Cerebral hemodynamics and oxygenation before and after modified ultrafiltration following corrective cardiac surgery in infants and children

Introduction

Modified ultrafiltration (MUF) at the termination of cardiopulmonary bypass (CPB) has been considered to remove accumulated fluid and inflammatory mediators and thereby to improve cerebral metabolic rate in infants after cardiac surgery. The aim of this study was to investigate change in cerebral hemodynamics and oxygenation before and after MUF following corrective cardiac surgery of congenital heart defects.

Methods

In 55 neonates and infants below the age of 9 month's (weight 7.5 ± 4kg) undergoing surgical correction of congenital heart disease by means of full flow CPB (120-150 ml/kg body weight) with moderate hypothermia (24 ± 6°C) and alpha-stat strategy were prospectively studied either to MUF (n = 25) or no MUF (n = 20). Continuous determinations of regional cerebral hemoglobin saturation (rSO₂) by near infrared spectroscopy (NIRS) and mean flow velocity (MFV) in the middle cerebral artery (MCA) by transcranial Doppler (TCD) provided qualitative on-line information of cerebral perfusion and oxygenation, The pulsatility index (PI) was calculated according to the formula (PI= maximal flow velocity-end-diastolic flow velocity/mean flow velocity). Other hemodynamic parameters such as mean arterial blood pressure (MAP), hemoglobin (Hb) and arterial oxygen saturation (SO₂) were simultaneously documented.

Results

There was no significant difference in bypass time and minimal rectal temperature in infants with and without MUF. An initially decreased diastolic flow velocity pattern - resulting in higher calculated PI - decreased significantly at the end of operation in infants with more than those without MUF (Table). The change in systemic and regional cerebral hemoglobin saturation was not significantly different in both groups.

Table Table. Parameters pre- and after ultrafiltration in infants with and without MUF

Conclusion

The magnitude of lowering the cerebrovascular resistance and possible improvements of cerebral perfusion after CPB was more observed in the MUF group. However, the beneficial effect to immediate postoperative hemodynamics and regional oxygenations seem to be not significant.