Abstract
Surgical implantation of radio transmitters is performed in waterfowl to track birds that do not tolerate externally applied equipment.1 It involves invasion of the coelomic cavity and ablation of the right abdominal air sac.1-3 When this procedure is performed in remote field sites, injectable anesthetics are popular because of difficulties with transportation of oxygen and inhalant anesthetics. Intravenous propofol is often used, along with a local anesthetic.2,3
Although propofol has been evaluated in waterfowl,2 to our knowledge, the physiologic effects during telemetry implantation have not been studied. Cardiopulmonary monitoring was performed in 14 common eiders (Somateria mollissima) anesthetized with propofol for transmitter implantation. Local bupivacaine was also administered. Venous samples were taken for blood gas analysis immediately prior to induction and at the end of surgery. Birds were intubated, maintained on room air, and ventilated at either 2 or 6 breaths/minute (2 bpm or 6 bpm, respectively).
Post-induction, 6 bpm birds had minimal voluntary respiration, while 2 bpm birds continued to take voluntary breaths. The 6 bpm birds developed lower end-tidal CO2 values and higher SpO2 values than 2 bpm birds. At surgery’s end, 6 bpm birds had higher venous pH values and lower pCO2 values than 2 bpm birds. Venous pH increased over time in 6 bpm birds, but not in 2 bpm birds. Lactate decreased over time in both groups. All recovered well and were alive 6 months postoperatively. Physiologic values can be maintained with propofol anesthesia with assisted ventilation at four to six bpm.
Acknowledgments
Thanks to Dr. Dan Mulcahy for contributions of equipment, supplies, and intellectual discourse and to Dr. Chris Fransom for assistance in performing procedures and recording data. Thanks also to U.S. Fish & Wildlife Service personnel with the Alaska Maritime National Wildlife Refuge for their technical and logistical support.
Literature Cited
1. Korschgen, C.E., K.P. Kenow, A. Gendron-Fitzpatrick, W.L. Green, and F.J. Dein. 1996. Implanting intra-abdominal radiotransmitters with external whip antennae in ducks. J. Wildl. Manage. 60:132–137.
2. Machin K.L., and N.A. Caulkett. 2000. Evaluation of isoflurane and propofol anesthesia for intraabdominal transmitter placement in nesting canvasback ducks. J. Wildl. Dis. 36:324–334.
3. Mulcahy, D.M., P. Tuomi, and R.S. Larsen. 2003. Mortality of male spectacled eiders (Somateria fischeri) and king eiders (Somateria spectabilis) given propofol, bupivacaine, and ketoprofen. J. Avian Med. Surg. 17:117–123.