High and low body temperature during the initiation of ventilation for near-term lambs.
OBJECTIVE
Recent literature suggests hypothermia may protect against lung injury. We evaluated body temperature as a variable in lung inflammation due to oxygenation and mechanical ventilation following delivery of near-term lambs.


METHODS
Twin fetuses were randomized prior to delivery at 140 d GA (term 150 d): unventilated controls, normothermic ventilated with room air, normothermic ventilated with 100% oxygen, low temperature ventilated (target 35 degrees C) with 100% oxygen, and high temperature (target 40 degrees C) with 100% oxygen. Lambs were intubated for gentle mechanical ventilation (tidal volume 7-8ml/kg). Temperature targeting was with radiant warmers and plastic wrap for normothermia, with heat lamps for hyperthermia, and with ice packs for hypothermia. Lambs were euthanized after 2h mechanical ventilation. Post-mortem, bronchoalveolar lavage fluid and lung tissue samples were evaluated for inflammatory responses by measuring inflammatory cell counts, protein, myeloperoxidase, protein carbonyl, and pro-inflammatory cytokine mRNA.


RESULTS
Target temperatures were achieved by 30min of age and tightly maintained for the 2h study. There were no differences in physiologic variables among groups except those directly resulting from study protocol-PaO2 from air vs. 100% oxygen and body temperature. Indicators of inflammation increased similarly in all ventilated groups compared to unventilated controls.


CONCLUSIONS
Moderate hyperthermia or hypothermia did not affect lung injury responses to the initiation of ventilation at birth in near-term lambs.
Ball
Molly K
MK
Cincinnati Children's Hospital Medical Center, Division of Pulmonary Biology, University of Cincinnati, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA.
Jobe
Alan H
AH
Polglase
Graeme R
GR
Kallapur
Suhas G
SG
Cheah
Fook-Choe
FC
Hillman
Noah H
NH
Pillow
Jane J
JJ
D000818:Animals; D001831:Body Temperature; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D002452:Cell Count; D004195:Disease Models, Animal; D005333:Fetus; D006801:Humans; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D007035:Hypothermia / Q000276:immunology; D007036:Hypothermia, Induced / Q000009:adverse effects*; D007231:Infant, Newborn; D007249:Inflammation / Q000209:etiology* / Q000276:immunology; D053583:Interleukin-1beta / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D008168:Lung / Q000473:pathology*; D011897:Random Allocation; D012121:Respiration, Artificial / Q000379:methods*; D012127:Respiratory Distress Syndrome, Newborn / Q000628:therapy; D012756:Sheep; D016896:Treatment Outcome; D014427:Twins
D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8