Ventilation in an artifically produced gas cavity under basal conditions

Abstract

Abstract The left hemithoraxes of 150 SPF rats were transformed into stable skin-lined gas cavities which were opened to the exterior. Fifty-nine of 75 rats so exposed survived with the natural, unilateral lung receiving air from the trachea, and the skin-lined hemithorax (an artificially produced gas cavity) receiving air independently from a thoracostomy. In the test rats the mean arterial pH, Po2, and Pco2, were 7.355 ± 0.17, 77.03 ± 2.56 mm. Hg, and 38.41 ± 2.41 mm. Hg respectively. The values were similar to those obtained for unoperated rats (7.349 ± 0.015, 80.18 ± 2.77 mm. Hg, and 38.24 ± 0.94 mm. Hg). Although the skin-lined hemithorax was functionally an open-ventilated gas cavity, its mean tidal volume (0.93 ± 0.07 ml.) and its mean minute-ventilation (271.6 ± 24.4 ml. per kg. per minute) were about half of normal. In the test the mean rate of respiration and the mean tidal volume were 98.5 ± 4.3 per minute and 1.68 ± 0.04 ml. as compared with 76.1 ± 5.3 per minute and 1.94 ± 0.12 ml. in the unoperated rats. The differences were significant. However, the difference between the mean minute-ventilation (tidal volume × rate of respiration) in the two groups was not significant. The values obtained were 506.1 ± 36.2 ml. per kg. per minute (test rats) and 407.0 ± 50.4 ml. per kg. per minute (unoperated rats). This suggested further that under basal conditions the test rats achieved adequate ventilation by means of a compensatory rise in the rate of respiration.