Research Priorities for Noninvasive Sampling of the Lower Respiratory Tract during Acute Respiratory Failure: An Official American Thoracic Society Workshop Report

Abstract

Research using lower respiratory tract (LRT) sampling may lead to improved understanding and management of patients with acute respiratory failure (ARF). Research bronchoscopy is a valuable tool for sampling the LRT during ARF. However, bronchoscopy may be limited by challenges with repeated sampling, the inability to sample the most severely ill patients, and increased resource utilization. "Noninvasive" sampling strategies, such as nonbronchoscopic bronchoalveolar lavage, endotracheal aspirate collection, and heat moisture exchange filter fluid collection, may expand the opportunity to collect LRT samples for research. Upper respiratory tract and sputum sampling may enable sampling in nonintubated patients with ARF, for whom there is no direct noninvasive access to the LRT. We convened a workshop with 32 experts from diverse continents, scientific backgrounds, and healthcare professions, all with experience in clinical or research practice during ARF. The Workshop goals were to review existing noninvasive sampling methods, evaluate their respective potential benefits and limitations, and identify future research priorities aimed at improving standardization and integration of these approaches into practice. Findings were generated by review of literature, expert presentations, meeting discussions, and electronic surveys using a modified Delphi approach. Participants agreed that each sampling method provides biologically meaningful data during ARF while also acknowledging that each method has benefits and limitations. Various potential advantages to noninvasive methods include reduced cost, enhanced speed, and ease of adoption compared with standard fiberoptic bronchoscopy. Despite the potential advantages, rigorous head-to-head comparisons between noninvasive methods and/or standard bronchoscopy are limited, which is a priority for future research. Additional research priorities include examination of the feasibility and benefit of serial sampling of the LRT and investigation of how LRT biomarkers are related to lung pathophysiology and patient-centered clinical outcomes during ARF. This Workshop Report provides guidance for investigators to integrate LRT sampling into their research and highlights key priorities, such as rigorous head-to-head comparison of sampling methods for research, to improve the standardization of noninvasive sampling methods and use of LRT sampling in research and clinical practice.

Keywords: acute respiratory distress syndrome; acute respiratory failure; lower respiratory tract; mechanical ventilation; pneumonia.

Figure 1.

Schematic of noninvasive sampling methods. ETA = endotracheal aspirate; HMEF = heat moisture exchange filter fluid; NBBAL = nonbronchoscopic bronchoalveolar lavage; URT = upper respiratory tract. Created with biorender.com.

Figure 2.

Perceptions of noninvasive sampling methods compared with standard fiberoptic bronchoscopy. Workshop participants were surveyed on their perceptions comparing each noninvasive sampling method to standard fiberoptic bronchoscopy. Scale: 1 = unfavorable profile, 3 = similar profile, and 5 = favorable profile; “Unknown” was provided as an option for sampling questions. ETA = endotracheal aspirate; HMEF = heat moisture exchange filter fluid; NBBAL = nonbronchoscopic bronchoalveolar lavage.

Figure 3.

Recommended minimum reporting items. A total of 31 of 32 Workshop participants responded to a survey when asked to designate whether a reporting item should be required or optional. Reporting items for which >66% of survey responses selected “required” are included above as minimum reporting requirements. Full results, including optional reporting items, are included in the data supplement. Created with biorender.com. ETA = endotracheal aspirate; HMEF = heat moisture exchange filter fluid; NBBAL = nonbronchoscopic bronchoalveolar lavage.