Intraobserver and interobserver reliability of standardized capillary refill time in dogs is high following observer training.

Abstract

To assess intraobserver and interobserver reliability of capillary refill time (CRT) measurement in dogs using a standardized technique after training. 20 dogs presented to the emergency room. Dogs presented to the emergency room were prospectively recruited. Using a timing device and standardized technique, CRT was measured at the oral mucosa of the inner lip. Measurements were performed by 2 emergency and critical care residents (observer 1 [Ob1] and observer 2 [Ob2]) and repeated 3 times by each observer for each dog. CRT values and signalment were recorded. Intraobserver and interobserver reliability were analyzed by calculation of the coefficient of variation (CV%), intraclass correlation coefficient (ICC), and minimal detectable difference. Reliability was considered high if CV% was lower than 10% and ICC was between 0.9 and 1. Median CRT for Ob1 was 1.22 seconds and for Ob2 was 1.19 seconds. Intraobserver reliability was high, evidenced by a median CV% of 6.2% (range, 1.0% to 18.6%) and 9.5% (range, 1.3% to 22.6%) and an ICC of 0.97 (95% CI, 0.94 to 0.99) and 0.95 (95% CI, 0.90 to 0.98) for Ob1 and Ob2, respectively. Between observers, the CV% was 4.4% (range, 0.8% to 17.5%) and the ICC was 0.98 (95% CI, 0.94 to 0.99), indicating high interobserver reliability. The minimal detectable differences for intraobserver and interobserver were 0.30 and 0.34 seconds, respectively. The reported high reliability of CRT despite its subjective nature enhances its usefulness in daily practice. However, further research on the validity of CRT is warranted.