Renal transplantation surgery (RTS) is a recognized treatment option since the late 1980s for cats with end-stage kidney disease. A large amount of data exists on surgical techniques, postoperative treatments and RTS complications. Other information regarding the effects of anesthesia-related variables though is limited.
Because of the serious nature and challenge of RTS for cat patients, surgeons and anesthesiologists, the authors wanted to identify factors associated with short-term (30 day) and overall survival rates in cats that had RTS. This study was a retrospective look at 94 cats that underwent RTS in a period from 1998 to 2010. As they went through the patients’ medical records, the data obtained included: cat signalment; anesthetic agents, techniques, and timings; supportive treatment; perioperative physical findings; and surgery and warm ischemia times.
Anesthetic induction was accomplished through IV administration of edomidate, etomidate and propofol, or propofol. All cats were given 1 or more m-opioid receptor agonists IV (oxymorphone, hydromorphone, methadone, fentanyl,). Benzodiazepines and lidocaine (lidocaine is no longer recommended for IV use in cats) were also administered IV as co-induction agents to 88 of the 94 cats. A balanced anesthetic technique using isoflurane (n=93) or desflurane (n=1) was used in all the patients. Co-maintenance with m-opioid receptor agonists in the majority of cases was accomplished plus administration post-surgery. Administration of m-opioid receptor antagonists (butorphanol, naloxone, acepromazine, or flumazenil) was used in 30 of the 94 cases. All cats received a balanced crystalloid solution during surgery at the median rate of 11 ml/hg/h. Five cats received a synthetic colloid solution; blood products were given to 90 cats in the form of whole blood or packed RBCs.
The median survival time for the cats in this study was 653 days. The proportion of cats that survived 30 days was 84%, 6 months (76%) and 3 years (30%). In this study, prolonged anesthesia time (median, 300 minutes) was associated with a decreased overall survival rate in cats that had RTS. The surgical time was not associated with short-term and overall survival rates. Additional factors that were not associated with survival rates were anesthetic agent used, amount and time of IV fluid administered, physiologic abnormalities, and blood product administration. All the cats receiving m-opioid receptor antagonists reached the 30-day survival point and the significance of this factor was considered due to the prevention of opioid-induced cardiorespiratory depression post-anesthesia. Maintaining an adequate hematocrit post-surgery also improves the odds of cats surviving for at least 30 days. Prevention of intraoperative decreases in blood oxygen saturation was also recommended but further study is needed. Cats that were 12 years of age and older that underwent RTS had a decreased overall survival time compared to younger cats.
In the long run, the authors highlighted the need for developing a plan to efficiently manage the anesthetic process so to decrease the negative impact on the patient’s overall survival. The key points are to minimize total anesthesia time, perform reversal of m-opioid agonists at the end of anesthesia, and prevention of intraoperative decreases in SpO2 (blood oxygen saturation) and postoperative decreases in hematocrit. (VT)