Objective: To determine if acute unilateral lung injury induces only local or systemic inflammatory effects by measuring the production of nitric oxide (NO) and its metabolites (nitrites and nitrates) in the injured and the contralateral lung and the blood initially and 4 hrs after injury.
Design: Unilateral hydrochloric acid instillation in split lung intubated subject studied over time.
Setting: Animal physiology laboratory.
Subjects: Five mongrel dogs.
Interventions: Instillation of 10 mL of 0.1 N hydrochloric acid into one lung via a plastic catheter. Bronchoalveolar lavage (BAL) was done at 4 hrs.
Measurements and main results: Unilateral acid instillation did not alter systemic blood pressure or cardiac output, nor did it induce arterial hypoxemia. The BAL nitrite and nitrate level on the side of injury was higher than the control side (3.6+/-1.36 vs. 1.5+/-1.58 mM, p < .05), and serum nitrites and nitrates levels also decreased from the levels before acid instillation levels (p < .05). Exhaled NO levels were measured only in three animals. The levels increased acutely on hydrochloric acid instillation from only the injured lung and returned to baseline over several minutes. However, the level of exhaled NO from the injured lung failed to increase 4 hrs after injury, despite the increase in BAL nitrites and nitrates.
Conclusions: Acute unilateral lung injury in the dog results in increased NO production that is compartmentalized to the injured lung. The increase in exhaled NO after injury is transient and does not allow one to monitor the progress of lung injury.