes from anesthesia induction | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Vasopressor agents, Continuous noninvasive hemoglobin measurement, Coronary artery bypass, Anesthesia, Blood pressure, Plasma volume