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

OBJECTIVE: To describe the haemodynamic response to fluid boluses (FB) in children after cardiac surgery.

DESIGN: A prospective observational pilot study.

SETTING: Single-centre, paediatric cardiac intensive care unit.

PARTICIPANTS: Children after cardiac surgery.

INTERVENTIONS: FB of 0.9% saline, 4% albumin or modified ultrafiltrate blood administered in less than 30 minutes.

MAIN OUTCOME MEASURES: 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.

RESULTS: 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.

CONCLUSION: 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.