Dynamic changes of lung lymph flow and the release of lysosomal enzyme from the lungs after severe steam inhalation injury in goats

Abstract

Chronic lung lymph fistulae were produced in six goats according to Winn's and Stothert's methods with our modification to define the pathophysiology of pulmonary oedema after severe steam inhalation injury. Arterial blood gas, lung lymph flow (Q̇ Lym), lymph/plasma total protein concentration ratio (UP), and β-glucuronidase (β-G) in plasma and lung lymph were monitored for 24h post-injury. The pathological changes in the lung tissues were also determined at the end of the study. It was found that directly after injury, Q̇ Lym increased steadily to a peak value at 6 h, followed by declining values at 18 and 24 h. L/P decreased promptly during the 60min after injury and then also steadily increased to a peak value at 4 h (P<0·05). A significant increase in plasma β-G was only observed at 4h post-burn. However, lung lymph β-G activities and lymph β-G transport increased immediately after injury, reaching a peak at 4h (5 and 12 times above baseline values, respectively, P<0·01). Significant hypoxaemia and hypocapnia occurred at 2 h post-burn and deteriorated progressively throughout the study. There were obvious pulmonary interstitial and alveolar oedema microscopically. This study demonstrates that the increase in transvascular fluid and protein flux after steam inhalation injury is mainly due to increased pulmonary microvascular permeability. Nevertheless, a hydrostatic pressure effect can not be completely excluded, especially in the first hour post-burn. Lysosomal enzyme release is considered to be one of the important factors which damage lung microvascular elements and induce an increase in their permeability.