Carbon dioxide detector

A carbon dioxide detector for determining the correct location of an endotracheal tube following intubation of a patient. The detector includes a housing with a first tubular member for connection to a endotracheal tube or the like, a second tubular member for connection to an anaesthetic circuit and an indicator to indicate the presence of carbon dioxide in the detector. Preferably the indicator is in the form of a transparent disc which sealingly engages an aperture in the housing, the disc having a chemical substance which provides a colour change indication when exposed to carbon dioxide from a patient.

FIELD OF THE INVENTION 
This invention relates to CO.sub.2 detectors and specifically to a form of 
a detector which can be used in combination with intubation of a patient 
by an endotracheal tube to determine whether proper insertion has been 
made. 
BACKGROUND OF THE INVENTION 
In surgery, as well as in situations where paramedic personnel are 
involved, it is commonly necessary to introduce an endotracheal tube into 
a patient to intubate the trachea and permit the passage of air into and 
out of the lungs of a patient, thereby aiding in or permitting 
respiration. During intubation, it is necessary to ascertain that the tube 
has been properly inserted and has been introduced into the trachea and 
not into the esophagus. 
Paramedics and medical personnel who intubate only occasionally may not be 
successful in entering the trachea one hundred percent of the time even 
during visual intubations. Should blind intubation be performed either 
nasally or orally with the aid of an airway intubator, then the 
practitioner needs every aid possible to ascertain the correct location of 
the endotracheal tube. If the tube is in the esophagus there is no return 
of CO.sub.2 and if it is in the trachea, CO.sub.2 will be present up to 
about 5% concentration. 
There are several conventional methods of diagnosing the correct placement 
of an endotracheal tube, such as listening to both sides of the patient's 
chest with a stethoscope; listening to the abdomen of the patient for air 
entering the stomach; pressing on the patient's chest and feeling the air 
coming up the endotracheal tube; seeing condensation on a transparent 
tube; using quantitive analyzers; and cyanosis during I.P.P.V. with an 
enlarging distended abdomem (Late sign). 
Quantitive analyzers provide accurate readings of the carbon dioxide level 
but they are expensive and bulky for a practitioner to carry around 
especially when all that is required is an indication as to whether or not 
CO.sub.2 is present. 
SUMMARY OF THE INVENTION 
The present invention provides a device to aid practitioners to quickly 
ascertain the correct location of an endotracheal tube following 
intubation, a device that will, in one breath of the patient, facilitate 
the diagnosis of accurate endotracheal tube location. 
Essential areas for the use of the present invention are operating rooms, 
emergency rooms, pediatric intensive care areas and areas involved with 
infant resuscitation. 
According to a broad aspect, the invention relates to a carbon dioxide 
detector for use with an endotracheal tube or the like or an anaesthetic 
circuit. The detector comprises a housing having a first tubular member 
for connection to an endotracheal tube or the like, second tubular member 
for connection to the anaesthetic circuit, and means for indicating the 
presence of carbon dioxide in the detector consisting of an aperture in 
the housing and transparent disc means for sealingly engaging the 
aperture. The disc means includes a chemical substance which provides a 
colour change indication when exposed to carbon dioxide in the housing. 
Following intubation of a patient, the detector is added to the anaesthetic 
circuit and one expiration by the patient will instantaneously change the 
colour of the chemical substance, readily identifying that the trachea has 
been properly intubated, especially in conjunction with other signs. 
Preferably, the connector has a right-angled configuration so that it can 
fit directly on to the end of an endotracheal tube and the clinician can 
then look directly down at the indicator disc changing in colour. 
One push of the chest of a patient who is not breathing will be sufficient 
to change the colour of the indicator and if the patient is breathing 
spontaneously then one expiration is adequate to effect the change. 
One form of chemical substance which can be used with this invention is 
Hydrazine salt, the indicator being a Gentian violet. The discs can 
contain Litmus paper type material or can be in powder form with a filter 
on each side thereof. The chemical can also be attached to a transparent 
disc with a sticky spray or the connector can be a removable disc sealed 
in an inert atmosphere with the indicator being exposed by removing a 
sticky metallic flap. The disc is then snapped on to the unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawing, a carbon dioxide detector indicated generally at 
10 is adapted for use with an endotracheal tube 12 or in an anaesthetic 
circuit encorporating a conduit 14. The detector 10 comprises a housing 
16, preferably of cylindrical configuration, and having a tubular opening 
18 at one end thereof for a slip-on or snap-on connection to the upper end 
of the endotracheal tube 12. A second tubular member 20 extends outwardly 
from the housing 16 and is adapted to connect the housing into an 
anaesthetic circuit incorporating the conduit 14. 
An end wall 22 of the housing 16 is provided with an aperture 24 having a 
flange or collar 26 which is adapted to receive a disc 28 in a 
snap-on/snap-off arrangement. The disc 28 is composed of a rim 30 with a 
transparent surface 32 providing visual indication of a chemical substance 
34 within the disc. 
The discs may be attached by a thread of plastic or the like 36 to a 
suitable form of connection such as a ring 38 which is connected to or 
integral with the tubular member 20. 
The discs are sealed in an inert atmosphere and the chemical indicator 34 
is exposed by removing a sticky metallic flap 40 (as on disc 28a) and the 
disc is then snapped on to the collar 26 of the aperture 24. 
In operation, the endotracheal tube 12 is connected to the housing 16 via 
the aperture 18 and the tubular member 20 is connected to the anaesthetic 
circuit via the conduit 14. The metallic flap 40 is peeled away from one 
side of the disc and the disc 28 is snapped on to the collar 26 of the 
housing. 
If the endotracheal tube 12 has been inserted into the patient, carbon 
dioxide which is present in the patient's trachea will be immediately 
detected and indicated by the colour change in the chemical substance 34. 
For example, using Hydrazine, the Gentian violet indicator will 
immediately turn blue thus providing the clinician with a quick indication 
that the tube 12 has been properly inserted in the trachea. 
While the present invention has been described in connection with a 
specific embodiment thereof and in a specific use, various modifications 
will occur to those skilled in the art without departing from the spirit 
and scope of the invention as set forth in the appended claims. 
The terms and expressions used in this specification are used as terms of 
description and not of limitation and there is no intention in the use of 
such terms and expressions to exclude any equivalents of the features 
shown and described or portions thereof but it is recognized that various 
modifications are possible within the scope of the invention claimed.