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Cerebral haemodynamic effects of changes in positive end expiratory pressure in preterm infants
D B Shortland1, D Field, L N Archer
1Department of Child Health, Leicester University Medical School.
Insights
Increasing positive end expiratory pressure (PEEP) in premature infants with respiratory disease did not adversely affect cerebral circulation. Changes in PEEP primarily impacted cerebral blood flow velocity through alterations in PaCO2 levels.
Area of Science:
- Neonatal Physiology
- Respiratory Medicine
- Pediatric Cardiology
Background:
- Mechanical ventilation is crucial for premature infants with severe respiratory disease.
- Positive end-expiratory pressure (PEEP) is a key ventilator setting affecting respiratory mechanics and gas exchange.
- The impact of PEEP on cerebral hemodynamics in neonates requires further elucidation.
Purpose of the Study:
- To investigate the effects of varying PEEP levels on cerebral blood flow velocity (CBFV).
- To assess the relationship between PEEP, arterial blood gases (PaO2, PaCO2), and mean arterial pressure (MAP).
- To determine the safety of commonly used PEEP ranges in mechanically ventilated neonates.
Main Methods:
- Observational study in mechanically ventilated premature infants.
- Stepwise increases in PEEP from 2 to 6 cm H2O were applied.
- Cerebral blood flow velocity (using Doppler ultrasound), arterial blood gases, and mean arterial pressure were monitored.
Main Results:
- Increased PEEP was associated with increased CBFV.
- No significant changes in mean arterial pressure were observed.
- PaO2 and PaCO2 significantly increased with rising PEEP.
- Multivariate analysis indicated PaCO2 as the primary driver (72%) of CBFV changes, not MAP.
Conclusions:
- PEEP adjustments within the studied range did not negatively impact neonatal cardiovascular or cerebral circulations.
- Changes in CBFV are predominantly influenced by PaCO2 levels, not mean arterial pressure.
- Current PEEP practices appear safe for cerebral hemodynamics in this vulnerable population.
Abstract:
The effects of changes in positive end expiratory pressure (PEEP) on cerebral blood flow velocity, arterial blood gases, and mean arterial pressure were studied in newborn infants. In mechanically ventilated premature infants with severe respiratory disease, an increase in PEEP from 2 to 6 cm H2O was associated with an increase in cerebral blood flow velocity. There was no significant change in mean arterial blood pressure. There was a significant increase in PaO2 and PaCO2 for every stepwise rise in PEEP. Multivariate regression analysis showed that 72% of the effect on cerebral blood flow velocity was attributable to PaCO2 alone and that any change in blood pressure was not likely to contribute to these changes. There was no evidence that changes in PEEP within the commonly used range adversely affected the neonatal cardiovascular or cerebral circulations.