This study investigated the potential for multiple exposures of propof
ol to induce oxidative injury, in the form of Heinz body production, t
o feline red blood cells. Anesthesia was induced in six healthy cats w
ith propofol (6 mg/kg, intravenous [IV]) and maintained for 30 minutes
with a propofol infusion (0.20 to 0.30 mg/kg/min, IV). The initial pr
otocol was designed for each cat to receive 10 consecutive days of pro
pofol anesthesia. All cats spontaneously breathed room air. Heart rate
, respiratory rate, and indirect blood pressure were measured and reco
rded before and during anesthesia. Time to complete recovery after eac
h infusion was measured and recorded. Heinz body analysis was performe
d before and after each day of propofol anesthesia. Based on predeterm
ined criteria for discontinuing daily infusions, the mean number of co
nsecutive days of propofol anesthesia was six and propofol administrat
ion did not continue beyond 7 days in any cat. Heart rate, respiratory
rate, and indirect blood pressure did not change significantly during
propofol anesthesia compared with awake values. Following the third c
onsecutive day of propofol anesthesia, there was a significant increas
e from baseline in the mean percentage of Heinz bodies. Hemolysis was
not detected in any cat. Recovery time significantly increased after t
he second consecutive day of propofol anesthesia compared with the fir
st day. Five of six cats developed generalized malaise, anorexia, and
diarrhea on day 5, 6, or 7, and two cats developed facial edema. All c
linical signs resolved without treatment 24 to 48 hours after disconti
nuing propofol anesthesia. This study suggests that consecutive day pr
opofol anesthesia in normal cats can induce oxidative injury to feline
red blood cells in the form of excessive Heinz body formation, result
in increased recovery times, and result in clinical signs of illness.
(C)Copyright 1995 by The American College of Veterinary Surgeons