Fan assembly for a rebreathe system

1. A rebreathe system for pulmonary function testing, comprising:

a breathing valve assembly configured to be fluidly coupled to a patient;

a flow control assembly coupled to the breathing valve assembly, the flow control assembly comprising an expire-only valve and an inspire-only valve, wherein when a rebreathe test is active, a gas exhaled by the patient flows out only through the expire-only valve and gas inhaled by the patient is provided only through the inspire-only valve;

a reservoir coupled to the expire-only valve and configured to receive the exhaled gas from the expire-only valve;

a carbon dioxide absorber comprising an outlet coupled only to the inspire-only valve of the flow control assembly and an inlet; and

a circulation system, comprising:

a base comprising a motor coupled to a first magnetic coupling plate; and

a fan assembly coupled to the base and comprising:

a housing comprising an inlet coupled to the reservoir and an outlet coupled to the inlet of the absorber;

a fan disposed within the housing and fluidly isolated from the motor; and

a second magnetic coupling plate fixedly coupled to the fan and magnetically coupled to the first magnetic coupling plate, wherein operation of the motor rotates the fan so as to pull the exhaled gas from the reservoir and push the exhaled gas through the absorber.

2. The rebreathe system of claim 1 , wherein the fan is a centrifugal fan.

3. The rebreathe system of claim 1 , wherein a bottom of the housing is positioned between the first magnetic coupling plate and the second magnetic coupling plate.

4. The rebreathe system of claim 1 , wherein the base includes a top plate defining an opening configured to accommodate the second magnetic coupling plate, the bottom covering the opening.

5. The rebreathe system of claim 1 , wherein the fan assembly further includes a central shaft, the fan being rotatable about the central shaft.

6. The rebreathe system of claim 5 , wherein the fan assembly further includes at least one bearing coupled to the housing and the central shaft such that the central shaft rotates within the bearing.

7. The rebreathe system of claim 1 , wherein the reservoir comprises a bag for storing exhaled gas.

8. A method of performing a pulmonary function test, the method comprising the steps of:

receiving exhaled gas from a patient through an expire-only valve and into a reservoir; and

operating a circulation system to draw the exhaled gas from the reservoir and push the exhaled gas through a carbon dioxide absorber, through an inspire-only valve, and directly to the patient, the circulation system comprising a base comprising a motor and a fan assembly comprising a housing, a fan disposed within the housing and fixedly coupled to a first magnetic coupling plate and the motor fixedly coupled to a second magnetic coupling plate that is magnetically coupled to the first magnetic coupling plate, such that, upon operation of the motor, the fan rotates.

9. The method of claim 8 , wherein the fan is a centrifugal fan.

10. The method of claim 8 , wherein a bottom of the housing is positioned between the first magnetic coupling plate and the second magnetic coupling plate.

11. The method of claim 8 , wherein the base includes a top plate defining an opening configured to accommodate the second magnetic coupling plate, the bottom covering the opening.

12. The method of claim 8 , wherein the fan assembly further includes a central shaft, the fan being rotatable about the central shaft.

13. The method of claim 12 , wherein the fan assembly further includes at least one bearing coupled to the housing and the central shaft such that the central shaft rotates within the bearing.

14. The method of claim 8 , wherein the reservoir comprises a bag for storing exhaled gas.