Influence of posture on pulmonary gas exchange and heart rate in chronic obstructive lung disease.

Sixteen subjects with chronic obstructive lung disease were studied in supine and sitting position. VT, VE, VD and VD/VT were definitely higher in the sitting position (p less than 0.001). PaCO2 was slightly lower in the sitting position, whereas Pa¿O2 was the same in both positions. P(A-a)O2 was essentially the same in both positions, but the estimated QS/QT was definitely lower in the sitting position. In patients with low FEV1.0 the heart rate showed a tendency towards higher values in the sitting position.