Abstract
Plasma concentrations of propofol (2, 6-diisopropylphenol, 1% injectable emulsion, Hospira Inc., Lake Forest, Il 60045), a common short-acting induction anesthetic, was investigated in six bottlenose dolphins (Tursiops truncatus), ranging from 12–27 years old, undergoing anesthesia for various diagnostic and treatment procedures. Dolphins were premedicated with a benzodiazepine, diazepam or midazolam, and then moved to a foam-padded table for anesthetic induction. Once intravenous access was obtained in the lateral caudal subcutaneous vein (LCSV) or central fluke vein, propofol was given as a slow intravenous bolus with range of 1.97–5.33 mg/kg to allow for orotracheal intubation and subsequent connection to sevoflurane gas anesthesia with assisted ventilation. Average time to intubation following propofol bolus was approximately 4.7 minutes. Whole blood samples were collected in EDTA at various times post-propofol administration and quickly centrifuged to store plasma at -80°C until analysis. Plasma concentrations were determined using liquid chromatography-tandem mass spectrometry. Preliminary pharmacokinetic analysis was performed on samples collected from dolphins in which it was possible to construct a complete concentration versus time profile. The mean elimination half-life ± SD (t1/2), mean residence time (MRT), systemic clearance (CL) and volume of distribution at steady state (Vss) were 125±28.9 min, 183.8±28.5 min, 12.4±2.78 mL/min/kg and 2.23±0.158 L/kg, respectively. Midazolam boluses administered during propofol infusion were observed to reduce the amount of propofol needed for intubation and minimize muscle fasciculation. Changes in plasma clearance concentrations possibly related to perfusion changes occurred during some procedures. Overall, propofol induction produced a consistent anesthetic state in dolphins that enabled intubation and transition to gas anesthesia.
Acknowledgements
The authors would like to thank Animal Health staff members at SeaWorld San Diego (Jen Rego, CVT, Jennifer Haselow, CVT, Melinda Tucker, CLS, Patty Alley, CLS, Joy Brackbill, CLS, and Kim Regan, CLS) and SeaWorld Orlando (Danielle Gaucher, CVT, Pam Bishop, CLS) for sample processing and storage. SeaWorld animal training staff for their exceptional care of the dolphins undergoing anesthetic procedures.
* Presenting author