Warning apparatus for a tracheotomy tube

The present invention pertains to an apparatus for maintaining and monitoring a breathing passage in the trachea of a patient. The apparatus is comprised of a tracheotomy tube for fitting into the trachea. The apparatus is also comprised of means for warning when the tracheotomy tube become obstructed to air flow. In a preferred embodiment, the warning means includes a sensor in contact with the tracheotomy tube for sensing when the tracheotomy tube becomes obstructed. In a more preferred embodiment, the sensor includes at least one temperature sensor disposed such that the temperature of the air in the tracheotomy tube is sensed and produces the temperature sensor signal corresponding to the air temperature in the tracheotomy tube. The temperature sensor is in electrical connection with an alarm which indicates when the tube is obstructed. In another embodiment, the sensor includes a capacitor disposed in the tracheotomy tube such that the capacitance of the capacitor corresponds to the percent occlusion of the tube when obstructed.

FIELD OF THE INVENTION 
The present invention is related to tracheotomy tubes. More specifically, 
the present invention relates to tracheotomy tubes which provide a warning 
when the tube becomes obstructed. 
BACKGROUND OF THE INVENTION 
Today, tracheotomy is one of the more commonly performed procedures in 
otolaryngology and head and neck surgery. 
Currently, a tracheotomy is performed for a variety of indications. The 
most common of these is airway obstruction, which can be either acute or 
chronic. Acute airway obstruction may be due to an infectious process, or 
any deep neck space infection. 
Chronic airway obstruction is usually due to the presence of a mass, 
sometimes benign but most often malignant. 
Tracheotomy may be done either at a patient's bedside, such as in an 
intensive care setting, or in the operating room. A midline skin incision 
is made from cricoid cartilage almost down to the jugulum. The trachea is 
then entered sharply, usually at the second or third ring. The orotracheal 
tube (if present) is withdrawn, and the airway is secured with the 
tracheotomy tube. 
There are typically three parts to a traditional tracheotomy tube: an outer 
tube, an inner tube, and a stylet or obturator. A stylet or obturator is 
used to introduce the tube into the trachea. The stylet fills the end of 
the outer tube and provides a tapered point so that the advancing end does 
not tear tissue. Once the tube is in place, the stylet is withdrawn 
immediately, because while it is in place, there is no airway. The inner 
cannula is then inserted and locked in place. Gauze tapes previously 
attached to the outer tube are tied around the neck. 
After the operation, the outer tube stays in the trachea until the surgeon 
believes it is safe to remove it for cleansing and inspection of the 
wound. Ordinarily, the nurse does not remove the outer tube unless 
specifically instructed by the physician because there is sometimes 
difficulty in replacing it. The mistake is to insert the tube into the 
soft tissue of the neck other than into the lumen of the trachea. 
The inner tube is the province of the nurse. This tube fits the inside of 
the outer tube snugly, yet loosely enough that it can be removed by light 
finger traction. 
In the immediate postoperative period, the inner tube should be removed, 
inspected and cleaned every two hours. If it is not done, small amounts of 
dried blood may cause difficulty in removing the cannula. It is by 
cleansing the inner tube that the airway is maintained. Cleaning is needed 
more often in a patient whose chest is filled with secretion than in a 
patient with laryngeal obstruction but no excessive secretions. 
In a patient whose chest is filled with secretions, suctioning must be done 
frequently--as often as every five minutes. In other patients, suctioning 
every two or three hours or even once or twice a day may be all that is 
necessary. In suctioning, the aim is to aspirate all secretions that have 
accumulated in the tracheobronchial tree since the last suctioning and 
which the patient is unable to cough up himself. 
Patients may develop obstructive plugs of dried mucus in the trachea that 
actually endanger his airway unless the tracheotomy tube is removed and 
the plug pulled out. 
If the tube is coughed out, it is usually because the ties were not 
sufficiently tight or because the tube was too short. This can amount to 
an emergency if it occurs in the first few hours after tracheotomy, 
because a sufficient tract has not yet been formed between skin and 
trachea to sustain breathing. The tube must be reinserted at once. 
To date, there are no devices to monitor the patency of tracheotomy tube. 
The present invention alerts the hospital staff to a clogged or dislodged 
tube. 
SUMMARY OF THE INVENTION 
The present invention pertains to an apparatus for maintaining a breathing 
passage in the trachea of a patient. The apparatus is comprised of a 
tracheotomy tube for fitting into the trachea. The apparatus is also 
comprised of means for warning when the tracheotomy tube becomes 
obstructed to air flow. In a preferred embodiment, the warning means 
includes a sensor in contact with the tracheotomy tube for sensing when 
the tracheotomy tube becomes obstructed. In a more preferred embodiment, 
the sensor includes at least one temperature sensor disposed such that the 
temperature of the air in the tracheotomy tube is sensed and produces the 
temperature sensor signal corresponding to the air temperature in the 
tracheotomy tube. The temperature sensor is in electrical connection with 
an alarm which indicates when the tube is obstructed. In another 
embodiment, the sensor includes a capacitor disposed in the tracheotomy 
tube such that the capacitance of the capacitor corresponds to the percent 
occlusion of the tube by the obstruction.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings wherein like reference numerals refer to similar 
or identical parts throughout the several views, and more specifically to 
FIG. 1 thereof, there is shown an apparatus 10 for maintaining a breathing 
passage in the trachea 12 of a patient 14. The apparatus 10 is comprised 
of a tracheotomy tube 16 for fitting into the trachea 12. The apparatus 10 
is also comprised of means for warning when the tracheotomy tube 16 
becomes obstructed to air flow. Preferably, the warning means includes a 
sensor in contact with the tracheotomy tube 16 for sensing when the 
tracheotomy tube 16 becomes obstructed. Both apparatuses include an alarm 
means 18 in communication with the sensor and which indicates when the 
tube 16 is obstructed. 
In a first embodiment, the sensor includes at least one temperature sensor 
20 disposed such that the temperature of the air in the tracheotomy tube 
16 is sensed and produces a temperature sensor signal corresponding to the 
air temperature in the tracheotomy tube 16. The temperature sensor 20 is 
in electrical connection with the alarm means 18. In a second embodiment, 
the sensor includes a capacitor 22 disposed in the tracheotomy tube 16 
such that the capacitance of the capacitor 22 corresponds to the percent 
occlusion of the tube 16 by the obstruction. 
Preferably, the apparatus 10 includes an inner cannula 24 with the 
capacitor 22 disposed therein such that the capacitance of the capacitor 
22 corresponds to the percent occlusion of the inner cannula 24 by an 
obstruction therein. The alarm means 18 is electrically connected to the 
capacitor 22 to indicate when the inner cannula 24 is obstructed. 
In the operation of the preferred embodiment, an outer cannula 26 with an 
obturator (not shown) disposed therein is inserted into the trachea 12 of 
the patient 14. The bladder 30 not present in all tubes positioned about 
the outer cannula 26 of the trachea tube 16 is expanded to the proper 
position to anchor the tube 16 in the trachea 12 of the patient 14. 
The obturator is then removed and the inner cannula 24 is inserted into the 
outer cannula 26. Temperature sensors 20 disposed in the end 32 of the 
inner cannula 24 which extends out of patient 14 senses the temperature of 
the air passing in and out of the patient through the trachea tube 16. The 
temperature of the air which is exhaled is several degrees warmer than the 
temperature of the air inhaled in a typical hospital environment. 
A first lead 34 connected to the temperature sensors 20 is also connected 
to the first signal processing circuit 36 disposed in a housing 38 fitted 
onto the patient 14, for instance in a pocket of his or her pajamas. The 
first signal processing circuit 36 provides a processed signal to a first 
alarm circuit 40. The first alarm circuit 40, which is powered by a 
battery 42 provides an alarm signal to an audio visual alarm 44, when the 
temperature sensors 20 do not detect a change in air temperature over a 
preset time interval period. A failure in the air temperature change in 
time set can be due to dislodging of the inner cannula 24 or cessation of 
breathing patterns due to some failure in the physiology of the patient, 
or the trachea tube 16 coming out of the patient 14. 
In the portion 46 of the inner cannula 24 that is disposed in the patient 
14 there is a first plate 48 and a second plate 50 with insulation 52 
disposed therebetween, all of which are built into the inner cannula 24. 
The first plate 48 and second plate 50 together form a capacitor 22. 
Second leads 54 connected to the first plate 48 and second plate 50 extend 
out to a low frequency oscillator 56 in the housing 38. A signal from the 
oscillator 56 received by a second signal processing circuit 58 which 
processes the signal and provides it to a second alarm circuit 60. The 
alarm circuit 60 provides that signal to a display 62 which displays the 
percent occlusion of the inner cannula 24. If the percent occlusion is 
over a predetermined amount, the audio visual alarm 44 is activated. The 
display 62, second alarm circuit 60, second signal processing circuit 58 
and low frequency oscillator 56 are also powered by the batteries 42. 
If any type of discharge fills the inner cannula 24, this causes a change 
in the capacitance of the capacitor 22 due to change in the dielectric 
constant between the first plate 48 and second plate 50 in the capacitor 
22. Accordingly, the capacitance of the capacitor 22 corresponds to the 
percentage occlusion in the inner cannula 24. 
Although the invention has been described in detail in the foregoing 
embodiments for the purpose of illustration, it is to be understood that 
such detail is solely for that purpose and that variations can be made 
therein by those skilled in the art without departing from the spirit and 
scope of the invention except as it may be described by the following 
claims.