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Circulatory effects of ventilator rate and end-expiratory pressure in unparalysed preterm infants
S Bohin1, A C Fenton, J R Thompson
1Department of Child Health, Leicester University Medical School, Leicester Royal Infirmary, UK.
Insights
Cerebral blood flow in paralysed preterm infants changes with blood pressure, unlike in unparalysed infants. This highlights the need to manage blood pressure carefully in paralysed infants to prevent ischaemic brain injury.
Area of Science:
- Neonatal neurology
- Cerebrovascular physiology
- Pediatric critical care
Background:
- Impaired cerebrovascular autoregulation is implicated in neonatal ischaemic brain injury.
- Previous research indicated a link between cerebral blood flow velocity (CBFV) and arterial blood pressure in paralysed preterm infants.
Purpose of the Study:
- To investigate the relationship between CBFV and arterial blood pressure in unparalysed preterm infants under mechanical ventilation.
- To compare cerebrovascular responses in paralysed versus unparalysed preterm infants.
Main Methods:
- Observational study in ventilated preterm infants.
- Monitoring of cerebral blood flow velocity (CBFV) and arterial blood pressure.
- Assessing CBFV changes in response to alterations in ventilator settings (rate, end-expiratory pressure) in unparalysed infants.
Main Results:
- In unparalysed infants, changes in CBFV were independent of concurrent arterial blood pressure fluctuations.
- This contrasts with findings in paralysed infants where CBFV changes were associated with blood pressure variations.
- The results suggest that paralysis may alter cerebrovascular autoregulation.
Conclusions:
- Maintaining stable arterial blood pressure is crucial in paralysed preterm infants to mitigate risks of ischaemic brain injury.
- The impact of different paralysing agents on cerebrovascular autoregulation requires further investigation.
Abstract:
Impairment of cerebrovascular autoregulation may be important in the pathogenesis of ischaemic brain injury in preterm infants. A previous study in ventilated preterm infants paralysed with pancuronium showed that changes in cerebral blood flow velocity (CBFV) were related to concomitant changes in arterial blood pressure. In a similar study in unparalysed infants, changes in CBFV in response to changes in ventilator rate or end-expiratory pressure were independent of associated changes in the arterial blood pressure. These results emphasize the importance of avoiding large swings in blood pressure in paralysed infants. Whether alternative paralysing agents have similar effects warrants further study.