title: Hypoxic/Ischemic models in newborn piglet: comparison of constant FiO2 versus variable FiO2 delivery.
abstract: A comparison of a constant (continuous delivery of 4% FiO2) and a variable (initial 5% FiO2 with adjustments to induce low amplitude EEG (LAEEG) and hypotension) hypoxic/ischemic insult was performed to determine which insult was more effective in producing a consistent degree of survivable neuropathological damage in a newborn piglet model of perinatal asphyxia. We also examined which physiological responses contributed to this outcome. Thirty-nine 1-day-old piglets were subjected to either a constant hypoxic/ischemic insult of 30- to 37-min duration or a variable hypoxic/ischemic insult of 30-min low peak amplitude EEG (LAEEG <5 microV) including 10 min of low mean arterial blood pressure (MABP <70% of baseline). Control animals (n = 6) received 21% FiO2 for the duration of the experiment. At 72 h, the piglets were euthanased, their brains removed and fixed in 4% paraformaldehyde and assessed for hypoxic/ischemic injury by histological analysis. Based on neuropathology scores, piglets were grouped as undamaged or damaged; piglets that did not survive to 72 h were grouped separately as dead. The variable insult resulted in a greater number of piglets with neuropathological damage (undamaged = 12.5%, damaged = 68.75%, dead = 18.75%) while the constant insult resulted in a large proportion of undamaged piglets (undamaged = 50%, damaged = 22.2%, dead = 27.8%). A hypoxic insult varied to maintain peak amplitude EEG <5 microV results in a greater number of survivors with a consistent degree of neuropathological damage than a constant hypoxic insult. Physiological variables MABP, LAEEG, pH and arterial base excess were found to be significantly associated with neuropathological outcome.
authors.affiliation: Perinatal Research Centre, Royal Brisbane and Women's Hospital, University of Queensland, Brisbane 4029, Australia. tbjorkman@somc.uq.edu.au
authors.forename: S Tracey
authors.initials: ST
authors.lastname: Björkman
authors.forename: Kelley A
authors.initials: KA
authors.lastname: Foster
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: O'driscoll
authors.forename: Genevieve N
authors.initials: GN
authors.lastname: Healy
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Lingwood
authors.forename: Chris
authors.initials: C
authors.lastname: Burke
authors.forename: Paul B
authors.initials: PB
authors.lastname: Colditz
mesh_terms: D000375:Aging / Q000502:physiology; D000758:Anesthesia; D000818:Animals; D000831:Animals, Newborn; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D001921:Brain / Q000473:pathology; D003627:Data Interpretation, Statistical; D004569:Electroencephalography / Q000187:drug effects; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology*; D010100:Oxygen / Q000008:administration & dosage*; D010101:Oxygen Consumption / Q000502:physiology*; D012121:Respiration, Artificial; D013552:Swine
chemical_list: D010100:Oxygen