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 Experts on Air

Optimizing HFOT settings. What does the evidence show?

Webinar #2
1. Using the HFOT guidelines 2. Optimizing HFOT settings 3. Monitoring during HFOT 4. Intubation in hypoxemic respiratory failure 5. HFOT in hypercapnic respiratory failure 6. HFOT outside critical care
Experts-Air_HFNC_Optimize-HFOT-settings_youtube
Video

2.  Optimizing HFOT settings. Input from physiological studies (Experts on Air)

Series 1, webinar 2: High flow oxygen therapy (HFOT)
How to optimize HFOT settings - Input from physiological studies
Speaker: Tommaso Mauri; Interviewer: Jens Bräunlich

In order to improve physiology and outcomes of patients supported by high flow oxygen therapy, it is crucial to adjust the flow rate, FiO2, temperature, and cannula size based on target physiological variables such as respiratory effort, ROX index, respiratory rate, etc., as well as on patient comfort. In this webinar, we will focus on how to optimize the high flow therapy through this physiology-based approach. Recorded on February 24, 2022; 15:00 (CET). (Subtitles automatically generated).
31 minutes
EN
Experts-Air_HFNC_use-HFOT-guidelines_youtube
Video

1.  Using the HFOT guidelines

36 minutes
EN
Experts-Air_HFNC_Monitoring-during-nasal-HFOT_youtube
Video

3.  Monitoring during HFOT

37 minutes
EN
Experts-Air_HFNC_Intubation-hypoxemic-respiratory-failure_youtube
Video

4.  Intubation in hypoxemic respiratory failure

30 minutes
EN
Experts-Air_HFNC_Hypercapnic-respiratory-failure_youtube
Video

5.  HFOT in hypercapnic respiratory failure

31 minutes
EN
Experts-Air_HFNC_Outside-critical-care_youtube
Video

6.  HFOT outside critical care

35 minutes
EN

Q&A Webinar #2.

Weaning from HFNC should be gradual as this is a potent non invasive support. FiO2 could be the first setting to decrease, while flow can be safely reduced after FiO2 becomes <50%. When FiO2 is <40% with flow <40 l/min, transition to standard oxygen, for example to discharge the patient from the ICU. This could be attempted with 2 hours of close monitoring.

See above.

The paper mentioned in my talk by Pinkham et al. is very recent and confirms values between 2 and 5 cmH2O (Pinkham M, Tatkov S. Effect of flow and cannula size on generated pressure during nasal high flow. Crit Care. 2020;24(1):248. Published 2020 May 24. doi:10.1186/s13054-020-02980-w1​).

I would be careful, for the study in Crit Care 2020 on flows > 60 l/min we used 2 humidifiers. 

See above.

We do use HFNC with NGT, usually smaller cannula, being careful of accurate positioning and checking from time to time. 

Aerosol shouldn't be an issue, HFNC can even grant improved delivery to the distal airways, see Reminiac F, Vecellio L, Bodet-Contentin L, et al. Nasal high-flow bronchodilator nebulization: a randomized cross-over study. Ann Intensive Care. 2018;8(1):128. Published 2018 Dec 20. doi:10.1186/s13613-018-0473-82​.

Yes, if the high flow is connected to a mask you just give a lot of oxygen, probably lose both PEEP effect (no occlusion of the nares) and CO2 washout (no direct flow in the upper airways), I would avoid that.

No, CO2 clearance is not affected as long as there is a circulation of gas, open mouth and venturi effect may reduce tha alveolar FiO2 and the PEEP effect, determining worsening oxygenation.

 

We normally use EIT by continuous monitoring of end-expiratory impedance before and after start of HFNC.

Disclaimer

The contents of this page are for informational purposes only and are not intended to be a substitute for professional training or for standard treatment guidelines in your facility. The responses to the questions on this page were prepared by the respective webinar's speaker;  any recommendations made here with respect to clinical practice or the use of specific products, technology, or therapies represent the personal opinion of the speaker only, and may not be considered as official recommendations made by Hamilton Medical AG. Hamilton Medical AG provides no warranty with respect to the information contained ion this page and reliance on any part of this information is solely at your own risk.

Bibliografia

  1. 1. Pinkham M, Tatkov S. Effect of flow and cannula size on generated pressure during nasal high flow. Crit Care. 2020;24(1):248. Published 2020 May 24. doi:10.1186/s13054-020-02980-w

 

  1. 2. Reminiac F, Vecellio L, Bodet-Contentin L, et al. Nasal high-flow bronchodilator nebulization: a randomized cross-over study. Ann Intensive Care. 2018;8(1):128. Published 2018 Dec 20. doi:10.1186/s13613-018-0473-8

Note

 

Effect of flow and cannula size on generated pressure during nasal high flow.

Pinkham M, Tatkov S. Effect of flow and cannula size on generated pressure during nasal high flow. Crit Care. 2020;24(1):248. Published 2020 May 24. doi:10.1186/s13054-020-02980-w

Nasal high-flow bronchodilator nebulization: a randomized cross-over study.

Reminiac F, Vecellio L, Bodet-Contentin L, et al. Nasal high-flow bronchodilator nebulization: a randomized cross-over study. Ann Intensive Care. 2018;8(1):128. Published 2018 Dec 20. doi:10.1186/s13613-018-0473-8



BACKGROUND

There is an absence of controlled clinical data showing bronchodilation effectiveness after nebulization via nasal high-flow therapy circuits.

RESULTS

Twenty-five patients with reversible airflow obstruction received, in a randomized order: (1) 2.5 mg albuterol delivered via a jet nebulizer with a facial mask; (2) 2.5 mg albuterol delivered via a vibrating mesh nebulizer placed downstream of a nasal high-flow humidification chamber (30 L/min and 37 °C); and (3) nasal high-flow therapy without nebulization. All three conditions induced significant individual increases in forced expiratory volume in one second (FEV1) compared to baseline. The median change was similar after facial mask nebulization [+ 350 mL (+ 180; + 550); + 18% (+ 8; + 30)] and nasal high flow with nebulization [+ 330 mL (+ 140; + 390); + 16% (+ 5; + 24)], p = 0.11. However, it was significantly lower after nasal high-flow therapy without nebulization [+ 50 mL (- 10; + 220); + 3% (- 1; + 8)], p = 0.0009. FEV1 increases after facial mask and nasal high-flow nebulization as well as residual volume decreases were well correlated (p < 0.0001 and p = 0.01). Both techniques showed good agreement in terms of airflow obstruction reversibility (kappa 0.60).

CONCLUSION

Albuterol vibrating mesh nebulization within a nasal high-flow circuit induces similar bronchodilation to standard facial mask jet nebulization. Beyond pharmacological bronchodilation, nasal high flow by itself may induce small but significant bronchodilation.