title: Cardio-renal recovery of hypoxic newborn pigs after 18%, 21% and 100% reoxygenation.
abstract: OBJECTIVE
  We examined the effects of 18%, 21% or 100% oxygen on the recovery of the heart and kidneys in a short-term survival model of neonatal hypoxia-reoxygenation (HR).
  
  
  METHODS
  Controlled, block-randomized animal study.
  
  
  METHODS
  University animal research laboratory.
  
  
  METHODS
  Large White piglets (1-3 days, 1.7-2.5 kg).
  
  
  METHODS
  Piglets received normocapnic hypoxia (15% oxygen) (2 h) and were reoxygenated with 18%, 21% or 100% oxygen (1 h) (n=7 per group) then 21% oxygen (2 h). Sham-operated pigs (n=7) had no HR.
  
  
  RESULTS
  Seventeen of 21 HR piglets recovered from moderate hypoxemia (mean PaO(2) 27-33 mmHg and pH 7.20-7.22, associated with tachycardia and hypotension). Systemic arterial pressure, heart rate, left renal arterial flow, oxygen transport, plasma troponin-I and creatinine levels were monitored and recovered with no differences among HR groups over 4 days after resuscitation. The 100% group had increased myocardial oxidative stress (oxidized glutathione levels) and the most cardiac HR-induced injury. There were no differences in renal oxidative stress and HR-induced injury among groups. Early oxygenation at 1 h after resuscitation correlated with the plasma troponin-I level at 6 h (r = -0.51 and 0.64 for SaO(2) and systemic oxygen extraction ratio, p<0.05, respectively) and renal HR-induced injury at 4 days (r =0.61 for renal oxygen delivery, p<0.05).
  
  
  CONCLUSIONS
  In hypoxic piglets, 18%, 21% and 100% reoxygenation caused similar systemic and renal hemodynamic and functional recovery. The indicators of oxidative stress and HR injury in myocardial and renal tissues suggest that the reoxygenation with 100% oxygen appears sub-optimal and the use of 18% oxygen offers no further benefit, when compared with 21% oxygen.
authors.affiliation: Royal Alexandra Hospital, 10240 Kingsway Avenues, Edmonton, Alberta, Canada. poyin@ualberta.ca
authors.forename: Po-Yin
authors.initials: PY
authors.lastname: Cheung
authors.forename: Laila
authors.initials: L
authors.lastname: Obaid
authors.forename: Marwan
authors.initials: M
authors.lastname: Emara
authors.forename: Yann
authors.initials: Y
authors.lastname: Brierley
authors.forename: Scott T
authors.initials: ST
authors.lastname: Johnson
authors.forename: Grace S
authors.initials: GS
authors.lastname: Chan
authors.forename: Laurence
authors.initials: L
authors.lastname: Jewell
authors.forename: Gregory
authors.initials: G
authors.lastname: Korbutt
authors.forename: David L
authors.initials: DL
authors.lastname: Bigam
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers / Q000378:metabolism; D001783:Blood Flow Velocity; D016009:Chi-Square Distribution; D004797:Enzyme-Linked Immunosorbent Assay; D005978:Glutathione / Q000378:metabolism; D006439:Hemodynamics; D000860:Hypoxia / Q000503:physiopathology / Q000628:therapy*; D007668:Kidney / Q000098:blood supply / Q000378:metabolism*; D008099:Liver / Q000098:blood supply / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D018384:Oxidative Stress; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011897:Random Allocation; D013552:Swine
chemical_list: D015415:Biomarkers; D005978:Glutathione