Journal of Applied Physiology, Vol 55, Issue 4 1051-1056, Copyright © 1983 by American Physiological Society
Lung mechanics following aspiration of 0.1 N hydrochloric acid
R. Winn, J. Stothert, B. Nadir and J. Hildebrandt
Pressure-volume curves were obtained from excised left lungs of goats at 4,
24, and 48 h after tracheal instillation of 2.5 ml/kg of 0.1 N HCl. Air
total lung capacity (TLC) at transpulmonary pressure (PL) = 35 cmH2O was
38.8 ml/kg body weight before acid, and was reduced sharply to 21.1 at 4 h,
then increased to 25.6 at 24 h and 32.1 at 48 h. Excess extravascular lung
water (EVLW) could account for only part of the volume reductions. Specific
compliance ratio of transpulmonary pressure to total lung capacity (CL/TLC)
between PL of 5 and 0 cmH2O was reduced from 0.074/cmH2O to 0.050, 0.048,
and 0.053/cmH2O, respectively. Saline TLC (PL = 10 cmH2O) changed from 44.8
to 32.4, 34.3, and 45.4 ml/kg, respectively, but CL/TLC did not, suggesting
airway obstruction. After injury, trapped volume at PL = 0 increased from
24.9 to 29.2, 43.3, and 37.3% TLC with air, and from 20.3 to 38.5, 33.1,
and 28.5%, respectively, with saline. Air volume at a PL = 10 cmH2O on
deflation fell from 82.0 to 72.1% TLC at 4 h, but was near control at 24
and 48 h. The reduction in ventilated volume was not reflected in
proportionately increased shunt; therefore, some compensatory
vasoconstriction must have occurred. We suggest that in affected regions
increased surface forces, increased EVLW, and airway obstruction caused
reductions of lung volume.
