System and method for automatic critical event notification

A critical event notification system continuously monitors patient statistics and lab data to detect critical events, and automatically pages a responsible physician or physicians, each having an alphanumeric pager. In particular, a computer is used to continually access real-time data and multiple hospital databases which are periodically updated. These databases include patient chart databases, databases corresponding to patient history and databases maintained by various labs. The computer, preferably a clinical information system, is automatically provided with certain data, or periodically extracts it from other, relational databases. The computer automatically reviews this data, makes the critical event determination, and formulates an alphanumeric message that is informative as to the patient's condition and the reasons why a critical event was detected. After automatically retrieving from a database a personal identification number ("PIN") for a remote pager of each physician responsible for the patient, the computer automatically establishes modem contact with a paging network, and causes the network to page each responsible physician and transmit to them the alphanumeric message. The alphanumeric message preferably indicates patient name, diagnosis, the event prompting the page, and the name and return telephone number of medical personnel at the hospital who are attending the particular patient.

The present invention relates to a system and method for automatic critical 
event notification. In particular, its preferred embodiment provides a 
device that automatically interrogates hospital databases to examine 
patient data, and automatically pages physicians if it has determined that 
a critical event has occurred. 
BACKGROUND 
Computers and other electronic devices have revolutionized the practice of 
medicine in many hospitals. 
For example, some hospitals feature computer workstations installed at many 
patient bedsides and nursing stations. These workstations sometimes 
utilize automated sensors, which are coupled to the workstations to 
provide continuous streams of electronic data regarding a patient's 
condition. This enables a nurse or hospital technician to display various 
types of data side-by-side for review, and also to periodically store the 
data as an electronic "chart," or as part of a permanent electronic 
record. For example, these systems may be connected to automatic sensors 
that measure levels of certain elements of a patient's blood, such as 
oxygen saturation. Other sensors that have been connected to these 
automatic computer monitoring systems include urimeters, respiratory 
sensors, heartbeat sensors, as well as other sensors. 
Computer workstations of the type just described sometimes operate by 
receiving continuous data, which a nurse or technician may selectively 
sample and store in the patient's chart. For example, one typical mode of 
employing this equipment would be for the nurse to sample the continuous 
data representing the patient approximately every hour and cause the data 
to be entered permanently on the patient's electronic chart. When a 
physician responsible for the patient's care then reviews a hard-copy 
print-out of this chart, or reviews it on the workstation's display 
screen, the physician may issue appropriate orders relating to the 
patient's care. 
Of course, electronic "beepers" and paging systems have also played an 
important role in medical care. They permit a nurse or other medical 
assistant to request that the physician immediately check-in with the 
nurse in response to an immediate patient condition. Recently, these 
"beepers" and paging systems have provided alphanumeric display capability 
using a liquid crystal display screen of the physician's beeper. 
Accordingly, a nurse can use a paging network to send the physician a 
message requesting a response from the physician. These paging systems are 
relatively easy to operate and may be sometimes operated directly from a 
nurse's workstation, e.g., by manually formatting an alphanumeric message 
and sending that message as an electronic mail message to a paging 
network. For example, a commercially-available system called "Starlink" 
permits a nurse or other person to type in a message using a computer 
keyboard, and send that message to a remote pager using a modem. The 
"Starlink" system provides a paging facility which receives this modem 
communication along with identifying information for the particular 
physician, which is looked up by the nurse and included as part of the 
modem transmission, and causes the alphameric message sent by the nurse to 
be transmitted to the particular physician's pager. 
Computers and other electronic equipment such as those specific systems 
mentioned above have gone far to improve the quality and nature of medical 
care, but they still rely on significant human interaction if they are to 
function correctly. For example, there are occasions when a critical or 
sensitive condition of the patient will go unnoticed by a nurse or 
hospital technician, and not be reported to the physician. Other times, 
specific orders relating to a patient's symptoms may be issued for a 
patient, but due to a change in staff workshift, the condition might not 
always be properly recognized or properly reported to the physician. 
Lastly, sometimes the physician is diverted from attending to another 
patient, because hospital staff page the physician regarding mundane 
matters. 
There is therefore an urgent need in the art for a system that 
automatically notifies a physician in response to predetermined events. 
Preferably, systems of this type would not be needed on an individual 
basis for each particular patient; rather, a need exists for a system 
capable of monitoring many patients, ascertaining the presence of critical 
or sensitive events should they occur, and automatically determining the 
identity of the physician or physicians to be notified of the condition. 
Finally, a need exists for a system that reviews many physical parameters 
to determine the existence of complex conditions, e.g., a bradycardia 
which persists beyond a defined length of time. The present invention 
solves these needs and provides many further related advantages. 
SUMMARY 
The present invention provides a critical event notification system that 
significantly enhances medical care. It permits review of a patient's 
diagnostic information, lab results, chart, or other data, automatically, 
by computer or similar equipment, and it provides for automatic paging of 
a responsible physician or physicians should a "critical event" be 
detected. That is to say, a decision to page an individual (a physician in 
the case of the preferred embodiment) is made automatically by the system, 
and does not require a direct human decision. As can be seen therefore, 
the present invention permits reduction in the number of pages by 
controlling paging directly in response to automatically detected critical 
events. In the context of medicine, it helps ensure that situations 
requiring the physician's attention will always be correctly and 
immediately recognized and reported to the physician via a technical and 
informative message. The present invention is not limited to medical care 
and physicians, and should present a wide range of applications outside of 
the medical profession. 
One form of the invention provides a system that automatically notifies an 
individual of the existence of a critical value of a measurement 
parameter. It does this using a computer system that automatically 
monitors input data, a remote pager carried by the individual and a paging 
network that can page the individual using the remote pager. The computer 
system has a communications device that permits it to selectively 
communicate with the paging network and automatically page the remote 
pager. The computer system monitors the input data, either as it arrives 
or by performing periodic reviews of that data after it has been stored to 
a memory or logging device. The computer system automatically compares the 
data representing the measurement parameter with a predefined quantity. If 
it detects a predetermined relation, e.g., that the predefined quantity is 
greater than data representing the parameter, it thereby determines that a 
critical event has occurred. The computer system then electronically and 
automatically determines that the individual should be notified of the 
critical event, and causes the paging network to page the individual. 
In the preferred embodiment of a medical device that automatically notifies 
physicians, discussed below, one critical event could be defined as a drop 
in a patient's calcium level (as determined from periodic analysis of the 
patient's blood) below a predetermined critical level, e.g., below ten 
milligrams per deciliter. In this example, the measurement parameter would 
be calcium level, and there could be many such parameters carried by the 
data, for example, phosphorus, oxygen, urea, nitrogen and/or magnesium 
levels. Each of these can be analyzed with respect to a critical event, 
e.g., when concentration of one of these elements falls above or below a 
predetermined level or between a range of values. 
Instantaneous detection of whether a single parameter of input data meets a 
predefined relation (e.g., greater than, less than, equal to, between a 
range, etc.) is not the only application of the invention. Rather, the 
invention can also be used to automatically perform sophisticated review 
and analysis. As one example, the invention applies to monitor of several 
parameters simultaneously, and ascertain a critical event only when two 
conditions have been concurrently met (e.g., one parameter greater than a 
first value and a second parameter less than a second value). As another 
example, the invention can be applied to periodic review of stored data, 
e.g., determination of a critical event when a patient has been maintained 
on mechanical ventilation with a sixty percent or greater oxygen level for 
over four hours, with updates as to oxygen content being electronically 
provided by the ventilator periodically. In fact, the preferred embodiment 
(a medical paging system) is programmable to allow user definition of 
certain "exception" conditions which define a critical event, and these 
may be programmed on a patient by patient basis. 
From the foregoing, it should be readily apparent that the present 
invention provides an important advance in the field of medicine. As but 
one example, a physician could have specialized monitoring of a patient 
with a heart condition, and be notified when conditions exist which might 
be normal for other patients or healthy individuals. The paging of the 
physician is automatic, and in further specific features of the invention, 
the paging includes an alphanumeric message that is displayed on a pager 
display screen. Formulation of this message is automatic, and the 
individual to be paged is immediately and informatively notified of the 
precise nature of the critical event. Using the example mentioned above, 
the physician could be notified that a patient's calcium level has dropped 
below eight milligrams per deciliter, and further, the precise calcium 
level, the patient's name and diagnosis, and the name of a nurse attending 
to the patient and his or her telephone number at the hospital. 
In another more detailed feature of the invention, multiple pagers are 
used, each having a unique PIN number, and the individual to be notified 
of the critical event may vary depending upon the event. In the preferred 
embodiment, multiple patients may be monitored, and particular physicians 
paged depending upon the type of critical event and the identity of the 
patient. PIN numbers for each physician may be stored in a database or 
table in software, such that the computer system can analyze patient 
statistics and page the appropriate physicians. For example, if a 
particular patient suffers from an abnormally fast heartbeat 
("tachyarrhythmia"), then a resident physician, an attending physician and 
a cardiologist on-call could each be paged. The resident and attending 
physicians would, in that example, be paged based upon their assignment to 
the particular patient, and the cardiologist would be paged based upon the 
particular condition. 
The invention may be better understood by referring to the following 
detailed description, which should be read in conjunction with the 
accompanying drawings. The detailed description of a particular preferred 
embodiment, set out below to enable one to build and use one particular 
implementation of the invention, is not intended to limit the enumerated 
claims, but to serve as a particular example thereof.

DETAILED DESCRIPTION 
The invention summarized above and defined by the enumerated claims may be 
better understood by referring to the following detailed description, 
which should be read in conjunction with the accompanying drawings. This 
detailed description of a particular preferred embodiment, set out below 
to enable one to build and use one particular implementation of the 
invention, is not intended to limit the enumerated claims, but to serve as 
a particular example thereof. The particular example set out below is the 
preferred specific implementation of a critical event notification system, 
namely, one that uses conventional pieces of equipment such as a pager 
network, remote alphanumeric pagers, computer systems and modems. The 
invention, however, may also be applied to other types of systems and 
equipment as well. 
I. Introduction To The Principal Parts 
FIG. 1 is an illustrative diagram of the preferred embodiment, showing use 
of a clinical information system, automatic alert algorithms, which 
monitor patient data to detect critical events, and a pager network. In 
particular, six pictorial blocks 11, 13, 15, 17, 19 and 21 are shown in 
FIG. 1 to help illustrate the operation of the preferred embodiment. They 
also help show how the present system automatically monitors patient data, 
detects the occurrence of critical events, and automatically notifies a 
physician. To perform this notification, the system automatically formats 
pager messages, as necessary, and itself automatically makes the decision 
to page the physician. The six blocks of FIG. 1 will be discussed in 
clockwise order, beginning at the top left, and proceeding in the 
direction of the various arrows seen in that figure. 
The clinical information system monitors the patients and runs the alerting 
algorithms that make the decision to page. It consists of a commercially 
available computer network, namely, a CareVue 9000 System, available from 
the Hewlett-Packard Company. This system has a number of autonomous, but 
networked, computer workstations that execute software and supervise 
patient data for a large number of patients. The system may be used only 
for extremely ill patients who require continuous monitoring, for example, 
patients in ICU or CCU ("Cardiologic Care Unit"), or it could also be 
applied hospital-wide. One or more workstations also serves as a "server" 
workstation, and can interface through a second network with a number of 
other computer systems and databases. Each workstation display receives 
both continuous data inputs for certain patient statistics, e.g., pulse, 
and also periodic data, for example, representing lab results, such as 
enzyme production, drug levels, blood cell counts, etc., when they are 
available. Each workstation is also visually supervised by a nurse, who 
reviews the continuous data inputs and selectively samples them, e.g., 
"charts" them, when the continuous data is representative of the patient's 
condition. Thus, for example, certain patient statistics are periodically 
sampled and stored by the workstation (under the nurse's control) in a 
patient file at selected time intervals, for example, each ten minutes, 
each hour, etc. 
A typical display screen for one of the workstations is seen in the first 
block 11 of FIG. 1. In that display screen, one patient's file or chart is 
seen, with the columns of the display representing regular time intervals 
(e.g., each hour, half-hour, etc.) and the rows representing patient 
statistics which have been sampled, or provided by an external computer 
system maintained by one of the hospital's labs. The rows typically 
include vital signs, such as respiration rate, temperature, heart rate, 
cardiac output and other statistics; they also typically include patient 
urine statistics, IV fluid intake, respirator oxygen percentage and 
volume, hemoglobin, blood calcium and potassium levels, etc. 
The second block 13 of FIG. 1 represents alerting algorithms that are used 
by the server workstation of the clinical information system, some at 
periodic intervals, some each time new data is received. In particular, 
the server workstation provides an interface between the clinical 
information system and the other computer systems. Each time new data for 
a patient is reported to the clinical information system by an external 
computer (e.g., a blood gas computer or a clinical lab computer), that 
data is then distributed by the server workstation to the particular 
workstation corresponding to the patient. The data is then incorporated 
into the patient's chart. The server workstation also interfaces the 
clinical information system with an archives database (e.g., a computer 
mass storage device), so that patient data can be periodically stored in 
and retrieved from patient files maintained in the archives database. 
The alerting algorithms, as mentioned, are of two types. First, some 
algorithms are used to detect critical events represented by incoming lab 
data, as that data is distributed by the server workstation to the 
particular workstation corresponding to the patient. While the server 
workstation distributes this data, the alerting algorithms review the data 
to determine if a "critical event flag" has been placed in the data by the 
hospital lab. Second, the server workstation also employs algorithms that 
periodically import selected data from patient files or particular 
workstations, as a logical unit of work, in order to perform more complex 
analysis, e.g., the detection of "exception conditions." For example, one 
exception condition is the state of a ventilator patient requiring a sixty 
percent or greater oxygen level for more than four hours. This type of 
analysis cannot be performed upon instantaneous measurements, such as upon 
only one data measurement obtained from hospital lab and distributed by 
the server workstation, and so, the analysis is performed on a periodic 
basis. 
The clinical information system and other hospital systems are structured 
as relational databases, which permit the server workstation and other 
hospital computer systems to import and export data from databases all 
over the hospital as part of a logical unit of work. Thus, the clinical 
information system has access to all of the computer data that it needs to 
complete its sophisticated review, and is not limited to a review of data 
that is stored by any one particular workstation or group of them. To 
obtain this data, the server workstation formats a request for a 
particular type of data, which it addresses to a computer system or 
database possessing that data. 
When the server workstation detects a critical event for a particular 
patient, either via a critical event flag (e.g., abnormal measurement 
data) or via the existence an exception condition (periodic patient file 
analysis), it automatically and immediately pages the responsible 
physician or physicians. To do this, the server workstation formulates an 
alphanumeric message that (1) identifies the patient and preliminary 
diagnosis (the medical ailment of the patient), (2) the particular 
critical event that has occurred and other critical alphanumeric 
information related to that critical event, and (3) provides the physician 
with the name of the responsible nurse at the hospital and a telephone 
number by which the physician can contact the nurse. The server 
workstation then dials a pager network via modem 23, as seen in the third 
block 15 of FIG. 1. The information automatically formulated and sent to 
the pager network includes not only the critical event information just 
described, but also a personal identification number ("PIN") for the 
particular remote pager to which the message is to be sent. 
As indicated by the fourth block 17 of FIG. 1, the preferred pager network 
is a network known as the "StarLink" system, and provides automatic 
alphanumeric paging under the control of a computerized paging system. In 
fact, users of this type of paging network typically receive computer 
software that allows one, a nurse for example, to type an alphanumeric 
message into a computer system via a keyboard, which then employs special 
software to transmit this alphanumeric message to the paging network via 
the modem 23. In the preferred embodiment, formulation of an alphanumeric 
message and obtainment of a PIN is automatically performed by software 
running on the server workstation, any time a critical event is detected, 
without human intervention. It thus helps eliminate human error and time 
delays incurred in first noticing critical events in a patient's 
condition, and then, in notifying the physician who is responsible for the 
patient's care. Once the message is transmitted to the paging network, a 
transmitter 25 is used to send out the alphanumeric message, via 
satellite, such that it may be addressed to a particular PIN. 
The fifth block 19 of FIG. 1, located at the bottom-middle of FIG. 1, shows 
an actual remote alphanumeric "beeper," or pager 27, which is preferably a 
commercially-available pager known as a "Palmtop" computer, and is also 
made by the Hewlett-Packard Company, model number 200LX. The pager is 
basically a notebook computer which includes a special circuit inserted 
into the side of the computer, namely a "StarLink" receiver circuit 29. 
This circuit includes radio frequency ("rf") circuitry necessary to 
intercept and decode messages addressed to that particular remote pager, 
as identified by the unique PIN associated with the receiver circuit 29. 
Finally, the sixth block 21 of FIG. 1 illustrates an alphanumeric display 
screen of the "Palmtop" device 27, which can simultaneously display 
numerous lines of text. In particular, the "Palmtop" device 27 is carried 
by each physician that is to be reached using the preferred embodiment. 
When the physician is paged, the display screen 31 indicates the patient's 
name, the particular critical event which triggered the page, the 
patient's diagnosis, and the number and name of a nurse to whom the 
physician can convey responsive orders. FIG. 1 does not show display of 
this latter information!. 
It is presently contemplated that this system will also provide for two-way 
communication, such that using the keyboard 33 of the "Palmtop" device 27, 
the physician can issue orders which are then transmitted in the reverse 
direction, e.g., to a paging or cellular radio network, via modem, page or 
radio link to the clinical information system, and to the pertinent 
workstation where the orders can be displayed to the nurse responsible for 
the patient. 
As can be seen from FIG. 1, the preferred embodiment is a medical system 
that uses automatic review of both continuous and periodic electronic data 
representing a patient to automatically and immediately notice and report 
critical events. Contact is automatically made to a remote pager 27 by the 
preferred embodiment, such that a physician is immediately informed of the 
existence and the precise nature of the critical event. Thus, the 
physician can determine the seriousness of the critical event and how to 
appropriately respond to it. 
With the principal parts of the preferred embodiment thus introduced, the 
design of the preferred system will now be described in further detail. 
II. FIG. 2; The Processing Of Patient Data 
FIG. 2 helps further illustrate the operation of the preferred system. 
Patient data for each patient is provided to the clinical information 
system from three sources: These include (a) periodic data representing 
test results from a blood gas computer; (b) periodic data representing 
test results from a clinical lab computer; and, (c) continuous data 
provided directly to one of the workstations from a variety of sensors. 
These sources are respectively indicated as rectangular blocks 35, 37 and 
39 at the bottom of FIG. 2. 
Each of the blood gas computer and the clinical lab computer are autonomous 
computer systems which are completely separate from the "CareVue 9000" 
clinical information system and the workstations. They each include export 
utilities which automatically send any new data to the server workstation, 
which performs critical value flag detection, as indicated by the 
reference numeral 41. This data is then distributed to the particular 
workstation associated with the patient corresponding to the data, which 
stores this information a part of the patient's chart, or file. This 
latter operation is designated by the reference numeral 43. 
In the preferred embodiment, data from the two periodic sources is 
electronically and automatically obtained, but is first reviewed by an 
assistant in the particular lab who can add notes or a critical flag to a 
patient file. The assistant then causes this data to be stored, in a 
storage device dedicated to the particular computer system, and the export 
utilities for the particular computer automatically send this data in a 
standard format, preferably the format known as "HL7". Table 1, below, 
provides an example of the "HL7" format. 
TABLE 1 
______________________________________ 
"HL7" Message Format 
______________________________________ 
MSH.vertline. .about..backslash.&.vertline.CLI.vertline.SUNQUEST.vertline. 
CLI.vertline.8SICU.vertline.19950612120434.vertline..vertline. 
ORU R01.vertline.118.vertline.P.vertline.2.1.vertline..vertline. M 
PID.vertline..vertline..vertline.000314643.vertline..vertline.DOE 
JOHN.vertline..vertline.19230501.vertline.M.vertline..vertline..vertline.. 
vertline..vertline..vertline..vertline..vertline..vertline..vertline..vert 
line..vertline. M 
OBR.vertline..vertline..vertline.L907569.vertline..vertline..vertline..ver 
tline.199506121100.vertline..vertline..vertline..vertline..vertline..vertl 
ine..vertline.199506121122 
.vertline..vertline..vertline..vertline..vertline..vertline..vertline..ver 
tline..vertline..vertline..vertline.F.vertline..vertline..vertline..vertli 
ne.M74281.vertline..vertline..vertline..vertline..vertline..vertline..vert 
line. M 
OBX.vertline.1.vertline.ST.vertline.CA CALCIUM.vertline.1.vertline.5.5.ver 
tline.MG/DL.vertline.8.3-10.7.vertline.L.vertline..vertline..vertline.F.ve 
rtline. M 
NTE.vertline..vertline..vertline.CRITICAL VALUE M 
OBX.vertline.3.vertline.ST.vertline.PHOS PHOSPHORUS.vertline.2.vertline.3. 
7.vertline.MG/DL.vertline.2.5-5.0.vertline..vertline..vertline..vertline.F 
.vertline. M 
OBX.vertline.4.vertline.ST.vertline.URCA URIC ACID.vertline.3.vertline.5.2 
.vertline.MG/DL.vertline.2.8-8.0.vertline..vertline..vertline..vertline.F 
OBX.vertline.5.vertline.ST.vertline.TBIL BILIRUBIN, TOTAL.vertline.4.vertl 
ine..05.vertline.MG/DL.vertline.0.1-1.2.vertline..vertline..vertline..vert 
line.F.vertline. M 
OBX.vertline.6.vertline.ST.vertline.DBIL BILIRUBIN, DIRECT.vertline.5.vert 
line.TOTAL B.vertline.MG/DL.vertline.&lt;0.3.vertline..vertline..vertline..ve 
rtline.F.vertline. M 
NTE.vertline..vertline..vertline.NOT CALCULATED M 
OBX.vertline.8.vertline.ST.vertline.TP PROTEIN, TOTAL.vertline.7.vertline. 
4.5.vertline.G/DL.vertline.6.0-8.5.vertline.A.vertline..vertline..vertline 
.F.vertline. M 
OBX.vertline.9.vertline.ST.vertline.ALB ALBUMIN.vertline.8.vertline.2.7.ve 
rtline.G/DL.vertline.3.5-5.5.vertline.A.vertline..vertline..vertline.F.ver 
tline. M 
OBX.vertline.10.vertline.ST.vertline.ALP ALKALINE PHOSPHATASE.vertline.9.v 
ertline.44.vertline.U/L.vertline.&lt;108.vertline..vertline..vertline..vertli 
ne.F.vertline. M 
OBX.vertline.11.vertline.ST.vertline.AST ASTATE AMINOTRANS 
SGOT!.vertline.10.vertline.55.vertline.U/L.vertline.&lt;35 
.vertline.A.vertline..vertline..vertline.F.vertline. M 
OBX.vertline.12.vertline.ST.vertline.ALT ALANINE AMINOTRANS 
SGPT!.vertline.11.vertline.23.vertline.U/L.vertline.&lt;40.vertline..vertlin 
e..vertline..vertline. 
F.vertline. M 
OBX.vertline.13.vertline.ST.vertline.MG MAGNESIUM.vertline.12.vertline.1.6 
.vertline.MG/DL.vertline.1.6-2.6.vertline..vertline..vertline..vertline.F. 
vertline. M 
______________________________________ 
In the fourth line of Table 1, above, the parameter .vertline.L.vertline. 
represents a critical event associated with a low calcium reading, as 
determined in the blood gas chemistry lab. This flag in the preferred 
embodiment is added by the assistant who monitors a display of the 
electronically-ascertained data; the software used by the particular 
computer system is used to automatically detect a critical value and bring 
it to the attention of the assistant, for example, using highlighting in 
the visual display. Upon noticing a critical value, the human assistant 
further utilizes the software to cause a critical flag to be attached to 
the record, as well as the note reflecting the existence of the critical 
value. Receiving this message, the workstation server simply monitors the 
"HL7" format to detect occurrence of the parameter .vertline.L.vertline., 
by comparing each data transmission of the message with this quantity. 
Further desired critical event parameters, and comparison characteristics 
that have actually been implemented, are indicated in tables 2 and 3, 
below. 
TABLE 2 
______________________________________ 
Critical Event Parameters 
Serum Chemistries Drug levels 
______________________________________ 
Sodium Phenytoin 
Potassium Theophylline 
Chloride Phenobarbital 
Bicarbonate Quinidine 
Calcium Lidocaine 
Hematology Procainamide 
Hemoglobin NAPA 
Hematocrit Digoxin 
White Blood Count Thiocyanate 
Partial Thromboplastin 
Gentamicin 
Time 
Prothrombin Time % Tobramycin 
Activity 
Arterial blood gas Cardiac Enzymes 
pH Creatinine kinase (CK) 
PO.sub.2 CK-MB 
PCO.sub.2 
______________________________________ 
TABLE 3 
______________________________________ 
Critical Event Parameters And Comparison Values 
Low High 
______________________________________ 
Na+ 120 160 
K+ 3.0 6.5 
Cl- 80 156 
HCO.sub.3 10 40 
Hgb 7 18 
Hct 21 60 
WBC 2 35 
______________________________________ 
Critical event detection can also be accomplished by programming the server 
workstation with alerting algorithms that look at the numerical value of 
each parameter to compare it to an associated number, instead of comparing 
the quantities in the "HL7" format with the alphanumeric quantity 
.vertline.L.vertline.. In this latter example, there would be no need for 
the lab assistant to insert a critical event flag into the "HL7" format 
message, but the critical event would be directly determined using 
numerical data within the "HL7" format message. In fact, automated review 
of this nature is implemented for determination of some exception 
conditions, e.g., some exception condition review is automatically 
triggered upon arrival of certain new data, such as from a ventilator. It 
is well within the skill of one familiar with computer systems to 
construct an alerting algorithm of this type. 
Irrespective of the manner in which a critical event is determined to 
exist, the clinical information system both stores the periodic 
information in the patient's file, and also proceeds to formulate a pager 
message, as indicated by a middle block 45 of FIG. 2, where parallelograms 
are used to represent actions taken by the clinical information system. 
During the formulation of a pager message, the system requests the 
identity of a physician PIN and the name of a nurse and corresponding 
telephone number from administrative files stored by an external, 
administrative computer 47. This administrative computer maintains a 
database of this information, and returns appropriate information 
depending upon staffing, for example, depending upon time of day, shift, 
etc. It automatically selects each appropriate physician PIN, a name of a 
responsible nurse whom the physician(s) may call in response to the page, 
and a telephone number. In requesting this information, the clinical 
information system provides an identity (number or name) for the 
particular patient, to be used by the administrative computer as an index. 
The administrative computer 47 returns this requested information to the 
clinical information system, which then inserts the requested information 
into the pager message and exports the PIN for each physician to be paged. 
Each PIN is used by the paging network as an address to which the 
alphanumeric message will be sent. 
At this same time, the clinical information system also sends the pager 
message to a pager message database log 50, which stores the pager message 
as a record of the critical event, for use in records, statistics and 
review of system performance. 
As to patient data from the third source 39, continuous data from the 
patient's bedside is directly provided to a particular workstation of the 
clinical information system by means of electronic sensors, such as heart 
rate sensors, IV monitors and the like. The software running on the 
clinical information system permits a nurse or technician to automatically 
sample and store this information as part of the patient's chart when 
readings are representative of the patient's condition. Typically, this 
will be done each hour for ICU patients, but it may be done at any desired 
time or time interval. 
As indicated by the block 43 of FIG. 2, the particular workstation 
dedicated to each patient displays both the just-mentioned samples of the 
continuous data, and also new lab data sent to it from the server 
workstation, as part of the patients' files. These files are periodically 
stored in a mass storage device, which act as a data archives. 
Periodically, alerting algorithms are employed by the workstation to 
determine the existence of an "exception" condition, an operation 
indicated by the parallelogram 51. The term "exception condition" refers 
to complex conditions that can be ascertained by a review of different 
data, representing the same or different parameters. As examples, one 
exception condition used in connection with a patient on a ventilator is 
whether the patient has required levels of oxygen ventilation of greater 
than 60% oxygen composition for over four hours duration. This type of 
condition cannot in the preferred embodiment be determined from just 
instantaneous data provided from directly from the ventilator, and so, 
patient files are periodically reviewed to look at several, time-spanned 
data entries representing oxygen composition. In fact, as mentioned, 
review of this data is triggered anytime new data is received. For 
example, if continuous data provided from the ventilator to the particular 
workstation has been sampled once each hour, then as each new data is 
received, the four most-recent ventilator data samples may be examined 
each hour to determine whether the exception conditions have been met (in 
the preferred embodiment, ventilator data is updated as often as once per 
minute). Other exception conditions may be based on a combination of 
different types of data, for example, an exception condition detecting a 
pathological arrhythmia could be based upon both instantaneous heart rate 
and respiration rate. Exception conditions used in the preferred 
embodiment are identified in table 4, below. 
TABLE 4 
______________________________________ 
Exception Conditions 
______________________________________ 
FiO.sub.2 &gt; 60% for 4 hours or more 
Urine output &lt; 0.3 cc/kg/hr and 
patient not admitted in renal failure 
Pulmonary capillary wedge pressure &gt; 22 mm Hg 
Systolic blood pressure &lt; 80 mm Hg and 
patient has no pulmonary artery catheter 
Systolic blood pressure &lt; 80 mm Hg and 
pulmonary artery wedge pressure &lt; 10 mm Hg 
Ventricular tachycardia (cardiac arrhythmia) 
Ventricular fibrillation (cardiac arrhythmia) 
Code Blue (cardiac arrest) 
PEEP &gt; 15 cm H.sub.2 O 
Readmission to SICU &lt; 48 hours after discharge 
______________________________________ 
Critical events in the preferred embodiment are ascertained using the 
alerting algorithms by (1) detection of a critical value flag in a "HL7" 
format message or (2) via detection of an exception condition. These 
operations are expressed as the parallelograms 41 and 51 found in roughly 
the middle of FIG. 2. Once a critical event is detected, software run by 
the server workstation is used to compile an alphanumeric pager message 
(as indicated by the parallelogram 45) and obtain a PIN for each physician 
to whom the message is to be sent. Once the message is formulated, it 
along with each physician PIN is sent to the "Starlink" paging network via 
modem, which causes the physician(s) to be paged and the alphanumeric 
message to be transmitted to them. This operation is designated by the 
reference numeral 53 of FIG. 2. 
Examples of physicians' remote beeper display of alphanumeric messages for 
each type of critical event (exception condition and critical value) are 
seen in FIGS. 10 and 11, respectively. In particular, these figures show 
use of the Hewlett-Packard model 200LX Personal Data Assistant, which has 
a multi-line alphanumeric display and a PCMCIA receiver fitted to the 
unit. One new system that shows promise for use in the future is the new 
M1490A Palmtop System, also available from Hewlett-Packard, which uses 
"PalmVue" software. This latter system has capabilities that allows it to 
display graphs and charts and the like, as part of the alphanumeric 
display. 
III. Hardware Of The Preferred Embodiment 
FIGS. 3 and 4 help illustrate the hardware of the preferred embodiment. 
FIG. 3 shows an overview of the entire system 55, whereas FIG. 4 shows the 
constituency of one of the "patient data" blocks 57 input to each 
workstation 59, as indicated in phantom in FIG. 3. 
Two different groups of computer systems 61 and 63 are seen in FIG. 3. 
First, the clinical information system 61 is seen at the right side of 
FIG. 3, and consists of multiple workstations 59 connected by a local area 
network 67, each workstation receiving continuous patient data as 
distributed by a server workstation 69. The server workstation 69 
interfaces with external hospital computer systems (designated 63) and 
databases, which are seen at the left-hand side of FIG. 3. They include 
(1) a blood gas lab computer 71, which is preferably a Digital Equipment 
Corporation ("DEC") model 11/23 computer system; and (2) a clinical lab 
computer 73, which is preferably a VAX model 8530 computer system. Each of 
these computer systems, as alluded to earlier, maintains its own database 
and memory, and uses scripting to export any new patient data to the 
clinical information system 61 as that data is stored on that system. 
Those desiring additional detail as to the interface between these 
computer systems 71 or 73 and the clinical information system 61, and how 
new data from these computer systems is processed, are referred to the 
following references: (1) "Inferencing Strategies For Automated Alerts On 
Critically Abnormal Laboratory And Blood Gas Data" by authors Shabot, 
LoBue, Leyerle and Dubin, Proceedings Of The Thirteenth Annual Symposium 
On Computer Applications In Medical Care, Washington, D.C., Nov. 5-8, 
1989; (2) "Real-Time Wireless Decision Support Alerts on a Palmtop PDA," 
by M. Shabot and M. LoBue, Nineteenth Annual Symposium On Computer 
Applications In Medical Care; and also (3) Decision Support Systems In 
Critical Care, Ed. M. Michael Shabot and Reed Gardner (Springer-Verlag 
1994). These references are hereby incorporated by reference into this 
disclosure, as though fully set forth herein. 
In addition to these computer systems, the external hospital computer 
systems also include (3) the scientific data center computer 49, which 
consists of a VAX cluster, and (4) the administrative computer 47, which 
is preferably an IBM mainframe. All four of these computer systems 47, 49, 
71 and 73 are coupled to the server workstation 69 via a second local area 
network 75, which is different than the network 67 for the clinical 
information system. Lastly, the server workstation also interfaces with a 
mass storage device 77 (labelled "data archives" in FIG. 3), used for 
storage of patient files, and the internal modem 23 which is used to 
report critical events to the pager network and page physicians. Many 
suitable modem and mass storage devices are available and appropriate, and 
selection of one is left to one of ordinary skill with computers. 
FIG. 4 helps show the constituency of each "patient data" block 57 of FIG. 
3. The patients 79 are monitored by three different devices, including 
ventilators 81, urimeters 83 and Merlin monitors 85. The ventilators 81 
can be any commercially-available ventilators, which will supply numerous 
types of information updates to the clinical information system, for 
example, consisting of many different parameters, each time there is any 
type of change in any one of them. Since the format of this data and its 
transmission does not necessarily match the format accepted by the CareVue 
9000 system, a digital interface 87 is constructed to adapt the 
transmission of information from the ventilators 81 to a uniform format 
that is placed upon a third network 93 that is coupled to the server 
workstation 69. Likewise, data from urimeters 83 must also pass through an 
interface 89 to place information on the network. Finally, the Merlin 
monitors 85 directly monitor IV sensors and life sign sensors, and provide 
this data through a HP Careport Merlin interface 91 onto the network 93. 
This latter interface is chosen to be a model 1000/A600, also available 
from the Hewlett-Packard company. With these interfaces 87, 89 and 91, 
data changes may be reported to the clinical information system 61 which 
may then sample the data to display current patient readings; the clinical 
information system is used to selectively sample these readings and write 
them to a permanent file, i.e., the patient's chart. 
IV. Software Of The Preferred Embodiment 
FIGS. 5-9 show functional blocks which correspond to the parallelograms 41, 
45, 51 and 53 seen in FIG. 2. FIGS. 5 and 6 in particular show functional 
block diagrams for detecting alerting triggers, based on critical value 
flags, and detection of exception conditions, respectively. FIG. 7 shows 
the formulation of a pager message, whereas FIGS. 8 and 9 together show 
the queuing and sending of pager messages under modem control, 
respectively. All of the software to effectuate these functions is written 
in C++ and is principally run on the server workstation 69. 
FIG. 5 has two general sections 95 and 97 which are illustrated in phantom; 
the first section 95 refers to activities of the external computer systems 
(either the blood gas computer 71 or the clinical lab computer 73), 
whereas the second section 97 shows activities performed by the clinical 
information system 61 as data from these computers is received and 
distributed. As indicated by the top section 95 of FIG. 5, scripting is 
used to generate a data record each time new data is received; this 
information is both written to the computer system's memory 99, and also 
placed into "HL7" format. At this time, scripting of the particular 
computer 71 or 73 is written so as to preferably detect and highlight the 
display of critical values. A lab technician also visually reviews the 
data as it appears to him on a monitor, to attach specific notes and 
flags, including critical value flags as appropriate. The message is then 
placed into the "HL7" format, and is stored in the memory 99 of the 
computer. The scripting for the computer 71 or 73 also copies this message 
and send it to the clinical information system 61. 
The clinical information system 61 of the preferred embodiment analyzes 
each new data message from either the blood gas computer 71 or the 
clinical lab computer 73 to determine whether the message contains a 
critical event flag, i.e., the quantity .vertline.L.vertline. if the 
message is "HL7" format. Accordingly, the server workstation 69 first 
determines whether this quantity is present, and if so, formulates a 
critical event message and causes it to be sent to the paging network. 
However, whether or not this quantity is present, the clinical information 
system 61 updates patient files 101 (i.e., the particular patient's chart 
stored in the data archives 77) to reflect the new data. 
FIG. 6 is a block diagram of one alerting algorithm that reviews exception 
conditions. In general, each exception condition has a dedicated algorithm 
that is run on a periodic basis, for example, each hour, or each time 
certain new data is received. When an algorithm is called, it extracts 
parameters as needed sequentially from each patient file 101 in the data 
archives 97, that is, from each patient file maintained by the server 
workstation. These parameters are compared to predetermined alphanumeric 
quantities, to ascertain whether they bear a predefined relation to those 
quantities. For example, using one example stated above relating to 
ventilators, an alerting algorithm retrieves each oxygen sample from the 
patient files for the previous four hours duration; with respect to each 
sample, the algorithm compares the sample with a quantity representing 
sixty percent oxygen. If all of the samples satisfy the relation that they 
are greater than this figure, a critical event is detected, and a specific 
message is formulated relating to the critical event. For example, the 
pager message seen in FIG. 10 represents two simultaneous critical events, 
including a ventilator oxygen component of greater than four hours, and a 
PEEP value that is greater than or equal to fifteen. The comparison 
quantities do not have to be numeric but, for example, may also be or 
include alphabetical or other quantities. 
FIG. 7 shows a functional diagram for the processing of detected critical 
events and message formulation. When a critical event is detected, the 
clinical information system 61 sends a patient identifier (a number 
corresponding to the particular patient, or to the particular hospital 
bed) to the administrative computer 47, and requests a physician PIN for 
each physician to be paged in response to detection of a critical event. 
For example, a critical event corresponding to an ICU patient might 
require paging of a resident and an attending physician. The 
administrative computer 47 stores information on physicians responsible 
for each patient's care, and returns the requested information to the 
clinical information system 61 for use in connection with paging. 
Additionally, however, the administrative computer 47 also stores 
information regarding the nurse to be contacted for the particular patient 
and the telephone number by which the physician(s) paged can contact the 
nurse to deliver orders in response to the page. This information is also 
returned to the clinical information system 61 by the administrative 
computer 47, for incorporation into the critical event message. Finally, 
one contemplated embodiment also sends an indication of the particular 
critical event to the administrative computer, in order that a specialist 
may be also paged. For example, if the particular critical event is the 
ventricular fibrillation exception condition, the clinical information 
system 61 may indicate to the administrative computer 47 that the 
physician PIN for a cardiologist on-call should also be returned to the 
clinical information system together with the other information. In this 
manner, an alphanumeric message is formulated for each PIN of a physician 
to be paged, and may consist of the following information: (1) critical 
event number; (2) type of critical event--either an exception condition or 
a critical (alert) value; (3) patient name; (4) patient number; (5) 
patient diagnosis; (6) patient location (e.g., ICU); (7) patient age; (8) 
date and time; and (9) other patient data, such as length of time that the 
patient has been in ICU, for example. All of this information is retrieved 
from the patient file by the clinical information system at the time that 
a critical event is detected. In addition to this information, the 
critical event detection algorithms also return to the message formulation 
routine information as to the (10) exact type of critical event (e.g., low 
blood pH level) that has been detected and (11) precise values that 
triggered detection the critical event (e.g., pH of 6.99). 
Finally, information maintained in databases stored in the external 
computer systems, namely, in the administrative computer system, is 
requested and provided to the clinical information system as just 
described. This information includes (12) physician PIN(s) for paging each 
physician responsible for the patient, (13) a nurse name and (14) a nurse 
telephone number. The physician PIN(s) are used to determine the number of 
messages that will be sent to the Starlink paging system, one copy 
addressed to each physician to be paged. The latter information is 
included in the alphanumeric message sent to each physician if the system 
is configured to monitor patients in diverse locations, e.g., it would be 
difficult to phone orders in without it. 
FIGS. 8 and 9 show the placing of alphanumeric messages into a queue for 
transmittal to the Starlink paging network. As indicated by FIGS. 8 and 9, 
each time a critical message is generated, it is placed into a queue of 
messages awaiting modem transmission. This implementation is preferred, 
because in a typical case, more than one physician will be paged, hence 
multiple messages can be generated by the clinical information system in a 
very short time period. An independent routine, as indicated by FIG. 9, 
retrieves messages from the queue and transmits them to the Starlink 
paging network via modem, and flags the message as having been sent. 
Use of a unique PIN for each physician permits messages to be independently 
directed to each physician. The Starlink network is effective, upon 
receiving a modem transmission containing a PIN and an alphanumeric 
message, to page the particular physician corresponding to the PIN and to 
display upon the remote beeper (the HP 200LX Personal Data Assistant) the 
precise alphanumeric message that was formulated by the software of the 
server workstation. Two examples of alphanumeric messages sent using the 
Starlink paging network are seen in FIGS. 10 and 11, as they would appear 
upon the 200LX remote beeper's display screen. 
Numerous prospective improvements to this preferred embodiment are 
contemplated to be within the scope of the present invention, as it is 
defined in the claims below. First, particular medical conditions have 
been chosen for critical event analysis in the preferred embodiment; it 
should be apparent that any type of medical condition may be programmed 
for critical event analysis. For example, the HP CareVue 9000 system can 
permit review of hundreds of parameters; a flowsheet showing some of these 
parameters reviewed by the clinical information system is seen in FIGS. 12 
and 13. The clinical information system can be programmed to detect nearly 
any condition or combination of conditions, instantaneous, 
time-distributed, or otherwise, as is believed to be appropriate. As 
another example of a prospective embodiment, the new "PalmVue" model 
M1490A system from Hewlett-Packard permits not only display of 
alphanumeric pager messages, but also graphical displays showing 
cardiographs and other types of information, as part of the pager message. 
It would be well within the skill of one familiar with hospital computer 
systems to implement pager messages that include waveforms, for example, 
cardiographs, as well as to implement waveform analysis as a critical 
event detection mechanism. Also, as mentioned, it is contemplated that 
alphanumeric display devices also include a keyboard 33, which can be used 
to automatically transmit orders and other information back to the 
hospital, so that the physician does not require access to a telephone. 
Finally, the present invention is not limited to applications dealing with 
medicine or hospital care. 
Having thus described an exemplary embodiment of the invention, it will be 
apparent that further alterations, modifications, and improvements will 
also occur to those skilled in the art. Further, it will be apparent that 
the present invention is not limited to use of a medical paging apparatus. 
Such alterations, modifications, and improvements, though not expressly 
described or mentioned above, are nonetheless intended and implied to be 
within the spirit and scope of the invention. Accordingly, the foregoing 
discussion is intended to be illustrative only; the invention is limited 
and defined only by the various following claims and equivalents thereto.