Designing the User Interface of a Nitroglycerin Dose Titration Decision Support System: User-Centered Design Study

Abstract

Background: Nurses adjust intravenous nitroglycerin infusions to provide acute relief for angina by manually increasing or decreasing the dosage. However, titration can pose challenges, as excessively high doses can lead to hypotension, and low doses may result in inadequate pain relief. Clinical decision support systems (CDSSs) that predict changes in blood pressure for nitroglycerin dose adjustments may assist nurses with titration.

Objective: This study aimed to design a user interface for a CDSS for nitroglycerin dose titration (Nitroglycerin Dose Titration Decision Support System [nitro DSS]).

Methods: A user-centered design (UCD) approach, consisting of an initial qualitative study with semistructured interviews to identify design specifications for prototype development, was used. This was followed by three iterative rounds of usability testing. Nurses with experience titrating nitroglycerin infusions in coronary care units participated.

Results: A total of 20 nurses participated, including 7 during the qualitative study and 15 during usability testing (2 nurses participated in both phases). Analysis of the qualitative data revealed four themes for the interface design to be (1) clear and consistent, (2) vigilant, (3) interoperable, and (4) reliable. The major elements of the final prototype included a feature for viewing the predicted and actual blood pressure over time to determine the reliability of the predictions, a drop-down option to report patient side effects, a feature to report reasons for not accepting the prediction, and a visual alert indicating any systolic blood pressure predictions below 90 mm Hg. Nurses' ratings on the questionnaires indicated excellent usability and acceptability of the final nitro DSS prototype.

Conclusion: This study successfully applied a UCD approach to collaborate with nurses in developing a user interface for the nitro DSS that supports the clinical decision-making of nurses titrating nitroglycerin.

Fig. 1

Results of the System Usability Score. Gray bars are individual participant scores. Orange bars are the mean score for each round of usability testing. Blue bars are the overall score across all three rounds. A score >68 indicates the above-average usability of a system. SUS, System Usability Score.

Fig. 2

Results of the Ottawa Acceptability of Decision Rules Instrument score. Gray bars are individual participant scores. Orange bars are the mean score for each round of usability testing. Blue bars are the overall score across all three rounds. OADRI, Ottawa Acceptability of Decision Rules Instrument.

Fig. 3

Overview of the nitro DSS prototypes. Red arrows indicate the changes to the nitroglycerin protocol feature. The red numeric values in figures from rounds 2 and 3 and the final version represent abnormal blood pressure measurements. Changes to the side effects row can be seen in prototypes tested in rounds 3 and 4. nitro DSS , Nitro glycerin Dose Titration D ecision S upport S ystem.

Fig. 4

Displays the original and final version of the graphs for the nitro DSS prototypes. The original version (on the left) includes a graph of the actual and predicted systolic blood pressure over time. The final version (on the right) includes the actual and predicted systolic blood pressure, a graph of the nitroglycerin dose over time, and the absolute error rate for nitro DSS when tested on patients from that organization. BP, blood pressure; nitro DSS , Nitro glycerin Dose Titration D ecision S upport S ystem.

Fig. 5

Displays the feature to report the reason for rejecting the prediction (final prototype; data are imaginary).

Fig. 6

Displays the alert for abnormal blood pressure prediction on the original (top) and final (bottom) prototypes (data are imaginary).