The Use of High Flow Nasal Cannula, Standard Face Mask and Standard Nasal Cannula in Morbidly Obese Patients

Study Overview
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Brief Summary
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It is standard practice in the United States and many parts of world to perform Gastrointestinal endoscopy with the patient under deep intravenous sedation. Obesity is accepted as a patient specific risk factor for hypoxic events during procedural sedation for GI endoscopic procedures. The obese population has a higher prevalence of obstructive sleep apnea (OSA), which is characterized by repeated obstruction of the upper airway, and leads to apnea and desaturation. This prospective, randomized study was designed to compare the effectiveness of the high flow nasal cannula, standard nasal cannula and standard face mask in morbidly obese patients with a high risk of sleep apnea, (BMI greater than 40, STOPBANG greater or equal to 5) receiving deep intravenous sedation during colonoscopies. This study will assess which method leads to a lower incidence of intraoperative desaturation events compared to the current standard of care.

Detailed Description
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The prevalence of morbid obesity is increasing worldwide. As the severity of obesity increases, the incidence of diagnosed obstructive sleep apnea also rises. Studies have shown an incidence of sleep apnea as high as 64% in patients with a body mass index (BMI) over 40 and 100% in patients with a BMI greater than 60. Patients with OSA have been shown to have significant desaturations under intravenous sedation due to airway narrowing and obstruction. Several studies have also shown that morbidly obese subjects, independent of a diagnosis of OSA, run a higher perioperative risk of adverse airway events, including hypoxia. Providing anesthesia for this patient population is challenging and requires careful titration of drugs and superb airway management skills. The current standard of care for oxygen delivery in this setting is a Salter nasal cannula. Humidified high flow nasal cannula (HFNC) oxygen therapy utilizes an air oxygen blend allowing from 21% to 100% FiO2 delivery and generates up to 60 L/min flow rates. The gas is heated (35 to 40 degree Celsius) and humidified through an active heated humidifier and delivered via a single limb heated inspiratory circuit (to avoid heat loss and condensation) to the subject through a large diameter nasal cannula. Theoretically, HFNC offers significant advantages in oxygenation and ventilation over conventional methods. Constant high flow oxygen delivery provides steady inspired oxygen fraction (FiO2) and decreases oxygen dilution. It also washes out physiologic dead space and generates positive end expiration pressure (PEEP) that augments ventilation. Some studies have demonstrated a positive effect of HFNC on the apnea-hypopnea index (AHI) showing that use of HFNC could decrease hypoxic episodes in subjects with repetitive upper airway obstruction such as obstructive sleep apnea. The STOP-BANG questionnaire (SB) has been used successfully to screen patients undergoing therapeutic endoscopic procedures at higher risk for sedation-related adverse events.

Official Title
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A Prospective, Randomized Trial Comparing the Use of High Flow Nasal Cannula, Standard Face Mask and Standard Nasal Cannula in Morbidly Obese Patients With High Risk of Obstructive Sleep Apnea Undergoing Colonoscopy

Conditions
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Desaturation of Blood, Colonoscopy

Intervention / Treatment
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* Other: Salter nasal cannula
* Other: Face mask
* Device: High Flow Nasal Cannula


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age between 18-80 Subjects undergoing colonoscopies Morbidly obese BMI equal or greater than 40 STOPBANG score equal or greater than 5 Exclusion Criteria: Subjects deemed hemodynamically unstable by the anesthesia team Subjects who are an aspiration risk and will require endotracheal intubation. Pregnancy Subjects with an allergy to propofol Patients who are unable to tolerate the high flow nasal cannula secondary to discomfort Subjects unwilling to sign consent Patients that received medications other than lidocaine and propofol

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: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Salter nasal cannula<br>A Salter nasal cannula will be used at 4L/ minute during the colonoscopy. The FiO2 delivered to the patient at this rate has been shown to be equal to 36% | Other: Salter nasal cannula<br>* Oxygen will be delivered by using standard nasal cannula<br>* Other names: Sedler Nasal Cannula;|
| Sham Comparator: Face mask group<br>A standard face mask will be used at 8L/minute during the colonoscopy. The FiO2 delivered to the patient at this rate has been shown to be equal to 60%. | Other: Face mask<br>* Oxygen will be delivered via face mask during colonoscopy<br>* Other names: Standard Face Mask;|
| Experimental: High Floow Oxygen delivery<br>Oxygen will be delivered by using high flow nasal cannula | Device: High Flow Nasal Cannula<br>* A high flow nasal cannula will be placed on the patient at a setting of FiO2 100% and titrated up to 60L/min depending on patient tolerance. 60 L/min is the max flow rate and will be used as tolerated for maximum benefit.<br>* Other names: Device The Comfort Flo system;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Oxygen saturation | The frequency of desaturation episodes (SpO2 <90%) | Intraoperative period |