title: Reduced pulmonary blood flow in regions of injury 2 hours after acid aspiration in rats.
abstract: BACKGROUND
  Aspiration-induced lung injury can decrease gas exchange and increase mortality. Acute lung injury following acid aspiration is characterized by elevated pulmonary blood flow (PBF) in damaged lung areas in the early inflammation stage. Knowledge of PBF patterns after acid aspiration is important for targeting intravenous treatments. We examined PBF in an experimental model at a later stage (2 hours after injury).
  
  
  METHODS
  Anesthetized Wistar-Unilever rats (n = 5) underwent unilateral endobronchial instillation of hydrochloric acid. The PBF distribution was compared between injured and uninjured sides and with that of untreated control animals (n = 6). Changes in lung density after injury were measured using computed tomography (CT). Regional PBF distribution was determined quantitatively in vivo 2 hours after acid instillation by measuring the concentration of [(68)Ga]-radiolabeled microspheres using positron emission tomography.
  
  
  RESULTS
  CT scans revealed increased lung density in areas of acid aspiration. Lung injury was accompanied by impaired gas exchange. Acid aspiration decreased the arterial pressure of oxygen from 157 mmHg [139;165] to 74 mmHg [67;86] at 20 minutes and tended toward restoration to 109 mmHg [69;114] at 110 minutes (P < 0.001). The PBF ratio of the middle region of the injured versus uninjured lungs of the aspiration group (0.86 [0.7;0.9], median [25%;75%]) was significantly lower than the PBF ratio in the left versus right lung of the control group (1.02 [1.0;1.05]; P = 0.016).
  
  
  CONCLUSIONS
  The PBF pattern 2 hours after aspiration-induced lung injury showed a redistribution of PBF away from injured regions that was likely responsible for the partial recovery from hypoxemia over time. Treatments given intravenously 2 hours after acid-induced lung injury may not preferentially reach the injured lung regions, contrary to what occurs during the first hour of inflammation. Please see related article: http://dx.doi.org/10.1186/s12871-015-0014-z.
authors: Department of Anesthesia and Intensive Care, Carl Gustav Carus University Hospital, Technische Universität Dresden, Dresden, Germany.
authors: Torsten
authors: T
authors: Richter
authors: Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden- Rossendorf, Dresden, Germany.
authors: Ralf
authors: R
authors: Bergmann
authors: Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts USA.
authors: Guido
authors: G
authors: Musch
authors: Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden- Rossendorf, Dresden, Germany ; Department of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, Germany.
authors: Jens
authors: J
authors: Pietzsch
authors: Department of Anesthesia and Intensive Care, Carl Gustav Carus University Hospital, Technische Universität Dresden, Dresden, Germany.
authors: Thea
authors: T
authors: Koch
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005710:Gallium Radioisotopes; D006851:Hydrochloric Acid / Q000633:toxicity*; D055370:Lung Injury / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008863:Microspheres; D049268:Positron-Emission Tomography; D011652:Pulmonary Circulation / Q000502:physiology*; D051381:Rats; D053120:Respiratory Aspiration / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed
chemical_list: D005710:Gallium Radioisotopes; D006851:Hydrochloric Acid
keywords: Acute lung injury; Adult respiratory distress syndrome; Positron emission tomography; Pulmonary circulation; Pulmonary perfusion; Respiratory aspiration