Pain on Injection of Propofol: The Effect of Injectate Temperature

Lee, Soo Kyung; Lee, Seung Joon; Kil, Ho Yeong; Yoon, Young Joon

Abstract

BACKGROUND: One of methods used to reduce pain on injection of propofol was cooling propofol. Recently, it was reported that warming propofol also could reduce pain compared to room temperature. We evaluated the effect of temperature of propofol on incidence and severity of pain on injection.
METHODS
Ninety healthy ASA physical status I or II patients who were scheduled for elective surgery were randomly allocated into three groups. They either received propofol maintained at room temperature(22~23 degrees C, group I), taken from the refrigerator(3~4 degrees C, group II) or warming to 36~37 degrees C using water bath(group III). A 22G intravenous cannula was inserted into the dorsum of the left hand and 5ml(50 mg) of undiluted propofol was injected over 5 seconds. The pain score, visual analog scale(VAS), site of pain, and complications were assessed 5 seconds after injection.
RESULTS
Both in pain score and VAS, group II(1.4+/-0.7, 3.9+/-2.0) reduced the incidence significantly compared with group I(2.1+/-0.9, 6.5+/-2.3, P<0.01) or group III(2.4+/-0.7, 7.6+/-1.6, P<0.001), but there was no difference between group I and group III. Eighty percent(24/30) of group 1,50%(15/30) of group II and 90%(27/30) of group III showed moderate to severe pain. During injection, one patient of group I showed involuntary movement and one patient of group III showed excitation.
CONCLUSIONS
Cooling propofol to 3-4 degrees C was better than warming to 36-37 degrees C or maintained at room temperature(22-23 degrees C) in terms of decreasing severity of pain on injection.