• Susane Bruder Silveira Gorayb, José Reinaldo Cerqueira Braz, Regina Helena Garcia Martins, Norma Sueli Pinheiro Módolo, and Giane Nakamura.
• Hospital das Clínicas (HC) do CET/SBA do Departamento de Anestesiologia da Faculdade de Medicina de Botucatu (FMB), UNESP, Botucatu, SP.
• Rev Bras Anestesiol. 2004 Feb 1;54(1):20-36.

Background And ObjectivesInhaled gas humidification and heating are necessary in patients under tracheal intubation or tracheostomy to prevent damage to respiratory system resulting from the contact of cold and dry gas with the airways. This study aimed at evaluating the effect of respiratory circle systems with carbon dioxide absorbers from Dräger's Cicero anesthesia machine (Germany) as to inhaled gases heating and humidification ability using low fresh gases flow (1 L min(-1)) or minimum flow (0.5 L min(-1)).MethodsParticipated in this study, 24 patients, physical status ASA I, aged 18-65 years, submitted to general anesthesia using Dräger's Cicero workstation (Germany) for abdominal surgery, who were randomly distributed in two groups: low flow group (LF) received 0.5 L min(-1) oxygen and 0.5 L min(-1) nitrous oxide, and minimum flow group (MF) received 0.5 L min(-1) oxygen only. Evaluated attributes were temperature, relative and absolute humidity of the operating room and of respiratory circuit gas.ResultsThere were no significant differences in inhaled gas temperature, relative and absolute humidity between groups, but they have increased along time in both groups, with influence of operating room temperature on inhaled gas temperature for both groups. Near optimal levels of humidity and temperature were reached as from 90 minutes in both groups.ConclusionsThere have been no significant differences in inhaled gas humidity and temperature with fresh gases low flow or minimum flow.

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