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Resuscitation with 100% O2 does not protect the myocardium in hypoxic newborn piglets
  1. W B Børke1,2,3,
  2. B H Munkeby1,3,5,
  3. L Mørkrid4,
  4. E Thaulow2,
  5. O D Saugstad1
  1. 1Department of Pediatric Research, Rikshospitalet University Hospital, Oslo, Norway
  2. 2Department of Pediatrics
  3. 3Institute for Surgical Research
  4. 4Department of Clinical Chemistry, Rikshospitalet
  5. 5Department of Anaesthesiology, Aker University Hospital, Oslo
  1. Correspondence to:
    Dr Børke
    Rikshospitalet, Oslo 0027, Norway;


Background: Perinatal asphyxia is associated with cardiac dysfunction secondary to myocardial ischaemia. Cardiac troponin I (cTnI) is a marker of myocardial necrosis. Raised concentrations in the blood are related to perinatal asphyxia and increased morbidity.

Objective: To assess porcine myocardial damage from enzyme release during hypoxaemia induced global ischaemia, and subsequent resuscitation with ambient air or 100% O2. To investigate whether CO2 level during resuscitation influences myocardial damage.

Design: Newborn piglets (12–36 hours) were exposed to hypoxaemia by ventilation with 8% O2 in nitrogen. When mean arterial blood pressure had fallen to 15 mm Hg, or base excess to < −20 mmol/l, the animals were randomly resuscitated by ventilation with either 21% O2 (group A, n = 29) or 100% O2 (group B, n = 29) for 30 minutes. Afterwards they were observed in ambient air for another 150 minutes. During resuscitation, the two groups were further divided into three subgroups with different CO2 levels.

Analysis: Blood samples were analysed for cTnI, myoglobin, and creatine kinase-myocardial band (CK-MB) at baseline and at the end of the study.

Results: cTnI increased more than 10-fold (p < 0.001) in all the groups. Myoglobin and CK-MB doubled in concentration.

Conclusion: The considerable increase in cTnI indicates seriously affected myocardium. Reoxygenation with 100% oxygen offered no biochemical benefit over ambient air. CK-MB and myoglobin were not reliable markers of myocardial damage. Normoventilation tended to produce better myocardial outcome than hyperventilation or hypoventilation.

  • troponin I
  • myocardium
  • heart
  • pig
  • resuscitation
  • cTnI, cardiac troponin I
  • PAP, pulmonary artery pressure
  • PIP, peak inspiratory pressure
  • PVR, pulmonary vascular resistance

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