[Effects of several methods of thoracic drainage on respiratory function]

The object of this study was to verify the influence on the pulmonary function of the pleural space ampliation with pleural drainage tube underwater seal, with several volumes or with variables negative pressures. We performed 42 New Zealand white rabbits of both sexes with an average age of 57 +/- 9.31 days and an average weight of 1720 +/- 181 g. The experimental protocol consisted of study group: P1 (n = 14) was performed a unilateral thoracostomy at the 5th. Intercostal space and P2 (n = 14) with bilateral pleural drainage. The pleural drainage tube (drain trocart ORX Vygon number 8) connected at small bottle (Fp), with 35 ml of extrapleural volume and at big bottle (FG) with 3940 ml of extrapleural volume and vacuum suction of various negative pressures (-5, -10, -15 and -20 cm H2O).

C1 (n = 7) with unilateral pleural drainage clamped and C2 (n = 7) with bilateral pleural drainage clamped. Anesthesia was induced with ketamine hydrochloride (7.5 ml/Kg) and propionilpromazyne (1.5 ml/Kg) intramuscular cocktail and after maintained with bolus injection of 1/4 induction dose. We studied the mortality, the the fluctuations of drain hydrostatic column, heart rate (FC), respiratory rate (FR) and blood gas tensions, after cannulation of right jugular vein and during the different phases of experimental design. Venous blood samples were obtained for pO2, pCO2 and pH measurements were repeated at 5' in both groups. The 50% of animals died in the P2 group during the drainage pleural of FG. The fluctuation of column of Fp was similar in both groups: P1 = 6.39 +/- 1.0, with a decrease of 0.64 +/- 0.23 and P2 = 6.37 +/- 1.29, with a decrease of 0.63 +/- 0.28, respectively. The vacuum suction of pleural cavity may produce a FR fall which recovery fast. The bilateral pleural drainage with negative pressures produced decreases of pCO2 and pO2. There is not modifications of Acid Base Balance in the experimental groups. We concluded that during bilateral pleural underwater seal connected a FG, because the increase of extrapleural space may produce a high mortality and a fall of respiratory rate with fast recovery. Also the pleural suction improved the CO2 diffusion into the alveolus. There is not modifications of pO2 in P1 group or decrease in the P2 group.