The Effect of an Opioid on the Lower Esophageal Sphincter During Anesthesia Induction

Study Overview
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Brief Summary
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This study evaluates the effects of adding an opioid (alfentanil) during anesthesia induction with respect to the barrierpressure in the esophagogastric junction. The secondary aim was to investigate whether the effect of cricoid pressure influences the barrierpressure.

Detailed Description
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During anesthesia induction and tracheal intubation one major concern is to avoid passive regurgitation of gastric content and aspiration. The lower esophageal sphincter is a muscle located at the distal end of the esophagus. It plays an important role in creating a barrier between the stomach and the esophagus. The term barrierpressure is defined as the pressure difference between the lower esophageal sphincter pressure and the pressure in the stomach (intragastric pressure). There are studies showing that opioids given iv/im, in the vein or in the muscle, may decrease the pressure in the lower esophageal sphincter and hereby increase the risk of aspiration. Nevertheless,other studies shows that opioids are still frequently given to patients during anesthesia induction. This is done in order to prevent the cardiovascular response to (the painful) intubation which can often be seen as an equally high risk for the patient as the risk of aspiration. In light of the above description, the investigators are planning a study in volunteers with the primary aim of investigating the effects of an opioid (alfentanil) on the pressures in the lower esophageal sphincter. Another safety measure taken during anesthesia induction is the so called cricoid pressure. This is based on the theory that passive regurgitation of gastric content may be prevented by occluding the esophagus by pressing on the cricoid cartilage. However, there are studies indicating that the application of cricoid pressure also may decrease the tonus of the lower esophageal sphincter. The secondary aim of the study is to investigate the effect of cricoid pressure application on the pressure in the lower esophageal sphincter. Measurements are being done using high-resolution solid-state manometry.

Official Title
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The Effect of Alfentanil on the Lower Esophageal Sphincter During Anesthesia Induction - a Study in Volunteers

Conditions
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Lower Esophageal Sphincter

Intervention / Treatment
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* Drug: alfentanil
* Drug: saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteer 18-40 years old Informed,signed and dated consent Exclusion Criteria: Pharyngoesophageal dysfunction Gastro/intestinal-,cardiovascular-,lung- or neurologic disease Ongoing medication Allergy to alfentanil, propofol, soya or peanuts Pregnancy or breast-feeding BMI>30 Participation in other clinical trial -ongoing or during last 30 days.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: opioid<br>Preoxygenation for 5 min. Injection of opioid (alfentanil 20 mikrogr/kg iv) after 2 min:Injection of induction drug(propofol 2-2.5mg/kg) after anesthesia induction: Application of cricoid pressure for 15 sec. | Drug: alfentanil<br>* 20 mikrogr/kg<br>* Other names: alfentanil = rapifen;|
| Placebo Comparator: placebo<br>Preoxygenation for 5 min. Injection of saline iv. after 2 min:Injection of induction drug(propofol 2-2.5mg/kg) after anesthesia induction: Application of cricoid pressure for 15 sec. | Drug: saline<br>* The amount of saline will be equal the amount (in ml) of the study-drug (alfentanil)in order to keep it blinded.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in barrierpressure (in mmHg) in the area of the lower esophageal sphincter. | Pressure variations in the lower esophageal sphincter will be measured continuously during the whole study. Registrations will be saved in the computer-software. Predetermined time points will be marked on the registrations for later evaluation. | 1 min after the application of the induction agent (propofol) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in barrierpressure (in mmHg) in the area of the lower esophageal sphincter. | Pressure variations in the lower esophageal sphincter will be measured continuously during the whole study. Registrations will be saved in the computer-software. Predetermined time points will be marked on the registrations for later evaluation. | during cricoidpressure application (continues for 15 sec) | 
| Changes in barrierpressure (in mmHg) in the area of the lower esophageal sphincter. | Pressure variations in the lower esophageal sphincter will be measured continuously during the whole study. Registrations will be saved in the computer-software. Predetermined time points will be marked on the registrations for later evaluation. | 1min after the opioid/placebo injection | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Lower Esophageal Sphincter, Barrier pressure