Ventilation in the Hospital Operating Room.

The USAF Occupational and Environmental Health Laboratory USAF OEHL investigated several aspects of the problem of ventilation in hospital operating rooms. The study reviewed existing nationally recommended ventilation rates and also discusses five factors that would affect the selection of a minimally acceptable ventilation rate in the operating room such as, control of temperaturehumidity, control of odors, control of flammable anesthetic agents, control of infections, and control of exposure to waste anesthetic agents. The report studies the effect of fresh air ventilation on exposure to waste anesthetic agents in depth. Forty-eight graphs illustrate the expected instantaneous and time weighted average nitrous oxide and halogenated agent air concentrations as a function of time under a variety of conditions. The mathematical model and FORTRAN computer used to develop the data for graphs are included as appendices to the report. The fresh air ventilation rates used in the model ranged from two to 15 air changes per hour. The operating room volumes used in the model were 2100 and 4655 cubic feet. Three different conditions of anesthesia delivery were studied intubation with a shut-off valve between the delivery tube and the mask, and a mask with 0, 15, and 30 mask leakage due to a poor fit. Finally, the effect of multiple surgical procedures on the anesthetic agent concentration in the operating room is addressed.