Automatic non-rebreathing valve.

EFFICIENT ventilation of the anaesthetized patient, without carbon dioxide absorption, can be carried out using the valve to be described. It is simple, reliable, efficient and silent. In figure 1 A and E are low resistance valves. P, and P2 form a bypass opening into the balloon B, which lies free in the exit tube X. The balloon is made of very thin rubber and is of such a size that when inflated without any distension of its wall it completely occludes the exit tube. When collapsed it offers negligible resistance to expiration. T is a three-way tap which if desired will close P, and open P2 to the atmosphere. The dotted lines indicate that the reservoir bag and the proximal end of the bypass may be placed anywhere between the gas machine and valve A.