GRAPHICS-TABLET FOR DATA-ENTRY IN COMPUTER-ASSISTED ...

GRAPHICS-TABLET FOR DATA-ENTRY IN COMPUTER-ASSISTED ANESTHESIA RECORD-KEEPING R. S. Newbower, Ph.D., J. B. Cooper, Ph.D., J. E. Edmondson, B.S., W. Reynolds Maier, M.D.

Bioengineering Unit, Department of Anesthesia Massachusetts General Hospital, Boston, MA 02114 A digitizing graphics tablet is used as the interface for computer-assisted record keeping during anesthesia management. The operator enters information on a standard paper record form in the normal fashion. The system receives, processes, stores, and displays temporal data, in real-time, about the amounts and types of drugs and fluids administered, the patient's vital signs and other relevant data. Handwritten numerals and a set of

problems. With the documentation function, there is also available the power of the computer to calculate, format and analyze to aid the anesthetist beyond mere assumption of the data storage task. Several approaches to computerassisted records have been suggested and some clinically implemented prototype systems have been described and evaluated in local trials (7, 8, 9, 10) . Common to all of these is the requirement for keyboard entry of most data that is not monitored electronically. Unfortunately, many of the most relevant clinical interventions and events fall into that category, e.g., blood loss, fluid and drug administrations, ECG interpretations, anesthesia machine settings. Thus, to date, automation has required a great deal of interaction with a new, unfamiliar system and the use of a skill (typing) at which most anesthetists are not facile. The success or failure of any application of computers, particularly in medicine, rests heavily on user acceptance - on adapting to the user's current practice and offering real and perceived benefits. Despite its deficiencies, the paper record has several advantages: it is compact, it uses a familiar skill (writing), it is inexpensive, and it may enhance vigilance by fostering periodic observation of the patient even during the noncrisis periods (those periodic observations may, indeed, prevent some crises). The keyboard/CRT computer data-entry link requires training and is bulky. As such, it may constitute a serious impediment to widespread application of computerassisted record keeping and monitoring. This is because the users, rightfully or not, may not be willing to pay the keyboard/CRT "price". To exploit the advantages of the manual paper record and to obviate the user aversion to the keyboard, we are examining the feasibility of using a digitizing graphics tablet for direct data entry to any computer-based anesthetic record keeping, analysis or financial accounting system. We have developed an interrupt-driven, real-time, software system to recognize a large amount of handwritten information via such a tablet, including symbols and numerals and their significance based on their location on a record form. This appears to be a promising new approach to data entry by physicians or nurses interacting with a computerized data-base system.

standard, anesthesia, vital-sign symbols are recognized, with toleration of a wide variety of writing styles and sizes. This approach is seen as fostering the acceptance of computer applications in routine anesthesia practice. It also suggests related applications such as for a software-

defined menu selection device, keying on previously entered or plotted data.

Record-keeping during anesthesia management is a necessary but tedious task for the anesthetist. The record is maintained manually and includes data on the patient's preoperative status and per-

iodic entries of intraoperative vital-signs, drug and fluid administration, key events, etc. Retrospective analysis (or defense) of intraoperatiie actions is probably the greatest incentive for maintaining the record, which is an established

medico-legal

requirement

(1, 2)

.

But,the

record also serves as a valuable intraoperative trend-indicator and as a reference for guiding future anesthetic interventions. The record may also be used as the source of financial accounting and billing information. The deficiencies of existing record-keeping practices are well known. Maintenance of the record occupies a major fraction of the anesthetist's workload (3,4,5) . The final document is often not sufficiently legible, accurate or complete to permit a meaningful analysis of the course of anesthesia, especially for those periods which are of greatest importance, i.e., induction, emergence and unexpected crises (6). Computer-based, automated record-keeping has long seemed to offer assistance in solving these

0195-4210/81/0000/0139$00.75 © 1981 IEEE

139

Hardware. A commercially available graphics digitizing tablet (Summagraphics Bit-pad One), has been interfaced to a Nova 3 Minicomputer, which is used as the prototype development system. The real time operating system occupies 20K words and the existing software 28K words of memory. In addition, 4K of disk space is accessed for run time storage. The graphics-tablet uses magnetostrictive technology to detect the position of a special ball-point pen anywhere on its 11" x 11" active surface, representing 2200 x 2200 points. A modified, but fairly standard anesthesia record form is placed on the surface of the tablet (Figure 1). This form is then used as the routine, paper anesthesia record and the entered information is digitized, immediately interpreted, and, in some cases, displayed to the anesthetist and/or stored for subsequent hard-copy printout. An 80 character, two-line alphanumeric display is placed at the top of the tablet, above the record form, and is used as the computer's sole visual communication device to the user, as described below. Audible communication is via a

1) Vital signs measurements - the program recognizes and interprets any of nine symbols entered in the vital signs area and deduces the plotted value and time of measurement from the location of the The recognizable symbols (familiar in symbol. anesthesia) are:

A V j

indirect diastolic blood pressure indirect

systolic

blood pressure

direct diastolic blood pressure

T direct systolic blood pressure *

heart rate

0

spontaneous ventilation rate

X

controlled ventilation rate

@

assisted ventilation rate

A

temperature

machine-generated tone. Symbolic entries are approximated as a series of straight lines and are characterized by the number of lines and how the lines are connected. The algorithm differentiates between closed and opened figures and between end-to-end connections or endto-midpoint connections. On average, recognition is completed 0.8 secs. after entry, although optimization of hardware and software could reduce that substantially. The data type, value (entry position on the ordinate) and measurement time (entry position on the time axis) are displayed for verification. The symbol recognition program tolerates various sizes and styles of entry exceptionally well. Preliminary estimates indicate that the combined rejection and error rate is under 5% even with untrained users.

2) Drug and fluid administration - the name of the drug or fluid is written on any line in the delivery area. The identity of the drug or fluid is then designated to the computer by touching the pen to one of the items named on a list in the menu area. Each item on the menu has a predesignated standard administration unit, e.g., mg, ml, units, L/min, which is subsequently displayed with the name of the item and the total tally of drug or fluid delivered to that patient. Non-standard units are accomodated by touching a selection in the alternate-units area. The entry of doses is accomplished simply by writing in the appropriate value numerically in line with the previously entered drug name and with the correct time of administration. The coordinate data generated by handwriting those numerals are then processed by a recognition algorithm which correctly identifies the individual digits in a string of digits. Recognition requires 0.5 seconds per digit, after rapid writing of the entire string. The algorithm approximates the handwritten digits by a series of vectors. Features of the configuration of the vectors and the distribution of data points are

Figure 1 Software. The active area of the tablet is organized into several rectangular areas according to the type of information to be recorded (Figure 2). Entry in each area is treated according to the function of that area.

140

used for numeral recognition. Four features are calculated for each digit: the average vertical location of the points, the average vertical location of vectors, the average coordinates of the last few points written and a fourth characteristic based on the number of pen pick-ups and directional changes. The resulting array' of parameters leads to a specific entry in a look-up table. These entries are labeled in a learning sequence in which the system is exposed to many different numeral styles together with correct

Applications.

The graphics-tablet based record will be only one component of a complete computer-assisted recordkeeping system. Those variables which are already easily measured and documented electronically could be displayed on a "soft" record such as a CRT display, in real-time, and need only be transferred to hard copy if and when the need arises. The often used aviation/anesthesia analogy (11, 12) is useful here. The need for a complete, post-hoc "crash" or complication record is probably infrequent. Devoting substantial resources or a substantial portion of the limited accessible anesthesia workspace to producing hard-copy information that is rarely needed may not be warranted. Other long-term or temporary data storage modes, e.g., tape or disk, are probably more appropriate for most monitored information. We anticipate several useful, processing actions using the data entered via the graphicstablet. Running totals of drug and fluid administration, computation of patient-specific drug

identities. 3) Other information - the record includes many check-off and fill-in items for routine information, e.g., patient ASA class, patient weight, monitoring devices and IV apparatus used. The numeral recognition algorithm is invoked for some of these areas. Schemes for entry of other relevant information, e.g., blood loss, ECG rhythm and events, are under development. Several other utility functions have also been implemented including timer, stopwatch and reminder features.

Anesthetist, Surgeon, Procedure, Date, Time on duty

Patient Identification

Alphabetic Entry Timer Functions

Equipment, Measurements, IV, Catheters, etc.

Alternate Drug

UJnits Pre-anesthetic Data

Drug,

Fluid,

Drug, Fluids, Gas Delivery and Fluid Loss

Drug Menu

Gas names

Time Event marKs

Events

Initial vital

Vital-signs

signs

EKG, CVP, PA Comments

.'t*~~~~~~~~a

*1 5 Remarks

I

Numeric

Post-Op Summary

Format of Anesthesia-Record Data Areas Figure 2

141

T Keyboard

L

I

Yes No Enter Clear

doses, and real time estimates of fluid balance are now being implemented on the prototype system. Prompting for vital-sign entries at appropriate intervals and drug dose/vital-sign response calculations also appear feasible. Comparisons between manually derived and existing automated measurements, e.g., automated non-invasive blood pressure, are planned. Perhaps of greatest inmediate utility will be a computer generated anesthetic-summary and patient-billing synopsis. These two latter features may, in fact, be pivotal to user acceptance because they would offer a measurable cost-benefit in routine practice. The appeal of the graphics tablet as a communication device extends beyond its use as a simple, familiar means of data-entry. The record form can be exploited as a task-specific, software-defined "imenu" through which the operator can retrieve raw or processed information about any specific item or time, past or present, in the computer database. For instance, pointing to any previously plotted time or time interval could act as a command for display of related stored or derived data. Instructional information could be requested by touching an item repeatedly. This approach makes the structure of the computerstored data visible to the user through the familiar, logical format of the paper record and, in effect, allows comnands to be in a simple, familiar graphical language. We suspect that these advantages would be useful in many medical applications in addition to anesthesia monitoring and recording-keeping.

9. Schneider, A.J.L.: Automated systems. In: Monitoring surgical patients in the operating room. Gravenstein, J.S., Newbower, R.S., et al., eds. Charles C. Thomas, 1979. 10. Rampil, I.J., Fleming, D.C.: An inexpensive microcomputer trend monitoring system. Proc. 6th New England Bioeng. Conf., 1978, p. 67-70. 11. Newbower, R.S., Cooper, J.B., Long, C.D.: Learning from anesthesia mishaps. Quality Review Bulletin, 7:10-16, 1981. 12. Gravenstein, J.S.: Failure to Monitor. In: Essential noninvasive monitoring in anesthesia. Gravenstein, J.S., Newbower, R.S., et al. eds. Grune and Stratton, 1980.

References

1. Dillon, J.B.: The prevention of claims for malpractice. Anesthesiology 18:794-796, 1957. 2. Engel, J.H.: Preventing malpractice suits relating to anesthesiology, documenting the record. Anesthesiology Rev. 4:40-41,

1977. 3. Drui, A.B., Behm, R.J. and Martin, W.E.: Predesign investigation of the anesthesia operational environment. Anesth. Analg. 52:584-591, 1973. 4. Boquet, G., Bushman, J.A. and Davenport, H.T.: The anaesthetic machine - a study of function and design. Br. J. Anaesth. 52:61-67, 1980. 5. Kennedy, P.J.: Analysis of tasks and human factors in anesthesia for coronary-artery bypass. Anesth. Analg. 55:374-377, 1976. 6. Zollinger, R.M., Kreul, J.F. and Schneider, A.J.L.: Man-made versus computer generated anesthesia records. J. Surg. Res. 22:419424, 1977. 7. Harbart, R.A., Paulsen, A.W. and Frazier, W.T.: Computer generated anesthesia records. 4th Annual Symp. Comp. Appl. in Med. Care V3, November 1980. 8. Burton, L.W., Block F., Davis D., Dowell, L. et al.: The Duke automated monitoring system and the objective anesthetic record. Scientific Exhibit, Ann. Meeting. Amer. Soc. Anesth. 1980, p. 178.

142