Elastic properties of the lung and the chest wall in young and adult healthy pigs

Understanding of the elastic pressure/volume (Pel/V) curve is still limited in health and disease. The aim of the present study was to elucidate the P el/V curve and elastance of the respiratory system (ERS) lung (EL) and ches t wall (ECW) in healthy pigs. Six young (20.8 kg) and seven adult (58.9 kg), anaesthetized, paralysed and ventilated pigs were studied, Pel/V curves mere recorded at zero end-expir atory pressure (ZEEP) and at positive end-expiratory pressure (PEEP) up to 40 cmH(2)O with a computer controlled ventilator during an insufflation at a low, constant flow. Pel/V curves of the respiratory system showed a complex pattern in both you ng and adult pigs, During the insufflation, ERS decreased, increased, fell, and increased again. A second Pel/V curve recorded immediately after the f irst one showed lower elastance and only one early fall in ERS. ECW fell ov er the initial segment and was then nearly stable, Difference between 1st a nd 2nd curves reflected changes in EL caused by recruitment during the 1st insufflation, At PEEP, such signs of collapse and recruitment mere reduced. A strong tendency to lung collapse contributes to a complex pattern of elas tic pressure/volume curves. At low volumes and distending pressures the che st mall contributes significantly to changes in respiratory system elastanc e.