Effects of tube thoracostomy on pleural fluid characteristics in sheep

We studied the pleural inflammatory response to tube thoracostomy by inserting an Argyle 32-Fr tube in the pleural space of 10 anesthetized sheep. An experimental pleural effusion was created by infusion of sterile normal saline (10 ml/kg) into the pleural space, and the animals were allowed to recover. Systemic blood and experimental pleural effusion (EPE) samples were obtained at time 0, 30 min, hourly for 6 h, and at 6-h intervals for a total of 48 h. EPE white cell count rose from 125 +/- 125 to 6,323 +/- 2,268/microliters (SE) at 6 h (P < 0.05) but showed marked variability at 42 and 48 h (P < 0.05), with values ranging from 8,000 to 22,000/microliters. The systemic white cell count rose from 5,195 +/- 914 to 9,640 +/- 1,110/microliters (P < 0.01) within the first 12 h and then remained stable. EPE protein increased from 0 +/- 0 to 3.73 +/- 0.2 g/dl at 48 h (P < 0.05). EPE lactate dehydrogenase rose from 44 +/- 12 IU/l to a peak of 638 +/- 55 IU/l at 24 h (P < 0.05). EPE glucose was significantly lower than serum glucose at 36, 42, and 48 h (P < 0.05). These data indicate that chest tube placement rapidly induces significant pleural inflammation and results in formation of a sterile exudate.