System and method for setting and displaying ventilator alarms

The invention is directed to a ventilation control system for controlling the ventilation of a patient. The ventilation control system utilizes a user-friendly user interface for the display of patient data and ventilator status, as well as for entering values for ventilation settings to be used to control the ventilator and for setting and displaying appropriate alarms settings and patient data.

BACKGROUND OF THE INVENTION 
1. Field Of The Invention 
This invention relates generally to the field of medical equipment for 
respiratory therapy and more specifically to the user interface for a 
ventilator used for monitoring and controlling the breathing of a patient. 
2. Description Of The Related Art 
Modern patient ventilators are designed to ventilate a patient's lungs with 
breathing gas, and to thereby assist a patient when the patient's ability 
to breathe on his own is somehow impaired. As research has continued in 
the field of respiration therapy, a wide range of ventilation strategies 
have been developed. For example, pressure assisted ventilation is a 
strategy often available in patient ventilators and includes the supply of 
pressure assistance when the patient has already begun an inspiratory 
effort. With such a strategy, it is desirable to immediately increase the 
pressure after a breath is initiated in order to reach a target airway 
pressure for the pressure assistance. This rise in pressure in the patient 
airway which supplies breathing gas to the patient's lungs allows the 
lungs to be filled with less work of breathing by the patient. 
Conventional pressure assisted ventilator systems typically implement a 
gas flow control strategy of stabilizing pressure support after a target 
pressure is reached to limit patient airway pressure. Such a strategy also 
can include programmed reductions in the patient airway pressure after set 
periods of the respiratory cycle in order to prepare for initiation of the 
next patient breath. 
As patient ventilator systems and their various components, including 
sensors and control systems, have become more sophisticated, and more 
understanding is gained about the physiology of breathing and the 
infirmities and damage which form the requirements for respiratory 
therapy, the number of variables to be controlled and the timing and 
interrelationships between the parameters have begun to confront the 
caregiver with a daunting number of alternative therapeutic alternatives 
and ventilator settings. Also, in such a complex environment, the 
interface between the ventilator and the caregiver has often not been 
adaptable to the capabilities of the operator, thus running the chance of 
either limiting the choices available to a sophisticated user or allowing 
a relatively less sophisticated user to chose poorly from the alternatives 
presented. Thus, it would be beneficial if a ventilator interface guided 
the user through the setup or therapy modification process, illustrating 
the relationship between changes, preventing incorrect or dangerous 
settings and sounding alarms or other audible indications of invalid 
settings when something is about to be done that exceeds limits, but also 
allowing the advanced and sophisticated user to gain access to the full 
range of ventilator capabilities through an interface which both presents 
the various parameters and allows the visualization of their 
relationships. 
Clinical treatment of a ventilated patient often requires that the 
breathing characteristics of the patient be monitored to detect changes in 
the breathing patterns of the patient. Many modem ventilators allow the 
visualization of patient breathing patterns and ventilator function and 
the caregiver adjusts the settings of the ventilator to fine tune the 
respiratory strategy being performed to assist the patient's breathing. 
However, these systems have been, up until now, relatively difficult to 
use by the unsophisticated user unless a limited number of options are 
selected. For example, in one prior art system, only a single respiratory 
parameter may be altered at a time. Moreover, the various respiratory 
parameters must often be entered into the ventilator controller in a 
prescribed order, or, where no order is prescribed, certain orders of 
entry should be avoided, otherwise the intermediate state of the machine 
before entry of the remaining parameters may not be appropriate for the 
patient. This inflexible approach to ventilator setup requires additional 
time and training if the user is to quickly and efficiently use the 
ventilator in a critical care environment. 
Previous systems have also been deficient in that it is often difficult to 
determine the underlying fault that has caused alarms to be sounded, and 
what controls or settings should be adjusted to cure the problem causing 
the alarm. For example, prior alarm systems have consisted of nothing more 
than a blinking display or light with an alarm to alert the user that a 
problem existed. Similarly, many prior art systems provided only limited 
assistance to a user or technician in setting the parameters to be used 
during treatment. For example, if a technician attempted to enter a 
setting that was inappropriate for the patient because of body size or for 
some other reason, the only alarm provided may have been an auditory 
indication that the value was not permitted, but no useful information was 
provided to assist the technician in entering an appropriate setting. 
One problem consistently presented by prior art ventilator control systems 
has been that the user interface has offered relatively little to guide 
and inform the user during the setup and use of the ventilator. Prior 
systems typically utilized a single visual display of the operating 
parameters of the ventilator and sensed patient parameters. Alternatively, 
prior systems may have numerous fixed numeric displays, certain of which 
may not be applicable during all ventilation therapies. Even when more 
than one display has been provided, users typically received limited 
feedback, if any, from the control system indicating the effect that 
changing one particular setting had on the overall respiratory strategy. 
If a parameter was to be adjusted, the display would change to display 
that particular parameter upon actuation of the appropriate controls, and 
allow entry of a value for that parameter. However, the user was provided 
with no visual cue as to how the change in the parameter value would 
effect the overall ventilation strategy, and thus had no assistance in 
determining whether the value entered for the parameter was appropriate 
for the patient. 
What has been needed and heretofore unavailable in patient ventilators is a 
user friendly graphic interface that provides for simultaneous monitoring 
and adjustment of the various parameters comprising a respiratory 
strategy. Such an interface would also preferably guide sophisticated 
users in implementing ventilation therapies, provide guidance on the 
relationships between parameters as they are adjusted, allow rapid return 
to safe operation in the event that an undesirable strategy was 
inadvertently entered, provide alarms that are easily understood and 
corrected and present all of the relevant information in an easily 
understood and graphic interface. The present invention fulfills these and 
other needs. 
SUMMARY OF THE INVENTION 
Briefly, and in general terms, the present invention is directed to a 
graphic user interface system for controlling a computer controlled 
ventilator to provide respiratory therapy to a patient. In a broad aspect 
of the invention, the invention includes a digital processor, a touch 
sensitive display screen and entry means cooperating to provide a 
user-friendly graphic interface for use in setting up and carrying out a 
wide variety of respiratory therapies. The processor controls the 
displaying of a plurality of screens, including user selectable graphic 
on-screen buttons for setting the values of various ventilator operating 
parameters for controlling the ventilator. Depending on the on-screen 
button touched, the processor causes different graphics to be displayed on 
the screens, provides graphic representations of the effect on the overall 
respiratory strategy caused by changes to the settings, and may also 
provide displays of patient data, alarm conditions, and other information. 
In one preferred embodiment of the invention, the system includes the use 
of a digitally encoded knob for altering selected and displayed values of 
ventilation parameters, with the acceptable values indicated and 
unacceptable values alarmed and/or limited to prevent harm to the patient. 
The digital encoded rotation of the knob may be analyzed by the processor 
and a magnification factor applied to the knob output to increase the 
speed with which displayed values are altered. The magnification factor 
may also be used in the event of an overshoot condition to assist a user 
in recovering from the overshoot. 
In another preferred embodiment of the invention, the processor may detect 
the connection of a patient to the ventilator when the ventilator is 
powered-up. The processor may then, in response to such a detection, start 
up the ventilator using a predetermined set of ventilator control settings 
deemed to be safe for the widest possible variety of patients. 
In a further preferred embodiment of the invention, the processor may only 
display ventilator control settings appropriate for a selected mode of 
ventilation. The ranges of values of the appropriate settings, or bounds 
of the ventilation, may be limited by the processor in response to the 
selected mode of ventilation such that only those values determined to be 
appropriate are displayed, thus limiting the opportunity to select 
incorrect settings. Additionally, the processor may be responsive to 
specific values entered for certain of the ventilator settings to adjust 
the ranges of values allowed for ventilator settings dependent on the 
certain settings. Further, the processor may be programmed to require that 
a so called "ideal body weight" be entered before beginning ventilation of 
a patient, and then only ranges of values for settings that would be 
appropriate for ventilation of a patient with that ideal body weight are 
displayed. 
In another presently preferred embodiment of the invention, the graphic 
user interface system includes at least two touch sensitive screen 
displays, a plurality of manual parameter controls, including at least one 
control knob that is activated upon selection of a parameter to be 
controlled and displayed on the screen, and a microprocessor controller 
which controls the logic and arrangement of the screen displays and the 
interface with the ventilator. The system of the invention includes 
protocols programmed into the microprocessor for entry of parameters 
within ranges predetermined to be appropriate for the patient parameters 
entered, alarms and other audible indications of invalid entry associated 
with entries outside of the acceptable ranges of parameters or 
inappropriate operation such as startup with a patient connected to the 
ventilator, and the ability to lock selected parameters while allowing for 
user variation of other parameters. 
In another presently preferred embodiment of the invention, the user is 
provided a graphic interface in which the user is allowed to view and 
adjust a variety of alarm limits and is able to vary the levels at which 
the alarms are set off, within limits that are preset by the programming 
of the microprocessor as representative of values that are not to be 
exceeded, either as a function of ideal body weight or general parameters 
for all patients. The resultant setting of a filtered set of alarms may 
then be used by the user to avoid the setting of parameters that are 
likely to result in patient distress or other problems with the therapy, 
while still allowing the sophisticated user to configure a therapy that is 
customized for the particular patient. 
In one presently preferred embodiment, the invention also allows the user 
an "undo" option in which a previously successful setting is reestablished 
after the user realizes that a series of proposed changes are likely to be 
unworkable for the patient. 
In yet another presently preferred embodiment of the invention, the user is 
provided with alarm indicators indicating the severity of a particular 
alarm. Alarm messages are also displayed in a selected screen area of the 
graphic user interface to assist the user in alarm recognition and 
understanding. Each alarm message may comprise an identifying message 
identifying the alarm being indicated, an analysis message providing 
information about the condition that caused the alarm to be indicated, and 
a remedy message suggesting steps that may be taken by the user to correct 
the alarm condition. 
In a further currently preferred embodiment of the invention, the processor 
allows the user to configure the graphic user interface to provide a 
display of the current and/or proposed breath parameters and a graphic 
representation of the breath timing controlled by those parameters. Such a 
display allows the visualization of relationships between breath 
parameters, and, while parameters are being changed, provides the user 
with a visual representation of the effect of the proposed changes on the 
ventilation strategy while simultaneously allowing the user to view 
current settings, thus allowing the user to simultaneously view "where 
they are now" and "where they are going to be." 
From the above, it may be seen that the present invention represents a 
quantum leap forward in the user interface available for patient 
ventilation. While assisting the sophisticated user in both visualizing 
the ventilation strategy and performance of the patient on the ventilator, 
it also guides and controls the less sophisticated user in setup and 
understanding of the relationships between ventilator settings. The 
invention provides these benefits while enforcing fail-safe functioning in 
the event of a variety of inadvertent or erroneous settings or 
circumstances. 
These and other features and advantages of the invention will become 
apparent from the following detailed description, taken in conjunction 
with the accompanying drawings, which illustrate, by way of example, the 
features of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention provides a sophisticated graphic user interface and 
alarm setup capability that allows great flexibility in the setup of the 
ventilator and the thresholding and display of alarms. More particularly, 
the invention allows the setup of alarms by the user so that graphic, 
aural and visible alarms of various urgency may be displayed to the user, 
and the setup of alarms is displayed graphically as well so that the ease 
of use and alarm setup is enhanced. 
The drawings will now be described in more detail, wherein like referenced 
numerals refer to like or corresponding elements among the several 
drawings. 
FIG. 1 shows a patient 1 receiving respiratory therapy from a ventilator 
system 10 having a graphic user interface 20 connected to and controlling 
a breath delivery unit, or respirator 22. The patient is connected to the 
respirator 22 by a patient circuit comprising an inspiratory line 2, and 
expiratory line 4, and a patient connection tube 6, all connected by a 
patient connector (not shown) of a type well-known in the art. The 
respirator 22 includes a processor or controller 60 which controls the 
real-time operation of the respirator 22. 
FIG. 2 depicts the graphic user interface 20 of FIG. 1 in more detail. 
Generally, the graphic user interface 20 comprises user inputs 25, a 
processor 30 and memory 35 comprising read only memory, random access 
memory or both. The memory 30 may be used to store current settings, 
system status, patient data and ventilatory control software to be 
executed by the computer. The processor 30 may also be connected to a 
storage device, such as battery protected memory, a hard drive, a floppy 
drive, a magnetic tape drive or other storage media for storing patient 
data and associated ventilator operating parameters. The processor 30 
accepts input received from the user inputs 25 to control the respirator 
22. The ventilation control system 20 may also include status indicators 
45, a display for displaying patient data and ventilator settings and an 
audio generator for providing audible indications of the status of the 
ventilator system 10. 
The memory 35 and a memory 65 associated with the respirator processor 60 
may be non-volatile random access memory (NVRAM) for storing important, 
persistent variables and configuration settings, such as current breath 
mode setup. Typically, during normal operation of the ventilation control 
system 20, such an NVRAM functions similarly to a typical random access 
memory. If, however, a low-voltage condition is detected, such as may 
occur during a brown-out or at the beginning of a power failure, the NVRAM 
automatically stores its data into non-volatile storage. 
The graphic user interface 20 includes an interface 32 for providing 
control signals from the processor 30 to the respirator processor 60 of 
the respirator 22, and also for receiving signals from sensors 27 
associated with the respirator 22 indicative of patient condition and the 
status of the respirator 22. The processor 30 of the graphic user 
interface 20 may also receive input representative of various clinical 
parameters indicating clinical condition of the patient 1 and the status 
of the respiratory therapy from the sensors 27 in the respirator 22. The 
interface may include, for example, an ethernet connection of a RS-232 
serial interface. A cable 34 having an appropriate number of conductors is 
used to connect the respirator 22 to an appropriate connector (not shown) 
of the interface 32. 
A preferred embodiment of the display 50 incorporating a user interface is 
illustrated in FIG. 3. Generally, the display 50 comprises an upper 
display 60 and a lower display 70, dedicated keys 80, 82, 84, 86, 88, 90, 
92, 94, 96, 98, 100, 102, 104 and knob 106. As will be described in more 
detail below, additional user inputs are dynamically provided by on-screen 
buttons that are drawn on the upper and lower displays 60 and 70. 
Typically, each dedicated key or on-screen button includes, within the 
outline of the button, either a graphic icon or text identifying the 
purpose of the button to the user. These graphic icons or text enhance the 
ease of use of what would otherwise be a confusing array of user inputs. 
Moreover, the use of graphic icons or text to identify the function of 
dynamically generated on-screen buttons provides for virtually unlimited 
opportunities to add functions to the graphic user interface 20 by 
upgrading the programming of the processor 30 as new functions are desired 
by the users of the system. Additionally, the use of graphic icons 
overcomes the potential problem of identifying the functions of a button 
where language comprehension may be a problem, such as the use of the 
ventilator in a country where English is not readily understood. 
Referring again to FIG. 3, key 80 is identified with a graphic design in 
the form of a stylized padlock. Actuation of key 80 by an operator locks 
the keys and buttons of the graphic user interface 20 to prevent 
inadvertent altering of the settings of the system. Keys 82 and 84 control 
the contrast and brightness of the displays 60, 70. Key 86 bears a 
stylized graphic design representative of a speaker emitting sound, and a 
graphic indicative of a volume control. Thus, key 86 is easily 
identifiable as a control for altering the loudness of audible alarm 
signals provided by the graphic user interface 20. Key 92 bears a "?" and 
actuation of key 92 activates a help system to assist a user in operating 
the graphic user interface 20. 
Keys 94, 96, 98 and 100 control various aspects of the ventilator, and are 
used by an operator to override the automatic settings of the graphic user 
interface 20. When key 94 is pressed, the processor 30 of the graphic user 
interface 20 provides a signal over the 32 to the processor in the 
respirator 22 instructing the respirator processor to ventilate the 
patient with 100% oxygen for two minutes. The processor in the respirator 
22 also starts a timer and causes the value of the time at any given 
instant to be written to a memory associated with the respirator 
processor. When the value in the respirator memory is equal to two (2) 
minutes, indicating that the 100% oxygen gas mixture has been provided to 
the patient for two(2) minutes, the respirator processor controls the 
respirator 22 to stop the flow of the 100% oxygen to the patient. If the 
user presses key 94 during the two (2) minute duration of the 100% oxygen 
ventilation, the value of the time stored in the memory is reset to "0" 
and timing continues for an additional two minutes. Typically, the 
respirator processor may be programmed to respond to any number of 
actuations of key 94 without prompting the user for validation or before 
sounding and displaying an alarm. Alternatively, the respirator processor 
may be programmed to respond to only a limited number of actuation of key 
94 before sending a signal through the interface 32 to the processor 30 of 
the graphic user interface 20 requesting the processor 30 to provide a 
visual prompt on the display 50 and/or to control the audio generator 55 
to sound an audible alarm indicating that an allowed number of actuations 
of key 94 has been exceeded. 
When key 96 is pressed during an exhalation, the processor 30 controls the 
ventilator to immediately provide an inspiration. Actuation of key 98 
results in an extension of the expiration phase. Similarly, actuation of 
key 100 results in a lengthening of the inspiration phase. 
Key 102 is labeled with the text "Clear" and actuation of key 102 causes 
proposed changes to the value of a currently selected setting, to be 
discussed in more detail below, to be cleared. Key 104 is labeled with the 
text "Accept." When key 104 is touched, any proposed changes to the 
ventilator settings are confirmed, and become the current ventilator 
settings. 
Knob 106 is used to adjust the value of an individual setting selected by 
pressing either keys 82, 84 and 86 or certain on-screen buttons. Knob 106 
is mounted on a shaft whose rotation is digitally detected by a rotary 
encoder/decoder, such that the processor 30 receives signals indicating 
not only the magnitude of the rotation of knob 106, but also the speed and 
rate of acceleration and deceleration of the rotation of knob 106. These 
signals are interpreted by the processor 30 to display allowable values 
for the selected setting. In one embodiment of the present invention, the 
processor 30 is responsive to the signals indicative of the speed of 
rotation of knob 106 to calculate a velocity based magnification factor 
dependent on how fast and how long the user turned the knob that is 
applied by the processor 30 to adjust the increment of the values 
displayed. The processor 30 uses this magnifying factor to increment the 
displayed values in larger increments when knob 106 is rotated rapidly, 
and incrementing the displayed values in smaller increments when knob 106 
is rotated slowly. 
A common problem using rotating knobs where a magnification factor is 
applied in this manner is that there is inevitable "overshoot" of the 
desired value. Following an overshoot, the user must reverse the direction 
of rotation of the knob. This reduces the speed of rotation of the knob to 
zero, and eliminates the magnification. Elimination of the magnification, 
however, results in more rotation and time to recover from the overshoot. 
One novel aspect of the present invention is that the processor 30 does 
not reduce the magnification factor to zero when the knob is counter 
rotated, as described above. Rather, the processor 30 applies a 
magnification factor to the counter rotation to reduce the amount of 
rotation of the knob 106 necessary to recover from the overshoot. The 
processor sets a time-based limit on how quickly the magnification factor 
is allowed to decrease, thus ensuring that some magnification remains 
during overshoot recovery. 
Additionally, the processor 30 may provide signals to the audio generator 
55 to cause the audio generator 55 to provide an audible indication of the 
rotation of knob 106. For example, the audio generator 55 may generate a 
"click" for a predetermined amount of rotation of the knob 106 or to 
signify that an on-screen button or dedicated key has been actuated. The 
audio generator 55 may also provide an audio signal to the user if the 
maximum or minimum value of the range of values for the selected setting 
has been reached, indicating that further rotation of the knob 106 will 
not cause any larger or smaller values to be displayed. 
Referring again to FIG. 3, the display area of the ventilation control 
system 20 comprises an upper display 60 and a lower display 70. The upper 
display 60 is divided into four non-overlapping areas. These areas are 
"vital patient data" area 110, an "alarm message" area 120, an 
"information area" 130 and a "controls" area 140. Area 130 is a 
multipurpose area that may be used to display, for example only, screens 
depicting current alarms, an alarm history log, real-time waveforms, 
measured patient data that is not otherwise displayed in the vital patient 
data area 110, quick reference information, a log of diagnostic codes, 
operational time for system components, a ventilator test summary, the 
current ventilator software/hardware configuration, a log of the results 
from running a short self test, apnea ventilation settings and safety 
ventilation settings. 
Similarly, the lower display 70 is divided into five non-overlapping areas. 
These areas are a "main settings" area 150, an "information area" 160, a 
"controls" area 170, a "symbol definition" area 180 and a "prompt" area 
190. Examples of information displayed in area 160 include, but are not 
limited to screens displayed during ventilator startup and ventilator 
setup, apnea setup, alarm setup, new patient setup, communications setup, 
date/time setup, miscellaneous setting not otherwise shown in the main 
settings area 150 and breath timing graphs. 
It will be understood that the labeling of the four non-overlapping areas 
of the upper display 60 and the labeling of the five non-overlapping areas 
of the lower display 70 are not critical to the present invention, but are 
for convenience only. Thus, the areas could have other labels, depending 
on the information desired to be conveyed. 
The display area also includes an alarm display area generally indicated by 
reference numeral 108. The alarm display area 108 includes a high urgency 
alarm indicator 110, a medium alarm urgency indicator 112 and a low 
urgency alarm indicator 114. The alarm urgency indicators 110, 112 and 114 
may be light emitting diodes or any other means of providing a visual 
indication of an alarm. Additional indicators (not shown) may also be 
included below the alarm indicators. 
Low urgency alarms are used to inform the user that there has been some 
change in the status of the patient-ventilator system. During a low 
urgency alarm, the low urgency alarm indicator 114 lights, an audible 
alarm having a tone indicating that a low urgency alarm event has 
occurred, and an alarm message is displayed in the alarm message area 120 
of the upper screen 60. During a medium urgency alarm, the medium urgency 
alarm indicator lights, a medium urgency audible alarm is sounded, and an 
alarm message is displayed in the alarm message area 120 of the upper 
screen 60. Because medium urgency alarms typically require prompt 
attention to correct the cause of the alarm, the medium urgency indicator 
may flash, and the audible alarm may sound repeatedly with a distinctive 
tone. 
High urgency alarms require immediate attention to ensure patient safety. 
During a high urgency alarm, the high urgency indicator 110, which may be 
colored red, flashes, a distinctive audible alarm is sounded and an alarm 
message is displayed in the alarm message area 120 of the upper screen 60. 
Referring now to FIG. 4, the overall hierarchical structure of the user 
interface comprising the keys, on-screen buttons and upper and lower 
display screens will be described. When the user of the ventilator turns 
on the power to the graphic user interface 20 and respirator 22 by 
actuating a power switch typically located on the respirator 22 (not 
shown), the processor 30 begins to power itself up by initiating a power 
on self test (POST). If the user actuates a test button, also typically 
mounted on the respirator 22 (not shown) during the time when the POST is 
running, the ventilator will start up in a SERVICE mode. If the test 
button is not actuated, the ventilator will start up in a VENTILATOR mode. 
When the graphic user interface starts up in the VENTILATOR mode, the lower 
display 70 of the graphic user interface 20 displays the ventilator 
startup screen 200 depicted in FIG. 5. When the ventilator startup screen 
200 is displayed, the main settings area 150 of the lower display has two 
subareas; the upper subarea 152 displays the main ventilator mode 
settings, while the lower subarea 154 displays the values of the 
ventilator settings appropriate to the main ventilator mode settings that 
were in use prior to powering down the graphic user interface 20 and 
respirator 22. 
The control area 170 on the lower screen 70 typically contains one or more 
on-screen buttons (see FIG. 8), but is blank on the ventilator startup 
screen 200, as illustrated in FIG. 5. This illustrates the dynamic nature 
of the various screens that are presented to the user to assist the user 
in selecting ventilator settings appropriate to a given respiratory 
strategy. At this stage of the startup process, no settings other than 
those illustrated are presented to the user so that the user may not 
inadvertently enter an inappropriate ventilator setting. Other novel 
features of the display of the present invention further assisting the 
user will be described below. 
A message instructing the user as to what action to take next is displayed 
in the prompt area 190. As indicated by the message displayed in the 
prompt area, it is important that the ventilator be setup before attaching 
the ventilator to a patient. 
As is illustrated by display depicted in FIG. 5, on-screen buttons such as 
buttons 225, 230 and 240 that are active and may be touched by the user to 
initiate activity are displayed so that the on-screen buttons appear to 
have a raised, three dimensional appearance. In contrast, on-screen 
buttons whose actuation is not appropriate on a particular screen are 
displayed having a flat, non-three dimensional appearance, as, for 
example, the on-screen buttons displayed in subarea 154 of the main 
settings area 150. 
The information area 160 of the ventilator startup screen 200 provides the 
user with three on-screen buttons to choose from to initiate the next step 
in completing the setup of the graphic user interface 20. The user may 
touch the SAME PATIENT on-screen button 225 followed by the off-screen 
ACCEPT key 104 to set up the ventilator with the settings displayed in the 
main settings area 150. If no previous patient settings are stored in the 
memory 35, the SAME PATIENT on-screen button will not be displayed. 
Alternatively, if the ventilator is being used to provide respiratory 
therapy to a patient different from the previously treated patient, the 
user may actuate the NEW PATIENT on-screen button 230. Actuation of the 
NEW PATIENT on-screen button 230 will result in the display of a new 
patient setup screen. The user may also choose to perform a short self 
test (SST) of the ventilator and the graphic user interface 20 by touching 
the SST on-screen button 240. The SST on-screen button 240 will not be 
displayed if the ventilator is already connected to a patient. 
The upper display 60 and the lower display 70 incorporate touch sensitive 
screen elements, such as, for example only and not by way of limitation, 
infrared touch screen elements, to allow for actuation of on-screen 
buttons, such as on-screen buttons 205, 210, 215, 220, 225, 230 and 240. 
The touch screen elements and the processor 30 operate in coordination to 
provide visual cues to the user as to the status of the on-screen buttons. 
For example, as described previously, the on-screen buttons are displayed 
in such a manner as to appear to be three-dimensional. When one of the 
on-screen buttons is actuated by the user touching the display screen with 
a finger, a pencil or other instrument, the touch screen elements detect 
the application of the finger, pencil or other instrument and provide the 
processor 30 with signals from which the screen location where the touch 
occurred may be determined. The processor 30 compares the determined 
location of the touch with the locations of the various buttons displayed 
on the current screen stored in the memory 35 to determine the button, and 
thus the action to be taken, associated with the location of the touch. 
The processor then changes the display of the touched on-screen button to 
make the button appear to be depressed. The processor may also alter the 
display of the text incorporated into the three-dimensional on-screen 
button. For example, the SAME PATIENT text displayed on the on-screen 
button 225 normally appears as white letters on a dark or gray button when 
the button is in an untouched state. When the button 225 is touched, the 
processor 30 may cause SAME PATIENT to be displayed as black letters on a 
white button. Additionally, the prompt area 190 may change to a white 
background with black letters to draw the user's attention to the prompt 
area 190 when a message is displayed in the prompt area 190. 
Typically, the action initiated by touching an on-screen button is obtained 
when the user lifts the finger, pencil or other instrument from the 
surface of the display screen. However, the processor may also be 
responsive to a user sliding the finger, pencil or other instrument off 
the on-screen button and onto the remaining surface of the display screen 
to reset the on-screen button in its un-actuated state and to take no 
further action. Thus, the action initiated by the touching of the 
on-screen button may only be obtained when the finger, pencil or other 
instrument is lifted from the portion of the display screen that is 
displaying the on-screen button. This feature allows the user to abandon a 
button touch without activating the function associated with the button in 
the case where the button was touched inadvertently or in error. 
When the NEW PATIENT on-screen button 230 is touched, the processor 30 
responds by displaying a new patient setup screen (not shown) and purges 
any previously entered settings from the memory 35. The new patient setup 
screen includes an IBW on-screen button for displaying and altering the 
value for the ideal body weight (IBW) of the patient. The new patient 
setup screen also includes a CONTINUE on-screen button; however, the 
CONTINUE button is not displayed until the IBW button is touched to ensure 
that the user adjusts the IBW to a suitable value. The CONTINUE button is 
displayed immediately after the IBW button is touched. Thus, if the value 
for IBW currently stored in the memory 35 is acceptable, the IBW does not 
need to be adjusted, and the CONTINUE button may be touched to accept the 
current value of the IBW. 
When the IBW on-screen button is touched, the value for IBW currently 
stored in the memory 35 of the graphic user interface 20 may be adjusted 
by the user by rotating the knob 106 to either increase or decrease the 
displayed value until the value for the IBW desired by the user is 
displayed. The user may then touch the CONTINUE button to store the new 
value for IBW in the memory 35. When the CONTINUE button is touched, the 
processor 30 responds by causing a vent setup screen to be displayed. 
Because the vent setup screen is being displayed in response to the 
completion of the new patient setup screen, the vent setup screen is 
displayed in a new patient mode, and is labeled accordingly. 
The processor 30 is responsive to the entered value for the patients' IBW 
to determine the initial values and ranges, or bounds, of the values of 
the various ventilator settings that are appropriate for use with a 
patient having that IBW. For example, the range of appropriate values for 
the various ventilator settings differ between adults and children. The 
processor will display only values that fall within the appropriate range 
of values for selection by the user during setup dependent upon the IBW, 
and will not accept values for settings that fall outside of the 
determined range. If the user attempts to enter a value outside of the 
appropriate range for that patient's IBW, the processor 30 may provide an 
audible indication of an attempt to enter an out of range value and/or a 
prompt to the user that the value is inappropriate. 
Referring now to FIGS. 6-8, the layout and functions of the vent setup 
screen will now be described. Traditionally, setting up a ventilator 
required a user to navigate through a number of confusing and complicated 
displays. A novel aspect of the present invention is the simplification of 
ventilator setup by hierarchically categorizing the ventilator controls 
and settings to minimize the number of choices available to a user on any 
one screen. The vent setup sequence used to configure the ventilator 
comprises two display phases. These two phases have been designed to 
simplify setup of the ventilator by grouping ventilator settings in 
logically arranged groups. Further, the settings entered during the first 
phase determine the settings presented to the user during the second 
phase. In this manner, only those ventilator parameters that are 
appropriate for the mode settings entered during the first phase are 
displayed. Additionally, the ranges of values, or bounds, of the displayed 
settings may be further limited as appropriate depending on the proposed 
ventilator mode and settings. Moreover, since some ventilator parameters 
may be dependent on the values selected for certain other ventilator 
parameters, the ranges of values for the dependent ventilator parameters 
may be limited in accordance with the settings of those independent 
ventilator parameters. In this manner, the user is presented only with 
those settings that are appropriate depending on settings already entered 
by the user. Such a hierarchical sequencing and presentation are useful in 
preventing the inadvertent entry of inappropriate ventilator settings. 
Once a value for IBW has been entered, the subsequent phases of the New 
Patient Setup process are similar to the "Vent Setup" sequence of screens 
which may be accessed at any time during normal ventilation by touching 
button 321 (FIG. 8). For example, in the first phase of New Patient Setup, 
a screen is displayed entitled "New Patient Setup" instead of "Current 
Vent Setup" and is preceded by a screen presenting the proposed setting 
for IBW. Similarly, in the second phase, the title of the screen is "New 
Patient Settings" instead of "Current Vent Settings." Accordingly, the 
following discussion address the "Vent Setup" sequence. 
When the vent setup screen is first activated, or following the IBW screen 
utilized during the new patient setup procedure described above, the Main 
Controls phase depicted in FIG. 6 is displayed. In the Main Controls 
phase, only buttons 302, 304 and 306, representing the main control 
settings, are visible in the information area 160 of the lower display 
screen 70. As shown in FIG. 8, however, the values for the currently 
selected main controls continue to be displayed in area 152, and the 
currently selected settings are displayed in area 154 of the main settings 
area 150 of the lower screen 70. The values displayed in areas 152 and 154 
remain visible at all times during ventilation setup; thus it may be 
assumed that they are displayed unless specific reference is made to the 
display of different information in areas 152 and 154. When the main 
controls screen is being displayed during the "New Patient Setup" 
sequence, the on-screen buttons in area 154 of the main settings area 150 
are displayed with a flat, non-three dimensional appearance, indicating 
that they cannot be actuated. During normal ventilation however, the 
on-screen buttons in area 154 may always be actuated by the user; thus 
they are displayed with a raised, three-dimensional appearance during 
normal ventilation. 
As depicted in FIG. 7, the present invention decomposes the traditional 
mode setting into a simple mode plus separate "mandatory type" and 
"spontaneous type" settings. There are three modes: "A/C", or 
assist/control mode; "SIMV" or synchronous intermittent mandatory 
ventilation; and "SPONT", for spontaneous respiration. Dependent on the 
mode and type selected, the processor 30 will display only those settings 
appropriate to that mode and mandatory type. For example, if the user 
selects "A/C" mode and "PC" mandatory type, the processor 30 will display 
on-screen buttons for changing ventilator settings related to pressure 
control of the ventilation. Similarly, selecting "SPONT" mode and "PS" 
spontaneous type results in the display of on-screen buttons for changing 
ventilator settings related to pressure support. 
Referring again to FIG. 6, Button 302 is labeled with "Mode"; Button 304 is 
labeled with "Mandatory Type"; and Button 306 is labeled with "Trigger 
Type." Each of the buttons 302, 304 and 306 also display the setting 
currently selected for each of the main control settings. For example, 
button 302 displays "A/C" indicating that assist/control mode is selected. 
Alternatively, where SIMV or SPONT modes are currently selected, button 
302 will display either SIMV or SPONT as appropriate. When either SIMV or 
SPONT modes are currently selected, a fourth button, button 308 (not 
shown) labeled with "Spontaneous Type" may also be displayed. Further, 
when the mode is set to SPONT, a message may be displayed below button 304 
indicating that the value displayed on button 304, "Mandatory Type," 
applies to manual inspiration only. 
As with others of the buttons used to make changes to the values of various 
operational parameters used by the processor 30 to control the respiratory 
therapy of a patient, the main control settings on the current vent setup 
screen are set by touching the desired one of the displayed buttons 302, 
304, 306 or 308 (not shown), and then rotating knob 106 until the desired 
value is displayed. When the desired value for the setting is displayed, 
the user may provisionally accept and store that value in the memory 35 by 
touching the continue button 310. Alternatively, if more than one main 
control setting needs to be changed by the user, the user may defer 
touching the continue button 310, and may instead select among the other 
buttons to change the values of a different main control settings. The 
user may, if so desired, change the values of each of the main control 
settings. When the user has changed all of the desired main control 
settings, the changed values for each of the main control settings may be 
provisionally accepted, pending completion of the second phase of the 
ventilator setup procedure, and stored in the memory 35 simultaneously by 
touching the continue button 310. Thus, the values for the main control 
settings may be accepted and stored in a batch, rather than one setting at 
a time. This is advantageous in that entry of multiple settings is easier 
and less time consuming. Batch entry is also useful in that all of the 
proposed values for the main control settings are displayed, and may be 
checked for entry errors by the user before being committed storage in the 
memory 35. 
When the continue button 310 is touched, the first phase of ventilator 
setup is complete and the second phase begins. In the second phase of 
ventilator setup, the processor 30 displays a proposed vent settings 
screen 320 to prompt the user to complete the vent settings phase of the 
setup procedure, as depicted in FIG. 8. The proposed vent settings screen 
is displayed in the information area 160 of the lower display 70 (FIG. 3). 
This screen includes a display 326 of the main control settings set in the 
first phase described above, and an area 328 where a plurality of buttons 
are displayed. The buttons displayed in the area 328 are for setting the 
values for particular ventilation parameters that are appropriate to the 
main control setting. Thus, the buttons displayed in area 328 are 
dependent upon the values selected for the main control settings in the 
first phase of the ventilator setup. This display of only those buttons 
whose settings are appropriate to their associated main control settings 
simplifies the display, thus aiding the user in setting up the ventilator 
and preventing inadvertent errors due to user confusion. 
As with the main settings screen displayed during the first phase of the 
vent setup procedure, the user may select a parameter to change by 
touching one of the on-screen buttons, such as the "P.sub.I "on-screen 
button 352. When the user touches button 352, the button appears to be 
depressed, and may change color and text contrast as described above. The 
user then adjusts the value of the setting by turning knob 106 (FIG. 3) 
until the desired value is displayed on the button 352. If the user is 
satisfied with the value entered for button 352, and the other displayed 
values, the user may touch the PROCEED button 356, followed by the ACCEPT 
key 104 (FIG. 3) to complete the vent setup procedure. Alternatively, the 
user may touch another one of the on-screen buttons, such as the "f" 
on-screen button 350. When button 350 is touched, button 352 "pops" up, 
indicating that button 352 is no longer selected, and button 350 appears 
to become depressed. An audible indication that the button is touched, 
such as a "click" may also be provided. In this manner, the values for all 
of the settings displayed may be changed one after another if desired, or 
only certain of the settings may be changed, as desired by the user. The 
user then may configure the ventilator to operate in accordance with all 
of the changed settings at once in a batch fashion by touching the PROCEED 
on-screen button 356, followed by pressing the off-screen ACCEPT key 104. 
FIG. 8 further illustrates additional aspects of the graphical features 
provided by the user interface 20 that assist the user in setting up and 
operating the ventilator. As depicted in FIG. 8, the main settings area 
152 displays the currently active main settings. These settings are easily 
compared with the main settings entered during the first phase of setup 
that are now displayed on the proposed vent settings screen in area 160. 
For example, as illustrated in FIG. 8, the ventilator is currently setup 
to ventilate in the SIMV mode, and the user has provisionally changed the 
mode to A/C, as indicated in the display 326. Another aspect of the 
invention is the visual prompt provided to a user that a particular 
setting has been changed. This aspect is illustrated by the change in the 
font used to display the value of the setting for "P.sub.I ", where the 
value "15.0" is displayed in italics, indicating that this value has been 
changed, compared to the normal font used to display the value "16" for 
"f", indicating that this value has not been changed. 
If any of the main settings were changed during the first phase of the vent 
setup procedure were changed, the PROCEED on-screen button 356 is 
displayed on the proposed vent settings screen 320. Similarly, if none of 
the main settings were changed, the PROCEED on-screen button is not 
displayed until one of the settings displayed during the second phase of 
the vent setup procedure is changed. If the user is satisfied with the 
values for the settings that have been entered, the user may touch the 
PROCEED on-screen button 356. The user may then complete configuration of 
the ventilator settings, replacing the current vent settings with the 
proposed settings, by pressing the off-screen ACCEPT key 104. The 
off-screen placement of the ACCEPT key 104 ensures that no inadvertent 
changes are made to the ventilator settings. 
If the processor 30 determines that the vent setup screen has been 
activated within a predetermined short period of time, for example, within 
45 minutes of the most recent time the vent setup screen was used to 
change values of the ventilator settings, the processor 30 may display a 
PREVIOUS SETUP button on the main settings screen 300 (FIG. 6). The 
processor 30 removes this button from the screen if any changes are made 
using the screen. If the user touches the PREVIOUS SETUP button (not 
shown) on the main settings screen, a screen similar to the second phase 
display depicted in area 160 (FIG. 8) is displayed, showing values for the 
settings as they were immediately prior to the last setting change made 
using the vent setup screen. The on-screen settings buttons are all 
displayed in the flat, non-three dimensional state, indicating that they 
cannot be adjusted. A prompt message is displayed in area 190 explaining 
that accepting the displayed values will result in the entire previous 
setup being restored, including old alarm and apnea settings. The previous 
setup may be re-instated by the user by touching the PROCEED button 356, 
followed by pressing the ACCEPT key 104. This feature of the present 
invention allows a user to quickly restore the ventilator to the settings 
state it was in prior to a major setup change in the event that the 
altered ventilation strategy is not successful. A time line is placed on 
the availability of the previous settings to avoid the possibility of 
re-imposing the settings when the patient's condition may have changed 
substantially. Individual changes to settings may be made to settings in 
the period following a major settings change without invalidating the 
settings stored for the previous setup. However, batch changes, that is, 
the changing of more than a single setting at a time, results in the 
stored previous settings being replaced with the most recent set of 
settings. This provides the user with the ability to fine tune the 
settings made during the major change without losing the ability to "UNDO" 
all of the major changes and return to the previous settings. 
Referring again to FIG. 8, the proposed vent settings screen 320 also 
includes a graphical representation, or breath diagram 330, of the breath 
cycle that will be provided to the patient based on the settings entered 
by touching the buttons displayed in area 328 and adjusting the resulting 
displayed values using the knob 106, as described above. The breath 
diagram 330 includes a time line 332 that is displayed for scale purposes 
only, an inspiration bar 334 indicating the portion of the total breath 
duration during which inspiration will take place, an expiration bar 336 
indicating the portion of the total breath duration during which 
expiration will take place, an inspiration/expiration ratio display 338 
and a total breath time display 346. Besides the graphical representation 
of the duration of the inspiration and expiration portions of the total 
breath cycle, text representing the selected value for the durations may 
be displayed in the respective bars 334 and 336. For example, the 
inspiration phase of the breath is set to require 1.0 seconds and the 
expiration phase is set to require 2.75 seconds. The colors or shading of 
the inspiration bar 334 and the expiration bar 336 are preferably 
different to facilitate a user distinguishing between them. For example, 
the inspiration bar 334 may be shaded dark with white text, indicating 
that the breath timing parameter is "locked", while the expiration bar 336 
may have grey shading and black text. It will be understood that this 
color scheme is only one example of a variety of color schemes that may be 
used to enhance the graphical representation of the breath cycle to 
provide a readily comprehensible display of either the current status of 
the ventilation or to assist a user in evaluating the effects of proposed 
changes to the ventilator settings. 
Lock on-screen buttons 340, 342 and 344 are displayed above the time line 
332 and display the lock status of the settings for the inspiration bar 
334, the inspiration/expiration ratio 338 and the expiration bar 336 
respectively. The user may change the lock status of the settings by 
selecting and touching one of the lock icons 340, 342, 344. For example, 
lock button 340 displays a graphical representation of a closed, or 
locked, padlock, while lock buttons 342 and 344 display graphical 
representations of open, or unlocked, padlocks. Touching lock button 340 
will result in the lock button changing to the open, or unlocked state. 
Similarly, touching lock buttons 342 or 344 will result in the touched 
lock button changing to the closed, or locked, state. The effect of the 
"locked" setting is that the setting will not be automatically changed in 
accordance with a subsequent change in the breath rate parameter, while 
both of the settings for the "unlocked" parameters, here, the expiration 
time and the ratio of inspiration to expiration, will be changed. 
The display of the lock buttons is dependent upon the selected main control 
settings. For example, in the representative example depicted in FIG. 8, 
main control setting Mandatory Type is set to "PC", thus causing the lock 
buttons to appear; if the Mandatory Type is set to "VC", the lock bottons 
would not be displayed. When the Mandatory Type is "PC", only of the of 
the three "breath timing" settings, T.sub.I, T.sub.E or I:E is displayed. 
T.sub.I is set by touching the on-screen button labeled T.sub.I, and 
adjusting the knob 106 until a desired value is displayed. The value will 
be displayed both on the on-screen button T.sub.I, and in the inspiration 
bar 334 of the breath diagram 330. Because the value for T.sub.I is 
locked, as evidenced by the closed lock button 340, and the dark shading 
of the inspiration bar 334, changes to the breath rate do not result in a 
change to the inspiration time; only the expiration time, 
inspiration/expiration ratio and the total breath time change. If another 
time parameter, such as T.sub.E was locked, changes to the rate would not 
affect T.sub.E, but T.sub.I and the inspiration/expiration time ratio 
would change. 
The above described relationship is apparent from FIGS. 9A-C. In FIG. 9B, 
the breath rate has been reduced; thus, the total breath time is 
increased, as indicated by the value in total time display 344b. Since the 
value for the inspiration time was locked, the relative length of the 
inspiration bar 334b did not change, while the relative length of the 
expiration bar 336b increased. A novel aspect of the present invention 
evident from the display depicted in FIG. 9B is the change in the location 
of the total breath time display 344b. In FIG. 9A, the total breath time 
display 344a is located below the time line 332a. In FIG. 9B, the 
expiration bar 336b has grown larger because of the increased breath time 
to the extent that the total breath time display 344b has approached the 
end of the time line 332b. The processor 30 maintains the location of each 
of the graphical features of the displays in the memory 35, and constantly 
assesses whether the display of a graphical feature, such as the breath 
diagram 330, on-screen buttons or text may possibly collide or overlap. In 
the case depicted in FIG. 9B, the processor 30 determined that the total 
breath time display 344b would be displayed sufficiently close to the end 
of the time line 332b that the total breath time display 344b would 
interfere with the display of the numerical scale of the time line 332b. 
Accordingly, the processor caused the total breath time display 344b to be 
displayed above the time line 332b to avoid such interference. It will be 
understood that the use of the total breath time display 344b is for 
purposes of example only. Any of the text or numeric values displayed in 
conjunction with the breath timing diagram 330 may be displayed as 
necessary to prevent interference with other graphical elements. 
The processor 30 is also responsive to the values of the setting to change 
the scale of the time line 332 when appropriate. As depicted in FIG. 9C, 
the total breath duration 344c has been increased again, and is now 
greater than the previous scale of the time line 332c. Accordingly, the 
processor 30 has caused the time line 332c to be displayed with a larger 
scale. As the scale of the time line 332c enlarges, the relative lengths 
of the inspiration and expiration bars 334, 336 also change. As was 
described above, if the relative length of the inspiration bar 334c 
becomes too small to allow the display of the value of the inspiration 
time setting within the bar as depicted, the processor may cause the value 
to be displayed either above, below or to the left of the time line 332c 
in the vicinity of the inspiration bar 334c. 
One advantage of a preferred embodiment of the invention is that the main 
control settings are displayed on both the vent setup screen and in the 
main setting area of the 152 of the lower display 150. Thus a user may 
adjust the main settings using either screen. However, it is particularly 
advantageous to make adjustments to the main control settings using the 
vent setup screen because only one main setting at a time may be changed 
in the main settings area 152, while multiple changes may be made in the 
vent setup screen and then accepted by the user and stored in the memory 
35 of the graphic user interface 20 by the user as a batch. 
Referring now to FIG. 10, the alarm setup screen will be described. 
Touching the "Alarms" button 215 (FIG. 5) on the lower screen 70 causes 
the processor 30 to display the alarm setup screen 400. The alarm setup 
screen 400 displays graphical representations for those user-adjustable 
alarms that are appropriate given the values selected for the main control 
settings. Thus, a user may be presented only with alarm settings required 
by the ventilation strategy already entered and stored in the memory 35 of 
the graphic user interface 20. This facilitates setup and prevents errors 
or omissions due to information overload given the relatively small size 
of the information display area 160 on the lower screen 70 of the graphic 
user interface 20. 
Ease of use is further enhanced in that each graphical representation 410a, 
410b, 410c, 410d and 410e of an alarm includes a label 415 identifying the 
patient data parameter associated with the alarm and a display 420 of its 
current value. The value for the alarm setting associated with particular 
patient data parameter setting is displayed on an on-screen button 425. To 
further enhance the usefulness and comprehensibility of the graphical 
representations 410a, 410b, 410c, 410d and 410e, the processor 30 causes 
the alarm on-screen button 425 to be displayed at a location along the 
graphical line that is proportional to the value of the setting with 
respect to total length of the graphical line. 
The user may adjust the setting of each of the displayed alarm settings by 
touching a selected alarm on-screen button, such as alarm button 425, and 
then rotating the knob 106 (FIG. 3) until the desired alarm setting is 
displayed on the alarm button 425. As the value for the alarm setting is 
changed by rotating the knob 106, the processor changes the position of 
the alarm button 425 along the graphical line, providing a visual display 
of the change to the user. The position of the displayed patient data 
parameter 420 is similarly adjusted. 
Certain alarm settings may also be turned off so that no alarm sounds for 
selected control settings. One possible display of an alarm in the off 
state is shown by the location and display of the alarm on-screen button 
425b. 
Some patient data parameters may require the setting of both upper and 
lower alarm limit values defining a range of acceptable values beyond 
which a user desires an alarm to be given, as is depicted by the graphical 
representation 410c. Alternatively, as depicted by the graphical 
representation 410d, a lower limit alarm may be turned off by the user, 
while setting an upper limit alarm to a selected value. Similarly, the 
upper limit alarm may be turned off while a value for a lower limit alarm 
is set. When all of the alarms are set, the user may store the values for 
one, or all of the alarm settings in a batch manner by touching the 
PROCEED button 430 followed by pressing the off-screen ACCEPT key 104. 
Referring now to FIG. 11, one exemplary layout of the upper display screen 
60 of the graphic user interface 20 will now be described. As described 
above, the upper display screen 60 includes four non-overlapping areas 
110, 120, 130 and 140. Generally, the upper display screen 60 provides a 
user with information regarding the state of the current ventilation 
therapy. Vital patient information is displayed in the vital patient 
information area 110. The information displayed in area 110 is always 
displayed when ventilation is in progress, even while the lower display 
screen 70 is being used to modify the settings controlling the 
ventilation. One novel aspect of the present invention is the display of 
the current breath type and breath phase in the breath type area 525 shown 
located in the upper left corner of the vital patient data area 110. In 
addition to the "CONTROL" breath type displayed, the ASSIST OR SPONT 
breath types may be displayed in accordance with the values for the main 
settings set as described above. The breath phase, that is, inspiration or 
expiration, is indicated by alternately reversing the display of the 
breath type in the breath type area 525. For example, the text displayed 
in the breath type area 525 may be displayed as black letters on a white 
background during the inspiration phase, and as white letters on a black 
background during the expiration phase. 
It is not unusual during the course of a ventilation treatment session for 
values of monitored parameters to exceed the limits set for the various 
alarms that may be active during the session. The processor 30 receives 
signals from the sensors 27 (FIG. 2) for a variety of monitored parameters 
through the interface 32 and compares the values of those inputs to the 
values associated with the alarm settings stored in the memory 35. When 
the processor determines that the value of an input violates the value or 
values for the limit or limits for a particular alarm setting associated 
with that input stored in the memory 35, the processor 30 may cause an 
audible alarm to be sounded, and displays a text prompt identifying the 
monitored parameter, the cause of the alarm and a proposed course of 
action to correct the out of limit condition in the alarm messages area 
120. If an event occurs that is potentially harmful to the patient, the 
processor 30 may also control the ventilator to abort delivery of the 
current breath until a user may intervene and correct the condition 
causing the alarm. 
Many alarm conditions, however, may exist that do not require immediate 
correction, but are useful to evaluate the course of the respiratory 
treatment. Accordingly, all alarms are accumulated in an "Alarm Log" that 
is a chronological listing of all alarms that have occurred and which may 
be reviewed in area 130 of the upper screen 130 (FIG. 3) at any time 
during or after respiratory treatment. If, for some reason, the alarm log 
contains records of alarm conditions than may be conveniently stored for 
latter viewing, the processor 30 may cause the oldest alarm records to be 
deleted, and thus they will not be available for viewing. 
If multiple alarm conditions occur during the course of treatment, the 
number of alarm messages may exceed the display area available in the 
alarm message display area 120. The processor 30 may display those alarms 
having the highest priority in the display area 120, scrolling alarms 
having a lower priority off the screen. The user may review alarms having 
a lower priority by touching the "More Alarms" button 510 displayed in the 
controls area 140. The scrolled alarm messages are displayed in the 
information area 130 of the upper screen 60. When the "More Alarms" button 
510 is touched, the upper screen 60 is temporarily re-arrange to merge 
areas 130 and 120 into a combined and larger active alarms display, as 
depicted in FIG. 12. Touching the "More Alarms" button 510 again causes 
the processor 30 to redisplay the default screen display depicted in the 
FIG. 11. 
Each alarm message 602 (FIG. 12) includes three messages to assist the user 
in correcting the cause of the alarm. A base message 604 identifies the 
alarm. As will be described more fully below, the user may touch the alarm 
symbol to display a definition of the alarm symbol in the symbol 
definition area 180 of the lower screen 70 (FIG. 3). An analysis message 
606 gives the root cause of the alarm, and may also describe dependent 
alarms that have arisen due to the initial alarm. A remedy message 608 
suggest steps that can be taken by the user to correct the alarm 
condition. 
As illustrated above, the processor 30 may be responsive to user commands 
to display various kinds of information in the information area 130. For 
example, FIG. 11 depicts one possible embodiment of the upper screen 60 
having five on-screen buttons for causing various information and data to 
be displayed in the information area 130. Touching "Waveform" button 515 
causes the processor 30 to display a graphical plot of the data pertinent 
to the respiratory therapy being given to the patient. Similarly, touching 
the "More Data" button 530 results in the processor 30 displaying a screen 
including a variety of data that may be useful to the user in assessing 
the status of the patient and the progress of the ventilation therapy. It 
will be understood that the present invention is not limited to including 
only the five on-screen buttons depicted in FIG. 11. Because the on-screen 
buttons are implemented by the processor 30, with suitable programming the 
processor 30 may be enabled to display different or additional on-screen 
buttons and perform actions in response to their actuation. 
Touching the "Waveform" button 515 displays a waveform display screen 550 
as illustrated by FIG. 13. This display allows for real-time plotting of 
patient data in the tow plots areas 552 and 554. Different plots may be 
displayed in each of the plot areas 552 and 554. A plot setup screen (not 
shown) may be accessed by the user by touching the "Plot Setup" button 
556. The user may select among plots of pressure versus time, volume 
versus time, flow versus time and pressure versus volume. 
The waveform display screen 550 also includes a "Freeze" button 558 for 
freezing any waveform that is currently being plotted in either plot area 
552 or 554. Touching button 558 causes a flashing "Freezing" message to be 
displayed until the current plot is completed and prevents any changes 
being made to the waveform display screen 550 by causing the various 
buttons controlling the scale of the displays, as well as buttons 556 and 
558 to disappear. The only visible button is an "Unfreeze" button (not 
shown). When the current plot is complete, plotting stops and the 
on-screen buttons reappear. 
Other displays may also be accessed by touching the on-screen buttons 
displayed in the controls area 140 of the upper screen 60. For example, 
touching the "Alarm Log" button 525 causes a screen listing all of the 
alarm events up to a predetermined maximum number of alarms, including 
those that have been corrected by the user, that have been sounded during 
therapy. Touching the "More Screens" button 520 causes the display of a 
set of additional on-screen buttons giving access to additional data not 
otherwise presented on the main display screens. This feature provides a 
flexible way to add new features and screens with minimal impact on the 
overall design of the graphic user interface. 
In some modes of operation, the respirator processor 60 (FIG. 2) is 
responsive to signals received from a sensor 27 in the ventilator to 
provide inspiration. In this manner, the inspiration may be provided when 
the patient begins to draw a breath in, which is sensed by the sensor and 
results in the respirator processor 60 causing the ventilator to provide 
an inspiration. The respirator processor 60 may be programmed to monitor 
the rate at which a patient triggers the sensor, and, when that rate falls 
below a predetermined number of breaths per minute, the value of which may 
be stored in the memory 65 (FIG. 2), the respirator processor 60 sends a 
signal through the interface 32 to the processor 30 of the graphic user 
interface 20. In response to this signal, the processor 30 displays an 
"Apnea Ventilation In Progress" screen 600 in area 130 of the upper 
display 60, as depicted in FIG. 14. A variety of information may be 
displayed on this screen to inform the user of the status of the patient 
and the ventilation. For example, the main control settings and the 
ventilation settings currently active may be displayed along with a 
message indicating that apnea ventilation is in progress. Simultaneously, 
the respirator processor 60 switches to "Apnea" mode and provides 
breathing assistance to the patient. 
When the respirator processor 60 automatically institutes "Apnea" mode in 
response to a lack of inspiration by the patient being treated, the 
respirator processor 60 controls the apnea ventilation using values of 
various settings entered by the user from an apnea setup screen 650 that 
may be displayed in the information area 160 of the lower screen 70 as 
depicted in FIG. 15 by touching the "Apnea" on-screen button 322 on the 
lower screen 70 of the graphic user interface 20. One useful feature of 
the manner in which the processor controls the displays of the graphic 
user interface is illustrated in FIG. 15. As is shown, the values for the 
main control settings and the on-screen buttons for setting the 
ventilation settings appropriate for those main control settings for the 
ventilation in process when "Apnea" mode was entered are displayed in 
areas 152 and 154 of the lower display screen (FIG. 5). Additionally, the 
current apnea settings are displayed in the information area 160, along 
with on-screen buttons which can be actuated in concert with the knob 106 
to adjust the apnea settings. 
Referring again to FIG. 5, another novel aspect of the present invention 
will now be described. The lower display screen 70 includes an area 180 in 
which the processor 30 may display a variety of messages to assist the 
user in setting up the graphic user interface. These messages may be 
different from, or in addition to prompts displayed by the processor 30 in 
the prompt area 190 of the lower display screen 70. One possible use of 
the area 180 is to provide a textual definition of a graphic symbol 
identifying a on-screen button. For example, when a user touches the 
"Waveform" on-screen button 515 on the upper display screen 60 (FIG. 11), 
the text "Waveform" may be displayed by the processor 30 in the display 
area 180. This feature provides the user with an easily accessible means 
to determine the functionality of any of the graphically identified 
on-screen buttons on either the upper or lower display screens 60, 70 
while allowing the elimination of textual information from the displayed 
on-screen button to simplify the display. 
It is generally an unsafe practice to power-up a ventilator with a patient 
already attached because the ventilator may attempt to ventilate the 
patient in a manner which would be harmful to the patient. The respirator 
processor 60 is responsive to detection of a such a condition to start an 
"Safety PCV" ventilation mode and to send a signal to the processor 30 of 
the graphic user interface 20 to sound an alarm. In this mode, the 
respirator processor 60 controls the respirator 22 using a pre-determined 
set of ventilator setting in pressure-control mode. These pre-determined 
settings are selected to safely ventilate the widest set of possible 
patients. Once the new patient, or same patient setup process is completed 
as described above, the processor terminates the "Safety PCV" mode, and 
begins ventilating the patient in accordance with the newly entered 
settings. 
From the above, it will be appreciated that the present invention provides 
important new capabilities in the setup and display of alarms for a 
patient ventilator which uses an advanced graphic user interface. While 
several forms of the invention have been illustrated and described, it 
will also be apparent that various modifications can be made without 
departing from the spirit and scope of the invention. Accordingly, it is 
not intended that the invention be limited, except by the appended claims.