Haemodynamic response to fluid boluses in children after cardiac surgery: a technical report.

Abstract

To describe the haemodynamic response to fluid boluses (FB) in children after cardiac surgery. A prospective observational pilot study. Single-centre, paediatric cardiac intensive care unit. Children after cardiac surgery. FB of 0.9% saline, 4% albumin or modified ultrafiltrate blood administered in less than 30 minutes. Heart rate, arterial blood pressure, central venous pressure, oesophageal temperature, and end-tidal carbon dioxide were measured continuously and reported minutely from 5 minutes before and 30 minutes after FB. A mean arterial pressure (MAP)-responsive episode was defined as a 10% increase in MAP from baseline. There were 21 FB recorded in 9 patients. Most patients (n = 8) weighed ≤ 6 kg, and three had univentricular circulation. Fourteen FB (67%) were 4% albumin and 15 (71%) were ≤ 7.5 mL/kg. There were nine MAP-responsive episodes (43%). Episodes of MAP responsiveness had a median MAP increment from baseline of 5 mmHg (interquartile range [IQR], 5-7) and 5 mmHg (IQR, 2-17) at 15 minutes and 30 minutes, respectively, significantly higher when compared with non-responsive episodes (median, 1 mmHg [IQR, -2 to 3]; and median, -1 mmHg [IQR, -3 to 1]; P < 0.01). In MAP-responsive episodes, median time to response was 6 minutes (IQR, 3-12) and seven episodes (78%) dissipated at a median of 2 minutes after response (IQR, 1-8). MAP response was not associated with fluid volume nor fluid composition. In this study, the haemodynamic response to FB in children is infrequent and unsustained. Larger studies are required to demonstrate the pattern of haemodynamic response of FB in critically ill children.