A. Introduction to High-Flow Nasal Cannula (HFNC) Therapy

This lesson provides an overview of High-Flow Nasal Cannula (HFNC) therapy, a non-invasive respiratory support technique that delivers heated and humidified oxygen at high flow rates.

B. Understanding High-Flow Nasal Cannula (HFNC) Therapy

High-Flow Nasal Cannula (HFNC) therapy is a non-invasive respiratory support method that delivers heated and humidified oxygen at higher flow rates than traditional nasal cannula.

• Traditional nasal cannulas deliver oxygen at flow rates of up to 6 L/min.
• HFNC can deliver oxygen at flow rates up to 60-70 L/min.
• The delivered gas is heated and humidified to body temperature, which improves patient comfort and physiological effects.

C. How HFNC Works

HFNC therapy works through several mechanisms:

• Reduction of Anatomical Dead Space: High flow rates flush out CO2-rich gas from the upper airway, improving ventilation efficiency.
• Delivery of High Oxygen Concentrations: HFNC can deliver FiO2 (fraction of inspired oxygen) up to 1.0, meeting the high oxygen demands of patients with respiratory distress.
• Positive Airway Pressure: HFNC generates a small amount of positive pressure, which can improve lung volume and reduce the work of breathing.
• Improved Humidification and Temperature Control: The heated and humidified gas helps to maintain mucociliary function, reduce airway inflammation, and improve patient comfort.

D. Components of a HFNC System

A typical HFNC system consists of the following components:

• Flow Generator: Delivers high flow rates of gas.
• Air-Oxygen Blender: Allows precise control of FiO2.
• Humidifier: Heats and humidifies the gas.
• Heated Circuit: Delivers the heated and humidified gas to the patient.
• Nasal Cannula: A special nasal cannula with larger-bore prongs designed for high flow rates.

E. Clinical Applications of HFNC

HFNC therapy is used in various clinical settings, including:

• Acute Hypoxemic Respiratory Failure: HFNC is often used as a first-line treatment for patients with hypoxemia due to conditions like pneumonia, ARDS, and cardiogenic pulmonary edema.
• Post-Extubation Support: HFNC can help prevent respiratory distress in patients after they have been extubated from mechanical ventilation.
• Pre-oxygenation before Intubation: HFNC can be used to improve oxygenation before intubation, which can be especially helpful in patients with difficult airways.
• Palliative Care: In patients with a do-not-intubate (DNI) order, HFNC can provide comfort and relieve dyspnea.

F. Advantages of HFNC

HFNC offers several advantages over traditional oxygen therapy and other non-invasive ventilation methods:

• Improved Patient Comfort and Tolerance: The heated and humidified gas is more comfortable than dry, cold oxygen, leading to better patient compliance.
• Effective Oxygenation: HFNC can deliver high concentrations of oxygen to meet the patient’s needs.
• Reduced Work of Breathing: The high flow rates help to reduce the work of breathing.
• Improved Mucociliary Clearance: The heated and humidified gas helps to maintain normal airway function.
• Non-invasive: HFNC does not require intubation, avoiding the associated complications.

G. Contraindications and Precautions

While HFNC is generally safe, there are some contraindications and precautions to consider:

• Absolute Contraindications:
  • Respiratory arrest
  • Inability to protect the airway
• Relative Contraindications/Precautions:
  • Severe upper airway obstruction
  • Epistaxis (nosebleeds)
  • Facial trauma
  • Patients at high risk of aspiration

It is crucial to monitor patients closely on HFNC and be prepared to escalate care if needed.

H. Initiating HFNC Therapy

The following steps are involved in initiating HFNC therapy:

• Patient Assessment: Assess the patient’s respiratory status, including oxygen saturation, respiratory rate, and work of breathing.
• Equipment Setup:
  • Set up the HFNC flow generator, air-oxygen blender, and humidifier.
  • Ensure the humidifier is filled with sterile water and set to the appropriate temperature (usually 37°C).
  • Connect the heated circuit and nasal cannula.
• Nasal Cannula Selection: Choose the appropriate size of nasal cannula. The prongs should fit snugly in the nares without causing blanching or obstruction.
• Starting Settings:
  • Flow Rate: Start with a flow rate of 20-30 L/min and adjust as needed. Higher flow rates (up to 60-70 L/min) may be required for some patients.
  • FiO2: Set the FiO2 based on the patient’s oxygenation status. Start with the FiO2 required to achieve the target SpO2.
• Patient Monitoring:
  • Continuously monitor the patient’s oxygen saturation, respiratory rate, heart rate, and work of breathing.
  • Assess the patient’s comfort level and adjust the cannula and flow rate as needed.
• Titration: Titrate the flow rate and FiO2 to achieve the desired clinical response.
  • Increase the flow rate to improve ventilation and reduce the work of breathing.
  • Adjust the FiO2 to maintain the target oxygen saturation.

I. Monitoring and Assessment

Regular monitoring and assessment are essential during HFNC therapy:

• Vital Signs: Monitor heart rate, blood pressure, and respiratory rate.
• Oxygen Saturation (SpO2): Continuously monitor SpO2 to ensure the target range is maintained.
• Respiratory Assessment: Assess the patient’s work of breathing, including the use of accessory muscles, nasal flaring, and chest retractions.
• Patient Comfort: Evaluate the patient’s comfort level and tolerance of the nasal cannula.
• Gas Exchange: Arterial blood gas (ABG) analysis may be necessary to assess the effectiveness of therapy, especially in patients with severe respiratory distress.
• Complications: Monitor for any complications, such as nasal irritation, epistaxis, or gastric distention.

J. Weaning from HFNC

When the patient’s condition improves, weaning from HFNC can be considered. There is no single weaning protocol, but general principles include:

• Improvement in Underlying Condition: The underlying cause of respiratory distress should be improving.
• Stable Vital Signs: The patient should have stable vital signs, including heart rate, blood pressure, and respiratory rate.
• Adequate Oxygenation: The patient should be able to maintain adequate oxygen saturation on lower FiO2 levels.
• Reduced Work of Breathing: The patient should exhibit minimal signs of respiratory distress.

The weaning process typically involves gradually decreasing the flow rate and FiO2 while closely monitoring the patient’s response.

K. Troubleshooting

Common issues and troubleshooting in HFNC therapy:

• Inadequate Oxygenation:
  • Increase FiO2 to meet the patient’s needs.
  • Assess for air leaks and ensure proper cannula fit.
  • Consider increasing flow rate.
• Patient Discomfort:
  • Ensure proper cannula size and fit.
  • Adjust the flow rate.
  • Provide oral care and humidification.
• Nasal Irritation or Bleeding:
  • Ensure proper cannula size and fit.
  • Increase humidification.
  • Consider a different type of cannula.
• Equipment Malfunction:
  • Check all connections and settings.
  • Troubleshoot the flow generator and humidifier.
  • Replace any malfunctioning equipment.

L. Documentation

Accurate and timely documentation of HFNC therapy is essential. Key elements to document include:

• Patient assessment before HFNC initiation
• Indications for HFNC
• HFNC settings (flow rate, FiO2)
• Cannula size and type
• Patient’s response to therapy
• Vital signs and oxygen saturation
• Respiratory assessment
• Any complications
• Changes in settings
• Weaning process

M. Practical Application and Skills

This session will include hands-on practice with HFNC equipment, focusing on:

• Setting up the HFNC system
• Selecting and fitting nasal cannulas
• Adjusting flow rates and FiO2
• Monitoring patients on HFNC
• Troubleshooting common issues

N. Question and Answer Session

This is your opportunity to ask questions and clarify any doubts regarding HFNC therapy.

O. Assessment and Evaluation

Your understanding and skills in HFNC therapy will be evaluated through:

• Practical skills demonstration
• Case scenario discussions
• Written or oral questions