Key words Animal
Springer Online Journal Archives 1860-2000
Abstract Objective: To study pressure-volume (P/V) curves over a wide pressure and volume range in pigs.¶Design: Dynamic and static P/V curves (Pdyn/V and Pst/V) and compliance of the respiratory system were studied. The effects of recruitment, positive end-expiratory pressure (PEEP) and body position were analysed.¶Setting: Research animal laboratory.¶Materials: Seven anaesthetised, paralysed and ventilated healthy pigs of 21 kg.¶Measurements: P/V curves up to a pressure of about 40 cmH2O were recorded with a computer-controlled ventilator. Pst/V curves were obtained with the static occlusion method and Pdyn/V curves during an insufflation at a low, constant flow rate.¶Results: Pdyn/V recording showed a complex pattern. During the insufflation compliance increased, fell, increased and fell again. A 2nd ¶Pdyn/V recording immediately following the 1st one was displaced towards higher volumes and showed only one maximum of compliance. The difference between the two curves reflected: (1) lung collapse during a period of 5 min of ventilation at zero end-expiratory pressure (ZEEP) following a recruitment manoeuvre, (2) recruitment during the measurement of the 1st Pdyn/V curve. These observations were similar in the supine and in the left lateral position. After ventilation at PEEP, 4 cmH2O, the signs of collapse and recruitment were reduced. It was confirmed that PEEP offers a partial protection against collapse. Pst/V curves showed higher volumes and higher compliance values compared to Pdyn/V curves. This reflects the influence of viscoelastance on Pdyn/V curves.¶Conclusion: The study demonstrates a particularly strong tendency to lung collapse in pigs.
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