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Comparison of three Methods of applying high flow nasal oxygen: in vitro study

Introduction

High flow nasal (HNF) requires precise control of the fraction of inspired oxygen (FiO2) and flow contributed as well as an adequate adjustment of temperature and humidity of the gas provided. There are several equipments for HNF. We evaluated the FiO2 and flow supplied with three different systems

Methods

There have been analyzed: (1) 'Oxygen Therapy' from Dräger Evita-XL®; (2) Fisher & Paykel Airvo® option; and (3) pack of flowmeters Debson®. Measurements were made in the distal part of the circuit that is used in clinical practice. Variables: programmed and measured FiO2, programmed and measured flow. We used the Oxygen Monitor Ohmeda 5120® and Flow Meter® Fisher-Porter. Before each measurement we checked and/or calibrated each of them. All measurements were performed at room temperature in the ICU of our hospital (23 to 26º).The data were processed using SPSS v.15.0.1, accepting a significance level of 95%.

Results

(1) FiO2 variation -0.001 ± 0.09 (-0.01 to 0.002); FiO2 percentage variation -0.012 ± 1.88 (-0.27 to 0.25); r2 = 0.999 and r = 0.998 (P < 0.000). Flow variation (l/minute) 5.45 ± 3.23 (4.94 to 5.96); flow percentage variation 19.59 ± 11.63 (17.75 to 21.43); r = 0. 997 and r2 = 0.994 (P < 0.000). (2) FiO2 variation -0.007 ± 0.26 (-0.011/-0.003); FiO2 percentage variation -1.4040 ± 4.73 (-2.15 to -0.67); r = 0.996 and r2 = 0.992 (P < 0.000). Flow variation (l/minute) 3.82 ± 3.85 (3.04 to 4.69); flow percentage variation 9.76 ± 8.08 (8.11 to 11.41); r = 0.969 and r2 = 0.939 (P < 0.000). (3) FiO2 variation -0.005 ± 0.26 (-0001 to 0009); FiO2 percentage variation -0.72 ± 5.2 (-1.5 to 0.1); r = 0.996 and r2 = 0.992 (P < 0.000). Flow variation (l/minute) 3.91 ± 1.26 (3.69 to 4.13); flow percentage variation 12.77 ± 5.33 (11.84 to 13.7); r = 0.996 and r2 = 0.992 (P < 0.000). See Figure 1.

Figure 1
figure1

Programmed and measured flow.

Conclusion

The FiO2 percentage variation in the Airvo® is higher than the other two devices, with no clinical relevance. The flow percentage variation of Evita XL® is superior to the other two devices; this may have some clinical relevance.

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Garach, M.M., Olga, O., Osorio, M.Y. et al. Comparison of three Methods of applying high flow nasal oxygen: in vitro study. Crit Care 19, P265 (2015). https://doi.org/10.1186/cc14345

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Keywords

  • Oxygen
  • Clinical Practice
  • Emergency Medicine
  • Clinical Relevance
  • High Flow