High-Velocity Nasal Insufflation for Respiratory Failure
Dr. Jerome Martin
Dyspnea and acute respiratory failure are among the top 5 reasons for patients to present to the Emergency Department. High-velocity nasal insufflation (HVNI), a type of high-flow nasal cannula (HFNC), decreases dead space to augment ventilation in addition to providing increased oxygenation at flow rates of 25-35 L/min. Typically, HFNC is used in hypoxemic respiratory failure and noninvasive positive pressure ventilation (NIPPV) is used for hypercapnic or mixed. HVNI could be helpful in supporting both hypoxic and hypercapnic respiratory failure presenting to the ED as it does provide some ventilatory support. When compared to NIPPV it not only improves patient comfort, but has increased ease of use.
Is there data to support the use of HVNI in undifferentiated respiratory failure?
Intubation rate of the HVNI group was 7% (95% CI 2-12%).
Wouldn’t it be great if we had an easier to use, more comfortable modality for patients who initially present to the ED with respiratory failure? And this paper tried to address this, but there were many limitations.
One obvious limitation is the inability to blind the treatment team by nature of the devices contributing to a possible early bias. The determination of treatment failure is sometimes subjective and based on the physician’s clinical judgement. The opinion of the treating physician in regards to HVNI as an effective treatment or not can skew the results.
The results of the article showed that there was not a statistical difference in the failure rate of HFNI vs NPPV in the initial treatment of undifferentiated respiratory failure. In my opinion that makes this an important article because many patients find greater comfort in the use of HFNI over NIPPV. For me it makes me feel more justified in utilizing HVNI at least initially in the ED to help respiratory distress. I can see it being of benefit in the patient who arrives anxious and doesn’t want to try the restrictive mask. HVNI also allows for another noninvasive modality attempt prior to the definitive intubation.
This paper also makes a strong argument for the use of HVNI prior to any ABG/VBG results. The full adoption of such a practice does require some more study. Further investigation into the efficaciousness of both of these respiratory support modalities depending on the specific cause of respiratory failure may be beneficial. Since the study wasn’t powered for subgroup analysis we are still left with the older trials which show that HFNC is useful in hypoxemic respiratory failure, but the utilization in hypercapnic failure compared to NIPPV needs further review.