Breathing indicator and ventilator

The device indicates the instantaneous volume of gases being breathed by a medical patient, and provides a means for "ventilating" the patient; i.e. causing the patient to breathe artificially. A pair of bellows is provided. The first bellows is pneumatically connected to the patient's respiratory system. The first bellows expands when the patient exhales in a closed system, contracts when the patient inhales or gases are forced into the patient's lungs. The second bellows is mechanically coupled to but pneumatically isolated from the first bellows. The second bellows preferably is connected to a manual resuscitation squeeze-bag which can be used to expand the second bellows and thereby compress the first bellows and force gases into the patient's lungs, thus ventilating the patient. An automatic non-rebreathing valve is used to ensure independent operation of the second bellows and the bag. The bellows are mounted so as to expand and contract along an arcuate path. An indicator indicates the excursions of the first bellows, and thus indicates the instantaneous volume of flow. Movement of the bellows along an arcuate path provides mechanical amplification of the movement of the indicator, thus giving improved resolution and accuracy. A disposable liner is provided for the first bellows so that the bellows itself will remain isolated from the gases breathed by the patient, and will be relatively easy to keep clean. Preferably, the second bellows has a cross-sectional area considerably smaller than that of the first, so that only a relatively small flow of gas from the squeeze-bag is effective to force a substantially greater volume of gas into the patient's lungs. Thus, the double-bellows arrangement serves as an amplifier for the squeeze-bag. In one embodiment of the invention, the movement of the bellows is in a vertical plane, and in another embodiment the movement is in a horizontal plane. An accumulator is used to indicate the total flow of gas breathed by the patient, and a timing device is used to indicate the "minute volume" of ventilation, i.e., the flow rate. An especially advantageous bellows construction is used.