Lung injury and recovery in a murine model of unilateral acid aspiration: functional, biochemical, and morphologic characterization.
BACKGROUND
Acid aspiration is a complication of general anesthesia. Most animal models developed to define its pathophysiology have focused on the acute (< or =24 h) phase of the injury. The authors describe a model of acid aspiration allowing the study of this type of lung injury over time.


METHODS
The authors instilled hydrochloric acid (0.1 m, 1.5 ml/kg) or normal saline in the right bronchus of mice. Lung injury was evaluated at 6 h, 12 h, 24 h, and 2 weeks by assessing arterial blood gases, respiratory system compliance, lung wet weight normalized by body weight, lung myeloperoxidase activity, and histology. Twelve hours and 2 weeks after injury, a computed tomography scan was obtained.


RESULTS
In the hydrochloric acid group, arterial oxygen tension decreased (P < 0.05) at 12 and 24 h, whereas it recovered at 2 weeks; respiratory system compliance was lower both at 24 h and 2 weeks (P < 0.05). Lung weight increased at 12 and 24 h (P < 0.05). Myeloperoxidase activity peaked between 6 and 12 h. Computed tomography at 12 h showed that almost 30% of the injured lung was abnormally aerated. Although reduced, the abnormalities were still present at 2 weeks as confirmed by a fibrotic scar well evident at histologic examination.


CONCLUSIONS
The authors characterized a murine model of regional acid aspiration allowing long-term survival. Despite a partial recovery, at 2 weeks the injury persisted, with evidence of fibrosis and lung compliance reduction. This long-term, low-mortality model seems suitable for assessment of the effects of different therapies on lung injury and repair.
Amigoni
Maria
M
Department of Experimental Medicine, University of Milano-Bicocca and Department of Perioperative Medicine and Intensive Care, San Gerardo Hospital, Monza, Italy.
Bellani
Giacomo
G
Scanziani
Margherita
M
Masson
Serge
S
Bertoli
Elisa
E
Radaelli
Enrico
E
Patroniti
Nicolò
N
Di Lelio
Alessandro
A
Pesenti
Antonio
A
Latini
Roberto
R
D000818:Animals; D001784:Blood Gas Analysis; D004195:Disease Models, Animal; D005260:Female; D005355:Fibrosis / Q000139:chemically induced / Q000473:pathology; D006851:Hydrochloric Acid / Q000008:administration & dosage / Q000633:toxicity*; D007322:Instillation, Drug; D008168:Lung / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D008170:Lung Compliance / Q000187:drug effects; D051379:Mice; D009929:Organ Size / Q000187:drug effects; D009195:Peroxidase / Q000187:drug effects; D011015:Pneumonia, Aspiration / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology; D011897:Random Allocation; D020127:Recovery of Function; D053120:Respiratory Aspiration / Q000473:pathology / Q000503:physiopathology; D012965:Sodium Chloride / Q000008:administration & dosage; D013997:Time Factors; D014057:Tomography, X-Ray Computed
D012965:Sodium Chloride; D009195:Peroxidase; D006851:Hydrochloric Acid