This invention relates to medical patient monitoring instruments and, in particular, to patient monitoring instruments which protect gas ports from contamination and blockage.
Patient monitors are in widespread use in hospitals and by emergency medical personnel for monitoring the vital signs of patients. In the past these monitors have been of substantial size and weight and employed a cathode ray tube monitor to display patient vital signs such as heartbeat, respiration, blood oxygen, and other parameters of bodily functions. Today these monitors are becoming smaller and lighter and, in many instances, are designed for portability. This portability enables the monitors to be used in their conventional settings in emergency rooms and intensive care units, and also enables them to be hung on a bedrail as a patient is moved from one location in a hospital to another. It also enables the monitors to be used in ambulances and other emergency vehicles, and even to be used at the site of an accident or other medical emergency. A portable monitor can even be placed in use out-of-doors, enabling emergency personnel to immediately begin monitoring a patient's vital signs and administering life-saving treatments afforded by the instrument.
One of the patient vital signs conventionally monitored by a patient monitor is end tidal CO2 (EtCO2). In this application a gas sampling line is fitted to the patient's respiratory system and the connector end of the gas sample collection tube is connected to the CO2 inlet of the monitor. A low pressure sampling pump draws the patient's breath into the patient monitor where it is analyzed and expelled through an outlet port. The results of the analysis are typically shown graphically or numerically on the display of the monitor.
The patient monitors in common use in hospitals generally leave the gas inlet and outlet ports for gas sampling unprotected, as there is generally little risk of contamination or blockage of the ports in the hospital setting. One commercially available capnography monitor does have a door which closes over the gas inlet port located on the top of the monitor. To access the inlet port the user must open the hinged door with one hand and insert and lock the collection tube connector with the other hand. However a portable patient monitor which is taken to accident sites by emergency medical personnel should be easier to operate. The collection tube should be connectable to the patient monitor with one hand, and should be possible by touch alone, as the medical technician is often directing his or her visual attention to an injured patient. Furthermore, such patient monitors are often used outdoors at an accident site such as alongside a highway. The inlet and outlet ports can readily become contaminated with blowing dust and other particulate matter from passing automobiles and should be protected against such hazards, but not in a way which significantly impedes the quick and simple connection of the gas line.
In accordance with the principles of the present invention, the gas inlet and outlet ports of a patient monitoring instrument are both protected from contamination when not in use. A spring-loaded door covers the unused ports and can be easily opened with the connector end of a gas sample collection tube. A guide on the door which can be located tactilely aids in both opening the door and guiding the collection tube connector to the mating connector on the monitor. When the sample collection tube connector is connected to the gas inlet the connected tube holds the door open and exposes the outlet port. The sample collection tube can be easily connected with only one hand by touch alone.
In the drawings:
a-4c illustrate components of the spring-loaded door mechanism of
a-5e illustrate the connection of a gas line connector to a gas inlet of a patient monitor of the present invention.
Referring first to
The monitor includes high voltage circuitry 16 for defibrillator operation. The high voltage circuitry produces the high voltage pulse necessary for defibrillation which is connected at the appropriate time by switching logic 14 to defibrillator electrodes coupled to the patient. This circuitry provides the high voltage shock needed to disrupt the heart from ventricular fibrillation. The shock level and waveform delivered for defibrillation can be automatically calculated by a processor in the monitor or can be manually set by an experienced medical technician or physician.
Power for the modules of the monitor is distributed by power handling circuits 20. The power handling circuits 20 will distribute power from batteries 22, from an a.c. supply 24, or from a DC supply 26. The a.c. and DC supplies are also coupled to circuitry which charges the batteries when the monitor is powered from these sources.
The information obtained by the monitor may be sent to other instruments or locations by communications circuitry 30. This may include a network connection, an RS232 connection, Bluetooth or infrared wireless connections.
The monitor is operated and adjusted by means of a keypad and controls 32. In a constructed embodiment the keypad is a membrane keypad providing integrity against environmental conditions. Controls such as an on/off switch, power level and shock delivery controls for defibrillation, a printer, and other functions may also be provided.
The monitor is operated under control of a central processing unit (CPU) 40. The CPU runs software stored on a read-only memory (ROM) 38. Flash ROM is also provided for the control of feature setups and new or special capabilities such as waveform information. Removable memory 36 is provided for storage of recorded information during a patient event such as ventricular fibrillation. Patient information such as cardiac waveforms before and after defibrillation are stored on the removable memory 36, which can be removed and given to a subsequent care-giver for review, record-keeping, and subsequent diagnosis. The removable memory 36 can also record voice information from a care-giver speaking into a microphone 48.
Beepers 34 are provided which produce sounds during certain monitoring functions such as a beep in response to each heart cycle. The beepers can also be used to issue audible alerts and alarms which a patient medical crisis is detected. Other audible information is provided by a loudspeaker 42. The loudspeaker 42 can reproduce pre-recorded voice instructions and information stored and reproduced from voice out circuitry 44. The loudspeaker can also reproduce tones 46 during operation of the keypad and other controls.
A display 50 is provided for the display of patient parameters, waveforms, and other patient data acquired by the monitor. The information to be displayed is provided to a display controller 52 which provides the necessary drive signals for display of the information on the display. In a constructed embodiment the display is a color LCD display, although other types of displays such as a CRT display may be used in a particular embodiment. The display controller 52 displays information in accordance with a color map provided by color map store 54. In a constructed embodiment the color map is stored in tabular form. In other embodiments the color map may be stored as an algorithm or other programmed information. In the constructed embodiment the display information is coupled to the display 50 with a color code by which the display controller selects the pixels for display of the desired information and background colors.
In accordance with the principles of the present invention a patient monitoring instrument is equipped with a door which protects both the inlet and outlet ports for the CO2 lines.
The CO2 door and spring mechanism of
b is a view of the rear of the door 80 which shows a door retaining snap 182 projecting from the rear of the door. The door 80 is assembled in the recessed panel 87 by pushing the retaining snap 182 through the door retaining slot 134 until the center leg of the retaining snap springs laterally to hold the door in place, as shown in
a-5e illustrate how the CO2 port door of
In
With the luer fitting 110 thus aligned with the luer receptacle 88, the user pushes the luer fitting into its mating receptacle as shown in
When the connector of the gas collection tube is retracted from the inlet port 90, the door 80 springs shut, resuming its protection of both the inlet and outlet ports 90, 92 of the patient monitor.
It will be recognized that two hands can be used to open the protecting door 80 and engage the collection tube connection, as in the prior art. The user can use a thumb or finger to press down on the projection 82 on the door 80 to open the door with one hand, then engage the inlet port with the connector of a collection tube held in the other hand. However it is anticipated that users will soon prefer the one-handed technique described above, particularly in emergency situations.