Humidification of anesthetic systems for prolonged procedures

The desirability of humidification of anesthesia systems for prolonged surgical procedures has been documented previously. Dry anesthetic gases damage the ciliated epithelium and cause respiratory heat loss. Chalon suggests that from 12 to 16 mg. of water/L. of gas is necessary to prevent damage to the tracheal epithelium. This study describes a method of obtaining values of from 21.5 plus or minus 0.4 to 39.3 plus or minus 0.1 mg. of water/L. by cycling the fresh gas flow through the carbon dioxide (CO2) absorber before exposure to the patient.