Nasal/oral cannula system and manufacturing
A nasal/oral cannula for collecting a flow of exhaled gases and its method of manufacture are disclosed. The cannula comprises an elongated tubular body having a first and a second end portion, a surface and an internal volume; a wall internally disposed within said tubular body, said wall defining a first subvolume of said internal volume in the lengthwise direction of the tubular body; and an inlet through said surface, for introducing exhaled gases into said first subvolume. The first end portion defines an exit port for exhaled gases from said subvolume, and said wall is arranged directly adjacent to said inlet.
1. A respiratory cannula for collecting a flow of exhaled gases, said cannula comprising:
an elongated hollow tubular body extending between a first end portion and a second end portion, the tubular body defining an internal volume;
a wall internally disposed within said tubular body, said wall defining a first subvolume of the internal volume in the lengthwise direction of the tubular body;
first and second hollow nostril prongs extending from the tubular body, one of the first and second hollow prongs comprising an inlet in fluid communication with the first subvolume of the internal volume and configured for transporting gas exhaled from the nostril of the patient to the first subvolume;
an aperture extending through said tubular body at a junction of the inlet and the internal volume;
wherein said first end portion defines an exit port for the gas from said subvolume, and
wherein said wall is arranged in immediate contact with the inlet so that no void volume for the flow of exhaled gases is created between the wall and the inlet.
2. The respiratory cannula according to claim 1 , wherein said wall is arranged within said tubular body to provide a flow path for exhaled gases from said inlet to said exit port such that essentially the entire first subvolume forms part of said flow path.
3. The respiratory cannula according to claim 1 , wherein said tubular body further comprises a length L, and said inlet is disposed at a distance of less than L/2 from said first end portion.
4. The respiratory cannula according to claim 1 , wherein said first and second hollow prongs extend substantially perpendicularly away from the tubular body.
5. The respiratory cannula according to claim 1 , wherein said tubular body further comprises a length L, and said inlet is disposed at a distance of about L/2 from said first end portion.
6. The respiratory cannula according to claim 5 , wherein a second of the first and second hollow prongs comprises an additional inlet configured as a second hole extending through said tubular body, said additional inlet disposed at a distance of less than L/2 from said first end portion.
7. The respiratory cannula according to claim 1 , wherein said tubular body further comprises a length L, and said inlet is disposed at a distance of more than L/2 from said first end portion.
8. The respiratory cannula according to claim 7 , wherein a second of the first and second hollow prongs comprises an additional inlet configured as a second hole extending through said tubular body, said additional inlet disposed at a distance of less than L/2 from said first end portion.
9. The respiratory cannula according to claim 8 , further comprising a third hollow prong extending from the tubular body and comprising a third inlet configured as a third hole extending through said tubular body, said second third inlet being arranged at a distance of about L/2 from said first end portion.
10. The respiratory cannula according to claim 1 , wherein said wall internally disposed within said tubular body further defines a second subvolume of said internal volume in the lengthwise direction of the tubular body.
11. The respiratory cannula according to claim 10 , wherein said second end portion defines an entrance port configured to allow a treating gas to enter said second subvolume.
12. The respiratory cannula according to claim 11 , wherein a second of the first and second hollow prongs comprises an outlet configured as a second hole extending through said tubular body, the outlet in fluid communication with the entrance port and configured for transferring said treating gas from said second subvolume to the patient.
13. A respiratory cannula system comprising:
a cannula comprising:
an elongated hollow tubular body extending between a first end portion and a second end portion, the tubular body defining an internal volume;
a wall internally disposed within said tubular body, said wall defining a first subvolume of the internal volume in the lengthwise direction of the tubular body;
first and second hollow nostril prongs extending from the tubular body, one of the first and second hollow prongs comprising an inlet in fluid communication with the first subvolume of the internal volume and configured for transporting gas exhaled from the nostril of the patient to the first subvolume;
an aperture extending through said tubular body at a junction of the inlet and the internal volume;
wherein said first end portion defines an exit port for the gas from said subvolume, and
wherein said wall is arranged in immediate contact with the inlet so that no void volume for the flow of exhaled gases is created between the wall and the inlet;
a first nozzle adapted for the transport of exhaled gases from the cannula, a first end of the first nozzle configured in size and shape to mate with the first end of the cannula; and
a sampling tube adapted for the transport of exhaled gases from the cannula to an analyzer, the sampling tube extending between a second end of the first nozzle and the analyzer.
14. The respiratory cannula system according to claim 13 , further comprising:
a second nozzle adapted for the supplementation of a treating gas to the cannula, a first end of the second nozzle configured in size and shape to mate with the second end of the cannula; and
a treating gas tube adapted for the transport of a treating gas from a treating gas source to the cannula, the treating gas tube extending between a second end of the second nozzle and the treating gas source.