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

Overview

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 \[2\].

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.