High Velocity Nasal Insufflation (Hi-VNITM)

Vapotherm's Hi-VNI Therapy is a cannula based, proven, effective therapy, with clinical outcomes similar to pressure-based ventilation therapies, providing rapid relief of dyspnea, hypoxia and hypercapnia. It reduces the work of breathing by washing out expired CO2, and loading the upper airway with moist, warm, oxygenated gas, which has the secondary benefit of improving secretion clearance and protecting respiratory tissue. The technology is easier than NIPPV for respiratory and nursing staff to use given that set up and availability for use takes 5 minutes, and with minimal patient education.

Primary Mechanism of Action

The primary mechanism of action is to purge the extrathoracic respiratory dead space (nasal, oral and pharyngeal cavities) of end-expiratory gas between each breath. The high velocity rates and cannula geometry ensure that the patient inspires only the fresh gas coming from the cannula without dilution because of entrainment of room air. This high flow of nasal cannula gas provides a multifactorial respiratory support that includes both efficient oxygen administration and effective elimination of CO2.

Hi-VNI uses the nasopharyngeal space as a reservoir for fresh gas, instead of a reservoir of end-expiratory gas, which means the inspired gas mixture at the alveolar level is very close to the delivered fresh gas mixture. As a result oxygenation at the alveolar level is highly efficient. The concept is similar to a non-rebreather mask, except that the reservoir is more proximal to the lung.

With Hi-VNI, CO2 is purged from the upper airway between breaths, this volume of CO2 is not re-breathed with subsequent inhalations. This elimination of CO2 reduces work of breathing, which typically manifests as a reduced respiratory rate, reflecting less work for the respiratory muscles.

The upper airway washout effect depends on the nasal cannula dimensions and a fit that supports rapid purging of gas. For Hi-VNI to be effective, the upper airway must be purged in the limited time between breaths, and accomplished with a reasonable and tolerable flow rate.

Secondary Mechanism of Action

Hi-VNI therapy does generate a small amount of positive expiratory pressure (PEP), which may impact the therapeutic effectiveness. The PEP is generated as the patient expires against the high velocity rate of the incoming fresh gas.

Hi-VNI is delivered through an open system (loose fitting nasal prongs), which means the inward flow of gas does not create significant pressure in the patient. The pressure created by Hi-VNI is roughly equivalent to the PEP generated by pursed lip breathing. The gas flows out through the patient's mouth and nose as fast as it flows in through the cannula

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