Case Reports of Inversed Ratio Ventilation

Case Reports of Inversed Ratio Ventilation

Creators Nonoue Tadahiko

Creators Yokota Kimio

Creators Ogasahara Hiroko

Creators Sari Atsuo

The prolongation of inspiratory time from an I : E ratio of 1:2 to a ratio of 4:1 significantly improved arterial oxygenation in 7 patients with acute respiratory failure due to pulmonary disease or cardiogenic lung edema when positive end-expiratory presure had failed. The reduction in the respiratory index (y) (y=-2.02x+9.392,r=-0.5732,p<0.05) and the pulmonary shunt ratio (y) (y=-5.502x+41.329, r=-0.5561, p<0.05) were in proportion to the prolongation of inspiratory time (x). A reduction in cardiac output and a concomitant reduction oxygen delivery were observed with the I : E ratio of 4 : 1 but not with an I : E ratio of 3 : 2 or 2.6 : 1 in patienta with pulmonary disease. However, two of three patients with cardiac diserse had a reduction in cardiac output and oxygen delivery with an I : E ratio of 1.2 : 1. The results suggest that the improvement of arterial oxygenation proportional to the prolongation of inspiratory time is due to the increase in the endexpiratory lung volume with a short exhalation time. Although this ventilatory pattern may be indicated when the effect of positive end-expiratory pressure on artrerial oxygenation has failed, an unduly long prolongation of inspiratory time is not suitable for patients with cardiac disease.

[ISSN]0513-1812

[NCID]AA00594272