Comparison of two anesthetic protocols for feline blood donation

Objective: To compare hemodynamic variables during, and recovery quality following, anesthesia for feline blood donation using intramuscular ketamine-midazolam-butorphanol (KMB) versus inhaled sevoflurane in oxygen (SEV). Study design: Prospective blinded, randomized, crossover study. Animals: Twenty healthy, client-owned, mixed breed cats, aged 4-8 years, weighing 5.2-6.4 kg. Methods: Cats were anesthetized with KMB for one donation and SEV for another. Heart rate (HR), respiratory rate (f_R), pulse quality, mucous membrane color, capillary refill time, arterial hemoglobin saturation with oxygen (SpO₂), and noninvasive arterial blood pressure (Doppler) were assessed by a blinded observer every 1 minute during collection. A nonblinded anesthesiologist delivered drugs and responded to hemodynamic changes. Each donation consisted of 55 mL of whole blood drawn via jugular puncture over 5-22 minutes. Donors received 60 mL subcutaneous lactated Ringer's solution before recovery. Donors were monitored for a minimum of 4 hours post-donation, before returning home. Owners, unaware of anesthetic protocol, completed a questionnaire regarding their cat's behavior during the 24 hours following donation. Results: Both protocols provided adequate restraint but were complicated by significant hypotension, requiring intervention in 16 (84%) SEV cats, and eight (42%) KMB cats. KMB cats experienced post-procedure hyperthermia, with body temperatures >103.5°F. All animals responded to symptomatic therapy within 2 hours. Owners noted a significantly faster return to normal behavior at home following SEV. Conclusion: All cats experienced hypotension, with many animals requiring intervention. There was no significant difference between protocols in incidence and severity of hypotension. The primary post-procedure complication was hyperthermia with KMB. Clinical relevance: As a result of the potential for hypotension during blood donation, intravenous (IV) access and blood pressure monitoring are recommended for all anesthetized donor cats, regardless of the anesthetic protocol. Post-procedure hyperthermia is a risk with KMB, so temperature monitoring is recommended. Return to normal behavior is faster with SEV.