Internal cannula mounted nebulizer
Provided herein are devices, systems, and methods for providing respiratory therapy to a patient using a nasal cannula comprising a cannula body, first and second inlet tubes, and a nasal prong for the delivery of a flow of breathing gas to the patient. Configured with the cannula is a nebulizer having an aerosol generator positioned to emit aerosolized medicament along a longitudinal axis of the nasal prong. A flow director is configured to direct the flow of breathing gas into the nasal prong such that the breathing gas flows along the longitudinal axis, such that the flow of aerosolized medicament is contained within the flow of breathing gas as it moves along the longitudinal axis of the nasal prong for delivery to the patient.
1. A system for providing respiratory therapy to a patient comprising:
a nasal cannula comprising a cannula body, first and second inlet tubes, and a nasal prong for the delivery of a flow of breathing gas to the patient, the flow of breathing gas supplied to the cannula body via the first and second inlet tubes,
the nasal prong having a longitudinal axis, an inlet in fluid communication with the cannula body, and an outlet for insertion into the nare of the patient;
a nebulizer adapted to receive a liquid medicament and having an aerosol generator positioned along and centered on the longitudinal axis at a point at which the flow of breathing gas has a theoretical zero flow rate, the aerosol generator operable to generate a flow of aerosolized medicament from the liquid medicament along the longitudinal axis; and
a flow director having a first portion and a second portion, the first portion coupled to the cannula body and adapted to receive the flow of breathing gas from the first and second inlet tubes and direct the flow of breathing gas into the nasal prong such that the breathing gas flows along the longitudinal axis, and
the second portion secured to the nebulizer and configured such that the flow of aerosolized medicament is contained within the flow of breathing gas as it moves along the longitudinal axis of the nasal prong for delivery to the patient,
wherein the flow of breathing gas is axisymmetric about the longitudinal axis of the nasal prong up to the point of theoretical zero flow rate, after which the flow is axially orientated with respect to the longitudinal axis of the nasal prong.
2. The system of claim 1 , wherein the breathing gas flows into the nasal prong along a path having a breathing gas axis that is symmetric along the longitudinal axis.
3. The system of claim 2 , wherein the flow director forms an annular gap between the inlet of the nasal prong and the nebulizer.
4. The system of claim 3 , wherein the flow director is configured such that the flow of breathing gas has a pressure drop in the nasal cannula that is largest across the annular gap.
5. The system of claim 4 , wherein the pressure drop in the flow of breathing gas across the annular gap is at least 30%.
6. The system of claim 3 , wherein the flow of breathing gas passes through the annular gap with a flow velocity that is constant at any point along the annular gap.
7. The system of claim 1 , wherein the flow director further comprises an anti-rotation element which prevents rotation of the flow of breathing gas within the cannula body as it is supplied to the cannula body via the first and second inlet tubes.
8. The system of claim 7 , wherein the anti-rotation element comprises a plurality of baffles symmetrically arranged about the flow director.
9. The system of claim 1 , wherein the nebulizer is removably attached to the flow director.
10. The system of claim 1 , wherein the flow director is coupled to the cannula body via an interference fit.
11. The system of claim 1 , wherein the aerosol generator comprises a vibrating mesh attached to a piezoelectric element.
12. The system of claim 11 , wherein the piezoelectric element is in electrical contact with a controller on a printed circuit board.
13. The system of claim 12 , further comprising wires that are in electrical contact with the printed circuit board for transmitting electrical signals from a signal generator to the vibrating mesh.
14. The system of claim 13 , further comprising a housing that is attached to the cannula body.
15. The system of claim 14 , wherein the housing is attached to the cannula body using a snap-fit connection.
16. The system of claim 15 , wherein the housing contains a reservoir filled with liquid medicament, the reservoir arranged such that the liquid medicament is in contact with an inner surface of the vibrating mesh.
17. The system of claim 16 , wherein the reservoir is in fluid communication with a liquid feed line comprising micro-bore tubing.
18. The system of claim 17 , wherein at least one of the liquid feed line or the wires is threaded through the first inlet tube or the second inlet tube of the nasal cannula.
19. The system of claim 1 , wherein the first and second inlet tubes are each coupled to a supply tube for fluidic communication with a source of breathing gas.