Expiratory flow limitation during mechanical ventilation: real-time detection and physiological subtypes

• Published in: Critical care (London, England) Vol. 28; no. 1; p. 171
• Main Authors: Junhasavasdikul, Detajin, Kasemchaiyanun, Akarawut, Tassaneyasin, Tanakorn, Petnak, Tananchai, Bezerra, Frank Silva, Mellado-Artigas, Ricard, Chen, Lu, Sutherasan, Yuda, Theerawit, Pongdhep, Brochard, Laurent
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 21.05.2024; BioMed Central
• Subjects: Adult; Aged; Clinical outcomes; Exhalation - physiology; Female; Hospitals; Humans; Lung diseases, Obstructive; Male; Mechanics; Middle Aged; Mortality; Patients; Physiological aspects; Physiology; Positive-Pressure Respiration - methods; Positive-Pressure Respiration - standards; Positive-Pressure Respiration - statistics & numerical data; Respiration, Artificial - methods; Respiration, Artificial - statistics & numerical data; Software; Tidal Volume - physiology; Ventilators; Chronic airflow obstruction; Obesity; Respiratory mechanics; Positive-pressure respiration; Mechanical ventilation
• ISSN: 1364-8535; 1466-609X; 1466-609X; 1364-8535; 1366-609X
• DOI: 10.1186/s13054-024-04953-9

Tidal expiratory flow limitation (EFL ) complicates the delivery of mechanical ventilation but is only diagnosed by performing specific manoeuvres. Instantaneous analysis of expiratory resistance (Rex) can be an alternative way to detect EFL without changing ventilatory settings. This study aimed to determine the agreement of EFL detection by Rex analysis and the PEEP reduction manoeuvre using contingency table and agreement coefficient. The patterns of Rex were explored. Medical patients ≥ 15-year-old receiving mechanical ventilation underwent a PEEP reduction manoeuvre from 5 cmH O to zero for EFL detection. Waveforms were recorded and analyzed off-line. The instantaneous Rex was calculated and was plotted against the volume axis, overlapped by the flow-volume loop for inspection. Lung mechanics, characteristics of the patients, and clinical outcomes were collected. The result of the Rex method was validated using a separate independent dataset. 339 patients initially enrolled and underwent a PEEP reduction. The prevalence of EFL was 16.5%. EFL patients had higher adjusted hospital mortality than non-EFL cases. The Rex method showed 20% prevalence of EFL and the result was 90.3% in agreement with PEEP reduction manoeuvre. In the validation dataset, the Rex method had resulted in 91.4% agreement. Three patterns of Rex were identified: no EFL , early EFL , associated with airway disease, and late EFL , associated with non-airway diseases, including obesity. In early EFL , external PEEP was less likely to eliminate EFL . The Rex method shows an excellent agreement with the PEEP reduction manoeuvre and allows real-time detection of EFL . Two subtypes of EFL are identified by Rex analysis. Clinical trial registered with www.thaiclinicaltrials.org (TCTR20190318003). The registration date was on 18 March 2019, and the first subject enrollment was performed on 26 March 2019.