Pulmonary mechanics in dogs given different doses of kerosene intratracheally

Kerosene was instilled intratracheally into mongrel dogs of either sex weighing 10 to 15 kg and anesthetized intravenously with sodium pentobarbital (25 mg/kg). Two different doses were used: 0.3 and 0.06 ml/kg. Pulmonary mechanics, including pressure-volume (P-V) curve, thoracic gas volume (Vtg), total lung capacity (TLC), total pulmonary resistance (RL), and chord compliance (CL) were measured by using a whole body plethysmograph, before and at various time intervals during the 2 wk after instillation. Histologic studies were also performed. In the high-dose (0.3 ml/kg) kerosene experiments there were significant decreases in Vtg, TLC, and CL values by 24 h, which returned to control values at 1 wk after kerosene instillation. The RL and CL normalized for TLC did not change. In contrast, in the dogs receiving the low dose (0.06 ml/kg), there was no significant change in any of these parameters at 24 h. Histologic examination revealed an early exudative phase consisting of exudation of macrophages, red cells, and edema (at 1 and at 24 h), and a later phase consisting of proliferative bronchiolitis (at 1 and at 2 wk). Animals receiving the low dose revealed the same pattern as those receiving the high dose at 24 h, but changes were less extensive. We conclude (1) that kerosene-induced lung injury causes loss of terminal air spaces at both low and high doses, and (2) that the shift in the P-V curve is dose dependent. We hypothesize that kerosene causes two types of physiologic lesions. In areas in which terminal air spaces remained open, an increase in compliance occurred, whereas in areas in which intraalveolar exudation occurred there was "drop-out" of lung units. The final P-V curve was determined by the relative proportions of these two types of areas.