The aim of this study is to determine the effect (on PaO2) of a modified mask associated to nasal cannula used for high flow oxygenation.

Study Design This is a single-center, randomized, blind investigator, 2-way crossover study design. Enrolled participants had severe hypoxia being treated at Intensive Care Unit associated with a hospital in Hornu (Epicura).

The study consisted of two intervention periods of 2 weeks separated by a washout period of 20 minutes. (Figure 1) The objective of the study is to determine whether adjunctive mask of our design (Double Trunk Mask - DTM) has an effect on increasing arterial pressure in Oxygen (PaO2) diagnosed with severe hypoxia.

The protocol and informed consent documents were reviewed and approved by a recognized ethics review board at the study facility. The study was performed in accordance with the Declaration of Helsinki.

Statistical Analysis

All participants who received this intervention and completed two phases of study were included in the efficacy analysis.

A sample size of 15 participants was needed to provide 90% power to detect a 10 mm Hg difference in PaO2. ANOVA for repeated measures followed by a post hoc test were used to compare the difference between participants receiving (CHFONP + DTM) and CHFONP alone.

The test was performed with a significance level of 0.05 (two-sided). Statistical analyses were carried out using SigmaPlot software version 11.0 (Systat Software Inc. UK).

Adverse Event Assessment

Safety was assessed by the number of participants with adverse events (AEs). AEs were collected by systematic assessment using terms from the Medical Dictionary for Regulatory Activities (MedDRA), version 11.1 in participants who received one or more doses of intervention. Adverse events during washout were not collected.

Inclusion Criteria:

Regardless of gender, at least 18 years of age and diagnosed with severe Hypoxia (PaO2/FiO2 < 300 mm Hg), dyspnea with severe rest at stake accessory muscles of respiration, respiratory rate (RR) ≥ 25 CPM, PaCO2 ≤ 45 mmHg, patient with an arterial catheter and without hemodynamic instability, Glasgow Coma Scale ≥ 12/15, written consent. Participants were also required to have a sufficient level of education to understand study procedures and be able to communicate with site personnel.

Exclusion Criteria Patients were excluded if they Hypercapnia (> 45 mm Hg with respiratory acidosis), cardiogenic pulmonary edema, COPD, pulmonary fibrosis, hypoventilation obesity syndrom, arterial pressure < 60 mm Hg or treatment by epinephrine > to 0,1 gamma/kg/minute, deterioration of awareness (Glasgow scale < or = 12), acute confusional state.

Participants were randomized in a 1:1 ratio to receive either (CHFONP) classical High Flow Oxygenation with nasal prongs (20 minutes) or CHFNOP with an adjunctive of a DTM.

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Assessor blind