High Flow Nasal Cannula Therapy

Initial Settings and Titration

The European Respiratory Society recommends starting with flow rates between 35-60 L/min for adults, titrated to patient comfort and respiratory effort 1
Higher flow rates (50-60 L/min) may provide greater physiological benefits including PEEP effect and dead space washout, as suggested by the Thorax journal 2
Adjust flow to patient tolerance, as some patients may experience discomfort at higher flows, according to the Thorax journal 3
The target temperature should be set between 34-37°C according to patient preference, with higher temperatures providing optimal humidification, as recommended by the European Respiratory Journal 1
FiO2 should be titrated to achieve target oxygen saturation, with a target SpO2 of 94-98% for patients without risk of hypercapnia, as suggested by the Thorax journal 3
For patients at risk of hypercapnic respiratory failure, the target SpO2 should be 88-92%, as recommended by the European Respiratory Journal 1

Respiratory rate should be monitored, as it should decrease with effective HFNC therapy, according to the European Respiratory Journal 1
Work of breathing should be assessed for accessory muscle use and patient comfort, as suggested by the Thorax journal 2
Oxygen saturation should be continuously monitored with pulse oximetry, according to the Thorax journal 3
Arterial blood gases should be monitored when necessary to assess response to therapy, as suggested by the Thorax journal 3

For hypoxemic respiratory failure, higher initial flow rates (50-60 L/min) may be more beneficial, and FiO2 should be titrated to maintain SpO2 targets, as recommended by the European Respiratory Journal 4
For post-extubation support, flow rates of 35-50 L/min are typically sufficient, and FiO2 should be titrated to maintain SpO2 targets, according to the European Respiratory Journal 5
For hypercapnic respiratory failure, a trial of NIV should be considered first before transitioning to HFNC, and HFNC may be used during breaks from NIV, as recommended by the European Respiratory Journal 1

The initial setup should include a flow rate of 40-50 L/min, a temperature of 37°C, and an initial FiO2 to achieve target SpO2, as recommended by the European Respiratory Journal 1
Flow rate adjustment should be based on patient comfort and respiratory effort, with increases of 5-10 L/min for increased work of breathing, and decreases of 5-10 L/min for patient discomfort, according to the European Respiratory Journal and Thorax journal 4, 3
FiO2 adjustment should be titrated in 5-10% increments to maintain target SpO2, with a target SpO2 of 94-98% for non-hypercapnic patients, and 88-92% for hypercapnic risk patients, as suggested by the Thorax journal and European Respiratory Journal 3, 1

Inadequate flow rate can lead to insufficient PEEP effect or dead space washout, as suggested by the Thorax journal 2
Excessive oxygen can lead to oxygen toxicity and potential harm, according to the Thorax journal 3
Delayed escalation can lead to delayed intubation and worse outcomes, as recommended by the European Respiratory Journal 4
Poor interface fit can lead to air leaks that reduce effectiveness, according to the Thorax journal 3
Insufficient humidification can lead to airway dryness and patient discomfort, as suggested by the Thorax journal 2

For pediatric patients weighing up to 10 kg, the American Thoracic Society recommends starting with a flow rate of ≥1 L/kg/min, and for patients above 10 kg, a flow rate of ≥10 L/min, as flows below these thresholds are considered conventional oxygen therapy, not HFNC 6, 7, 8
The European Respiratory Society suggests that maximum flow typically is 60 L/min for adults, with some patients unable to tolerate flows above 40 L/min despite potential physiological benefit 9

For patients with hypercapnic respiratory failure, such as COPD, the European Respiratory Society recommends considering non-invasive ventilation first, and if not tolerated, HFNC at 35-60 L/min may be attempted, with lower SpO2 targets (88-92%) 9
In hypoxemic respiratory failure, higher flows (50-60 L/min) provide greater PEEP effect and dead space washout, according to the Thorax journal 10

The European Respiratory Society suggests monitoring patient comfort scores, as some patients cannot tolerate flows >40-50 L/min despite theoretical benefit 9
Patient comfort should improve with effective HFNC therapy, as reported in the European Respiratory Journal 9