Effects of bronchoscopy on lung volumes and pressures during mechanical ventilation

SESSION TITLE: Mechanical Ventilation: Beyond the basics SESSION TYPE: Original Investigations PRESENTED ON: 10/09/2023 08:30 am - 09:30 am PURPOSE: The use of bronchoscopy in the medical intensive care unit for diagnostic and therapeutic purposes has become increasingly common, particularly for managing acute respiratory distress syndrome (ARDS). Performing bronchoscopy in this patient population is considered high risk, and precautions to minimize risk should be taken. At present, there is little evidence guiding mechanical ventilatory techniques during bronchoscopy. The present study aims to determine the optimal mechanical ventilation strategy in patients with mild, moderate, and severe ARDS. OBJECTIVES: The primary objective of this study is to determine the optimal mechanical ventilation strategy in simulated patients with mild, moderate, and severe ARDS. METHODS: A simulation-based study using a mechanical ventilator attached to a breathing simulator (ASL 5000, IngMar Medical sw3.6) programmed to represent a passive patient during a bronchoscopy procedure. The simulated patient was assumed to be a male with a height of 175 cm and an ideal body weight of 71 kg, resulting in a tidal volume (VT) equal to 410 mL to 550ml (6-8ml /kg of IBW). An 8.0mm endotracheal tube and an Ambu® ascopeTM 4Broncho bronchoscope with an outer diameter of 5.0mm were used. The experiments were done using four different levels of compliance: normal 50 mL/cm H2O, mild ARDS 45 mL/cm H2O, moderate ARDS 40 mL/cm H2O, and severe ARDS 35 mL/cm H2O. A predetermined 6.5% decrease in tidal volume would result in a clinically significant increase in PaCO2. RESULTS: For the simulated model under VC-CMVs with the introduction of the bronchoscope, there was a significant increase in autoPEEP, which progressively worsened as compliance decreased (normal 20%; mild 52%; moderate 71%; severe 75%) with the introduction of the bronchoscope. For the simulated model under PC-CMVs, all lung compliance models saw a nearly 40% decrease in tidal volume (normal -46%, mild –37%, moderate -40%, severe –39%). A 40% decrease in tidal volume would result in an expected increase in PaCO2 by 98mmHg. CONCLUSIONS: Multiple complications from performing bronchoscopy in patients receiving mechanical ventilation have been shown, and care to reduce these risks should be taken. Utilizing mechanical ventilation with either a volume control or pressure control mode has pitfalls that the proceduralist must be aware of. CLINICAL IMPLICATIONS: Currently the recommendations for the management of mechanical ventilation while performing bronchoscopy are limited. The present study highlights the considerations to be reviewed to more safely perform the procedure. DISCLOSURES: No relevant relationships by Jason Amadei Consultant relationship with IngMar Medical Please note: 2020 to present Added 03/22/2023 by Robert Chatburn, source=Web Response, value=Consulting fee Consultant relationship with Inovytec Please note: 2020 to present Added 03/22/2023 by Robert Chatburn, source=Web Response, value=Consulting fee Consultant relationship with Ventis Please note: 2020 to present Added 03/22/2023 by Robert Chatburn, source=Web Response, value=Consulting fee Consultant relationship with IngMar medical Please note: 2021 to present Added 04/01/2023 by Eduardo Mireles-Cabodevila, source=Web Response, value=Consulting fee No relevant relationships by Christopher Yurosko