Perceptual distortions during simultaneous continuous monitoring of fetal and maternal heart rate in laboring patients

OBJECTIVE: Our previous work examined the effect on assessment of fetal well-being when presenting twin fetal heart rate tracings (FHRT) simultaneously on screen. To further examine the potential impact of subconscious perceptual influences on fetal well-being, the current study presented singleton FHRT with and without simultaneous presentation of maternal heart rate in a within-subjects design. Tracings were taken from archival cases with either normal or abnormal Apgar scores to identify differential impact depending on final outcome. All tracings were evaluated for variability, accelerations, decelerations, and overall concern. STUDY DESIGN: = 32) assessed FHRTs from 20 singleton gestations that resulted in live births (half with normal Apgar scores (control group), half with a 5-minute Apgar < 7 (at-risk group)) presented either alone or with maternal heart rate on the same tracing. Nurses were naïve to the fact that the fetal heart rate tracings presented in the unpaired condition were the same as those presented in the paired condition. Within-subjects assessments were then compared between the two conditions. RESULTS: Each nurse participant completed ratings on four metrics for each of 20 singleton gestations across two conditions, plus rated three tracings per condition again to determine test-retest reliability within each condition (52 FHRT assessments, 208 metrics total per participant). The intraobserver impact of visual context was calculated as the frequency of changed opinions regarding an individual metric (e.g. variability) between the paired and unpaired contexts for control versus at-risk FHRT. Participants demonstrated substantial self-agreement when assessing variability, accelerations, and decelerations for control FHRT, but only moderate agreement for the same metrics when assessing at-risk FHRT. In addition, assessment of level of concern demonstrated moderate intraobserver agreement for control FHRT but lowered to only slight agreement for at-risk FHRT. CONCLUSIONS: The simultaneous presentation of fetal heart rate tracings with maternal heart rate tracings introduces both intraobserver and interobserver variances in interpretation of decelerations and overall level of concern, particularly for at-risk FHRT. These changes in interpretation are likely due to the influence of subconscious perceptual decision-making and additional cognitive load in separating multiple streams of information. This may theoretically affect outcomes in cases in which visual information is nuanced. Medical professionals may want to exercise caution when adding more than one tracing to the visual array, as it may affect decision-making.