Hypotensive Effect of Anaesthesia With TCI

Study Overview
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Brief Summary
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Hypotension will often complicate induction of anaesthesia. The investigators want to test the hypothesis that Target Controlled Infusion, as opposed to Velocity Controlled Infusion, leads to less degree of hypotension.

Detailed Description
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Severe hypotension may be a serious complication to induction of anaesthesia. The patients preoperative clinical circulatory status will help define the risks of such a side-effect. A patient with a preexisting heart condition will be at increased risk for morbidity/mortality in relation to anaesthesia induction. Total intravenous anaesthesia may be delivered by two different approaches. The old way where the drug (Propofol and/or Remifentanil) is delivered in a velocity (mg/kg x hour or microg/ kg x min) specified by the anaesthetist. Hereafter called Velocity Controlled Infusion (VCI). At induction, to get effect of the drug, a high infusion rate is desired. A high infusion rate is associated with increased risks of hypotension if it is not adjusted in accordance with the current circulatory status of the patient. A failure to adjust may be futile for the patient. Therefore, induction takes some time because infusion rate is set within a relatively safe range. After a few minutes, once airway control is achieved, the infusion rate must be adjusted down to avoid hypotension. There is a more modern way of adjusting the infusion rate, the so called Target Controlled Infusion. With this approach, the pump delivering the drug will help the anaesthetist to select the appropriate infusion rate for any given situation. The anaesthetist selects a preferred concentration of the drug at the target, that is in the circulation. The pump then administrates the drug, first at high rate and then at lower rate, taking into account the patients age, weight and sex and the preferred target concentration. It is possible that this help from the machine is associated with less risk for hypotension at anaesthesia induction. If this is so it would have an impact on which of TCI and VCI that would be the best choice of anaesthesia. This would have special impact when giving anaesthesia to patients with a heart condition.

Official Title
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The Effect of Target Controlled Infusion as Opposed to Velocity Controlled Infusion on Hypotension at Induction of Total Intravenous Anaesthesia

Conditions
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Blood Pressure, Hypotension

Intervention / Treatment
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* Other: Target Controlled Infusion
* Other: Velocity Controlled Infusion


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: * All patients scheduled for anaesthesia at Östersunds Hospital ASA class I-II Exclusion Criteria: On beforehand decision to start continous delivery of blood pressure increasing drug at induction. Any contraindication to Total Intravenous Anaesthesia

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: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Target Controlled Infusion<br>This group of patients will have their anaesthesia induced with Target Controlled Infusion (TCI) | Other: Target Controlled Infusion<br> <br> |
| Other: Velocity Controlled Infusion<br>This group of patients will have their anaesthesia induced with Velocity Controlled Infusion (VCI) | Other: Velocity Controlled Infusion<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hypotension | Relative maximal decrease of blood pressure (in mmHg) by anaesthesia induction (%) | 20 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pharmacological measures to increase blood pressure | Number of doses of drug to increase blood pressure | 20 minutes | 
| Drug consumption | Amount (milligram) of Propofol delivered and amount (mikrogram) of Remifentanil delivered. | From the start of anaesthesia induction to the time of airway control (Laryngeal airway working in place of tracheal tube working in place). | 
| PONV (Postoperative Nausea and Vomiting) | Dose and name of any drug given to reduce PONV at any time defined above (in addition to profylaxis with the same aim) | From end of anaesthesia to 2 hours or when leaving the PostAnaesthesia Care Unit |