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Cardiorespiratory effects of changes in end expiratory pressure in ventilated newborns
  1. Koert A de Waal1,
  2. Nick Evans2,
  3. David A Osborn2,
  4. Martin Kluckow3
  1. 1
    RPA Newborn Care, Royal Prince Alfred Hospital, Sydney, Australia
  2. 2
    RPA Newborn Care and University of Sydney, Sydney, Australia
  3. 3
    Department of Neonatology, Royal North Shore Hospital and University of Sydney, Sydney, Australia
  1. Koert A d e Waal, Academic Medical Centre, Department of Neonatology, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands; k.a.dewaal{at}amc.nl

Abstract

Background: Positive pressure ventilation in premature infants can improve oxygenation but may diminish cerebral blood flow and cardiac output. Low superior vena cava (SVC) flow increases risk of intraventricular haemorrhage, and higher mean airway pressure is associated with low SVC flow. Whether this is a direct effect of positive pressure ventilation or a reflection of severity of lung disease is not known. This study aimed to determine if positive end expiratory pressure (PEEP) in ventilated newborns could be increased without clinically relevant cardiorespiratory changes.

Method: Ventilated newborns were studied before and 10 min after increasing PEEP (5 cm H2O to 8 cmH2O) and again when PEEP returned to baseline. Echocardiographic and respiratory function measurements were collected during the intervention.

Results: In 50 infants, increased PEEP was associated with a non-significant difference in mean SVC flow of −5 ml/kg/min (95% CI −12 to 3 ml/kg/min) but a significant reduction in right ventricular output of 17 ml/kg/min (95% CI 5 to 28 ml/kg/min). The increase in lung compliance was non-significant (median difference 0.02 ml/cmH2O/kg) and the decrease in lung resistance (18 cmH2O/l/s; 95% CI 10 to 26 cm H2O/l/s) was significant. Changes (%) in lung compliance and SVC flow, when corrected for Paco2, were positively associated (regression coefficient 0.4%; 95% CI 0.2% to 0.6%).

Conclusion: A short-term increase in PEEP does not lead to significant changes in systemic blood flow, although 36% of infants in the present study had clinically important changes in flow (±25%). The intervention can improve dynamic lung function, especially airway resistance. Improvements in compliance tend to be associated with improvements in blood flow.

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Footnotes

  • Funding: Koert A de Waal was partially funded by the Ter Meulen Fund, Royal Netherlands Academy of Arts and Sciences.

  • Competing interests: None.

  • Abbreviations:
    Fio2
    fractional inspired oxygen
    MCA
    middle cerebral artery
    Paco2
    arterial carbon dioxide pressure
    PEEP
    positive end expiratory pressure
    RVO
    right ventricular outflow
    SVC
    superior vena cava
    TPV/RVET
    time to peak velocity divided by the right ventricular ejection time

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