From the Guidelines
For Acute Care Unit (AAU) patients requiring High Flow Nasal Cannula (HFNC) support, the initial FiO2 should be set at 40-50% with a flow rate of 30-40 liters per minute, as this balance provides effective oxygenation and patient comfort while allowing room for titration based on the patient's response 1.
Key Considerations for HFNC Therapy
- The initial flow rate and FiO2 settings are crucial for patient comfort and effective oxygenation.
- Clinicians should assess the patient's oxygen saturation (SpO2) target, typically 92-96% for most adults, and adjust FiO2 accordingly 1.
- The flow rate can be increased up to 60 liters per minute if needed, but starting at a moderate range helps with patient tolerance.
- Close monitoring of the patient during the first hour of therapy is essential, checking vital signs, work of breathing, and oxygen saturation.
- If the patient shows signs of respiratory distress or declining oxygen levels despite HFNC support at maximum settings (FiO2 >60% and flow rate >50 L/min), escalation to non-invasive ventilation or intubation should be considered promptly 1.
Physiological Benefits of HFNC
- The washout of anatomical dead space
- Provision of positive airway pressure
- Delivery of adequately humidified oxygen These benefits support the use of HFNC as a non-invasive form of respiratory support in acute settings, as recommended by recent guidelines 1.
From the Research
Initial FiO2 and Flow Rate Limits for AAU Patients Requiring HFNC Support
- The initial FiO2 (fraction of inspired oxygen) and flow rate limits for Acute Care Unit (AAU) patients requiring High Flow Nasal Cannula (HFNC) support are not explicitly stated in the provided studies 2, 3, 4, 5, 6.
- However, the studies discuss the use of HFNC in various clinical settings, including hypoxemic respiratory failure, post-extubation respiratory failure, and peri-intubation period 2, 3, 4.
- The flow rate and FiO2 for HFNC can be adjusted based on the patient's clinical condition and response to treatment, but specific limits are not provided in the studies 3, 5.
- One study compared HFNC to non-invasive ventilation in acute hypoxia and found that HFNC had no effect on intensive care unit length of stay, hospital length of stay, patient reported comfort, or patient reported dyspnea 6.
- Another study discussed the practical application and clinical uses of HFNC in adults, including its unique respiratory physiologic effects, device settings, and clinical indications, but did not provide specific limits for FiO2 and flow rate 3.
Key Considerations for HFNC Use
- HFNC has been successfully used in critically ill patients with several conditions, such as hypoxemic respiratory failure, hypercapneic respiratory failure, and post-extubation respiratory failure 3, 4.
- The optimal treatment for early hypoxemic respiratory failure is unclear, and both HFNC and non-invasive ventilation are used 5.
- Strict physiological monitoring remains of paramount importance to promptly detect the need for endotracheal intubation and not delay protective ventilation 4.