Effect of Bispectral Index (BIS) Titrated Propofol Sedation on Lower Esophageal Sphincter Pressures and Esophageal Function in Intensive Care Patients

Study Overview
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Brief Summary
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Eligible patients will be allocated to receive propofol sedation titrated to 3 different Bispectral Index (BIS) levels in a random order. Primary hypothesis: Deepening propofol sedation - as determined by BIS - lowers esophageal pressure in critical care patients.

Detailed Description
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Patient will be selected from the ICU, based on the defined inclusion and exclusion criteria. Potential study subjects will be screened by the research fellow or the on-site study co-investigator. Eligible patients will be allocated to receive propofol sedation titrated to 3 different BIS levels in a random order. BIS XP monitors (Aspect Medical Systems, Norwood, MA, USA) will be used which are relatively resistant to EMG artifact; a BIS sensor will be position on forehead of the patient after the skin is degreased and gently abraded. Esophageal pressure monitoring will be performed by a catheter inserted from the nose to the esophagus and left there trough the study period. If patients are on sedation they will be placed on propofol sedation for a washout period. Each patient will receive propofol sedation by continuous infusion titrated to a different levels of BIS in a randomized fashion according to a computer-generated random-number sequence; BIS levels of 70, will be targeted (Anxiolysis/high-frequency EEG activity, beta-augmentation); BIS levels of 50 will be targeted, (Low frequency EEG activity, theta-delta activity); BIS levels of 35 will be targeted (low frequency EEG activity). A propofol infusion will be titrated by the investigators to the designated BIS target according to randomization. Clinical personnel will not be blinded to the study, and if patient has clinically significant change in hemodynamic parameters study will be interrupted. Each BIS target level will be kept as constant as possible for at least one hour; thereafter, lower esophageal pressures will be recorded for 15 minutes using high resolution esophageal manometry. Studies will be done in supine position [Most ICU patients are now kept head-up.], and the manometric assembly will be positioned to record from the hypopharynx to the stomach with 4-6 of the sensors positioned in the stomach. All patients will otherwise receive routine ICU care and medications without interruption of standard clinical care.

Official Title
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Effect of BIS Titrated Propofol Sedation on Lower Esophageal Sphincter Pressures and Esophageal Function in Intensive Care Patients

Conditions
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Respiration, Artificial

Intervention / Treatment
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* Other: BIS 70 maintained
* Other: BIS level 50
* Other: BIS 35


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-80 years of age Written informed consent from relatives Clinically stable Mechanically ventilated < 2days Require sedation and expected to be given propofol Exclusion Criteria: Recent injury or other pathologic condition of the esophagus Major bronchopleural fistula History of liver failure History of renal failure History of major neuromuscular disease Multiple trauma Upper motor nerve injury Hypersensitivity to propofol Recent gastrointestinal surgery Patients with a diagnosed or suspected condition that may give false results in BIS monitoring. Tracheostomized patients

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: BIS 70<br>BIS levels of 70, will be targeted (Anxiolysis/high-frequency EEG activity, beta-augmentation); | Other: BIS 70 maintained<br>* Each patient will receive propofol sedation by continuous infusion titrated to a BIS level of 70.<br>* Other names: esophageal function;|
| Active Comparator: BIS 50<br>BIS levels of 50 will be targeted, (Low frequency EEG activity, theta-delta activity) | Other: BIS level 50<br>* Each patient will receive propofol sedation by continuous infusion titrated to a BIS level of 50.<br>* Other names: esophageal function;|
| Active Comparator: BIS 35<br>BIS levels of 35 will be targeted (low frequency EEG activity) | Other: BIS 35<br>* Each patient will receive propofol sedation by continuous infusion titrated to a BIS level of 35.<br>* Other names: esophageal function;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Deepening propofol sedation - as determined by BIS - lowers esophageal pressure in critical care patients. | Sedation will also be evaluated with the bispectral index of the electroencephalogram. BIS of the EEG data will be acquired with 4 BIS-sensor electrodes and a BIS XP monitor. The BIS will be recorded electronically at one-minute intervals. Heart rate, blood pressures (diastolic and systolic), respiratory rate, core temperature and oxygen saturation will be recorded every 5 minutes during the measurement period of the study. | for 15 minutes after assigned BIS level has been maintained for one hour, while in the ICU | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Deepening propofol sedation - as measured by Sedation Agitation Scale, Richmond Agitation Scale Score, and Ramsay sedation scale - lowers esophageal pressure in critical care patients. | The SAS uses a 1 to 7 point scale to make a determination of the patient's level of agitation and sedation from a rating of 7 dangerously agitated to a rating of 1 unarousable (Table 1). Clinical sedation assessments using SAS and RASS scales will be measured every 10 minutes through the study period. | every 10 minutes, while sedated in the ICU | 
| Modifying the target level of BIS titration affects upper esophageal pressures and esophageal peristalsis. | Upper esophageal sphincter pressures, transient LES relaxations, and regurgitations will be evaluated by the GI team from recorded data from high resolution manometry. | for 15 minutes after assigned BIS level has been maintained for one hour, while in the ICU | 
| There is an association between ventilator associated pneumonia and baseline lower esophageal and barrier pressure. | Patients will be followed for their stay in the hospital for occurrence of ventilator associated pneumonia. | daily, until hospital discharge | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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breathing machine, mechanical ventilator