[Improved climatization of anesthetic gases by modifying the Sulla 808 V anesthesia equipment]

Maintenance of a physiological airway climate is one of the goals of anaesthesia ventilation. This may be achieved by integration of heat and moisture exchangers (HME's) or--more economically--by reducing fresh gas flow rate down to the minimal-flow-range. Conventional bag-in-bottle ventilators with hanging bellows do not allow operation with minimal-flow-rates; flow reduction results sooner or later in a positive-negative-pressure ventilation pattern; especially so in patients suffering from COPD. This problem may be overcome by uncoupling fresh gas flow from tidal volume by means of integrating a reservoir bag and a special valve system to the circle system. This technique was hitherto restricted to high class anaesthetic workstations; since recently it became available as an update modification for the Sulla 808 VTM anaesthesia machine (Dräger, Lübeck). With a setting previously described the effect of this modification on airway climate was investigated in a prospective, randomized clinical study. Twenty-four consenting patients were randomly assigned to be ventilated with either high (6.0 L/min, n = 12) or minimal (0.6 L/min, n = 12) fresh gas flow rate. The time course of inspiratory temperature and humidity was measured over a period of 120 minutes; water content was calculated from relative humidity and temperature. In the minimal-flow-group, already after 60 minutes a temperature of 28.6 +/- 0.9 degrees C and a water content of 17.6 +/- 1.9 mg H2O/L were achieved (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)