The Physiologic Effect of the Flow Generated by High Flow Nasal Cannula in Mild Respiratory Failure
Condition: Respiratory Failure
MeSH terms: Respiratory Insufficiency
Study type: Interventional

Summary: 
      High flow nasal cannula (HFNC) oxygen therapy is increasingly used for hypoxemic respiratory
      failure and is proving useful in avoiding or delaying intubation and mechanical ventilation.
      However, basic information regarding the physiologic effects of this method is missing. In
      this study, the effects of oxygen delivery by HFNC on oxygenation, ventilation and
      cardiovascular vital signs in patients with mild hypoxemic respiratory failure were
      evaluated.
    

Detailed description: 
      Oxygen (O2) therapy delivered by means of High Flow Nasal Cannula (HFNC) is being
      increasingly used. This device, capable of delivering high flow, oxygen enriched gas, has
      been shown to reduce intubation rates in patients with hypoxemic respiratory failure. The
      primary components of HFNC are "nasal prongs" (or cannulae) that are inserted into the
      nostrils, a device which provides a warmed and humidified air / oxygen mixture and regulators
      that control oxygen concentration, temperature and total gas flow. Commercially available
      systems can deliver up to 40 - 60 liters per minute (LPM) of oxygen flow.

      This method of non-invasive oxygen delivery has several presumed important working
      principals. Firstly, the high flow rate may meet the patient's own inspiratory flow rate.
      This enables accurate delivery of a high fractional inspired concentration of oxygen (FiO2).
      Second, the high gas flow might also produce a certain degree of Continuous Positive Airway
      Pressure (CPAP). In addition, the heated and humidified gas might also wash out/reduce the
      physiological airway dead space of the patient. Furthermore, HFNC is more comfortable and
      might be better tolerated than other Non-Invasive Ventilation (NIV) devices, such as Bi-level
      positive airway pressure (BiPAP). This, in turn, can prolong the time the patient is
      comfortably connected to the HFNC device.

      Information regarding the basic physiologic influence of HFNC on oxygenation, ventilation and
      vital signs is missing in the literature. Patients with mild respiratory failure provide an
      opportunity to examine this topic. On one hand, these patients suffer from respiratory
      failure manifested by hypoxemia, on the other hand the respiratory failure is mild to the
      extent that removal of the conventional oxygen therapy (COT) will not lead to immediate
      respiratory collapse. This prospective study evaluates the physiologic effects of HFNC in 28
      patients with mild respiratory failure.
    

Intervention name(s): HFNC
Intervention type(s): Device
Intervention description(s): The patients with mild hypoxemia, defined as the need for conventional oxygen therapy (COT) using nasal cannula at 4-5 liters per minute (LPM) to maintain O2 Saturation >90%, were commenced on HFNC therapy
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: high flow nasal cannula; oxygenation; ventilation; conventional oxygen therapy; Arterial Blood Gasses