Open-drop anesthesia for small laboratory animals.

This study examined the effect of temperature on volatile concentrations of 2 inhalant anesthetics, isoflurane (ISO) and sevoflurane (SEVO), delivered via open-drop technique, as well as the characteristics of induction and recovery using the open-drop method in mice. Testing revealed that temperature had no effect on the volatile concentration of either ISO or SEVO. However, it was determined that open-drop delivery of ISO or SEVO is a viable means of anesthetizing mice under certain conditions. The volatile concentration required to induce anesthesia in mice following the application of 0.5 mL of anesthetic in an induction chamber of 725 mL volume at 87.6 kPa and 20°C was measured with a precision gas analyzer. For ISO, anesthesia was induced at concentrations of 6.80 ± 0.57% [mean ± standard deviation (s)] after 35.70 ± 6.95 s (n = 10), while SEVO induction took significantly longer (45.50 ± 9.96 s) and required higher volatile concentrations [7.41 ± 0.57% (n = 10)]. The animals recovered rapidly from both ISO and SEVO-based induction.