Cardiac Output Measurement With Echocardiography and Pressure Recording Analytical Method in Pediatric Patients Admitted to the Cardiac Intensive Care Unit: A Retrospective Assessment of Bias Between the Two Methods

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, MostCare, 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.

Participants: Children admitted to the pediatric cardiac intensive care unit who underwent echocardiography with CO measurement.

Interventions: None.

Measurements And Main Results: Thirty-five patients were included. BiasCO was -0.02 (0.26) L/min (percentage error 36%). BiasCI was 0.07 (0.34) L/min/m (percentage error 18%). Biases and percentage errors were higher in 24 nonsupervised echocardiographies. A negative biasCO (overestimation by MostCare) was associated with post-surgical status (v cardiomyopathy), higher systolic arterial pressure, and spontaneous breathing (v intubation). When only absolute values were considered, biasCO correlated with age, weight, arterial pressure, and heart rate, whereas biasCI was associated with a femoral arterial cannula, no use of inotropes, and the absence of mechanical ventilation. After adjustment, biasCO remained independently associated with patients' body weight(p = 0.0001). BiasCI showed a nonlinear 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 a femoral cannula carry the highest bias. When younger patients are considered, CI should be evaluated instead of CO, because biases are better highlighted by indexing data on body surface area. In children, both echocardiography and MostCare may be responsible of inaccurate CO/CI assessment.