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How to set high flow oxygen therapy

Article

Author: Clinical Experts Group, Hamilton Medical

Date of first publication: 14.12.2017

Last change: 13.07.2020

More information on physiological effects; initial flow setting lowered from 60 to 30

High flow oxygen therapy combines several physiologic effects.

How to set high flow oxygen therapy

Personalized instead of standardized settings

The physiologic effects of HFOT are improved oxygenation, reduced inspiratory effort and work of breathing, improved lung mechanics, increased end-expiratory lung volumes (EELV), probably due to the positive end-expiratory pressure (PEEP) effect, increased carbon dioxide (CO2) clearance by washout of anatomic dead space, and improved comfort (Mauri T, Turrini C, Eronia N, et al. Physiologic Effects of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1207-1215. doi:10.1164/rccm.201605-0916OC1​, Goligher EC, Slutsky AS. Not Just Oxygen? Mechanisms of Benefit from High-Flow Nasal Cannula in Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1128-1131. doi:10.1164/rccm.201701-0006ED2​). 

The PEEP effect and the decrease in in respiratory rate are flow-dependent and better with higher flow rates (Mauri T, Alban L, Turrini C, et al. Optimum support by high-flow nasal cannula in acute hypoxemic respiratory failure: effects of increasing flow rates. Intensive Care Med. 2017;43(10):1453-1463. doi:10.1007/s00134-017-4890-13​, Parke RL, Bloch A, McGuinness SP. Effect of Very-High-Flow Nasal Therapy on Airway Pressure and End-Expiratory Lung Impedance in Healthy Volunteers. Respir Care. 2015;60(10):1397-1403. doi:10.4187/respcare.040284​, Pisani L, Fasano L, Corcione N, et al. Change in pulmonary mechanics and the effect on breathing pattern of high flow oxygen therapy in stable hypercapnic COPD. Thorax. 2017;72(4):373-375. doi:10.1136/thoraxjnl-2016-2096735​, Luo JC, Lu MS, Zhao ZH, et al. Positive End-Expiratory Pressure Effect of 3 High-Flow Nasal Cannula Devices. Respir Care. 2017;62(7):888-895. doi:10.4187/respcare.053376​). However, the decrease in PaCO2 and minute ventilation are achieved at 30 l/min and do not change at higher flows (Mauri T, Alban L, Turrini C, et al. Optimum support by high-flow nasal cannula in acute hypoxemic respiratory failure: effects of increasing flow rates. Intensive Care Med. 2017;43(10):1453-1463. doi:10.1007/s00134-017-4890-13​). Until now, settings for flow and temperature have been heterogeneous for adult patients and what they perceive as comfortable varies greatly. This suggests that the therapy might benefit from more personalized rather than standardized settings (Mauri T, Galazzi A, Binda F, et al. Impact of flow and temperature on patient comfort during respiratory support by high-flow nasal cannula. Crit Care. 2018;22(1):120. Published 2018 May 9. doi:10.1186/s13054-018-2039-47​).

 

Initial settings and adjustments

Flow: While many of the targeted physiologic variables show the most benefit at higher flows, patient comfort and compliance to therapy are key factors that should not be ignored. The set flow should take into consideration the severity of the patient’s condition.

Although there is no standard way to set the flow, an approach now used frequently in clinical practice is to initiate with a minimum flow of 30 l/min, and monitor dyspnea and the respiratory rate. If there is no improvement, the flow can be titrated according to patient comfort. You can increase it in increments of 10 l/min up to 60 l/min, and monitor the patient’s clinical condition. Note that any discomfort is usually due to the velocity of gas rather than the flow itself, and may be eased by using a large-bore cannula.

Temperature: In order to optimize the humidification effect, the temperature should be set at 37°C.

Oxygen: Oxygen is adjusted to maintain SpO2 within target ranges of 92%-96% for most patients and 88%-92% for patients with chronic respiratory disease (O'Driscoll BR, Howard LS, Davison AG; British Thoracic Society. BTS guideline for emergency oxygen use in adult patients [published correction appears in Thorax. 2009 Jan;64(1):91]. Thorax. 2008;63 Suppl 6:vi1-vi68. doi:10.1136/thx.2008.1029478​, Beasley R, Chien J, Douglas J, et al. Thoracic Society of Australia and New Zealand oxygen guidelines for acute oxygen use in adults: 'Swimming between the flags'. Respirology. 2015;20(8):1182-1191. doi:10.1111/resp.126209​).

This bedside tip is based on the example of high flow oxygen therapy with Hamilton Medical ventilators, however the information applies to the use of high flow oxygen therapy in general.

Full citations below: (Mauri T, Turrini C, Eronia N, et al. Physiologic Effects of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1207-1215. doi:10.1164/rccm.201605-0916OC1​, Goligher EC, Slutsky AS. Not Just Oxygen? Mechanisms of Benefit from High-Flow Nasal Cannula in Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1128-1131. doi:10.1164/rccm.201701-0006ED2​)

Screenshot showing high flow therapy settings on HAMILTON-C6 ventilator
Figure 1: High flow oxygen therapy on the HAMILTON-C6
Screenshot showing high flow therapy settings on HAMILTON-C6 ventilator
Figure 1: High flow oxygen therapy on the HAMILTON-C6
Screenshot showing high flow therapy settings on HAMILTON-G5 ventilator
Figure 2: High flow oxygen therapy on the HAMILTON-G5
Screenshot showing high flow therapy settings on HAMILTON-G5 ventilator
Figure 2: High flow oxygen therapy on the HAMILTON-G5

High flow oxygen therapy on Hamilton Medical ventilators

High flow oxygen therapy is available as an option on all our ventilators. We also offer compatible high flow interfaces and a compatible humidifier. In just a few steps, you can change the interface and use the same device and breathing circuit to accommodate your patient’s therapy needs. 

We also have some exclusive offers for HFNC enthusiasts where something exciting about high flow nasal cannula therapy is waiting you.

The basics of high flow nasal cannula therapy e-book

Free e-book

The basics of high flow nasal cannula therapy

Our e-book on high flow nasal cannula therapy gives you an overview of the working principles and clinical benefits, as well as practical information about choosing the right interface, adjusting the settings, and monitoring your patients.

Download e-book

Footnotes

References

  1. 1. Mauri T, Turrini C, Eronia N, et al. Physiologic Effects of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1207-1215. doi:10.1164/rccm.201605-0916OC
  2. 2. Goligher EC, Slutsky AS. Not Just Oxygen? Mechanisms of Benefit from High-Flow Nasal Cannula in Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1128-1131. doi:10.1164/rccm.201701-0006ED
  3. 3. Mauri T, Alban L, Turrini C, et al. Optimum support by high-flow nasal cannula in acute hypoxemic respiratory failure: effects of increasing flow rates. Intensive Care Med. 2017;43(10):1453-1463. doi:10.1007/s00134-017-4890-1
  4. 4. Parke RL, Bloch A, McGuinness SP. Effect of Very-High-Flow Nasal Therapy on Airway Pressure and End-Expiratory Lung Impedance in Healthy Volunteers. Respir Care. 2015;60(10):1397-1403. doi:10.4187/respcare.04028
  5. 5. Pisani L, Fasano L, Corcione N, et al. Change in pulmonary mechanics and the effect on breathing pattern of high flow oxygen therapy in stable hypercapnic COPD. Thorax. 2017;72(4):373-375. doi:10.1136/thoraxjnl-2016-209673
  6. 6. Luo JC, Lu MS, Zhao ZH, et al. Positive End-Expiratory Pressure Effect of 3 High-Flow Nasal Cannula Devices. Respir Care. 2017;62(7):888-895. doi:10.4187/respcare.05337
  7. 7. Mauri T, Galazzi A, Binda F, et al. Impact of flow and temperature on patient comfort during respiratory support by high-flow nasal cannula. Crit Care. 2018;22(1):120. Published 2018 May 9. doi:10.1186/s13054-018-2039-4
  8. 8. O'Driscoll BR, Howard LS, Davison AG; British Thoracic Society. BTS guideline for emergency oxygen use in adult patients [published correction appears in Thorax. 2009 Jan;64(1):91]. Thorax. 2008;63 Suppl 6:vi1-vi68. doi:10.1136/thx.2008.102947
  9. 9. Beasley R, Chien J, Douglas J, et al. Thoracic Society of Australia and New Zealand oxygen guidelines for acute oxygen use in adults: 'Swimming between the flags'. Respirology. 2015;20(8):1182-1191. doi:10.1111/resp.12620

Physiologic Effects of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure.

Mauri T, Turrini C, Eronia N, et al. Physiologic Effects of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1207-1215. doi:10.1164/rccm.201605-0916OC



RATIONALE

High-flow nasal cannula (HFNC) improves the clinical outcomes of nonintubated patients with acute hypoxemic respiratory failure (AHRF).

OBJECTIVES

To assess the effects of HFNC on gas exchange, inspiratory effort, minute ventilation, end-expiratory lung volume, dynamic compliance, and ventilation homogeneity in patients with AHRF.

METHODS

This was a prospective randomized crossover study in nonintubated patients with AHRF with PaO2/setFiO2 less than or equal to 300 mm Hg admitted to the intensive care unit. We randomly applied HFNC set at 40 L/min compared with a standard nonocclusive facial mask at the same clinically set FiO2 (20 min/step).

MEASUREMENTS AND MAIN RESULTS

Toward the end of each phase, we measured arterial blood gases, inspiratory effort, and work of breathing by esophageal pressure swings (ΔPes) and pressure time product, and we estimated changes in lung volumes and ventilation homogeneity by electrical impedance tomography. We enrolled 15 patients aged 60 ± 14 years old with PaO2/setFiO2 130 ± 35 mm Hg. Seven (47%) had bilateral lung infiltrates. Compared with the facial mask, HFNC significantly improved oxygenation (P < 0.001) and lowered respiratory rate (P < 0.01), ΔPes (P < 0.01), and pressure time product (P < 0.001). During HFNC, minute ventilation was reduced (P < 0.001) at constant arterial CO2 tension and pH (P = 0.27 and P = 0.23, respectively); end-expiratory lung volume increased (P < 0.001), and tidal volume did not change (P = 0.44); the ratio of tidal volume to ΔPes (an estimate of dynamic lung compliance) increased (P < 0.05); finally, ventilation distribution was more homogeneous (P < 0.01).

CONCLUSIONS

In patients with AHRF, HFNC exerts multiple physiologic effects including less inspiratory effort and improved lung volume and compliance. These benefits might underlie the clinical efficacy of HFNC.

Not Just Oxygen? Mechanisms of Benefit from High-Flow Nasal Cannula in Hypoxemic Respiratory Failure.

Goligher EC, Slutsky AS. Not Just Oxygen? Mechanisms of Benefit from High-Flow Nasal Cannula in Hypoxemic Respiratory Failure. Am J Respir Crit Care Med. 2017;195(9):1128-1131. doi:10.1164/rccm.201701-0006ED

Optimum support by high-flow nasal cannula in acute hypoxemic respiratory failure: effects of increasing flow rates.

Mauri T, Alban L, Turrini C, et al. Optimum support by high-flow nasal cannula in acute hypoxemic respiratory failure: effects of increasing flow rates. Intensive Care Med. 2017;43(10):1453-1463. doi:10.1007/s00134-017-4890-1



PURPOSE

Limited data exist on the correlation between higher flow rates of high-flow nasal cannula (HFNC) and its physiologic effects in patients with acute hypoxemic respiratory failure (AHRF). We assessed the effects of HFNC delivered at increasing flow rate on inspiratory effort, work of breathing, minute ventilation, lung volumes, dynamic compliance and oxygenation in AHRF patients.

METHODS

A prospective randomized cross-over study was performed in non-intubated patients with patients AHRF and a PaO2/FiO2 (arterial partial pressure of oxygen/fraction of inspired oxygen) ratio of ≤300 mmHg. A standard non-occlusive facial mask and HFNC at different flow rates (30, 45 and 60 l/min) were randomly applied, while maintaining constant FiO2 (20 min/step). At the end of each phase, we measured arterial blood gases, inspiratory effort, based on swings in esophageal pressure (ΔPes) and on the esophageal pressure-time product (PTPPes), and lung volume, by electrical impedance tomography.

RESULTS

Seventeen patients with AHRF were enrolled in the study. At increasing flow rate, HFNC reduced ΔPes (p < 0.001) and PTPPes (p < 0.001), while end-expiratory lung volume (ΔEELV), tidal volume to ΔPes ratio (V T/ΔPes, which corresponds to dynamic lung compliance) and oxygenation improved (p < 0.01 for all factors). Higher HFNC flow rate also progressively reduced minute ventilation (p < 0.05) without any change in arterial CO2 tension (p = 0.909). The decrease in ΔPes, PTPPes and minute ventilation at increasing flow rates was better described by exponential fitting, while ΔEELV, V T/ΔPes and oxygenation improved linearly.

CONCLUSIONS

In this cohort of patients with AHRF, an increasing HFNC flow rate progressively decreased inspiratory effort and improved lung aeration, dynamic compliance and oxygenation. Most of the effect on inspiratory workload and CO2 clearance was already obtained at the lowest flow rate.

Effect of Very-High-Flow Nasal Therapy on Airway Pressure and End-Expiratory Lung Impedance in Healthy Volunteers.

Parke RL, Bloch A, McGuinness SP. Effect of Very-High-Flow Nasal Therapy on Airway Pressure and End-Expiratory Lung Impedance in Healthy Volunteers. Respir Care. 2015;60(10):1397-1403. doi:10.4187/respcare.04028



BACKGROUND

Previous research has demonstrated a positive linear correlation between flow delivered and airway pressure generated by high-flow nasal therapy. Current practice is to use flows over a range of 30-60 L/min; however, it is technically possible to apply higher flows. In this study, airway pressure measurements and electrical impedance tomography were used to assess the relationship between flows of up to 100 L/min and changes in lung physiology.

METHODS

Fifteen healthy volunteers were enrolled into this study. A high-flow nasal system capable of delivering a flow of 100 L/min was purpose-built using 2 Optiflow systems. Airway pressure was measured via the nasopharynx, and cumulative changes in end-expiratory lung impedance were recorded using the PulmoVista 500 system at gas flows of 30-100 L/min in increments of 10 L/min.

RESULTS

The mean age of study participants was 31 (range 22-44) y, the mean ± SD height was 171.8 ± 7.5 cm, the mean ± SD weight was 69.7 ± 10 kg, and 47% were males. Flows ranged from 30 to 100 L/min with resulting mean ± SD airway pressures of 2.7 ± 0.7 to 11.9 ± 2.7 cm H2O. A cumulative and linear increase in end-expiratory lung impedance was observed with increasing flows, as well as a decrease in breathing frequency.

CONCLUSIONS

Measured airway pressure and lung impedance increased linearly with increased gas flow. Observed airway pressures were in the range used clinically with face-mask noninvasive ventilation. Developments in delivery systems may result in this therapy being an acceptable alternative to face-mask noninvasive ventilation.

Change in pulmonary mechanics and the effect on breathing pattern of high flow oxygen therapy in stable hypercapnic COPD.

Pisani L, Fasano L, Corcione N, et al. Change in pulmonary mechanics and the effect on breathing pattern of high flow oxygen therapy in stable hypercapnic COPD. Thorax. 2017;72(4):373-375. doi:10.1136/thoraxjnl-2016-209673

: We studied the effects of high flow oxygen therapy (HFOT) versus non-invasive ventilation (NIV) on inspiratory effort, as assessed by measuring transdiaphragmatic pressure, breathing pattern and gas exchange. Fourteen patients with hypercapnic COPD underwent five 30-min trials: HFOT at two flow rates, both with open and closed mouth, and NIV, applied in random order. After each trial standard oxygen therapy was reinstituted for 10 min. Compared with baseline, HFOT and NIV significantly improved breathing pattern, although to different extents, and reduced inspiratory effort; however, arterial carbon dioxide oxygen tension decreased but not significantly. These results indicate a possible role for HFOT in the long-term management of patients with stable hypercapnic COPD.

TRIAL REGISTRATION NUMBER

NCT02363920.

Positive End-Expiratory Pressure Effect of 3 High-Flow Nasal Cannula Devices.

Luo JC, Lu MS, Zhao ZH, et al. Positive End-Expiratory Pressure Effect of 3 High-Flow Nasal Cannula Devices. Respir Care. 2017;62(7):888-895. doi:10.4187/respcare.05337



BACKGROUND

High-flow nasal cannula (HFNC) is supposed to provide additional PEEP compared with conventional oxygen therapy. However, the exact determinants of this PEEP effect are unclear. We investigated the factors that might affect the PEEP and compared PEEP performance among 3 HFNC devices.

METHODS

Three available HFNC devices were evaluated: the AIRVO 2 device and 2 mechanical ventilators (SV300 and Monnal T75). A device consisting of a test lung (5600i) and an airway model (AMT(IE)) was used to simulate spontaneous breathing. The flows ranged from 0 to their maximum flow with an interval of 10 L/min. The pressures were measured at 4 sites (nasopharynx, supraglottis, carina, and lung) under compliances of 50 and 100 mL/cm H2O and tidal volume of 300, 500, and 700 mL with the mouth closed or open. The influencing factors were determined by multiple linear regression. The sum of squares reduction test was used to compare working curves of PEEP effect among 3 devices. Pairwise comparisons were conducted by using Tukey's multiple comparisons test within an overlap of flow from 0 to 50 L/min.

RESULTS

A quadratic curved relationship between PEEP and flow was observed (coefficients were 8.97 × 10-3 for flow and 4.79 × 10-4 for a quadratic element of flow, respectively) but evanished when the mouth was open. The PEEP increased along with lung compliance (coefficient was 2.58 × 10-3). Despite the difference in working curves, both the mechanical ventilators performed slightly better than the AIRVO 2 device at higher flows (40 and 50 L/min).

CONCLUSIONS

The mouth status, flow, and compliance were the 3 major influencing factors of PEEP effect, whereas performance of the 2 mechanical ventilators was slightly superior to that of the AIRVO 2 device at higher flows.

Impact of flow and temperature on patient comfort during respiratory support by high-flow nasal cannula.

Mauri T, Galazzi A, Binda F, et al. Impact of flow and temperature on patient comfort during respiratory support by high-flow nasal cannula. Crit Care. 2018;22(1):120. Published 2018 May 9. doi:10.1186/s13054-018-2039-4



BACKGROUND

The high-flow nasal cannula (HFNC) delivers up to 60 l/min of humidified air/oxygen blend at a temperature close to that of the human body. In this study, we tested whether higher temperature and flow decrease patient comfort. In more severe patients, instead, we hypothesized that higher flow might be associated with improved comfort.

METHODS

A prospective, randomized, cross-over study was performed on 40 acute hypoxemic respiratory failure (AHRF) patients (PaO2/FiO2 ≤ 300 + pulmonary infiltrates + exclusion of cardiogenic edema) supported by HFNC. The primary outcome was the assessment of patient comfort during HFNC delivery at increasing flow and temperature. Two flows (30 and 60 l/min), each combined with two temperatures (31 and 37 °C), were randomly applied for 20 min (four steps per patient), leaving clinical FiO2 unchanged. Toward the end of each step, the following were recorded: comfort by Visual Numerical Scale ranging between 1 (extreme discomfort) and 5 (very comfortable), together with respiratory parameters. A subgroup of more severe patients was defined by clinical FiO2 ≥ 45%.

RESULTS

Patient comfort was reported as significantly higher during steps at the lower temperature (31 °C) in comparison to 37 °C, with the HFNC set at both 30 and 60 l/min (p < 0.0001). Higher flow, however, was not associated with poorer comfort. In the subgroup of patients with clinical FiO2 ≥ 45%, both lower temperature (31 °C) and higher HFNC flow (60 l/min) led to higher comfort (p < 0.01).

CONCLUSIONS

HFNC temperature seems to significantly impact the comfort of AHRF patients: for equal flow, lower temperature could be more comfortable. Higher flow does not decrease patient comfort; at variance, it improves comfort in the more severely hypoxemic patient.

BTS guideline for emergency oxygen use in adult patients.

O'Driscoll BR, Howard LS, Davison AG; British Thoracic Society. BTS guideline for emergency oxygen use in adult patients [published correction appears in Thorax. 2009 Jan;64(1):91]. Thorax. 2008;63 Suppl 6:vi1-vi68. doi:10.1136/thx.2008.102947

Thoracic Society of Australia and New Zealand oxygen guidelines for acute oxygen use in adults: 'Swimming between the flags'.

Beasley R, Chien J, Douglas J, et al. Thoracic Society of Australia and New Zealand oxygen guidelines for acute oxygen use in adults: 'Swimming between the flags'. Respirology. 2015;20(8):1182-1191. doi:10.1111/resp.12620

The purpose of the Thoracic Society of Australia and New Zealand guidelines is to provide simple, practical evidence-based recommendations for the acute use of oxygen in adults in clinical practice. The intended users are all health professionals responsible for the administration and/or monitoring of oxygen therapy in the management of acute medical patients in the community and hospital settings (excluding perioperative and intensive care patients), those responsible for the training of such health professionals, and both public and private health care organizations that deliver oxygen therapy.