Influence of F_IO2on P_aCO2During Noninvasive Ventilation in Patients With COPD

Abstract

BACKGROUND:The administration of a high F IO 2 to COPD patients breathing spontaneously may result in hypercapnia, due to reversal of preexisting regional hypoxic pulmonary vasoconstriction, resulting in a greater dead space. Arterial blood gas trends have not been reported in these patients. In a 31-bed medical ICU in a teaching hospital we prospectively investigated the response of 17 CO 2 -retaining COPD patients, after acute respiratory crisis stabilization with noninvasive ventilation, to an F IO 2 of 1.0 for 40 min, after having been noninvasively ventilated with an F IO 2 of < 0.50 for 40 min. RESULTS: The mean ؎ SD baseline findings were: P aO 2 101.4 ؎ 21.7 mm Hg, P aCO 2 52.6 ؎ 10.4 mm Hg, breathing frequency 17.8 ؎ 3.7 breaths/min, tidal volume 601 ؎ 8 mL, and Glasgow coma score of 14.8 ؎ 0.3. P aO 2 significantly increased (P < .001) when F IO 2 was increased to 1.0, but there was no significant change in P aCO 2 , breathing frequency, tidal volume, or Glasgow coma score. CONCLUSIONS: During noninvasive ventilation with an F IO 2 sufficient to maintain a normal P aO 2 , a further increase in F IO 2 did not increase P aCO 2 in our CO 2 -retaining COPD patients.

The efficacy and safety of high-flow nasal cannula therapy in patients with COPD and type II respiratory failure: a meta-analysis and systematic review

“…PaCO 2 and PaO 2 are not necessarily proportional. Once hyperventilation sets in, blood gas exchange in the patient’s alveoli is restricted; PaO 2 may also decrease significantly [ 30 ]. The results of our meta-analysis have found that compared with NIV, HFNC is more beneficial in reducing the PaCO 2 level, length of hospital stay and the incidence of nasal facial skin breakdown, no effect differences in the PaO 2 , the incidence of tracheal intubation and mortality were found between HFNC and NIV treatments.…”

Effectiveness assessment of a guideline based protocol for ventilatory support management of COPD exacerbations in an emergency department

“…The strength of the present approach is that all COPD cases were confirmed using spirometry ( Fig. 1 ), whereas in the majority of previous studies 5 , 6 , 19 , 21 , 26 , 27 , 28 this approach was not used for the COPD diagnosis. 1 Furthermore, other clinical conditions than COPD that could be responsible for acute respiratory failure and represented potential confounding elements in previous works were not included.…”

Influence of FIO2on PaCO2During Noninvasive Ventilation in Patients with COPD: What Will Be Constant Over Time?—Reply

“…In conclusion, our study had the clear objective of evaluating the safety of brief increases in F IO 2 (during respiratory therapy procedures and during O 2 saturation decreases secondary to maladjustments or interface leaks) in CO 2 -retaining subjects with COPD and undergoing NIV. 10 No other clinical objective exists in sustained increases in F IO 2 , except temporarily, because in cases of persistent refractory hypoxemia, endotracheal intubation and mechanical ventilation are mandatory.…”