Increased alveolar fluid clearance following thoracotomy: report of a case and results of an analysis

Time-dependent effect of pneumonectomy on alveolar epithelial fluid clearance in rat lungs

OBJECTIVE

Because pneumonectomy initiates compensatory growth of the remaining lung, we determined the time-dependent effects of pneumonectomy on alveolar fluid clearance capacity.

METHODS

Alveolar fluid clearance capacity with the Evans blue-labeled albumin concentration was measured in rats 3 hours, 2 days, 7 days, 14 days, and 28 days after left pneumonectomy. The mechanisms responsible for the increase in alveolar fluid clearance were explored.

RESULTS

Alveolar fluid clearance in the remaining lung was normal through 7 days and then increased 14 and 28 days after pneumonectomy. The increase in alveolar fluid clearance at 28 days after pneumonectomy was accounted primarily by an increase in amiloride-sensitive transport. The expression of epithelial sodium channel messenger RNA was increased in the remaining lung and in type II alveolar epithelial cells isolated from rats 28 days after pneumonectomy. The number of isolated type II cells was larger in pneumonectomized rats than in control rats. Also, beta-adrenergic agonist therapy increased the rate of alveolar fluid clearance at the 3-hour and 28-day time points.

CONCLUSIONS

The capacity to remove alveolar fluid in the remaining lung is maintained at a normal level for up to 7 days after pneumonectomy in a rat, and then there is a marked increase in amiloride-sensitive alveolar fluid transport capacity that might depend, at least in part, on increased expression of epithelial sodium channels in type II cells and in part on the increased number of type II cells.

Serum KL-6, a novel mucin-like glycoprotein, as an indicator of interstitial pneumonitis following lobectomy

Serum KL-6 has been shown to be a useful marker of active interstitial pneumonitis in patients who have not undergone lobectomy. Considering that KL-6 is produced mainly in the distal airway epithelium, the present study was conducted to determine whether resected lung volume influenced the postoperative KL-6 levels, and also to evaluate whether it is a useful parameter in patients who have undergone lobectomy. The serum KL-6 levels decreased by 36% 1 week after lobectomy, but returned to the preoperative levels by 2 months postoperatively. Although the KL-6 levels increased by 100% 3 to 4 months after lobectomy, the levels were significantly lower than those in interstitial pneumonitis (P < 0.05). The decrease in the KL-6 levels correlated with the number of resected lung segments, but not with the changes in white blood cell count, lactate dehydrogenase level, or C-reactive protein level. In comparison with the lobectomy patients, the serum KL-6 levels decreased by half in patients who had undergone partial resection (P < 0.05). The results of this study suggest that the serum KL-6 level may be a useful indicator of interstitial pneumonitis after lobectomy. Serum KL-6 levels are influenced by the volume of the resected lung, and probably also by the upregulation of KL-6 production.

Proliferation of alveolar type II epithelial cells in residual lungs following thoracotomy

We have found that the number of alveolar type II epithelial cells was markedly increased in the alveolar walls along with the visceral pleura of an excised residual lung in patients who had undergone an exploratory thoracotomy with partial lobectomy seven or nine days prior to the second thoracotomy with resection of the residual lung. Such increase in proliferation of alveolar type II epithelial cells was not found in the excised lung not exposed to a prior thoracotomy, and not in the excised lung exposed to a prior thoracotomy more than 1 year before the second thoracotomy. These findings suggested that remodelling of the alveolar epithelial cells occurred in the residual lung in the early period following thoracotomy.