Comparison of effects of thiopental, propofol or ketamine on the cardiovascular responses of the oculocardiac reflex during strabismus surgery
Abstract
BACKGROUND: The oculocardiac reflex (OCR), which is most often encountered during strabismus surgery in children,
may cause bradycardia, arrhythmias and cardiac arrest following a variety of stimuli arising in or near the eyeball. The
main purpose of this study was to evaluate the effects of various anesthetic regimens on modulation of the cardiovascular
effects of the OCR during strabismus surgery.
METHODS: Three hundred ASA physical status I-II patients, scheduled for elective strabismus surgery under general
anesthesia, randomly allocated in a double blind fashion to one of the three anesthetic regimens: group P: propofol (2
mg/kg), alfentanil 0.02 mg/kg and atracurium 0.5 mg/kg at induction; group K: ketamine racemate (2 mg/kg), alfentanil
0.02 mg/kg and atracurium 0.5 mg/kg at induction; group T: thiopental (5 mg/kg), alfentanil 0.02 mg/kg, and atracurium
0.5 mg/kg at induction. Mean arterial pressure (MAP) and heart rate (HR) were recorded just before induction, at
1, 15, 30, 45 and 60 minutes after induction. OCR was defined as a 20 beats/minute change in HR induced by traction
compared with basal value.
RESULTS: Mean HR (± SD) during total period of surgery in group P was significantly slower than that in group K
(111.90 ± 1.10 vs. 116.7 ± 0.70, respectively; P<0.05). Mean HR changes (± SD) in group K was significantly higher
than that in group P (11.2 ± 1.44 vs. 8.7 ± 1.50 respectively, P<0.05). MAP changes (± SD) was significantly lower in
patients in group P compared with patients in group K or T (12.5 ± 1.13 vs. 19.3 ± 0.80 or 18.9 ± 0.91, respectively;
P<0.05). Incidence of OCR was significantly lower in patients in group K compared with patients in group T or P (9%
vs. 16% and 13%. Respectively; P<0.05).
CONCLUSIONS: Induction of anesthesia with ketamine is associated with the least cardiovascular changes induced by
OCR during strabismus surgery.
KEY WORDS: Oculocardiac reflex, strabismus surgery, ketamine, propofol, thiopental.
may cause bradycardia, arrhythmias and cardiac arrest following a variety of stimuli arising in or near the eyeball. The
main purpose of this study was to evaluate the effects of various anesthetic regimens on modulation of the cardiovascular
effects of the OCR during strabismus surgery.
METHODS: Three hundred ASA physical status I-II patients, scheduled for elective strabismus surgery under general
anesthesia, randomly allocated in a double blind fashion to one of the three anesthetic regimens: group P: propofol (2
mg/kg), alfentanil 0.02 mg/kg and atracurium 0.5 mg/kg at induction; group K: ketamine racemate (2 mg/kg), alfentanil
0.02 mg/kg and atracurium 0.5 mg/kg at induction; group T: thiopental (5 mg/kg), alfentanil 0.02 mg/kg, and atracurium
0.5 mg/kg at induction. Mean arterial pressure (MAP) and heart rate (HR) were recorded just before induction, at
1, 15, 30, 45 and 60 minutes after induction. OCR was defined as a 20 beats/minute change in HR induced by traction
compared with basal value.
RESULTS: Mean HR (± SD) during total period of surgery in group P was significantly slower than that in group K
(111.90 ± 1.10 vs. 116.7 ± 0.70, respectively; P<0.05). Mean HR changes (± SD) in group K was significantly higher
than that in group P (11.2 ± 1.44 vs. 8.7 ± 1.50 respectively, P<0.05). MAP changes (± SD) was significantly lower in
patients in group P compared with patients in group K or T (12.5 ± 1.13 vs. 19.3 ± 0.80 or 18.9 ± 0.91, respectively;
P<0.05). Incidence of OCR was significantly lower in patients in group K compared with patients in group T or P (9%
vs. 16% and 13%. Respectively; P<0.05).
CONCLUSIONS: Induction of anesthesia with ketamine is associated with the least cardiovascular changes induced by
OCR during strabismus surgery.
KEY WORDS: Oculocardiac reflex, strabismus surgery, ketamine, propofol, thiopental.
Keywords
Oculocardiac reflex, strabismus surgery, ketamine, propofol, thiopental.