Effect of Breathing Circuits on Intraoperative Body Temperature

To evaluate differences in intraoperative body temperature between heated huimid breathing circuit and conventional breathing circuit

Inclusion Criteria:

• aged 18-70 years,
• ASA I or II
• patients scheduled for craniotomy under general anesthesia

Exclusion Criteria:

• ASA III or IV
• Duration of anesthesia time less than 4 hours
• emergency operation