Physiologic measurements of cognitive load in clinical reasoning.

Objectives: Cognitive load is postulated to be a significant factor in clinical reasoning performance. Monitoring physiologic measures, such as heart rate variability (HRV) may serve as a way to monitor changes in cognitive load. The pathophysiology of why HRV has a relationship to cognitive load is unclear, but it may be related to blood pressure changes that occur in a response to mental stress.

Methods: Fourteen residents and ten attendings from Internal Medicine wore Holter monitors and watched a video depicting a medical encounter before completing a post encounter form used to evaluate their clinical reasoning and standard psychometric measures of cognitive load. Blood pressure was obtained before and after the encounter. Correlation analysis was used to investigate the relationship between HRV, blood pressure, self-reported cognitive load measures, clinical reasoning performance scores, and experience level.

Results: Strong positive correlations were found between increasing HRV and increasing mean arterial pressure (MAP) (p=0.01, Cohen's d=1.41). There was a strong positive correlation with increasing MAP and increasing cognitive load (Pearson correlation 0.763; 95 % CI [; 95 % CI [-0.364, 0.983]). Clinical reasoning performance was negatively correlated with increasing MAP (Pearson correlation -0.446; 95 % CI [-0.720, -0.052]). Subjects with increased HRV, MAP and cognitive load were more likely to be a resident (Pearson correlation -0.845; 95 % CI [-0.990, 0.147]).

Conclusions: Evaluating HRV and MAP can help us to understand cognitive load and its implications on trainee and physician clinical reasoning performance, with the intent to utilize this information to improve patient care.