Incidence and Nature of Respiratory Impairment in Consecutive Patients Undergoing Bronchoscopy Under Conscious Sedation: A Pilot Study

Study Overview
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Brief Summary
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This study aims to characterize airflow patterns during bronchoscopy under conscious sedation, and determine the incidence of obstructive and central respiratory events. The investigators also plan to monitor the degree and frequency of oxygen desaturation throughout the procedure. To achieve this, investigators use a physiologic monitoring device (NOX T3, K082113) that has been FDA approved for the screening and diagnosis of sleep disordered breathing [1]. The results from this pilot study will be used to assess the feasibility of a prospective study utilizing continuous external negative pressure (Pneuway). This negative pressure is applied through a neck mask to alleviate upper airway collapsibility and can potentially decrease the number of apneas during bronchoscopy under conscious sedation [2].

Detailed Description
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Background and Rationale: Diagnostic bronchoscopic procedures are commonly performed in patients with various forms of pulmonary disorders associated with abnormal chest imaging. During these procedures, the vocal cords are intubated using a flexible scope. Patients need sedation and analgesia, and conscious sedation is typically administered. Hypoxemia is a potential complication during bronchoscopy. Contributing factors in addition to the underlying lung pathology, include depression of the respiratory center and decreased upper airway muscle tone that occur during conscious sedation [3]. Upper airway obstruction including obstructive apnea is often unrecognized during these procedures till hypoxemia is apparent [4]. Propofol, a common drug used for conscious sedation, is known to cause respiratory depression, and potentially central and/or obstructive apneas with a direct dose-response pattern [5]. Others, including benzodiazepines and opiates, can also cause respiratory depression leading to central or obstructive events. Respiratory depression is potentiated when any of the above medications are combined [6]. Objectives: The objective of the study is to identify the incidence of airflow limitation during bronchoscopy under conscious sedation, and further characterize it as obstructive or central. The primary endpoint is the incidence of obstructive and central apneic events during bronchoscopic procedures. The secondary outcomes include incidence of oxygen desaturation and need for escalation of care. Study Design: After informed consent is obtained, the NOX-T3 monitoring system, a commonly used portable sleep device that detects obstructive and central apneas, is placed prior to starting the procedure, and remains in place up to 30 minutes following the procedure. The NOX-T3 monitoring system includes a nasal cannula that sits over the nares, an elastic band that goes around the chest, and another one that goes around the abdomen, and a finger probe that is placed on the index finger. All subjects undergo bronchoscopy with standard of care including the monitoring of blood pressure, respiratory rate and oxygen saturation. All subjects have the NOX-T3 applied in addition to standard of care monitoring. Data is assessed following the completion of the procedure. Subjects' participation in this study ends at the completion of their standard of care visit. All the NOX-T3 studies are scored and interpreted by study investigators. Data Management: This is an observational and descriptive study with an estimated sample size of 30. Data collected will be reviewed with a statistician and investigators will report on patients' demographics. The study investigators will also present the incidence of apneic respiratory events and characterize them as obstructive or centrals. Investigators will further differentiate obstructive respiratory events to either apneas or hypopnea. Data on oxygen desaturations unrelated to apneic events will also be recorded.

Official Title
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Incidence and Nature of Respiratory Impairment in Consecutive Patients Undergoing Bronchoscopy Under Conscious Sedation: A Pilot Study

Conditions
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Conscious Sedation, Bronchoscopy

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with respiratory pathology that require bronchoscopy for further diagnostic evaluation, as part of standard of care Age of 18 years or older. Our study does not include the recruitment of vulnerable populations such as cognitively impaired adults, pregnant women, pregnant minors, minors, wards of the state, non-viable neonates, neonates of uncertain viability and prisoners. Exclusion Criteria: Oxygen requirement of more than 4 Liter prior to procedure. Intubation or any airway support. Presence of severe cardiopulmonary or neurologic disease as determined by the investigator. Nasal congestion/obstruction preventing proper placement and monitoring of air flow Inability to provide informed consent. All vulnerable population mentioned above.

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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of obstructive and central apneic events. | Obstructive apnea are defined as more than 90% cessation of air-flow that lasts for at least 10 seconds, despite the presence of respiratory and abdominal muscle effort. Obstructive hypopnea is when more than 30% cessation of air-flow occurs that lasts for at least 10 seconds, and is associated with oxygen desaturation of at least 3% from baseline. Central apnea is when cessation of air-flow occurs secondary to absent respiratory and abdominal muscle effort, that lasts for at least 10 seconds. | Throughout the bronchoscopic procedure. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Oxygen desaturation | Oxygen desaturation of more than 3% from baseline which are unrelated to apneic events. | Throughout the bronchoscopic procedure. | 
| Need for escalation of care | Need for escalation of care, including but not limited to, increasing supplemental oxygen, jaw thrust, patient stimulation or interrupting the administration of conscious sedation drug. | Throughout the bronchoscopic procedure. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Central apnea, Obstructive apnea, Oxygen desaturation, Escalation of Care, conscious sedation, Bronchoscopy, Respiratory impairment