Carotid peak flow velocity variation as a surrogate of aortic peak flow velocity variation in a pediatric population.

Abstract

Background: Carotid peak velocity variation (ΔVpeak_Car) is an alternative to aortic peak velocity variation (ΔVpeak_Ao) and has been used in the pediatric population. Children's physiology and anatomy are heterogeneous throughout their growth. For this reason, the predictive value of ΔVpeakCar as a surrogate of ΔVpeakAo can vary at different ages. We hypothesize that the ability of ΔVpeak_Car as a surrogate of ΔVpeak_Ao changes throughout childhood.

Aim: Analyze the concordance and the tracking ability of ΔVpeak_Car and the ΔVpeak_Ao at different stages of development.

Methods: Patients from 0 to 12 years were included. Three groups were defined: under 12 months (G1), between 12 and 60 months (G2), and over 60 months (G3). After anesthesia induction and mechanical ventilation, maximal and minimal aortic and carotid peak flow were measured. ΔVpeak_Ao and ΔVpeak_Car were calculated. Pearson test and simple linear regression were performed. Bland-Altman analysis was performed to determine concordance. 4-quadrant analysis was used, followed by polar analysis of the vectors, to complement the concordance analysis and determine the tracking ability of ΔVpeak_Car to surrogate ΔVpeak_Ao.

Results: Sixty-seven patients were enrolled. 22 (32.4%) patients in G1, 21 (31.3%) in G2 and 24 (35.8%) in G3. The determination coefficient (r) between ΔVpeak_Ao and ΔVpeak_Car in G1 was 0.44 (p < 0.001) with a slope value of 0.61 (SE = 0.11; 95% CI:0.3-0.91). In G2, r² = 0.56 (p < 0.001) with a slope value of 0.59 (SE = 0.14; 95% CI:0.35-0.82); and in G3, r² = 0.85 (p < 0.001) with a slope value of 1.11 (SE = 0.10; 95% CI:0.91-1.31). Bland-Altman analysis showed to G1 a mean bias of -0.37 (LOA - 7.87 to 7.53), to G2 -0.07 (LOA - 7.37 to 7.23) and G3 0.55 (-3.81 to 4.91). Concordance rates were 100% in G3, 95% in G2, and 93% in G1.

Conclusions: ΔVpeak_Car showed good correlation and tracking ability with ΔVpeak_Ao in schoolchildren. In younger children, it was not reliable enough.