Respiratory assistance apparatus

1. A head-mounted respiratory assistance apparatus configured to provide a respiratory gases stream to a user, comprising:

a main body securable to the head of a user;

a blower unit provided on the main body having a gases inlet to receive a supply of gases from the surrounding atmosphere and which is operable to generate a pressurised gases stream at a gases outlet, wherein the blower unit comprises a casing and wherein the gases outlet extends radially outward from a center of the casing; and

a patient interface provided on the main body having a gases inlet which is fluidly connected via a gases flow path to the gases outlet of the blower unit and which is configured to deliver the pressurised gases to the user's nose and/or mouth via one or more gases outlets,

wherein the gases flow path from the gases inlet of the blower unit to the gases outlet(s) of the patient interface is substantially sealed such that there is zero bias flow along the gases flow path, and

wherein the blower unit comprises a lightweight shroudless impeller, wherein the impeller comprises a plurality of separated impeller blades extending outward from a central hub of the impeller, and a motor with a rotatable drive shaft that is configured to rotate the impeller.

2. The head-mounted respiratory assistance apparatus according to claim 1 wherein the apparatus is configured to passively humidify and warm the pressurised respiratory gases in the gases flow path via accumulated heat and moisture build up within at least a portion of the gases flow path.

3. The head-mounted respiratory assistance apparatus according to claim 2 wherein the gases flow path is configured to accumulate heat and moisture build-up within at least a portion of the air flow path from exhaled gases from the user flowing back into the gases flow path from the patient interface.

4. The head-mounted respiratory assistance apparatus according to claim 2 further comprising one or more heat and moisture exchangers (HMEs) in the gases flow path of the respiratory assistance apparatus.

5. The head-mounted respiratory assistance apparatus according to claim 1 wherein the gases flow path volume between the gases inlet of the blower unit and the gases outlet(s) of the patient interface is less than approximately 200 mL.

6. The head-mounted respiratory assistance apparatus according to claim 5 wherein the gases flow path volume between the gases inlet of the blower unit and the gases outlet of the patient interface is in the range of approximately 50 mL to approximately 150 mL.

7. The head-mounted respiratory assistance apparatus according to claim 1 wherein the casing of the blower unit comprises upper and lower internal surfaces that enclose the impeller, and wherein the impeller has a plurality of blades that are substantially open to the upper and lower internal surfaces of the casing by virtue of being shroudless or otherwise having reduced material.

8. The head-mounted respiratory assistance apparatus according to claim 7 wherein the blower unit further comprises a partition to define first and second interior regions within the casing, the first region being defined by the casing and the partition and comprising the gases inlet and motor, the second region being defined by the casing and the partition and comprising the impeller, and wherein the first and second regions are fluidly connected by an opening formed in or by the partition.

9. The head-mounted respiratory assistance apparatus according to claim 8 wherein the impeller has an axis of rotation, the partition extending radially from the axis of rotation.

10. The head-mounted respiratory assistance apparatus according to claim 8 wherein the casing further comprises a volute that is fluidly connected to the second region by an air passage, and wherein the gases outlet of the blower unit is proximate the periphery of the volute.

11. The head-mounted respiratory assistance apparatus according to claim 1 wherein the motor of the blower unit comprises: a stator, and at least one bearing structure to support the rotatable drive shaft within the stator, the bearing structure comprising one or more bearings that are supported by one or more bearing mounts about an axis of the rotatable drive shaft.

12. The head-mounted respiratory assistance apparatus according to claim 11 wherein the stator comprises a stator frame, and an outer portion of the one or more bearing mounts engages the stator and/or an inner surface of the stator frame.

13. The head-mounted respiratory assistance apparatus according to claim 12 wherein the one or more bearing mounts are flexible and/or resilient, and wherein the one or more bearing mounts have a curved annular body and when engaged with the stator and/or stator frame, the annular body is coerced into an engaged configuration that provides preload to the one or more bearings.

14. The head-mounted respiratory assistance apparatus according to claim 11 wherein the blower unit further comprises a motor mount that couples the stator and the casing to provide compliant support to the motor.

15. The head-mounted respiratory assistance apparatus according to claim 11 wherein the rotatable drive shaft is plastic.

16. The head-mounted respiratory assistance apparatus according to claim 15 wherein the motor further comprises a rotor within the stator, and wherein the plastic rotatable drive shaft is formed and coupled to the rotor by injection moulding.

17. The head-mounted respiratory assistance apparatus according to claim 1 wherein the gases inlet of the patient interface is fluidly connected to a tubular connector of the gases outlet of the blower unit.

18. The head-mounted respiratory assistance apparatus according to claim 1 wherein the gases outlet of the blower unit comprises an outlet aperture that extends radially outward from the center of the casing and extends outwardly from a peripheral wall of the casing.

19. The head-mounted respiratory assistance apparatus according to claim 1 wherein a surface of each of the plurality of separated impeller blades is parallel to an axis of rotation of the impeller.

20. The head-mounted respiratory assistance apparatus according to claim 1 wherein each of the plurality of separated impeller blades comprises a forward swept blade tip.