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Restoration of cardiopulmonary function with 21% versus 100% oxygen after hypoxaemia in newborn pigs
  1. D Fugelseth1,4,
  2. W B Børke1,2,3,
  3. K Lenes2,
  4. I Matthews1,2,
  5. O D Saugstad1,
  6. E Thaulow2
  1. 1Department of Paediatric Research, Rikshospitalet University Hospital, Oslo, Norway
  2. 2Department of Paediatrics, Rikshospitalet University Hospital
  3. 3Institute for Surgical Research, Rikshospitalet University Hospital
  4. 4Department of Paediatrics, Ullevål University Hospital, Oslo
  1. Correspondence to:
    Dr Fugelseth
    Department of Paediatrics, Ullevål University Hospital, NO-0407 Oslo, Norway;


Objective: To assess the consequences of hypoxaemia and resuscitation with room air versus 100% O2 on cardiac troponin I (cTnI), cardiac output (CO), and pulmonary artery pressure (PAP) in newborn pigs.

Design: Twenty anaesthetised pigs (12–36 hours; 1.7–2.7 kg) were subjected to hypoxaemia by ventilation with 8% O2. When mean arterial blood pressure fell to 15 mm Hg, or arterial base excess was ⩽ −20 mmol/l, resuscitation was performed with 21% (n  =  10) or 100% (n  =  10) O2 for 30 minutes, then ventilation with 21% O2 for 120 minutes. Blood was analysed for cTnI. Ultrasound examinations of CO and PAP (estimated from tricuspid regurgitation velocity (TR-Vmax)) were performed at baseline, during hypoxia, and at the start of and during reoxygenation.

Results: cTnI increased from baseline to the end point (p<0.001), confirming a serious myocardial injury, with no differences between the 21% and 100% O2 group (p  =  0.12). TR-Vmax increased during the insult and returned towards baseline values during reoxygenation, with no differences between the groups (p  =  0.11) or between cTnI concentrations (p  =  0.31). An inverse relation was found between increasing age and TR-Vmax during hypoxaemia (p  =  0.034). CO per kg body weight increased during the early phase of hypoxaemia (p<0.001), then decreased. Changes in CO per kg were mainly due to changes in heart rate, with no differences between the groups during reoxygenation (p  =  0.298).

Conclusion: Hypoxaemia affects the myocardium and PAP. During this limited period of observation, reoxygenation with 100% O2 showed no benefits compared with 21% O2 in normalising myocardial function and PAP. The important issue may be resuscitation and reoxygenation without hyperoxygenation.

  • CO, cardiac output
  • cTnI, cardiac troponin I
  • LVP, left ventricular pressure
  • PAP, pulmonary artery pressure
  • TR-Vmax, peak tricuspid regurgitation velocity
  • resuscitation
  • cardiac troponin I
  • cardiac output
  • pulmonary hypertension
  • pig

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