Cardiac output measurement with echocardiography and pressure recording analytical method in pediatric patients admitted to cardiac intensive care unit: a retrospective assessment of bias between the two methods

Abstract Objectives This study aimed to compare, in a cohort of critically ill children with biventricular anatomy and no cardiovascular shunt, cardiac output (CO) and cardiac index (CI) assessed by echocardiography and a continuous pulse contour method, MostCareUP, to measure the differences between these techniques (biasCO and biasCI), and their association with clinical variables. Design Retrospective study. Setting Tertiary pediatric cardiac intensive care unit (PCICU). Participants Children admitted to the PCICU who underwent echocardiography with CO measurement. Interventions None. Measurements and Main Results Thirty-five patients were retrieved. BiasCO was -0.02(0.26) L/min (percentage error 36%). BiasCI was 0.07(0.34) L/min/m2 (percentage error 18%). Biases and percentage errors were higher in 24 non-supervised echocardiographies. A negative biasCO (overestimation by MostCareUP) was associated with post-surgical status (vs. cardiomyopathy), higher systolic arterial pressure, and spontaneous breathing (vs. intubation). When only absolute values were considered, biasCONONEG correlated with age, weight, arterial pressure, and heart rate, whereas biasCINONEG was associated with femoral arterial cannula, no use of inotropes and the absence of mechanical ventilation. After adjustment, biasCONONEG remained independently associated with patients’ body weight(p=0.0001). BiasCINONEG showed a non-linear relationship with weight below 20 kg and above 40 kg. Conclusions Children with extreme low or high weights, those who are extubated and those with femoral cannula carry the highest bias. When younger patients are considered, CI should be evaluated instead of CO, since biases are better highlighted by indexing data on body surface area. In children, both echocardiography and MostCareUP may be responsible of inaccurate CO/CI assessment.