Method and system with divided cannula having low oxygen flow rate and improved end-tidal CO2 measurement
Inventors
Assignees
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Publication Number
US-9814854-B2
Publication Date
2017-11-14
Expiration Date
Abstract
A nasal cannula having a face piece including first and second nares which each communicate with a respective nostril of a patient. A septum divides the face piece into first and second flow paths such that the first flow path communicates with the first nare and the second flow path communicates with the second nare. A leading end of the first nare is configured to form a fluid barrier within a first nostril and facilitate only supplying an insufflation gas, via the first flow path, to the patient and prevent exhausting any exhaust gas, of the patient, through the first nostril. A leading end of the second nare is configured to facilitate collecting some of the exhaust gas, from the patient, via the second flow path as well as exhausting a remainder of the exhaust gas out through a second nostril of the patient.
Core Innovation
The invention relates to a divided nasal cannula that separates insufflation and sampling into first and second flow paths for first and second nares. A septum divides an elongate face piece into the first and second flow paths so that the first flow path communicates with a first nare and the second flow path communicates with a second nare.
In the first flow path, a leading end of the first nare includes a peripherally extending sealing member adapted to engage adjacent tissue of a nasal passage of a first nostril to form a fluid barrier within the first nostril. This fluid barrier facilitates only supplying an insufflation gas via the first flow path and prevents exhausting any exhaust gas past the fluid barrier, the first nare, and the peripherally extending sealing member, including where the sealing member is integrally formed as a single piece from a same material.
In the second flow path, a leading end of the second nare is configured to collect some of the exhaust gas via the second flow path and exhaust a remainder out through the second nostril. The second nostril is further configured as a dedicated sampling location for end-tidal carbon dioxide measurement, with described variations including dedicated sampling openings formed in sidewalls and sizing constraints intended to keep the sampling nare open.
Claims Coverage
Independent claims are clm-00001, clm-00018, and clm-00020. Across these independent claims, the central claim coverage centers on a divided face piece with first and second flow paths, a sealing member forming a fluid barrier in an insufflation nare to prevent exhaust gas passage, and a second nare configured to collect exhaust gas for sampling end-tidal CO2 measurement, with additional structural and connection features in clm-00018 and a method for improving measurement in clm-00020.
Fluid barrier forming peripherally extending sealing member in first nare to prevent exhaust gas
A leading end of the first nare comprises a peripherally extending sealing member adapted to engage adjacent tissue of a nasal passage of the first nostril to form a fluid barrier within the first nostril to facilitate only supplying an insufflation gas via the first flow path and prevent exhausting any exhaust gas past the fluid barrier, the first nare and the peripherally extending sealing member, the first nare being integrally formed as a single piece from a same material.
Divided face piece with septum defining first and second flow paths
An elongate face piece comprising first and second nares and a septum dividing the face piece into first and second flow paths such that the first flow path communicates with the first nare and the second flow path communicates with the second nare.
Second nare configured to collect exhaust gas and exhaust remainder through second nostril
A leading end of the second nare being configured to facilitate collecting some of the exhaust gas via the second flow path as well as exhausting a remainder of the exhaust gas out through the second nostril.
Dedicated oxygen supply and end-tidal CO2 detection tube connections
A first opening formed in a first end of the face piece while a second opening is formed in an opposite second end of the face piece, with an oxygen supply tube connected to the first opening and an end-tidal CO2 detection tube connected to the second opening, the oxygen supply tube being connected to a source of an oxygen gas and the end-tidal CO2 detection tube being connected to a carbon dioxide monitoring device.
Method dedicating first nostril for insufflation and second nostril for exhaling and sampling end tidal CO2
Dedicating the first nostril of the patient for solely supplying the insufflation gas and preventing exhausting any exhaust gas past the fluid barrier, and dedicating the second nostril of the patient for solely exhaling gas and sampling the end tidal CO2 gas via the second nare.
Sidewall opening permitting accumulation and reentry of insufflating gas
At least one opening being formed in a sidewall of the first nare and axially located between the radially extending sealing member and another end of the first nare opposite the leading end, wherein the at least one opening permits the insufflating gas to collect and accumulate temporarily in a nasal region closely surrounding and adjacent the first nare, and reenter into the first nare through the at least one opening and be inhaled by the patient during inhalation.
One-way valve behavior for the first nare
A one-way valve of the first nare permitting insufflating gas to pass when open and preventing exhausting of exhaust gas when closed.
Inlet-side opening constraint for second nare to reduce occlusion
An opening configuration intended to prevent an undesirable level of suction from developing and drawing nasal tissue to occlude the inlet of the second nare.
The independent claims collectively cover a divided nasal cannula with a septum-defined first and second flow path, a sealing member forming a fluid barrier in the insufflation nare to prevent exhaust gas passage, and a second nare configured to collect exhaust gas while exhausting remainder for sampling end-tidal CO2 measurement. Additional coverage includes dedicated tube connections for oxygen supply and carbon dioxide monitoring, structural features affecting gas accumulation and reentry, and dedicated method steps dedicating each nostril for insufflation versus exhalation and sampling.
Stated Advantages
Improved dissolved oxygen delivery at reduced oxygen flow (down to ~3 L/min), as described in the document summary.
Less dilution of exhaled gases for more accurate end-tidal CO2, reported as ~35–38 mmHg versus 40 mmHg in the document summary.
Documented Applications
End-tidal CO2 measurement using a divided nasal cannula that collects exhaust gas via a second nare while supplying insufflation gas via a first nare, including tube connections to a carbon dioxide monitoring device.
Using a divided cannula to dedicate a first nostril for insufflation and a second nostril for exhaling and sampling end-tidal CO2 gas to improve measurement.
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