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Appropriate positive end expiratory pressure level in surfactant-treated preterm infants
G Dimitriou1, A Greenough, B Laubscher
1Children Nationwide Regional Neonatal Intensive Care Centre, 4th floor, Ruskin Wing, King's College Hospital, London SE5 9RS UK.
Insights
In preterm infants treated with surfactant, increasing positive end expiratory pressure (PEEP) above 3 cmH(2)O can lead to overdistension and CO(2) retention. Lower PEEP levels may be more appropriate after surfactant administration.
Area of Science:
- Neonatal Medicine
- Respiratory Physiology
- Pediatric Critical Care
Background:
- Positive end expiratory pressure (PEEP) is a standard ventilation strategy for preterm infants, particularly those with severe respiratory distress syndrome (RDS).
- Surfactant administration is also a key intervention for RDS, aiming to improve lung function.
Purpose of the Study:
- To investigate the effects of varying positive end expiratory pressure (PEEP) levels on lung volume, compliance, and blood gases in surfactant-treated preterm infants.
- To determine if modest PEEP levels could cause lung overdistension and carbon dioxide (CO(2)) retention in this population.
Main Methods:
- Eight preterm infants (median gestational age 28 weeks) with RDS were studied 18 hours post-surfactant treatment.
- Functional residual capacity (FRC) was measured using helium dilution to assess lung volume.
- Compliance and arterial blood gases (pH, paCO(2)) were measured at three randomized PEEP levels (0, 3, and 6 cmH(2)O).
Main Results:
- Increasing PEEP from 0 to 3 cmH(2)O and further to 6 cmH(2)O significantly increased functional residual capacity (FRC).
- PaCO(2) levels increased significantly with higher PEEP settings (P < 0.02).
- Specific compliance and pH decreased significantly as PEEP increased (P < 0.05 and P < 0.02, respectively).
Conclusions:
- Following surfactant treatment, positive end expiratory pressure (PEEP) levels of 3 cmH(2)O or lower appear to be appropriate for preterm infants.
- Higher PEEP levels may lead to lung overdistension and impaired gas exchange in surfactant-treated infants.
Unlabelled:
Positive end expiratory pressure (PEEP) is routinely used when ventilating preterm infants, and high levels are recommended in those with severe respiratory distress syndrome (RDS). Elevation of PEEP increases lung volume, as does surfactant administration. We postulated that in surfactant-treated infants even modest PEEP levels could result in overdistension and (CO(2)) retention. To test that hypothesis, lung volume, compliance and arterial blood gases were measured in eight preterm infants (median gestational age 28 weeks, range 26-35 weeks) at three PEEP levels. The infants, all with RDS, were studied at a median time of 18 h, (range 12-68 h) after their last dose of surfactant. Infants were routinely nursed at 3 cmH(2)O of PEEP, the PEEP level was then raised to 6 cmH(2)O or lowered to 0 cmH(2)O in random order. The new setting was maintained for 20 min; the PEEP level was then changed to the third level (0 or 6 cmH(2)O) again for 20 min. At the end of each 20-min period, lung volume, compliance and blood gases were measured. Lung volume was assessed by measuring functional residual capacity (FRC) using a helium dilution technique. Compliance was measured by relating the volume change from a positive pressure inflation maintained until no further volume change occurred to the pressure drop (peak inflating pressure PEEP). Increasing PEEP from 0 to 3 cmH(2)O and particularly to 6 cmH(2)O resulted in increases in FRC (P < 0.05), oxygenation (ns) and paCO(2) (P < 0.02). Specific compliance (compliance/FRC) (P < 0.05) and pH (P < 0.02) fell.
Conclusion:
Following surfactant treatment, relatively low levels of positive end expiratory pressure (