O1060 Oct.4: 2:24pm - Volume Guarantee Ventilation in Neonates Treated With Hypothermia for Hypoxic Ischaemic Encephalopathy

Background
Neonatal hypoxic ischaemic encephalopathy (HIE) is brain injury due to perinatal hypoxia associated with significant mortality and long-term morbidity. Beside therapeutic hypothermia optimal intensive care and respiratory support is critical to improve neurodevelopmental outcome and to prevent injury progression. Respiratory management represents particular challenges as these infants frequently require mechanical ventilation, hyperventilate and are at risk of hypocapnia. Volume targeted ventilation (VTV) has been shown to reduce the risk of hypocapnia in preterm infants; however, there have been no reports of VTV in infants suffering from HIE.
Objective
To investigate the tidal volumes and peak inflating pressures during VG ventilation of babies undergoing therapeutic hypothermia for HIE and how these parameters correlate with the spontaneous breathing effort of these infants. We also investigated if the use of VG in these infants prevents hypocapnia.
Methods
We retrospectively analysed computationally collected ventilator data of babies ventilated by a Fabian ventilator, using synchronized intermittent mandatory ventilation (SIMV) with VG (n=28) or without VG (n=8) during inter-hospital transport over a 29-month period between March 2017 and April 2019. We included babies who were born at ≥36 weeks’ gestation, were less than 24 hours old and were treated with hypothermia for HIE. Ventilator data were recorded automatically every two seconds and analysed using the Python computer language.
Results
The expiratory tidal volume of the ventilator inflations (VTemand) was lower in the SIMV-VG group (median [IQR]: 4.9 [4.6-5.3] mL/kg) than in the group ventilated with SIMV without VG (median [IQR]: 7.1 [5.3-8.0] mL/kg, p=0.01). (Figure 1A). Babies receiving SIMV-VG had lower peak inflating pressures (PIP) (median [IQR]: 10.7 [7.8-17.2] cmH2O, versus 17.5 [16.6-19.4] cmH2O, p=0.01). (Figure 1B) There was no significant difference between the groups in pCO2 at the end of the transport. Most babies ventilated with SIMV-VG maintained VTemand within 1 mL/kg of the target value. Babies with strong spontaneous breathing had a mean PIP <10 cmH2O but this did not result in adverse events or worsening of acidosis during the transfer. (Figure 2)
Conclusion
Volume guarantee ventilation in babies with HIE and therapeutic hypothermia reduces the tidal volume of ventilator inflations but does not influence minute ventilation or CO2 elimination. Using VG in babies with HIE leads to low peak inflating pressure, particularly in babies with strong breathing effort; however, the low PIPs did not result in worsening of the acidosis in these infants.