Portable checklist system

A computerized checklist system for use in the medical field preferably comprises a checklist unit adapted to be held in an operator's hand and a cradle for supporting the checklist unit. Each of these components includes a microprocessor for controlling the operation thereof. An optical link is provided to transmit data between the devices. The checklist unit includes suitable memory for storing alphanumeric checklist data including a sequence of checklist items. A display and a voice synthesizer selectively output checklist items. The checklist unit includes a keypad having a plurality of control switches for enabling an operator of the checklist unit to enter one of a plurality of signals indicating that the operator has taken one of a plurality of predetermined actions in response to each checklist item outputted by on the display and/or spoken by the voice synthesizer. The handheld unit also includes a program, responsive to processing of the checklist items during a work session, for storing a session log, the session log including data identifying each checklist item outputted during the work session, the signal entered by the operator in response to each checklist item, and a time when such signal was entered by the operator. Following placement of the handheld unit in the cradle after the work session, the session log data is downloaded to the cradle and then printed in a predetermined format.

TECHNICAL FIELD 
The present invention relates generally to self-contained data storage and 
display devices and, in particular, to a computerized checklist system 
that displays and speaks preprogrammed alphanumeric data in a 
predetermined sequence. 
BACKGROUND OF THE INVENTION 
Printed checklists have been used extensively in many fields to ensure the 
safe and consistent operation of sophisticated equipment and systems. For 
example, during an operation or other medical procedure, a medical 
specialist must often follow certain instructions in a predetermined 
manner to enhance the efficacy of a given procedure. Moreover, during the 
procedure it is often necessary to produce a contemporaneous or 
"real-time" record associated therewith to verify the operator's diligence 
during the procedure. Such records can be of critical evidentiary 
significance should a question arise concerning the proper performance of 
the procedure. 
Misuse of a checklist can have far-reaching consequences. In the medical 
application, such misuse can create tremendous risks to the patient 
undergoing the procedure and, of course, increase the attendant liability 
of the physician. Thus, there is a great need for a checklist management 
system which is portable and easy to use, which allows the operator to 
focus on the procedures being implemented rather than on the checklist, 
which prevents the accidental omission of checklist items, and which 
enables the operator to produce a contemporaneous record verifying 
compliance with the checklist. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a novel computerized checklist 
system for use in the medical field and in other applications in which it 
is necessary for an operator to have a portable unit for use in sequencing 
through checklists. 
It is still another object of the invention to provide a handheld 
computer-controlled checklist system which is easy to use and allows the 
operator to focus his or her attention on procedures instead of 
recordkeeping tasks. 
It is yet another object of the invention to provide a checklist 
management/recordkeeping device for verifying an operator's compliance 
with checklist obligations. 
It is a further object of the invention to provide a handheld computerized 
checklist management system that displays and speaks preprogrammed 
alphanumeric data in a predetermined sequence and then records responses 
thereto to create a self-authenticating record of an operator's successful 
compliance with a diagnostic procedure. 
These and other objects of the invention are provided in a computerized 
checklist system comprising a digital processor, storage means connected 
to the digital processor for storing alphanumeric checklist data including 
a sequence of checklist items, output means connected to the digital 
processor for selectively outputting checklist items, program control 
means for controlling the digital processor to effect presentation, by the 
output means, of the checklist items, and a plurality of switches for 
enabling an operator of the checklist system to enter one of a plurality 
of signals indicating that the operator has taken one of a plurality of 
predetermined actions in response to each checklist item outputted by the 
output means. According to the invention, the system further includes 
program control means, responsive to processing of the checklist items 
during a work session, for generating a session log. The session log 
includes data identifying each checklist item outputted during the work 
session, the signal entered by the operator in response to each checklist 
item, and a time indication of when such signal was entered by the 
operator. Moreover, for recordkeeping purposes the system derives a 
verification code from the session log data. The verification code is 
uniquely associated with the session log data for the work session. The 
system also includes printer means for generating a printout of the 
session log in a predetermined format along with the verification code to 
facilitate subsequent verification of the session log data. 
According to the more specific aspects of the invention, the computerized 
checklist system comprises two basic components: a checklist unit adapted 
to be held in an operator's hand, and a cradle for supporting the 
checklist unit. Each of these components includes a microprocessor for 
controlling the operation thereof. An optical link is provided to transmit 
data between the devices. The checklist unit includes suitable memory for 
storing alphanumeric checklist data including a sequence of checklist 
items. A display and voice synthesizer selectively output checklist items. 
The checklist unit includes a keypad having a plurality of control 
switches for enabling an operator of the checklist unit to enter one of a 
plurality of signals indicating that the operator has taken one of a 
plurality of predetermined actions in response to each checklist item 
outputted by on the display and/or spoken by the voice synthesizer. The 
handheld unit also includes a program, responsive to processing of the 
checklist items during a work session, for generating a session log, the 
session log including data identifying each checklist item outputted 
during the work session, the signal entered by the operator in response to 
each checklist item, and a time when such signal was entered by the 
operator. Following placement of the handheld unit in the cradle after the 
work session, the session log data is downloaded to the cradle and then 
printed in a predetermined format. 
The foregoing has outlined some of the more pertinent objects of the 
present invention. These objects should be construed to be merely 
illustrative of some of the more prominent features and applications of 
the invention. Many other beneficial results can be attained by applying 
the disclosed invention in a different manner or modifying the invention 
as will be described. Accordingly, other objects and a fuller 
understanding of the invention may be had by referring to the following 
Detailed Description of the preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, the computerized checklist system of the present 
invention is generally identified by reference numeral 10. Computerized 
checklist system 10 includes two (2) primary components: a handheld 
checklist unit 12 and a charger stand unit 14. The units are connected via 
an optical link 15 and an electrical power connection 17. The handheld 
unit 12 is preferably battery-powered and functions to read and manage the 
checklist for the operator. The charger stand unit 14 provides the 
necessary mechanical and electrical interfaces for recharging the 
batteries of the handheld unit 12, as well as the necessary electronics to 
interface the unit charger 14 to a dot matrix printer 16 via a Centronics 
parallel data link 19. A voltage converter 18 transforms 110 a.c. line 
voltage into appropriate d.c. voltages and supplies the electrical power 
required to recharge the batteries of the handheld unit 12 and drive the 
charger unit electronics. A personal computer 20 is optionally used and 
interfaces with the charger unit 14 through a Centronics parallel data 
link 21. 
Referring now to FIG. 2, a detailed schematic diagram is shown of the 
handheld checklist unit 12. This unit includes a power supply comprising 
batteries 11 and voltage regulator 13. A microprocessor 22 controls the 
operation of the device. Microprocessor 22 receives inputs from keypad 24 
and infrared optical transceiver 26, and it generates outputs to a liquid 
crystal display 28 and a voice module or synthesizer comprising 
digital-to-analog converter 30, audio filter 32, audio amplifier 34 and a 
speaker 36. Control programs for the microprocessor 22 are supported in 
firmware EPROM 38, and the unit includes a random access memory (RAM) 40 
for use by the microprocessor during processing for storing session log 
data as will be described. A data EPROM 42 is provided for supporting the 
checklist in the form of speech data, text data for the display, help 
screen data, etc. Data EPROM 42 can be supported in a removable cartridge 
41 so that (by exchanging cartridges) the device is programmable for 
different checklists or an alternative checklist application. RAM 40 and 
EPROM 42 are addressable through the address generator 43 controlled by 
the microprocessor 22. A real-time clock circuit 44 is also provided to 
generate real-time indications representing start and stop times of 
various checklist action items. The RAM 40 and clock circuit 44 are 
connected to a battery backup source 46 to maintain power thereto should 
the batteries rundown. 
The infrared optical transceiver 26 of the handheld checklist unit 10 
comprises an infrared light emitting diode (LED) and a phototransistor. 
The transceiver cooperates with a similar device in the charger unit 14 to 
create the optical link 15 between the units. In particular, and with 
reference now to FIG. 3, the charger stand includes a power supply 
comprising a voltage regulator 52 and a constant current source 54. The 
output of the voltage regulator drives the internal electronics of the 
charger while the output of the constant current source is connected by 
metal connection 17 to the handheld checklist unit 12. The charger unit 14 
includes a microprocessor 56 which receives inputs from the infrared 
optical transceiver 58 and generates outputs to interface circuit 60. 
Interface circuit 60 is connected to the dot matrix printer 64, while 
interface circuit 62 is connected to the optional personal computer 64. A 
firmware EPROM 66 includes the control programs necessary to control the 
microprocessor 56. 
The optical link 50 between the checklist unit 12 and the charger unit 14 
comprises an uplink (through the LED of the transceiver 58 to the 
phototransistor of the transceiver 26) and a downlink (through the LED of 
the transceiver 26 to the phototransistor of the transceiver 58). The link 
50 is especially advantageous in the operating room environment where it 
is required to minimize exposure of the system electronics to fluids and 
other materials that might otherwise affect the operation of the devices. 
Referring now to FIG. 4, a view of shown of a facing portion 77 of the 
handheld unit 12. As described above, the unit includes the keypad 24, 
display 28 and the speaker 36. The keypad includes a plurality of switches 
for entering commands to control the management of the checklist. 
According to the invention, a checklist of alphanumeric data is preferably 
organized into a predetermined sequence of sublists, wherein each of the 
sublists has a title and includes a predetermined sequence of checklist 
items. Each checklist item normally includes a "challenge" having a 
corresponding "response." Typically, but not always, it will be desired to 
effect presentation of the alphanumeric data in the predetermined sequence 
of sublists starting with a first sublist and a first checklist item in 
the first sublist. The switches of the keypad provide control of such 
presentation and preferably include the following buttons: 
1) GO: for entering a checklist category and marking checklist items as 
completed and thus automatically advance to the next checklist item; 
2) SKIP: for marking a checklist item as "not completed" and thus placing 
the item at the end of a sublist being processed while advancing to the 
next checklist item in the sublist. Depression of the SKIP button also 
skips past a sublist; 
3) EXIT: for causing all completed items to be marked as not completed and 
automatically advancing the program to speak and display the title of a 
current sublist being processed; 
4) N/A: for marking the current checklist item as not applicable to the 
diagnostic routine and advancing to the next item. Items marked N/A are 
not repeated for action at the end of the sublist; 
5) GET: for causing the unit to read another independent checklist which is 
entered by depressing GO. It operates only when a title line is displayed; 
and 
6) HELP: for causing information about a current item or function to be 
displayed in a continuous format across the display. 
The keypad includes up and down arrow keys for volume control. Although not 
shown, the keypad may include a BACK key to enable the reprocessing of an 
item. A REPEAT key may also be used to replay an item if the item was not 
understood. Depression of the REPEAT key does not affect the "complete" 
status of the checklist item in any way Alternatively, the "Repeat" and 
"Back" functions are effected by holding down one of the other buttons 
(such as the "GO" button) for predetermined times, e.g., one second for 
"Repeat" and two seconds for "Back." Moreover, the handheld unit also 
includes a second GO switch 80 mounted in the sidewall of the handheld 
unit so that the unit can be securely held in the operator's hand while 
allowing easy access to the GO operation. This feature is especially 
advantageous in the operating room environment in which the specialist 
needs to have a free hand for performing tasks associated with the 
procedure. 
In general, the operation of the system 10 is as follows. The operator 
powers up the hand held computer unit 12, selects the appropriate 
procedure corresponding to the present situation, and then performs the 
checklist using the function keys described above. A time-stamped log of 
each keypress is saved in battery-backed RAM 40 so that a "session log" 
record is maintained of the performance of that procedure. After the 
procedure is completed, the operator returns the handheld unit 12 to the 
recharger stand 14 where the batteries 11 are recharged. If the unit 12 is 
returned to the stand while it is still powered up, the unit 12 
automatically prints a directory of all sessions that have yet to be 
printed, and also those that have been printed once before. All sessions 
that have never been printed are automatically printed, and moved to a 
list of those that have been already printed once. Additionally copies of 
those logs already printed may be obtained by further interactions with 
the handheld unit. 
Referring now to FIG. 5, a logic diagram is shown of the detailed operation 
of the portable checklist system of the present invention. The operation 
begins at step 82 with system initialization. At step 84, the system 
conducts a self-test. If the system fails the test, the display 24 
displays an error message at step 86 and the system halts operations at 
step 61. If the self-test is passed, a test is performed at step 88 to 
determine if the handheld unit 12 is in the cradle of the charger unit 14. 
If not, the unit is supported in the operator's hand and the operation 
begins. 
A test is then performed at step 104 to determine if the procedure is a 
"cold start," which means that the unit 12 has not been used since a prior 
session was downloaded and printed. If the result of the test at step 104 
is positive, backup session logs are erased at step 105. If the result of 
the test at step 104 is negative, or following the erasure of the backup 
logs at step 105, the method continues at step 106 to create a new session 
log. This log is supported in the RAM 40 of the handheld unit 12 as 
described above. 
At step 89, a test is performed to determine if one of the buttons of the 
keypad 24 is depressed. If the down arrow key is depressed, continuous 
self-tests are repeatedly executed at step 107. If any other key is 
depressed, the method inverts challenge-only parameters at step 108. This 
enables the unit to speak either "challenge-only," or both "challenge" and 
"response" depending upon whether the status flag is "1" or "0." In the 
"challenge-only" mode, "responses" are not announced by the unit. When the 
operator presses a key to terminate step 107, when step 108 is completed, 
or if no key is depressed at step 89, the method continues to perform a 
final self-test at step 109. If the test is passed, the system displays 
and announces "Ready" at step 90. 
The system then enters a waiting mode at step 111 until a key, other than a 
volume key, is depressed. If a volume key is depressed, the gain of the 
audio amplifier 34 is adjusted accordingly at step 110. At step 112, the 
microprocessor 22 reads the volume setting, the first checklist procedure 
and the procedure parameters. At step 91, the routine indexes to the title 
of the first sublist of the selected procedure. At step 92, the system 
displays and announces the next item. After an item has been displayed and 
announced, the operator must respond by depressing at step 93 one of the 
buttons of the keypad (or the side-mounted GO button). If a timeout occurs 
before the operator responds, the system announces "Ready" at step 94 and 
returns to step 93 awaiting a response. If the HELP key is depressed, the 
routine displays the item's help screen at step 114 and returns to step 
93. If one of the volume arrow keys is depressed, the gain of the audio 
amplifier 34 is adjusted at step 115 and the routine returns to step 93. 
If an optional REPEAT key of the keypad is depressed, the system announces 
"Repeat" at step 113 and returns to step 92 to display and announce the 
item again. As described above, "Repeat" can be generated by holding down 
the "GO" button for a predetermined time, e.g., one (1) second. 
If any other key is depressed, the routine continues at step 116 to store 
in the RAM 40 the identity of the key and a time-stamp indication 
generated by the real-time clock circuit 44. The routine then branches to 
perform a plurality of checklist management functions depending on which 
of the keypad buttons is depressed. If the GO button is depressed, a test 
119 is performed to determine if the item is a title. If so, the routine 
marks all items as "skipped" at step 120 and indexes to the first item in 
the sublist at step 121. The routine then continues at step 138 and 
returns to step 92 to display and announce the first item in the sublist. 
If the outcome of the test at step 119 is negative, or if the N/A button 
is depressed by the operator following step 116, the system performs a 
test at step 121 to determine if the item is a title. If so, the routine 
indexes to the title line of the next sublist in the procedure at step 
122, continues at step 138 and then returns to step 92 to display and 
announce the title. 
If the result of the test at step 121 is negative, the routine marks the 
item as not skipped at step 139. If the SKIP button is depressed following 
step 116, and following step 139, the method performs a test at step 123 
to determine if the item is a title. If so, the method continues at step 
138 and then returns to step 92 to display and announce the title of the 
sublist. If the item is not a title of a sublist, the method continues at 
step 140 to test whether the item is the last item in a sublist. If not, 
the routine performs a test at step 141 to determine if the item has been 
marked as skipped. If the item has been marked as skipped as determined by 
the test at step 141, the routine continues at step 138 and returns at 
step 92 to display and announce the item. If the item has not been marked 
as skipped, the routine indexes to the next item in the sublist at step 
142 and returns to step 140 to again test whether the item is the last 
item in the sublist. If the outcome of the test at step 140 is positive, 
the routine performs a test at step 143 to determine if any items of the 
sublist were skipped. If so, the routine indexes to the first item in the 
sublist after the title at step 144 and returns to step 140. If the 
outcome of the test at step 143 indicates that no items were skipped, the 
routine advances to step 145 and displays and announces "Complete." 
Thereafter, the system waits for a key to be depressed at step 134. Help 
screens are displayed at step 132 if necessary and/or the volume is 
adjusted at step 133. The routine continues at step 135 to save the key 
originally depressed and to generate a time stamp indication in the 
session log being generated in the RAM 40. If a GET, GO, N/A or SKIP 
button is then depressed, the routine indexes at step 136 to the title 
line of the next sublist of the procedure, continues at step 138 and then 
returns to step 92. If the EXIT button is depressed following step 135, 
the routine indexes at step 137 to the title line of the current sublist, 
continues at step 138 and then returns to step 92. 
Depression of the EXIT button following step 116 also causes the system to 
perform a test at step 124 to determine if the item is a title. If so, the 
routine continues at step 138 and returns to step 92. If the item is not a 
title, the routine indexes to the title of the current sublist at step 125 
and continues at step 138. Finally, if the GET button is depressed, a test 
is performed at step 126 to determine if the item is a title. If not, the 
routine defaults to step 124 and continues. If the outcome of the test at 
step 126 is positive, the routine indexes at step 127 to the title item of 
the first sublist of the next procedure, saves the new procedure in the 
RAM at step 128, announces the name of the new procedure at step 129, and 
then continues at step 138. 
As also shown in FIG. 5, the routine is responsive to depression of a BACK 
key following steps 116 or 135 and announces "Back." As noted above, the 
"Back" function can alternatively be implemented by depressing the "GO" 
button for a predetermined time, e.g., two (2) seconds. Thereafter, the 
routine re-indexes at step 131 to the previously indexed item and 
continues at step 138. The routine is also responsive to an input/output 
interrupt following steps 116 or 135 to perform a test at step 117 to 
determine the nature of the interrupt. If the test indicates a low power 
situation, a low power shutdown is performed at step 118, although the 
session log data is retained in the battery-powered RAM 40. If the test at 
step 117 indicates that the handheld unit 12 has been placed back into the 
cradle unit 14, the routine returns to step 82. At this point the result 
of the test at step 88 will be positive and the routine continues, enters 
a printing mode of operation. 
In particular, and according to one important feature of the invention, the 
session log is then downloaded, through the downlink of the optical link 
50, from the RAM 40 of the handheld unit 12, through the charger unit 14 
and then to the printer. As described above, the microprocessor 56 of the 
charger unit controls the printer via the link 19. At step 100, a session 
log directory of all sessions that have yet to be printed (or have been 
printed before) is printed. At step 101, the routine continues to print 
the current session log data. At step 102, logs are converted from 
"unprinted" to "backup" status. 
Referring now to FIG. 6, an example is shown of a representative session 
log. As can be seen, the log includes various session log directory 
information in an identifier field 150. The log includes several column 
fields: an N/A field 160, an APP (or "applicable") field 162, a checklist 
item field 164, a time field 166 and a response field 168. The title of 
the procedure is printed above the checklist item field 164 as well as a 
time stamp indicating when the procedure was entered (by depression of the 
GO button as indicated). The various checklist items are then displayed in 
sequential order as well as the various times at which the items were 
displayed and announced. If "GO" were depressed, an "x" is placed in the 
APP field 162; an "x" is placed in N/A field 160 if "N/A" were depressed. 
For procedure or sublist titles, these indications (or any other buttons) 
appear in field 168 instead. The session log also indicates when the 
sublist was COMPLETE, as well as the time at which the handheld unit was 
placed back into the cradle (as indicated by the IO in the last column). 
The session log further includes a verification field 152 which includes 
one or more attestation lines 154 and a date line 156. 
According to another feature of the invention, before the session log data 
is downloaded to the charger unit for printing, a control routine controls 
the microprocessor 22 to generate a security or ID Code which is also 
printed in an ID code field 158 of the session log. The ID Code is 
preferably generated by calculating a checksum of all bytes printed on a 
page, post-encrypted by a mathematical formula. In particular, after the 
checksum is calculated (based on the number of and type of actual data 
characters printed on the session log page) this value (which is a 
two-byte number) is exclusive-or'd (bit-by-bit) with a (secret) two-byte 
bit mask to create the ID Code. Once the ID Code for the page (and thus 
the session log is originally calculated), any change to the session log 
printout data will necessarily produce a different ID Code. In other 
words, the session log data will map into a unique security code and no 
other security code. This feature of the invention creates a 
self-authenticating record of the session which cannot be altered without 
being immediately recognized. 
The computerized checklist system of the present invention is designed to 
function like an additional member of the medical team whose only 
responsibility is to read, manage and document the checklist. The operator 
does not have to read or fumble with a written checklist, which improves 
safety by reducing the workload. Furthermore, the computerized checklist 
system provides an accurate and consistent presentation of checklist items 
in sequence without the possibility of inadvertently omitting an item in 
the sequence. 
It should be appreciated by those skilled in the art that the specific 
embodiments disclosed above may be readily utilized as a basis for 
modifying or designing other structures for carrying out the same purposes 
of the present invention. It should also be realized by those skilled in 
the art that such equivalent constructions do not depart from the spirit 
and scope of the invention as set forth in the appended claims.