Portable single patient use carbon dioxide detector

This invention relates to carbon dioxide (CO 2 ) detectors. More particularly, it refers to a device containing CO 2 calorimetric indicator paper, the device attached to an endotracheal tube for detecting CO 2 levels in the breath of a patient following intubation.

U.S. Pat. No. 4,691,701 describes an early portable CO 2 detector in the form of a transparent disc containing a chemical substance exhibiting a color change indication when exposed to carbon dioxide from a patient.

U.S. Pat. Nos. 5,197,464 and 5,291,879 describe methods of monitoring CO 2 levels in a patient using a reversible indicator solution so that the indicator changes color continuously with the breathing of a patient.

Other references that include references to CO 2 color change devices are U.S. Pat. Nos. 4,790,327; 4,928,687; 4,994,117; 5,005,572; 5,166,075; 5,179,002; 5,846,836 and 5,965,061.

A critical step in the intubation of a patient is a determination that the breathing tube or intubation tube or endotracheal tube is placed in the trachea and not in the esophagus. If the tube is in the esophagus, there is no return of CO 2 from a patient's breath. If the tube is in the trachea, CO 2 will be present up to about five percent concentration. Since it is common in emergency situations for less highly skilled technicians to apply endotracheal tubes attached to a cardiopulmonary resuscitator (CPR) to a patient's airway, it is important to have a portable single patient breathing apparatus such as a CPR containing a device confirming the proper initial placement and continuous placement of the endotracheal tube. A CO 2 detector communicating with a CPR bag apparatus serves this purpose. Although such detector's exist, alternate detectors which provide ease of use, low cost and connection to existing CPR apparatus is needed.

The invention described herein is an improvement over prior CO 2 detectors used with CPR bags to ventilate patients. This CO 2 detector has an easily mountable colorimetric indicator paper that continues to change color over several days in response to a patient's exhaled breath. It is easily mountable in communication with a CPR bag, is lightweight and gives easily readable and reliable CO 2 detection.

The inventive CO 2 detector has a top housing integral with an inhale/exhale port. This port is connected to a CPR bag. A clear plastic disc is mounted to the top housing. The clear plastic disc is integral with a disc support containing snap legs engageable to complimentary grooves on the circumference of a bore through the top housing. Indicator paper is mounted on the inside surface of the plastic disc. Backing paper on the indicator paper is removed by pulling on the backing paper protruding from a slot below the disc. A bottom housing is glued or heat welded to the housing cover after a filter and baffle are mounted between the top housing and the bottom housing containing a downwardly directed port. This bottom housing port is connected to an intubation tube leading to a patient's trachea. Provided the tube is properly placed, the breath of the patient will cause a color change on the calorimetric indicator paper viewed through the clear plastic cover of the CO 2 detector of this invention.

The invention can be best understood by those having ordinary skill in the art of patient intubation by following the detailed description when considered in conjunction with the accompanying drawings in which:

FIG. 1 is an exploded view in perspective of the indicator paper being affixed to a bottom surface of a disc for the CO 2 detector of the invention.

FIG. 2 is a perspective view of the indicator paper backing prior to insertion in a slot on a disc support.

FIG. 3 is a perspective view of the indicator paper backing inserted into the slot on the disc support.

FIG. 4 is an exploded view in perspective of the components in the top housing of the CO 2 detector.

FIG. 5 is an exploded view in perspective of the components included in the bottom housing of the CO 2 detector.

FIG. 6 is an exploded view of components of the CO 2 detector.

FIG. 7 is a bottom plan view of the baffle shown in FIG. 6 .

FIG. 8 is a perspective view of the CO 2 detector.

FIG. 9 is an elevational view in section of the CO 2 detector of FIG. 8 along line 9 — 9 .

FIG. 10 is an elevational view in section showing the route of a patient's breath through the CO 2 detector.

FIG. 11 is an elevational view in section showing the route of air flow from a CPR bag going to the patient through the CO 2 detector.

Throughout the following detailed description, the same reference numerals refer to the same elements in all figures.

The CO 2 detector 10 of this invention shown in FIG. 8 has several principal components as shown in FIG. 6 . The detector 10 has a bottom housing 12 , a filter 14 resting on ridges 16 integral with a top surface of a floor 17 of the bottom housing 12 . On top of filter 14 is a baffle 18 containing multiple air holes 20 and an air flow guide 22 on a top surface 21 of baffle 18 . A top housing 24 contains an integral inhale/exhale port 26 . Also attached to the top housing 24 is a clear plastic disc 28 overlaying a calorimetric indicator paper covered by backing paper 32 .

Referring to FIGS. 1-3, the CO 2 calorimetric indicator paper 30 , employed in this invention, is affixed to a bottom surface 42 of disc 28 . Disc 28 is integral with a disc support 36 . The disc support 36 has multiple snap legs 38 and a slot 40 for receiving and subsequently removing a backing paper 32 . The colorimetric CO 2 indicator paper 30 comes covered on a top surface by the paper backing 32 and on a bottom surface by a paper backing 34 . Initially, the paper backing 34 is removed so that an adhesive on the bottom surface of the colorimetric CO 2 indicator paper 30 can be stuck to a bottom surface 42 of disc 28 . As seen in FIG. 2, the paper backing 32 is folded down and passed through slot 40 as shown in FIG. 3 . When the indicator paper is ready for use, the paper backing 32 protruding from slot 40 is pulled out to expose the bottom surface of the indicator paper 30 .

As seen in FIG. 4, the clear plastic disc 28 loaded with the indicator paper and its backing paper 32 is engaged over a disc support lock 46 in top housing cover 24 . The pliable sealing ring 44 is interposed between the disc 28 outer edge and the outer edge of the disc support lock 46 . Sealing ring 44 seals slot 40 after the backing paper 32 is pulled out to expose indicator paper 30 .

The CO 2 detector is assembled as shown in FIGS. 5-6. The bottom housing 12 contains an aperture 52 and ridges 16 . An O-ring 50 is placed around the edge of aperture 52 and a port 48 is then dropped in above the O-ring so that top annular edge 56 of the port 48 rests on the O-ring 50 . A retaining ring 54 snaps into groove 80 in the port 48 as the port 48 seats in aperture 52 . The filter 14 is then laid over the ridges 16 . Ridges 23 shown in FIG. 7, on the bottom surface 25 of the baffle 18 is placed over filter 14 . The top housing 24 containing the inhale/exhale port 26 and the clear plastic disc 28 is then snap fit, glued or heat welded along edge 58 to surface 60 on the bottom housing. Ridges 16 on the bottom housing floor 17 and ridges 23 from the bottom surface 25 of baffle 18 hold the filter 14 in position.

As shown in FIG. 9, the top housing 24 has a skirt 62 that rests on the top surface of baffle 18 and a skirt 64 on baffle 18 rests on the filter 14 .

As shown in FIGS. 8 and 10, the rotatable port 48 which is attached to an intubation tube 70 leads to a patient's trachea, not shown. As the patient breathes out, CO 2 gas is expelled as shown in FIG. 10 through the port 48 and through the CO 2 detector 10 . As the air passes by the calorimetric indicator paper 30 , it causes the paper to change color indicating-that up to five percent of the breath contains CO 2 . The breath passes out through port 26 and through a CPR bag patient port 72 . When the CPR apparatus 68 expels air or oxygen, the air or oxygen passes down as shown in FIG. 11 through the port 26 , passes by the indicator paper 30 to change its color once again, with the air or oxygen then passing out through port 48 and then through an intubation tube 70 to the patient's trachea. If the intubation tube 70 is not located in the trachea but has been improperly placed or ends up some how in the esophagus then the patient's breath, as shown in FIG. 10, will not contain higher than ambient CO 2 and will not change the color of the indicator paper 30 . This is an indication that the intubation tube 70 is in the wrong position in the patient's body and should be immediately changed to place it properly into the trachea.

The components of the invention are made of plastic with the disc made of clear plastic. The remaining components may or may not be made out of the clear plastic. The filter paper is commercial grade obtained from 3M Corporation identified as FILTRETE®. The indicator paper backing 32 and 34 can be any acceptable commercial grade backing paper with a calorimetric indicator 30 such as described in U.S. Pat. Nos. 5,005,572 and 5,965,061, incorporated herein by reference.

The above description has described specific structural details of the CO 2 detector of this invention. However, it will be within one having ordinary skill in the art to make modifications without departing from the spirit and scope of the underlying invention's inventive concept. The inventive concept is not limited to the structure described, but includes such modifications as would be considered equivalent.