A Safe Nonrebreathing System

Abstract

A bacteria-free humidified atmosphere is considered beneficial to the anesthetized patient. To achieve this goal, a humidified nonrebreathing system was constructed by placing a Garthur heat and moisture exchanger distal to a Frumin valve inserted at the terminal end of a Mapleson E system. An initial inspired relative humidity of 50 ± 5 percent at 25 ± 1° C. (9.8 to 13.4 mg. water/L.) rose to and maintained itself at 61 ± 1 percent at 26 ± 1° C. (13.8 to 16.5 mg. water/L.) after 1 hour of clinical use. No significant cytologic damage was found in tracheobronchial washings from patients placed on the system for 3 hours, but damage was found in a group that breathed dry gas for the same duration of time. All equipment remained bacteriologically sterile proximal to the nonrebreathing valve. This system is recommended as an efficient, cytologically and bacteriologically safe, and much cheaper alternative to the disposable circle absorber equipment which has recently appeared on the market.