ABSTRACT

The minimum alveolar concentration of isoflurane (MAC_isoflurane) was determined in seven green iguanas, Iguana iguana, using a standard double bracketing technique. Following chamber induction, anesthesia was maintained with isoflurane in 100% O₂ using mechanical ventilation of 25 ml/kg body weight, at a rate of two breaths per minute. Following an equilibration period of 25 min at each percentage of isoflurane tested, response to a supramaximal electrical stimulus applied to the ventral portion of the tail was assessed. Arterial blood was collected from the right carotid artery for determining blood gas values in iguanas maintained at 1.5 times their individual MAC_isoflurane. As measured by time to loss of righting reflex, chamber induction time was 23 ± 7 min (range 18 – 35 min). Mean (±SD) MAC_isoflurane was 1.62 ± 0.40%, median MAC was 1.60 %, with a range of 1.10 to 2.15%. Values for pH, partial pressure of carbon dioxide (PaCO₂) in kPa (mmHg), partial pressure of oxygen (PaO₂) in kPa (mmHg), bicarbonate concentration (HCO₃⁻) mmol L⁻¹ base excess (mmol L⁻¹), oxygen saturation (%), concentrations of sodium (Na+) (mmol L⁻¹), calcium (Ca⁺⁺) (mmol L⁻¹), potassium (K⁺) (mmol L⁻¹,), and chloride (Cl⁻) (mmol L⁻¹), and anion Gap (mmol L⁻¹ ) were 7.49 ±0.03, 4.75 ±0.13 (34.6 ±2.7), 14.2 ± 1 .6 (106.7 ± 12.0), 25.7 ± 1.2, 2.4 ±1.4, 94.4 ± 5.2, 151.1 ± 2.6, 1.03 ± 0.15, 2.0 ± 0.6, 123.8 ± 4.4, and 3.6 ± 1.7 respectively. The MAC of isoflurane was lower than minimum alveolar concentration values previously published for green iguanas. The pH, oxygen saturation, and PaO₂ were higher than reported in prior publications in which blood was collected from the femoral artery or ventral coccygeal vessels, and the mean PaO₂ was lower than in a previous publication in which blood was collected from the left carotid artery.