Variable throat jet venturi
A variable throat jet venturi for delivering ventilation gas to a patient includes a jet nozzle, a deformable throat body arranged to receive ventilation gas output by the jet nozzle and defining a gas inlet and a gas outlet, and a housing containing the deformable throat body. The housing may define an entrainment opening which is open to ambient air and a pilot pressure port for pressurizing a plenum between an outer wall of the deformable throat body and an inner wall of the housing. A pilot pressure line may be fluidly coupled to the pilot pressure port. A controller may be programmed to energize the pilot pressure line to constrict the deformable throat body during an exhalation phase of positive end-expiratory pressure (PEEP) therapy.
1. A variable throat jet venturi for delivering ventilation gas to a patient, the variable throat jet venturi comprising:
a jet nozzle;
a deformable throat body arranged to receive ventilation gas output by the jet nozzle and defining a gas inlet and a gas outlet; and
a housing containing the deformable throat body, the housing defining a pilot pressure port for pressurizing a plenum between an outer wall of the deformable throat body and an inner wall of the housing, the housing having a portion that flares outwardly away from the plenum and defines an entrainment opening which is arranged to draw ambient air directly therein, wherein the deformable throat body is arranged to receive the ventilation gas output by the jet nozzle through the entrainment opening of the housing.
2. The variable throat jet venturi of claim 1 , wherein a distal tip of the jet nozzle is outside the entrainment opening.
3. The variable throat jet venturi of claim 1 , wherein, with the plenum in a first pressurization state, the variable throat jet venturi achieves a shutoff pressure P shutoff at the gas outlet of at least 55 cmH 2 O at a jet nozzle pressure P n of 10.5 psig and a jet nozzle flow V′ n equal to or less than 30 slpm and, with the plenum in a second pressurization state, the variable throat jet venturi achieves a gas outlet pressure P aw of 10 cmH 2 O at a jet nozzle flow V′ n of less than 10 slpm.
4. The variable throat jet venturi of claim 3 , wherein, with the plenum in the second pressurization state, the variable throat jet venturi achieves a gas outlet pressure P aw of 10 cmH 2 O at a jet nozzle flow V′ n of less than 5 slpm.
5. The variable throat jet venturi of claim 3 , wherein, with the plenum in the first pressurization state, a ratio A t /A n of a cross-sectional area of the deformable throat body to a cross-sectional area of the jet nozzle is between 20 and 30 and, with the plenum in the second pressurization state, the ratio A t /A n is between 2.0 and 5.0.
6. A patient ventilation interface comprising:
the variable throat jet venturi of claim 1 ; and
a nasal coupler for fluidly coupling the gas outlet of the deformable throat body to a nostril of the patient.
7. The patient ventilation interface of claim 6 , wherein the nasal coupler comprises a nasal pillow.
8. A non-invasive ventilation system comprising:
the patient ventilation interface of claim 6 ; and
a pilot pressure line fluidly coupled to the pilot pressure port.
9. The non-invasive ventilation system of claim 8 , further comprising a controller programmed to energize the pilot pressure line to constrict the deformable throat body during an exhalation phase of positive end-expiratory pressure (PEEP) therapy.
10. The non-invasive ventilation system of claim 8 , further comprising a multi-lumen tube having a ventilation gas lumen terminating in the jet nozzle and a pilot pressure lumen in fluid communication with the pilot pressure line.
11. A method of varying a ratio between a throat diameter and a jet nozzle diameter of a variable throat jet venturi for delivering ventilation gas to a patient, the method comprising:
providing a deformable throat body arranged to receive ventilation gas output by a jet nozzle, the deformable throat body defining a gas inlet and a gas outlet; and
pressurizing a plenum between an outer wall of the throat body and an inner wall of a housing containing the deformable throat body to constrict the deformable throat body, the housing having a portion that flares outwardly away from the plenum and defines an entrainment opening which is arranged to draw ambient air directly therein, wherein the deformable throat body is arranged to receive the ventilation gas output by the jet nozzle through the entrainment opening of the housing.
12. The method of claim 11 , wherein said pressurizing the plenum includes energizing a pilot pressure line fluidly coupled to a pilot pressure port defined by the housing.
13. The method of claim 12 , wherein said energizing is performed during an exhalation phase of positive end-expiratory pressure (PEEP) therapy.
14. The method of claim 11 , wherein said pressurizing comprises pressurizing the plenum from a first pressurization state, in which the variable throat jet venturi achieves a shutoff pressure P shutoff at the gas outlet of at least 55 cmH 2 O at a jet nozzle pressure P n of 10.5 psig and a jet nozzle flow V′ n equal to or less than 30 slpm, to a second pressurization state, in which the variable throat jet venturi achieves a gas outlet pressure P aw of 10 cmH 2 O at a jet nozzle flow V′ n of less than 10 slpm.
15. The method of claim 14 , wherein, with the plenum in the second pressurization state, the variable throat jet venturi achieves a gas outlet pressure P aw of 10 cmH 2 O at a jet nozzle flow V′ n of less than 5 slpm.
16. The method of claim 14 , wherein, with the plenum in the first pressurization state, a ratio A t /A n of a cross-sectional area of the deformable throat body to a cross-sectional area of the jet nozzle is between 20 and 30 and, with the plenum in the second pressurization state, the ratio A t /A n is between 2.0 and 5.0.
17. A variable throat jet venturi for delivering ventilation gas to a patient, the variable throat jet venturi comprising:
a jet nozzle;
a deformable throat body arranged to receive ventilation gas output by the jet nozzle and defining a gas inlet and a gas outlet; and
a housing containing the deformable throat body, the housing defining a pilot pressure port for pressurizing a plenum between an outer wall of the deformable throat body and an inner wall of the housing, the housing having a portion that flares outwardly away from the plenum and defines an entrainment opening which is arranged to draw ambient air directly therein, wherein the deformable throat body is arranged to receive the ventilation gas output by the jet nozzle through the entrainment opening of the housing.
18. The variable throat jet venturi of claim 17 , wherein, with the plenum in a first pressurization state, the variable throat jet venturi achieves a shutoff pressure P shutoff at the gas outlet of at least 55 cmH 2 O at a jet nozzle pressure P n of 10.5 psig and a jet nozzle flow V′ n equal to or less than 30 slpm and, with the plenum in a second pressurization state, the variable throat jet venturi achieves a gas outlet pressure P aw of 10 cmH 2 O at a jet nozzle flow V′ n of less than 10 slpm.
19. The variable throat jet venturi of claim 18 , wherein, with the plenum in the second pressurization state, the variable throat jet venturi achieves a gas outlet pressure P aw of 10 cmH 2 O at a jet nozzle flow V′ n of less than 5 slpm.
20. The variable throat jet venturi of claim 18 , wherein, with the plenum in the first pressurization state, a ratio A t /A n of a cross-sectional area of the deformable throat body to a cross-sectional area of the jet nozzle is between 20 and 30 and, with the plenum in the second pressurization state, the ratio A t /A n is between 2.0 and 5.0.