Spontaneous Breathing Patterns During Maximum Extracorporeal CO2 Removal in SubjectsWith Early Severe ARDS.

Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
Department of Morphology, Surgery and Experimental Medicine, Section of Anesthesia and Intensive Care, University of Ferrara, Italy
Department of Medicine and Surgery, Research Centre on Public Health, University of Milan-Bicocca, Monza, Italy

Extracorporeal Carbon Dioxide Removal ; Respiratory Distress Syndrome, Acute ; Extracorporeal Membrane Oxygenation ; Respiration

Human; Prospective Studies; Italy; Chi Square Test; Fisher's Exact Test; Kruskal-Wallis Test; Spearman's Rank Correlation Coefficient; Male; Female; Middle Age; Descriptive Statistics; Education, Continuing (Credit)

BACKGROUND: Switching patients affected by early severe ARDS and undergoing extracorporeal membrane oxygenation (ECMO) from controlled ventilation to spontaneous breathing can be either beneficial or harmful, depending on how effectively the breathing pattern is controlled with ECMO. Identifying the factors associated with ineffective control of spontaneous breathing with ECMO may advance our pathophysiologic understanding of this syndrome. METHODS: We conducted a prospective study in subjects with severe ARDS who were on ECMO support ≤ 7 d. Subjects were switched to minimal sedation and pressure-support ventilation while extracorporeal CO2 removal was increased to approximate the subject's total CO2 production (VCO2). We calculated the rapid shallow breathing index (RSBI) as breathing frequency divided by tidal volume. We explored the correlation between certain characteristics recorded during pretest controlled ventilation and the development of apnea (ie, expiratory pause lasting > 10 s; n = 3), normal breathing pattern (ie, apnea to RSBI ≤ 105 breaths/min/L; n = 6), and rapid shallow breathing (RSBI > 105 breaths/min/L; n = 6) that occurred during the test study. RESULTS: The ratio of extracorporeal CO2 removal to the subjects' VCO2 was >90% in all 15 subjects, and arterial blood gases remained within normal ranges. Baseline pretest Sequential Organ Failure Assessment score, total VCO2 and ventilatory ratio increased steadily, whereas PaO2/FIO2 was higher in subjects with apnea compared to intermediate RSBI >105 breaths/min/L and elevated RSBI >105 breaths/min/L. In subjects with rapid shallow breathing, baseline lung weight measured with quantitative computed tomography scored higher, as well. CONCLUSIONS: In early severe ARDS, the factors associated with rapid shallow breathing despite maximum extracorporeal CO2 extraction include less efficient CO2 and O2 exchange by the natural lung, higher severity of organ failure, and greater magnitude of lung edema.

Allied Health; Blind Peer Reviewed; Double Blind Peer Reviewed; Editorial Board Reviewed; Expert Peer Reviewed; Peer Reviewed; USA

0020-1324

NLM UID: 7510357

For CE see www.rcjournal.com

20200626

20200630

http://dx.doi.org/10.4187/respcare.07391

144207919