STUDY OF THE VENTILATORY FUNCTION IN DOGS WITH FLAIL CHEST

Thus far, the instability of the thoracic wall had never been studied in dogs. In order to analyze the impact of a dog's flail chest on the ventilatory function, the Tidal Volume (TV), Respiratory Frequency (RF ) and Minute Volume (MV) was studied in six animals. Six dogs were ana esthetized and subjected to an experimental flail chest by fracturing one to five ribs without damaging the underlying pleura. The above men tioned parameters were measured initially (basal) and after the fractu re of each rib. The TV decreased from an initial value of 320.8 +/- 40 .1 cc (250-375) to 250 +/- 35.4 cc (200-300) after the first rib fract ure and to 183 +/- 34.2 (125-225) after the fracture of the fifth rib (p < 0.005). The RF increased from a basal value of 9.1 +/- 2.32 resp/ min (6-12) to 15.1 +/- 6.6 resp/min (10-28) after the first rib fractu re and to 34.5 +/- 15.2 resp/min (17-55) after the fracture of the fif th rib (p <0.005). The MV increased from an initial value of 2891.6 +/ - 626 cc (2275-3900) to 3637.5 +/- 1064 cc (2700-5600) after the first rib fracture and to 6120.8 +/- 2410 cc (2975-9625) after the fracture of the fifth rib (p < 0.005). It is concluded that the experimental f lail chest in dogs leads to a decrease of the TV and to an increase of both the RF and the MV.