Changes in cardiac output and stroke volume as measured by non-invasive CO monitoring in infants with RSV bronchiolitis.

Objectives: The primary aim of the study was to determine the changes, if any, in cardiac output (CO) and stroke volume (SV) in normal infants with RSV bronchiolitis. The secondary aim was to determine whether changes in CO (ΔCO) and SV (ΔSV) are associated with changes in respiratory rate (ΔRR).

Methods: Non-invasive CO recordings were obtained within 24 h of admission and discharge. Changes in CO, SV, and HR measurements were compared using paired t-tests. The effect of fluid boluses during the first 24 h (<60 or ≥60 cc/kg) on CO was assessed by 2 way ANOVA with time and group as main effect. The relationship between ΔRR and ΔCO or ΔSV was assessed by linear regression. Data is presented as Mean ± SEM and mean differences with 95 % confidence interval (p < 0.05 considered significant).

Results: 15 infants with RSV bronchiolitis were studied. CO (1.31 ± 0.13 to 1.11 ± 0.11 l/min (0.21 [0.04-0.37]) and SV (9.42 ± 1.10 to 7.75 ± 0.83 ml/beat (1.67 [0.21-3.12]) decreased significantly while HR (142.1 ± 4.0 to 145.2 ± 3.1 beats/min 3.0 [-5.3 to 11.3]) was unchanged. SV (p = 0.02) and CO (p = 0.04) significantly decreased only in the 7 infants that received ≥60 cc/kg. ΔRR correlated significantly with ΔCO (r (2) = 0.28, p = 0.04); but not with ΔSV (r (2) = 0.20, p = 0.09).

Conclusions: ∆CO was related to ΔSV and not Δ HR. The ∆CO and ΔSV were affected by fluid boluses. ΔRR correlated with ΔCO. Non-invasive CO monitoring can trend CO and SV in infants with bronchiolitis during hospitalization.