The acute effect of pulmonary burns on lung mechanics and gas exchange in the rabbit.

To determine the role of the thermal element in the production of lung injury uncomplicated by the inhalation of fumes and soot, 18 anaesthetized, paralysed and ventilated rabbits were subjected to a steam burn of the respiratory tract. Transpulmonary pressure (difference between airway and pleural pressure) was recorded under static conditions between functional residual capacity and 40 ml above this point and the values obtained were used to calculate lung compliance. Static compliance decreased progressively with time in each of the experimental animals, the maximum decrease occurring within the 1st hour. Ten of the 18 animals died within 4 hr of the burn. There was little impairment of gas exchange. This data would suggest the clinical value of the early measurement of lung compliance in the evaluation of thermal pulmonary burns. Postmortem studies showed the presence of pulmonary oedema with intra-alveolar peribronchial and perivascular haemorrhages. The lesions were most prominent centrally, apparently because the dissipation of the heat resulted in less damage to the peripheral areas of the lung. Pulmonary megakaryocytosis was noted in seven of the experimental animals. This may have been a non-specific reaction to lung trauma.