Patient monitor human interface design

Hewlett-Packard Journal, Oct, 1991 by Gerhard Tivig, Wilhelm Meier

Avoiding Operating Errors. All choices for a given function are always shown. There are no hidden choices. The status of a given setting is shown before a change is initiated. Prompt messages and prompt sounds are used to inform the user if an action cannot be executed properly. Actions like pressing Confirm or finishing multistep procedures (e.g., zeroing a pressure line) always result in a prompt message and sound.

Graphics. In addition to digital readouts, graphic elements are widely used. This includes size bars for amplitude adjustments and audible volume control and alarm and value bars to indicate the current range of alarm limits.

User Defaults and Configuration Sets. The basic design goal is that it be possible to turn on the monitor, attach the transducers and electrodes to the patient, and start monitoring without any further settings or adjustments. This means that the monitor will initiate at power-on with a set of user-definable settings. These user defaults can be specified at installation time and changed whenever required. They are stored in nonvolatile memory and read after monitor restart. This applies to every parameter module in the Component Monitoring System.

In addition, a whole set of user settings related to one specific Component Monitoring System element, such as the display or the recorder configuration, can be bundled together and accessed by a single keypush. For example, all screen related attributes, such as waveform assignment to display channels, number of waveforms, speed of waveforms, and overlapping formats, can be put together as one screen choice. Up to three different screen choices can be stored in nonvolatile memory. This supports applications in the operating room, where depending on the course of surgery, specific screen layouts have to be accessible without complex interaction.

Finally, the concept of a configuration set supports the monitor's ease of use and flexibility by customizing the parameter algorithm behavior and the parameter settings according to the specific environment (operating room or ICU) or to the patient's age (adult, pediatric, or neonate). The user can specify or change the monitor's behavior simply by selecting one of the four available configuration sets prestored in the monitor. This again simplifies the monitor's setup in an environment like the operating room, where patients of different ages undergo surgical interventions.

The Resting Display

The resting display is what the Component Monitoring System shows when no user interaction is taking place. Fig. 3 shows a typical resting display.

Since the monitor's main task is to measure a patient's vital signs and give an alarm if a critical situation occurs, the top line is reserved for alarm information. It also contains the patient's name, the current date and time, and the basic configuration of the monitor-for example, a classification of the patient and the application area for which the internal algorithms are optimized.

The next line contains status and prompt messages informing the user about events that are not as critical as alarms, but give information about such things as successfully finished recordings or parameter calibration procedures.