A Mechanical Respirator as an Adjunct to Closed System Anesthesia.∗

The average operating room makes no provision for mechanically maintaining artificial respiration in patients during operation. In the absence of adequate pulmonary ventilation, other resuscitative measures are generally of little value in advanced respiratory or cardiac failure. 1 Such accidents are sufficiently common in the operating room to warrant a carefully organized plan for resuscitation and especially to include in this plan a method of artificial respiration for the surgical patient. During the past 2 years a mechanical respirator, of a type commonly used in physiological laboratories for the intermittent insufflation of compressed air down a tracheal catheter, has been kept available on the operating floors of the University Hospitals. During this period of time the respirator has been successfully used in 4 cases of acute cardio-respiratory failure and might have been successful in several other cases if the artificial respiration could have been instituted more promptly. This fact aroused the interest of the author in developing a simple, dependable mechanical respirator as an integral part of the commonly used anesthesia machines. Since the introduction of carbon dioxide absorbing technic and the use of a tight fitting face mask, creating a closed lung-bag system, the simplest effective method of artificial pulmonary ventilation in the event of inadequate spontaneous respirations is by rhythmic manual compression of the rebreathing bag. Utilizing this principle, the following apparatus was constructed.† (Fig. 1.) The rebreathing bag of the anesthesia machine is enclosed in a rigid airtight container, B, made of pyralin, a nonbreakable plastic, and it is attached to the sodalime canister A, in this case, of a Heidbrink anesthesia machine. Air under pressure, from any source 8, is intermittently injected into the space between the rigid container and the rebreathing bag through inlet 5 which can be controlled as to rate and volume by valves 9 and 6. Between injections the space around the bag is automatically opened to the atmosphere through the exhaust valve 7.