Water absorbing trap to protect an infrared exhaled carbon dioxide apnea monitor of a patient's respiration

• US 4,446,869 A
• Filed: 03/07/1983
• Issued: 05/08/1984
• Est. Priority Date: 03/07/1983
• Status: Expired due to Fees

• Current Assignee: Biochem International Incorporated W238 N1650 Rockwood Drive Waukesha Wisconsin 53186
• Original Assignee: Trimed
• Inventors: Knodle, Daniel W.
• Primary Examiner(s): Recla, Henry J.
• Application Number:
  US06/472,722
• Time in Patent Office: 428 Days
• Field of Search: 128/716-730, 128/205.24, 128/205.12, 128/205.27, 128/205.29, 128/204.18, 128/205.23, 128/204.21, 128/204.23, 128/207.18 , 128/207.14, 137/197, 137/199, 137/172, 55/387
• US Class Current: 600/529
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices
• CPC Class Codes: Y10T 137/3006 Liquids separated from liquid
• CPC Class Codes: Y10T 137/309 Fluid sensing valve

Abstract

A water trap is connected to a cannula which has a substantially constant internal diameter and which communicates moisture laden patient exhalations therethrough to an analyzer. The trap includes a body having a recess adapted for receiving a water absorbing compound which has an aperture therethrough for communicating dried exhalations to the analyzer. A second recess in the body is adapted for receiving another water adsorbing compound which similarly has an aperture of same diameter. When the first compound becomes substantially saturated and thereby permits moisture laden exhalations to pass therethrough, then the second compound absorbs those exhalations and swells for thereby closing its aperture and preventing communication of moisture laden exhalations to the analyzer.

Claims

1. A water trap in combination with a cannula means having a substantially constant pre-selected internal diameter communicating moisture laden patient exhalations to an analyzer, comprising:

(a) a body having a recess with a diameter in excess of said pre-selected diameter and with a pre-selected volume;

(b) inlet adaptor means connected to said body and including an aperture in fluid communication with said recess;

(c) said cannula means having a first end adapted to receive patient exhalations and a second end, said inlet adaptor means secured to said second end of said cannula means and for maintaining said second end internal diameter constant while secured;

(d) said aperture coaxial with said second end when secured to said inlet adaptor means and having a diameter equal to said pre-selected diameter;

(e) water absorbent means disposed in said recess and including an aperture therethrough coaxial with said inlet adaptor means aperture and having a diameter equal to said pre-selected diameter;

(f) said water absorbent means having a volume substantially equal to said pre-selected volume and adapted for drying exhalations;

(g) exit means connected to said body and including an aperture coaxial with and in fluid communication with said water absorbent means aperture; and

,

(h) an analyzer connected to said exit means, said exit means adapted for communicating dryed exhalations from said body to said analyzer.

2. A water trap as defined in claim 1, further comprising:

(a) a second recess having a pre-selected volume disposed in said body coaxial with said recess and having a diameter in excess of said pre-selected diameter;

(b) said second recess positioned intermediate said recess and said exit means and in fluid communication therewith;

(c) water activated absorbing means disposed in said second recess and including an aperture therethrough coaxial with said water absorbent means aperture and having a diameter equal to said pre-selected diameter;

(d) said water activated absorbing means having a volume substantially equal to said second recess pre-selected volume; and

,

(e) said water activated absorbing means adapted for rapidly swelling when contacted by water for closing said water activated absorbing means aperture and thereby prohibiting moisture laden exhalations to be communicated therethrough to said exit means whereby substantially complete filling of said water absorbent means causes moisture laden exhalations to be communicated therethrough into contact with said water activated absorbing means.

3. A water trap as defined in claim 2, wherein:

(a) said water activated absorbing means is a cross linked polyvinyl pyrrolidone.

4. A water trap as defined in claim 2, wherein:

(a) said water activated absorbing means is not water soluble.

5. A water trap as defined in claim 2, wherein:

(a) said water activated absorbing means is a cross linked polymer having a humidity insensitive coating.

6. A water trap as defined in claim 2, wherein:

(a) said coating consisting essentially of approximately 90% by weight polyvinyl pyrrolidone and approximately 10% by weight aryl-sulfonamide formaldehyde resin.

7. A water trap as defined in claim 2, wherein:

(a) said water activated absorbing means having a critical mass determined by the expanded mass necessary to completely close said water activated absorbing means aperture.

8. A water trap as defined in claim 1, wherein:

(a) said water absorbent means is a high density polyethylene expanded to a sufficient porosity and treated to be hydrophyllic.

9. A water trap as defined in claim 1, wherein:

(a) said water absorbent means having a minimum critical thickness along the direction of said water absorbent means aperture determined by said water absorbent means aperture surface area needed for collectively absorbing water from said exhalations.

10. A water absorbing system for patient exhalation analyzers, comprising:

(a) an analyzer;

(b) water trap means connected to said analyzer;

(c) cannula means having a first end adapted for receiving exhalations of a patient and a second end in fluid communication with said water trap means and said analyzer thereby, said cannula means first end adapted for being secured to said patient in a position for receiving exhalations;

(d) said cannula means having a constant internal diameter;

(e) said water trap means including a body having a recess with an internal diameter in excess of said cannula means internal diameter and with a pre-selected volume;

(f) inlet adaptor means connected to said body in fluid communication with said recess for securing said second end of said cannula means to said water trap means and for maintaining said cannula means second end internal diameter constant, said inlet adaptor means having an internal diameter coaxial with and equal to said cannula means second end internal diameter;

(g) water absorbent means positioned in said recess and having an aperture therethrough coaxial with and having a constant internal diameter equal to said inlet means internal diameter for drying exhalations by absorbing moisture therein, said water absorbent means having a volume substantially equal to said recess volume; and

,

(h) exit means in fluid communication with said water absorbent means aperture and said analyzer for communicating dried exhalations to said analyzer and having an internal diameter coaxial with and equal to said water absorbent means aperture internal diameter.

11. The system as defined in claim 10, further comprising:

(a) a second recess disposed in said body intermediate said recess and said exit means and having a pre-selected volume;

(b) said second recess coaxial with said recess and said exit means and in fluid communication therewith;

(c) water activated absorbing means disposed in said second recess and including an aperture therethrough coaxial with said water absorbent means aperture and having a diameter equal to said water absorbent means aperture diameter;

(d) said water activated absorbing means having a volume substantially equal to said second recess volume; and

,

(e) said water activated absorbing means adapted for rapidly swelling when contacted by water to thereby close said water activated absorbing means aperture for prohibiting moisture laden exhalations to be communicated therethrough to said analyzer whereby substantially complete filling of said water absorbent means causes moisture laden exhalations to be communicated therethrough into contact with said water activated absorbing means.

12. The system as defined in claim 11, wherein:

(a) said water activated absorbing means is a cross linked polyvinyl pyrrolidone.

13. The system as defined in claim 11, wherein:

(a) said water activated absorbing means is a cross linked polymer coated with a humidity insensitive material.

14. The system as defined in claim 13, wherein:

(a) said humidity insensitive coating consists essentially of approximately 90% by weight polyvinyl pyrrolidone and approximately 10% aryl-sulfonamide formaldehyde resin.

15. The system as defined in claim 11, wherein:

(a) said water activated aborbing means having a critical mass determined by the expanded means necessary to completely close said water activated absorbing means aperture.

16. A water trap as defined in claim 2 or 11, wherein:

(a) said recess diameter exceeds said second recess diameter; and

,

(b) said recess volume exceeds said second recess volume.

17. The system as defined in claim 10, wherein:

(a) said water absorbent means is a high density polyethylene expanded to a sufficient porosity and treated to be hydrophyllic.

18. The system as defined in claim 10, wherein:

(a) said water absorbent means having a minimum critical thickness along the direction of said water absorbent means aperture determined by said water absorbent means aperture surface area needed for collectively absorbing water from said exhalations.

19. The system as defined in claim 10, wherein:

(a) said first end of said cannula means adapted for being positioned within a nose adaptor.

20. A method of protecting an apnea monitor from the entry of water condensed from the exhaled breaths of critical patients passing through a cannula, so the apnea monitor optically sensing exhaled carbon dioxide via infrared absorption will not be diminished or stopped in its signal rendering capacity, comprising the steps of:

(a) passing the water and exhaled breaths by the sufficient surface of a water absorbing polymer to absorb all the water during a specified operating time of the apnea monitor; and

(b) also passing the exhaled breaths, leaving the water absorbing polymer, by a sufficient surface and volume of a second polymer, which, if ever water passes through the water absorbing polymer, will become quickly saturated with water to block the passage of exhaled breaths and water so they will not enter the apnea monitor.