ANESTHESIA INSTRUMENTATION USER INTERFACE

Abstract: A display system for anesthesia monitoring comprising a low form factor display unit (10) and a grouping of controls to provide increased functionality. The grouping provides access through a Dedicated group (16) to functions of an immediate nature such as controlling audible alarms and declaring events. The grouping also provides a Menu/Navigation set of controls (14). A context group (18) allows the Menu Navigation controls to be used differently depending on the mode the system is operating in. The display color codes different parameters shown on the display and inverts the burst suppression trend line so as to provide a more intuitive representation of how deeply anesthetized the patient is.

Description: FIELD OF THE INVENTION The current invention relates to the field of medical anesthesia. More particularly it relates to the field of electronic monitoring of a patient undergoing anesthesia, especially for use during and after surgical operations. The invention more specifically relates to the user interface of the instrument used to monitor a patient's state of awareness. BACKGROUND OF THE INVENTION Traditionally in the administration of anesthesia it has been the practice for an anesthesiologist to use clinical signs from the patient to estimate the depth of the patient's anesthesia before and during surgical procedures requiring anesthesia. In recent years, however, it has become possible and practicable to manipulate certain transduced bodily signals, in particular electro-encephalographic signals, to produce an indication of how anesthetized or alternatively how awake a patient is. An instrument that may be the basis of potentially life-or-death, and frequently very rapid, decisions in the operating room, however, must do more than naively present the available information to the clinician - it must present the relevant data in such a way that the information is instantly intelligible and distinguishable from other states potentially portrayed by the instrument. Additionally, because of the crowded nature of and limited available space in many operating rooms, an instrument that provides information related to the patient's anesthetic state during surgery must have a small form factor. In particular, space available to the anesthesiologist or nurse anesthetist can be extremely limited. The instrument must further provide a simple means of control and a clear, concise, and intuitive display. On the other hand, the size restriction limits the size of the visual interface. The simplified control requirement comes from the limited time that the user can allocate to operating the instrument. The user's time allocation also drives the requirement for a concise and intuitive information display. The typical user, an anesthesiologist or nurse anesthetist performs numerous tasks to assess the patient's clinical state and to modify the delivery of drugs necessary to properly manage the patient during surgery. For the instrument to be usable in this environment, it must not be time consuming to configure and operate. For the instrument to be effective in this environment, the user must also be able to access and understand the displayed information within seconds. It is therefore an object of the current invention to provide a user interface for an electronic anesthesia monitoring instrument which conforms to the space requirements of the operating room while simultaneously providing simplicity and responsiveness of control and intuitiveness of the information displayed by the interface. SUMMARY OF THE INVENTION The current display system optimizes use of screen area by presenting only mode appropriate information. In part it establishes this optimization by creation of a multifunction label area such that each label position may be used for multiple functions. The system also combines notifications of events with display of actions required to respond to those events. It further minimizes time and actions required to access any required functionality option. The Context Groups and their dynamic labeling also provide for highly flexible and adaptable user interaction sequencing. The system further provides immediate access to a small subset of functions of an immediate nature and minimizes the number of physical inputs, thereby providing ease of use along with lower cost. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic depiction of the face of the display system. Figure 2 shows the mathematically logical display of awareness and burst suppression. Figure 3 portrays the intuitive display of awareness and an inverted burst suppression display. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A system for electronically monitoring a patient's state of anesthesia using electroencephalograph signals is described in a prior patent application, Ennen, et al., U. S. Patent Application No. 09/431,632, filed November 2, 1999, which is incorporated by reference herein. That application describes, among other things, the information which will be produced for the anesthesia practitioner but does not disclose the most effective way of presenting that information to the anesthesiologist/nurse anesthetist. With respect to the current invention, the preferred embodiment of the anesthesia monitoring instrument's user interface physical components consists of an approximately 6.5 inch diagonal VGA (640/480) resolution color (256) display with 12 front panel pushbuttons as shown in Figure 1. With reference to Figure 1, the 12 tactile pushbuttons are organized into 4 functional groups: Power 12, Menu/Navigation 14, Dedicated 16, and Context 18. There is a single pushbutton 11 that performs Power-On/Standby control. The Menu/Navigation group 14 has 4 directional arrows 15 that are used to identify selections from a graphically presented drop-down (on the display screen) menu system. The Dedicated group 16 provides three buttons 17 giving direct access to functions of an immediate nature: controlling audible alarms 17A, declaring events 17B, and requesting hard copy 17C. The Context group 18 pushbuttons 19 are, through physical placement and labeling, associated with the display. Context sensitive labels, associated with the Context pushbuttons, define the action to be performed upon activation. The Context pushbuttons support the Context System that serves as the basis for the user interface design (see below). This functional grouping of pushbuttons and the associated Context System allows a minimal set of user inputs to support both immediate function access and a simple means of instrument configuration. The small number of user inputs improves physical access, while the Dedicated 16 and Context 18 groups minimize the time required to operate the instrument. To optimize the use of the small form factor display a Context System served as the basis for the design of the user interface. This system is based on two concepts. The first concept is to organize the information presentation into pages that support the operational modes, allowing the optimization of the information displayed relative to the mode. The second concept is to dynamically reconfigure the context labels, and thereby the readily available user actions, based on the instrument or user context. Combining these concepts optimizes the use of the minimal display area, while still providing an informative display and the user's ready access to required functions. The context sensitive labels and pushbuttons support dynamic reconfiguration of the user's available actions. A context typically consists of display of context targets/labels, association of context pushbuttons with targets/labels, and possible context related display entities, e.g., menu items during menu context. In the current embodiment and currently known best mode, the contexts is use are: Trend Page context; EEG Page context; Review Page context; Status Page context; Check Electrode context; Adjust Parameter context; Date/Time context; and Menu context. Each one of these contexts associates different choices with the context buttons depending on which context the display is in at the time. The anesthesia monitoring system to which the display system is connected generally has a plurality of modes of operation. In the current embodiment, these are: Startup; Calibration; Acquisition; and Review. Each mode of operation has associated with it one or more of the above listed contexts. When the user changes modes the associated mode page is presented and that page's context labels are displayed. For example, when EEG waveform page is displayed, context labels are presented that provide for amplitude and time formatting of the displayed waveforms. If the user then changes to Trend Review Mode, the amplitude and time labels are removed and the Trend Review context labels that provide for scrolling forward and backward through the trend are presented. Asynchronous events may cause new contexts to be added to or replace existing label context. The instrument continuously monitors electrode impedance. If an impedance measurement falls outside an acceptable range a 'check electrode' label context is displayed and actuation of the associated pushbutton changes to a page to one which identifies the offending electrode(s). The primary derived parameter of the instrument is a measure of the patient's level of consciousness or awareness. This derived parameter is displayed as a filled chart where the ordinate is the derived parameter and time is the abscissa. This displayed trend is the primary focus when a user directs attention to the instrument. To make interpretation of the displayed information intuitive the filled chart is color-coded. A surgical maintenance range can be defined by declaring upper and lower values of the derived consciousness parameter. The anesthesiologist guides the patient within this maintenance range to minimize delivered medication while maintaining an appropriate level of consciousness. The chart is colored: values falling within the maintenance range are- green, values outside the range are yellow-orange. Trend points are drawn white if there is insufficient information to properly update the derived parameter. In many instances the anesthesiologist does not need to know the exact value of the derived parameter, only the approximate value and trend during the last few minutes. The assessment that 'the patient is running in the appropriate range' is visualized easily by the color mapping of the trend. An additional design feature which provides a more intuitive presentation of the 'depth of consciousness' trend is the manner in which the Burst Suppression parameter is plotted as part of the derived parameter trend. Burst Suppression is an electro-encephalographic signature of a patient's brain state. At low levels of conscious the Electro-encephalographic signals exhibit periods of isoelectric behavior. These isoelectric periods end in a burst of electrical activity. The burst suppression parameter is a measure of the percentage of time spent in suppression (isoelectric) per minute. The standard plots of the level of consciousness and suppression parameters are shown In Figure 2. This is the mathematically logical manner of presentation. However, Figure 2 does not present the information in a clinically logical or intuitive manner. Higher levels of suppression reflect more time spent with isoelectric electro-encephalographic signals and thereby lower levels of consciousness. By inverting the sense of the Suppression graph and plotting it coincident with the Awareness parameter the 'grand' chart becomes significantly more clinically intuitive (see Figure 3). The Suppession trend is plotted in blue. At some level of suppression, the value of the Awareness parameter is zero, with the patient depth of consciousness then primarily related to the high levels of suppress electroencephalograph signals. Figure 3 represents the trends combined into a single color code chart.

Claims: CLAIMS We claim: 1. A display system for practitioner use of an electronic anesthesia monitoring system, said display system comprising a. A monitor mounted in a small form factor display unit and electronically configured to receive signals from an anesthesia monitoring system; and b. A plurality of controls on the face of said small form factor display unit grouped into a plurality of functional groups. 2. The display system of Claim 1 in which the plurality of functional groups comprises a Power group, a Menu/Navigation group, a Dedicated group, and a Context group. 3. The display system of Claim 2 in which the Power group comprises at least one button performing Power On/Standby control. 4. The display system of Claim 2 in which the Menu/Navigation group comprises a plurality of directional arrow buttons. 5. The display system of Claim 2 in which the Dedicated group comprises a plurality of buttons, said plurality comprising at least one button for controlling audible alarms, at least one button for declaring events, and a button for requesting a hard copy. 6. The display system of Claim 2 in which the Context group comprises a plurality of buttons such that the function of each of the plurality of buttons differs according to the Context in operation, said function being displayed on the display screen according to which Context is in operation. 7. The display system of Claim 1 in which the monitor display simultaneously displays a plurality of parameters from the anesthesia monitoring system. 8. The display system of Claim 7 in which the plural displayed parameters are color coded. 9. The display system of Claim 7 in which the plural displayed parameters comprise at least an awareness parameter and a burst suppression parameter. 10. The display system of Claim 9 in which the burst suppression parameter is displayed inverted so that high values are at the bottom of a portion of the display showing burst suppression and low values of the burst suppression parameter are at the top, whereby an intuitive impression of the patient's state of anesthesia visually related to the awareness parameter is communicated to the user. 11. The display system of Claim 6 in which the context varies according to the mode of operation of the system.

Inventors: ENNEN DAVID W, ORTEGA HENRY R III, ENNEN, DAVID, W., ORTEGA, HENRY, R., III
Applicants: PHYSIOMETRIX INC, PHYSIOMETRIX, INC.
Application year: 2000
Main classification: A61M
IPC codes: A61B5