Observation charts with overlapping blood pressure and heart rate graphs do not yield the performance advantage that health professionals assume: an experimental study
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Melany J Christofidis1, Andrew Hill, Mark S Horswill
1School of Psychology, The University of Queensland, St Lucia, Brisbane, Australia.
Insights
Overlapping vital sign graphs do not improve nurse recognition of abnormalities. Separate graphs, especially with alerting systems, enhance performance for both trained and untrained nurses.
Area of Science:
- Medical Informatics
- Human Factors Engineering
- Clinical Observation
Background:
- Health professionals often prefer overlapping graphs for blood pressure and heart rate.
- This preference is partly due to the 'Seagull Sign,' a visual cue for physiological abnormalities.
Purpose of the Study:
- To determine if overlapping vital sign graphs improve recognition of abnormalities.
- To evaluate the impact of graph format and alerting systems on chart interpretation.
Main Methods:
- A mixed-design experiment involving 3x2x2 variables: participant group, graph format (separate vs. overlapping), and alerting system (present vs. absent).
- Nurses (trained or untrained) and novices viewed chart extracts with normal and abnormal vital signs, judging their physiological status.
Main Results:
- Participants responded faster and made fewer errors with separate blood pressure and heart rate graphs.
- This improvement was more pronounced when an integrated track-and-trigger system was present.
- No performance advantage was found for overlapping graphs, even for nurses trained in the 'Seagull Sign.'
Conclusions:
- Overlapping vital sign graphs do not offer the assumed performance benefits for nurses.
- Separate graphing, particularly with alerting systems, appears superior for recognizing vital sign derangements.
- Findings challenge the common practice of overlapping graphs in clinical observation charts.
Aim:
To investigate whether overlapping blood pressure and heart rate graphs improve chart-users' ability to recognize derangements in these vital signs on hospital observation charts.
Background:
Many health professionals prefer blood pressure and heart rate graphs to overlap. One justification is the use of a visual cue called the 'Seagull Sign' to detect physiological abnormalities.
Design:
A 3 × 2 × 2 mixed-design experiment, with three independent variables: participant group, graph format (separate vs. overlapping) and alerting system (integrated colour-based track-and-trigger system present vs. absent).
Methods:
Over 64 experimental trials, 'Seagull-trained' nurses and novices randomly assigned to receive 'Seagull training' or remain untrained, viewed sequences of blood pressure and heart rate observations recorded on four different chart design extracts. The designs represented a crossing of the graph format and alerting system variables. For each design, eight cases contained normal data and eight contained an abnormal systolic blood pressure or heart rate observation (half of which yielded a Seagull Sign on overlapping plots). Participants (tested between January-May 2011) judged whether observations were physiologically normal or abnormal.
Results:
Across all cases, participants from all groups responded faster and made fewer errors when blood pressure and heart rate observations were graphed separately, especially when a track-and-trigger system was present. Even for 'Seagull-trained' participants viewing 'Seagull Sign available' cases, no advantage of overlapping graphs was found.
Conclusions:
These findings suggest that overlapping graphs do not yield the performance advantage that many health professionals assume, either for novices or experienced nurses, even when the Seagull Sign is used.
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