Sevoflurane anesthesia in desert tortoises (Gopherus agassizii)

The effects of sevoflurane on anesthesia induction, recovery, ventricular p ressures, heart rate, ventricular pH, blood gas values, and electrolytes we re evaluated in desert tortoises (Gopherus agassizii). Tortoises were orotr acheally intubated while awake and ventilated manually with 3-7% sevofluran e in oxygen (1 L/min) to achieve desired expired sevoflurane concentrations . Data, consisting of induction time, recovery time, systolic, diastolic, a nd mean ventricular pressures, heart rate, ventricular pH, blood gas values , and electrolytes, were collected prior to anesthesia and sequentially at 2.50% and 3.75% expired sevoflurane as measured at the junction of the endo tracheal tube and the breathing circuit. Blood pressure was measured and bl ood samples were collected through a 25-ga needle passed through a cardiac access port that was placed while the tortoises were in dorsal recumbency. Mean (+/-SE) induction time was 2.55 +/- 0.55 min, recovery time was 27.58 +/- 7.55 min, and duration of anesthesia was 105 +/- 12 min. Mean (+/-SD) v alues for systolic, diastolic, and mean ventricular pressures in awake tort oises were 28 +/- 3 mm Hg, 22 +/- 2 mm Hg, and 24 +/- 2 mm Hg, respectively . Sevoflurane (2.5% expired) significantly decreased systolic (14 +/- 3 mm Hg), diastolic (12 +/- 1 mm Hg), and mean (13 +/- 1 mm Hg) ventricular pres sures compared with those of awake tortoises. Ventricular pressures did not decrease further with increasing depth of anesthesia. Heart rate (32 +/- 4 beats/min) did not change significantly under sevoflurane anesthesia. Sevo flurane administration increased ventricular Po-2 but did not change Na+, K +, or iCa(++) concentrations. Sevoflurane appears to provide safe and effec tive anesthesia with rapid induction and recovery.