Eutectic mixtures of local anesthetics (EMLA) Valtonen et al. found that topical use of EMLA cream in children did not significantly reduce pain during propofol injections. Diluting propofol with glucose or lipids can reduce the concentration of propofol and thus reduce the incidence of pain. This is based on the findings of Stokes et al. , Klement and Arndt, and Doenicke et al. [24]. They propose that the pain caused by propofol injection is directly related to the concentration of propofol in the free water phase.
Stokes et al. found that diluting propofol with 5% glucose was able to significantly reduce the incidence of severe pain from 32% to 10% and the incidence of all pain from 50% to 24%. Klement and Arndt[23] reported that intradiluting propofol with 10% lipids was more effective in reducing the pain of propofol injection than diluting it with 5% glucose, while Doenicke et al. [24] showed that propofol injection pain could be further reduced when higher concentrations of fat emulsion were used in propofol preparations.
McCrirrick and Hunter studied the effect of injection temperature on the pain of propofol injection. They found that when propofol was administered at 48 ° C, the incidence of injection pain could be significantly reduced from 46% to 23%. The efficacy of propofol was not affected. They speculated that a temperature of 48 C might slow down the kinin cascade.
Barker et al. used cold saline to reduce the incidence of pain from propofol injections. They found that pretreatment with 10ml of 0.9% normal saline at 48 C prior to propofold injection significantly reduced the incidence of pain from propofol injection comparable to cold propofol (48 C) and room temperature propofol mixed with 0.05% lidocaine.
There were no significant differences between the two treatment groups. Fletcher et al. found that heating propofol to 37 8C significantly reduced the incidence of pain from propofol injections, from 59% to 22%. They propose two mechanisms: temperature may affect the release of the medium, and high temperature may affect the distribution coefficient and thus the concentration of propofol in the water phase. However, special care needs to be taken to avoid water contamination in the water bath where propofol is used to heat the injection.
