Claims
- 1. An apparatus for introducing deadspace into a breathing circuit, comprising:
a deadspace portion of the breathing circuit located to receive gases exhaled by a patient upon positioning the breathing circuit in communication with an airway of the patient; a primary expiratory pathway through the breathing circuit; a flow restrictor positioned along said primary expiratory pathway downstream from a junction of said deadspace portion with said primary expiratory pathway; and a two-way valve positioned along or at an end of said deadspace portion, said two-way valve having:
a first, closed position for causing exhaled gases to flow through said flow restrictor; and a second, opened position for causing at least a portion of exhaled gases to flow into said deadspace portion.
- 2. The apparatus of claim 1, wherein said deadspace portion comprises at least a volume-adjustable section.
- 3. The apparatus of claim 2, wherein said volume-adjustable section is length expandable and length contractible.
- 4. A method for estimating the partial pressure of carbon dioxide in alveolar blood (PACO2) of an individual, comprising:
calculating a concentration of carbon dioxide in the parallel deadspace (PDSCO2) of an airway of the individual; and determining an end tidal partial pressure of carbon dioxide (etCO2) of the individual.
- 5. The method of claim 4, further comprising determining a perfusion ratio (r).
- 6. The method of claim 5, wherein:
- 7. The method of claim 4, wherein said calculating comprises calculating said concentration of carbon dioxide in the parallel deadspace of the individual on a breath-by-breath basis.
- 8. The method of claim 4, wherein said calculating comprises:
determining a mixed inspired volume of carbon dioxide (ViCO2) inhaled by the individual; at least estimating an airway deadspace of the individual; determining a partial pressure of end tidal carbon dioxide (etCO2) of a previous breath of the individual; and determining a tidal volume (Vt) of the individual's breathing.
- 9. The method of claim 8, wherein said calculating further comprises:
at least estimating a functional residual capacity (FRC) of alveoli of lungs of the individual.
- 10. The method of claim 9, wherein
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No. 09/767,363, filed Jan. 23, 2001, pending, which is a continuation of application Ser. No. 08/770,138, filed Dec. 19, 1996, now U.S. Pat. No. 6,306,098, issued Dec. 23, 2001.
Divisions (1)
|
Number |
Date |
Country |
Parent |
09767363 |
Jan 2001 |
US |
Child |
10657909 |
Sep 2003 |
US |
Continuations (1)
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Number |
Date |
Country |
Parent |
08770138 |
Dec 1996 |
US |
Child |
09767363 |
Jan 2001 |
US |