Terminology for High Flow Nasal Cannula and Nasal CPAP in the ICU Setting
In the ICU setting, high flow nasal cannula (HFNC) and nasal continuous positive airway pressure (CPAP) are distinct respiratory support modalities with specific terminology and definitions that differentiate them from conventional oxygen therapy. 1
High Flow Nasal Cannula (HFNC)
- HFNC is defined as a respiratory support device that delivers heated and humidified oxygen at high flow rates (up to 60 L/min) through a nasal cannula interface 1
- Also referred to as HFNO (high-flow nasal oxygen) or HHHFNC (heated, humidified high-flow nasal cannula) in some clinical contexts 1
- In pediatric settings, HFNC is specifically defined as flow delivered at ≥1 L/kg/min for patients up to 10 kg and ≥10 L/min for patients above 10 kg 1
- When flow rates fall below these thresholds, the therapy is considered conventional oxygen therapy rather than HFNC 1
Nasal CPAP
- CPAP is defined as positive pressure with a single continuous distending pressure delivered without an artificial airway via an interface that aims to provide an occlusive fit 1
- When delivered via nasal interface (mask, pillows/prongs), it is specifically termed nasal CPAP 1
- Unlike HFNC, nasal CPAP requires an occlusive interface to maintain the continuous positive pressure 1
Distinguishing Features in ICU Terminology
- HFNC is categorized as a form of noninvasive respiratory support distinct from both conventional oxygen therapy and noninvasive ventilation 1
- Nasal CPAP is classified as a form of noninvasive ventilation (NIV) in the ICU, though some literature uses NIV and CPAP terminology interchangeably 1
- The key distinction in ICU terminology is that HFNC delivers high flow without requiring an occlusive interface, while nasal CPAP delivers continuous positive pressure through an occlusive nasal interface 1
Clinical Application Terminology
- In ICU documentation, HFNC is typically specified with its flow rate (L/min) and FiO₂ parameters 1, 2
- Nasal CPAP is documented with pressure level (cmH₂O) and FiO₂ parameters 1
- The ROX index ([SpO₂/FiO₂]/breathing frequency) is a commonly used metric in ICU documentation when monitoring HFNC therapy effectiveness 3
Common Pitfalls in Terminology
- A frequent error is using NIV and CPAP terms interchangeably, when CPAP is actually a specific mode of NIV 1
- Another common mistake is failing to distinguish between conventional nasal cannula oxygen and HFNC based on flow rates 1
- The interface used (occlusive vs. non-occlusive) is a critical component in correctly identifying and documenting the respiratory support modality 1
By understanding these distinct terminologies, clinicians can ensure accurate documentation, appropriate application, and effective communication regarding respiratory support modalities in the ICU setting.