TY - JOUR T1 - Influence of inspired oxygen concentration on PaCO<sub>2</sub> during noninvasive ventilation in patients with chronic obstructive pulmonary disease JF - Respiratory Care DO - 10.4187/respcare.02816 SP - respcare.02816 AU - Augusto Savi AU - Juçara Gasparetto Maccari AU - Túlio Frederico Tonietto AU - Ana Carolina Peçanha Antonio AU - Roselaine Pinheiro de Oliveira AU - Marcelo de Mello Rieder AU - Evelyn Cristina Zignani AU - Émerson Boschi da Silva AU - Cassiano Teixeira Y1 - 2013/08/13 UR - http://rc.rcjournal.com/content/early/2013/08/13/respcare.02816.abstract N2 - Background: The administration of a high inspired oxygen concentration (FIO2) to chronic obstructive pulmonary disease (COPD) patients breathing spontaneously may result in hypercapnia; due to reversal of preexisting regional hypoxic pulmonary vasoconstriction resulting in a greater deadspace. In these patients, during noninvasive ventilation (NIV), the arterial gases behavior was not previously studied. Objectives: To investigate the response of CO2-retaining COPD patients, after acute respiratory crisis stabilization using noninvasive ventilation (NIV), to a high inspired oxygen concentration (FIO2 = 1.0) after having been noninvasively ventilated with FIO2 ≤ 0.50 for a period of time. Design: Experimental prospective study. Setting: A 18-bed medical-ICU in a university teaching hospital. Patients: CO2-retaining COPD patients recovering from acute respiratory failure using NIV. Interventions: FIO2 increased to 1.0. Measurements and Main Results: Seventeen NIV-ventilated CO2-retaining COPD patients were studied both at their baseline FIO2 (0.25 to 0.50), and following a 40-min period of exposure to an FIO2 of 1.0. Mean (±SD) baseline findings were: PaO2 of 101.4 ± 21.7mmHg, PaCO2 of 52.6 ± 10.4mmHg, respiratory rate (RR) of 17.8 ± 3.7breaths/min, tidal volume (VT) of 601 ± 8mL, and Glasgow coma scale (GCS) of 14.8 ± 0.3. Statistical analysis using the paired Student’s t-test showed that the PaO2 (290.5 ± 35.7mmHg; p &lt;0.001) increased significantly when the FIO2 was increased to 1.0, but there was no significant change in PaCO2 (51.5 ± 12.3mmHg), RR (17.5 ± 2.8breaths/min), VT (608 ± 8mL) and GCS (14.8 ± 0.3). Conclusion: These results show that during noninvasive ventilation with an FIO2 sufficient to maintain a normal PaO2, a further increase in FIO2 does not result in an increased PaCO2 in this group of CO2-retaining COPD patients. ER -