Cardiac index as a surrogate marker for anxiety in pediatric patients undergoing ambulatory endoscopy: a prospective cohort study

<i>Objective.</i>Pediatric patients undergoing medical procedures often grapple with preoperative anxiety, which can impact postoperative outcomes. While healthcare providers subjectively assess anxiety, objective quantification tools remain limited. This study aimed to evaluate two objective measures-cardiac index (CI) and heart rate (HR) in comparison with validated subjective assessments, the modified Yale Preoperative Anxiety Scale (mYPAS) and the numeric rating scale (NRS).<i>Approach.</i>In this prospective, observational cohort study, children ages 5-17 undergoing ambulatory endoscopy under general anesthesia underwent simultaneous measurement of objective and subjective measures at various time points: baseline, intravenous placement, two-minutes post-IV placement, when departing the preoperative bay, and one-minute prior to anesthesia induction.<i>Main Results.</i>Of the 86 enrolled patients, 77 had analyzable CI data and were included in the analysis. The median age was 15 years (interquartile range 13, 16), 55% were female, and most were American Society of Anesthesiologists (ASA) Physical Status 2 (64%), and had previous endoscopies (53%). HR and CI correlated overall (<i>r</i>= 0.65, 95% CI: 0.62, 0.69;<i>p</i>< 0.001), as did NRS and mYPAS (<i>r</i>= 0.39, 95% CI: 0.34, 0.44;<i>p</i>< 0.001). The correlation between HR and CI was stronger with NRS (<i>r</i>= 0.24, 95% CI: 0.19, 0.29;<i>p</i>< 0.001; and<i>r</i>= 0.13, 95% CI: 0.07, 0.19;<i>p</i>< 0.001, respectively) than with mYPAS (<i>r</i>= 0.06, 95% CI: 0.00, 0.11;<i>p</i>= 0.046; and<i>r</i>= 0.08, 95% CI: 0.02, 0.14;<i>p</i>= 0.006, respectively). The correlation with mYPAS for both HR and CI varied significantly in both direction and magnitude across the different time points.<i>Significance.</i>A modest yet discernable correlation exists between objective measures (HR and CI) and established subjective anxiety assessments.