title: Mild hypothermia increases pulmonary anti-inflammatory response during protective mechanical ventilation in a piglet model of acute lung injury.
abstract: BACKGROUND
  The effects of mild hypothermia (HT) on acute lung injury (ALI) are unknown in species with metabolic rate similar to that of humans, receiving protective mechanical ventilation (MV). We hypothesized that mild hypothermia would attenuate pulmonary and systemic inflammatory responses in piglets with ALI managed with a protective MV.
  
  
  METHODS
  Acute lung injury (ALI) was induced with surfactant deactivation in 38 piglets. The animals were then ventilated with low tidal volume, moderate positive end-expiratory pressure (PEEP), and permissive hypercapnia throughout the experiment. Subjects were randomized to HT (33.5°C) or normothermia (37°C) groups over 4 h. Plasma and tissue cytokines, tissue apoptosis, lung mechanics, pulmonary vascular permeability, hemodynamic, and coagulation were evaluated.
  
  
  RESULTS
  Lung interleukin-10 concentrations were higher in subjects that underwent HT after ALI induction than in those that maintained normothermia. No difference was found in other systemic and tissue cytokines. HT did not induce lung or kidney tissue apoptosis or influence lung mechanics or markers of pulmonary vascular permeability. Heart rate, cardiac output, oxygen uptake, and delivery were significantly lower in subjects that underwent HT, but no difference in arterial lactate, central venous oxygen saturation, and coagulation test was observed.
  
  
  CONCLUSIONS
  Mild hypothermia induced a local anti-inflammatory response in the lungs, without affecting lung function or coagulation, in this piglet model of ALI. The HT group had lower cardiac output without signs of global dysoxia, suggesting an adaptation to the decrease in oxygen uptake and delivery. Studies are needed to determine the therapeutic role of HT in ALI.
authors.affiliation: Área de Cuidados Críticos, Hospital Padre Hurtado, Santiago, Chile; Centro de Investigación de Medicina Veterinaria, Escuela de Medicina Veterinaria, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, Santiago, Chile.
authors.forename: Pablo
authors.initials: P
authors.lastname: Cruces
authors.forename: Benjamín
authors.initials: B
authors.lastname: Erranz
authors.forename: Alejandro
authors.initials: A
authors.lastname: Donoso
authors.forename: Cristóbal
authors.initials: C
authors.lastname: Carvajal
authors.forename: Tatiana
authors.initials: T
authors.lastname: Salomón
authors.forename: María Fernanda
authors.initials: MF
authors.lastname: Torres
authors.forename: Franco
authors.initials: F
authors.lastname: Díaz
mesh_terms: D055371:Acute Lung Injury / Q000517:prevention & control*; D000758:Anesthesia; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015415:Biomarkers / Q000097:blood; D001777:Blood Coagulation / Q000502:physiology; D002199:Capillary Permeability / Q000502:physiology; D053148:Caspase 3 / Q000097:blood; D016207:Cytokines / Q000097:blood; D006439:Hemodynamics / Q000502:physiology; D007036:Hypothermia, Induced / Q000379:methods*; D007249:Inflammation / Q000517:prevention & control*; D008168:Lung / Q000473:pathology; D053717:Pneumonia, Ventilator-Associated / Q000517:prevention & control*; D011175:Positive-Pressure Respiration; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000009:adverse effects*; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology; D013552:Swine
chemical_list: D015415:Biomarkers; D016207:Cytokines; D053148:Caspase 3
keywords: acute lung injury; cytokines; hypothermia; mechanical ventilation; oxygen uptake; pediatric