Oxygenation through High Flow Delivery Systems (HFO) is described as capable of delivering accurate F iO2 . Meanwhile, peak inspiratory flow ) of patients with acute hypoxemic respiratory failure can reach up to 120 L/min, largely exceeding HFO flow. Currently, very few data on the reliability of HFO devices at these high are available. We sought to evaluate factors affecting oxygenation while using HFO systems at high in a bench study. Spontaneous breathing was generated with a mechanical test lung connected to a mechanical ventilator Servo-i®, set to volume control mode. Gas flow from a HFO device was delivered to the test lung. The influence on effective inspired oxygen fraction of three parameters (F iO2 0.6, 0.8, and 1, from 28 to 98.1 L/min, and HFO Gas Flows from 40 to 60 L/min) were analyzed and are reported. The present bench study demonstrates that during HFO treatment, measured F iO2 in the lung does not equal set F iO2 on the device. The substance of this variation (ΔF iO2 ) is tightly correlated to (Pearson’s coefficient of 0.94, p-value < 0.001). Additionally, set F iO2 and Flow at HFO device appear to significatively affect ΔF iO2 as well (p-values < 0.001, adjusted to ). The result of multivariate linear regression indicates predictors ( , Flow and set F iO2 ) to explain 92% of the variance of delta F iO2 through K-Fold Cross Validation. Moreover, adjunction of a dead space in the breathing circuit significantly decreased ΔF iO2 (p < 0.01). The present bench study did expose a weakness of HFO devices in reliability of delivering accurate F IO2 at high as well as, to a lesser extent, at below equivalent set HFO Flows. Moreover, set HFO flow and set F IO2 did influence the variability of effective inspired oxygen fraction. The adjunction of a dead space in the experimental set-up significantly amended this variability and should thus be further studied in order to improve success rate of HFO therapy.

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The accuracy of 476 oxygen flowmeters was investigated using a thermal mass flowmeter in eight hospitals in France and Belgium. Different oxygen flow rates (2 to 15 l/min) were evaluated at the patient's bed. When the sample was considered as a whole, the accuracy of delivered flow was acceptable but precision was poor. The variability of the delivered flow between devices was greater when a low flow rate was required. Compensated-pressure oxygen flowmeters for these low rates were more accurate than their non-compensated counterparts. This study emphasizes the need to individually adapt the oxygen flow rate each time a patient has to move from one flowmeter to another.

Aim The objective of the study was to assess mortality rates in COVID-19 patients suffering from acute respiratory distress syndrome (ARDS) who also requiring mechanical ventilation. The predictors of mortality in this cohort were analysed, and the clinical characteristics recorded. Material and method A single centre retrospective study was conducted on all COVID-19 patients admitted to the intensive care unit of the Epicura Hospital Center, Province of Hainaut, Belgium, between March 1st and April 30th 2020. Results Forty-nine patients were included in the study of which thirty-four were male, and fifteen were female. The mean (SD) age was 68.8 (10.6) and 69.5 (12.6) for males and females, respectively. The median time to death after the onset of symptoms was eighteen days. The median time to death, after hospital admission was nine days. By the end of the thirty days follow-up, twenty-seven patients (55%) had died, and twenty–two (45%) had survived. Non-survivors, as compared to those who survived, were similar in gender, prescribed medications, COVID-19 symptoms, with similar laboratory test results. They were significantly older (p = 0.007), with a higher co-morbidity burden (p = 0.026) and underwent significantly less tra-cheostomy (p < 0.001). In multivariable logistic regression analysis, no parameter significantly predicted mortality. Conclusions This study reported a mortality rate of 55% in critically ill COVID-19 patients with ARDS who also required mechanical ventilation. The results corroborate previous findings that older and more comorbid patients represent the population at most risk of a poor outcome in this setting.