Abstract

From October through December 2009, 84 cold-stunned sea turtles were admitted alive to New England Aquarium (NEAq) for rehabilitation. The animals were photographed, given a complete physical exam and blood was collected for archive, PCV, total solids, and blood gas analysis via a point-of-care analyzer (Critical Care Express, NOVA Biomedical, Waltham, MA). During the exam, routine measurements were taken, body condition and external lesions were noted, and temperature, heart rate and respiration rate were recorded. The heart rate was measured using an IMEX PocketDop 3 Doppler (Corometrics Medical Systems Inc, Wallingford, CT) or Vet 180Plus ultrasound with C11/7-4MHz transducer (SonoSite Inc, Bothell, WA). In certain cases, no heart rate could be accurately determined, but cardiac activity was noted on echocardiography. These turtles were given emergency medications such as doxapram hydrochloride 5mg/kg IV, IM or IT, atropine sulfate 0.05mg/kg IV, IM or IT, epinephrine 1:1000 0.05ml/kg IV or IT, 50% dextrose 0.5ml/kg IV in fluids, 84% sodium bicarbonate 1mEq/kg SC in fluids, and fluid therapy as determined by electrolyte levels.

Cold-stunned turtles may be affected by respiratory acidosis due to hypoventilation, poor perfusion and anaerobic metabolism.² Depending on the status of the patient, such animals may be intubated and given 100% oxygen or 21% oxygen (room air) via intermittent positive pressure ventilation (IPPV). During the 2009/2010 winter, a Maquet Servo-i Ventilator with Conchatherm Neptune Heated Humidifier (Hudson RCI, Durham, NC) was loaned to NEAq by Maquet Inc, Bridgewater, NJ for use on such turtles. The ventilator was set in infant patient, synchronized intermittent mechanical ventilation (SIMV) pressure control + pressure support mode at 2cm H₂O positive end expiratory pressure (PEEP) and 8cm H₂0 peak inspiratory pressure (PIP). Respiratory rate was set between 1 breath/min and 4 breaths/min at the discretion of the attending clinician.

Four turtles, two Kemp's ridley sea turtles (Lepidochelys kempii) and two green sea turtles (Chelonia mydas), had blood gas analyses shortly before and after IPPV of varying duration (Table 1). Values shown for pH and pCO₂ are temperature corrected (TC) automatically by the analyzer for patient core temperature at the time of analysis. pO₂ is not considered in the current report due to the inaccuracies using the standard calculations utilized by the analyzer.¹ pH and pCO₂ improved markedly in all animals. Improvement in HCO₃^- was also noted in two of the four turtles. Table 2 lists pH, pCO₂ and HCO₃^- from convalescent Kemp's ridley sea turtles during rehabilitation at NEAq² and from green sea turtles at 25°C³ for comparison.

The use of the ventilator appeared to be effective in all cases (i.e., acidosis improved and animals became more responsive); however, it is not possible to determine the specific effects of ventilation vs. the effects of other supportive care (e.g., fluid therapy, improved heart rate and perfusion). Despite these initial improvements, the four patients eventually succumbed to disorders secondary to extended hypothermia, including granulomatous pneumonia, renal failure, hypercalcemia and hyper/hypoglycemia.

Table 1. Dates and duration animals were placed on Maquet servo-i ventilator along with blood gas data prior to intubation and after extubation.

Table 2. Mean healthy sea turtle blood gas parameters +/- SD.

Acknowledgements

The authors would like to thank the NEAq Animal Health Department and Rescue and Rehabilitation Department staff and volunteers for devoting long hours to the care of the sometimes overwhelming number of sea turtles during this winter. We also thank Kevin O'Brien and Sean Shortall of Maquet Inc for their generous loan of the Maquet Servo-i Ventilator as well as Paul Nuccio and Truman Read from Brigham and Women's Hospital, Boston, MA for helpful insights on mechanical ventilation.

References

1.  Chittick EJ, Stamper MA, Beasley JF, Lewbart GA, Horne WA 2002. Medetomidine, ketamine, and sevoflurane for anesthesia of injured loggerhead sea turtles: 13 cases (1996-2000). J Am Vet Med Assoc 221:1019-1025.

2.  Innis CJ, Tlusty M, Merigo C, Weber ES 2007. Metabolic and respiratory status of cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii). J Comp Physiol B 177:623-630.

3.  Kraus DR, Jackson DC 1980. Temperature effects on ventilation and acid-base balance of the green turtle. Am J Physiol Regul Integr Comp Physiol 239:R254-R258.