Histological study on the effect of acid aspiration on the lung of albino rat

ABSTRACT

Aspiration of gastric acid is still a common clinical problem and potentially catastrophic since it is a life-threatening complication that can occur in patients with depressed level of consciousness. Pulmonary aspiration is a serious potential complication of pharmaco-sedation and general anesthesia. This study was carried on 75 adult albino rats divided into four groups to identify the effects and consequences of this injury on the structure of the lung. Acidic solutions of different pHs and volumes were instilled into the trachea of these rats, and studied versus time factor. It was found that the severity and consequences of this injury were affected by both pH and volume of the aspirated acidic solution. Morbidity and mortality following aspiration were enhanced with an increased volume of aspirate or a more acidic pH. The reaction was hemorrhagic and necrotizing when the aspirate was highly acid. Acid aspiration was manifested initially by a chemical burn resulting in an immediate and direct insult to the airways and blood capillaries, with subsequent hemorrhage, edema and damage to type I pneumocytes. The second phase was characterized mainly by mononuclear cellular infiltration, predominantly neutrophils. This resulted in destruction of elastic fibers and surfactant inactivation. This in addition to surfactant deficiency with subsequent degeneration in type II pneumocytes resulted in atelectasis. This was followed by fibrosis and regeneration of bronchial and alveolar epithelial cells. Since this injury is fatal, therefore it is recommended to eliminate its predisposing factors and to apply means of preventing its occurrence