Characterization and optimization of ice-slurry injection through intravascular catheters
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Citation
Abstract
OBJECTIVES: Ice slurry injection has been proven to be an effective method for non-invasive fat removal. In contrast to conventional cryolipolysis with topical cooling, it is more time-efficient, customizable and able to target lipid rich tissue, such as fat or myelin sheaths around nerves, anywhere within the human body accessible with a needle. This method of selectively targeting lipid-rich tissue via ice slurry injection has been shown to lead to fat reduction and can also be used as a treatment for pain by targeting myelin sheaths around peripheral nerves. The ice slurry used for these indications is composed of 10-15% mixture of glycerol in normal saline in the temperature range of -5C to -9C. The ice particles within the ice slurry are capable of extracting heat from the target tissue as they melt “while maintaining the slurry temperature near zero” (Garibayan, 2019). The latent heat of fusion of ice particles “is about 80 times higher than the heat capacity of liquid water.” (Garibyan, 2019) Up until now, slurry has been delivered into tissue via injection using a standard needle. The objective of this work was to test if intravascular catheters could be used to deliver slurry into the body via the vascular system for tissue cooling. We also wanted to examine the effect warm blood has on the cooling capacity of the ice slurry as it is injected through the catheters. To be able to test this, an in-vitro testing system was created. We hypothesized that catheters could be used to deliver ice slurry into the body via the vascular system and that the use of the insulated catheters will minimize the effect of warm blood on ice slurry temperature compared to standard non-insulated intravascular catheters. METHODS: 6F Focal Cool Khione (92 cm), 6F H-stick Cordis vista britetip guiding catheter (100 cm), 5F Terumo destination peripheral guiding sheath (45 cm), and 6F H-stick Cordis vista brite tip guiding catheter (55 cm) were the four catheters used in this study. The slurry mixture composed of normal saline and 15% glycerol was used for all the studies. The slurry mixture was produced by mixing 1,275 mL of normal saline and 225 mL of 100% glycerol and cooled to a temperature of -9℃ using the ice slurry device (Figure 2).
An experimental setup was created that included two type T thermocouples positioned in such a way that they almost touch each other in a 35mm petri dish. This benchtop setup was used to record the temperature of the ice slurry after it traveled through the full length of the catheter. Experiments were conducted to determine the optimal setup for recording slurry temperatures after passage through the catheter. To determine the effect of warm blood on the cooling capacity of slurry traveling through the catheters, a warm water bath set to 37℃ was utilized.
RESULTS: Experiments conducted in this study showed that catheters can be used to aid in the delivery of ice slurry intravascularly. Results also showed that insulated catheters can minimize the effect of warm blood, reducing the cooling capacity of the ice slurry compared to non-insulated standard intravascular catheters. Factors such as length, inner diameter, and construction of the catheter can alter the changes in the temperature of the ice slurry as it travels through the catheter. CONCLUSION: In conclusion, catheters can be used in the delivery of ice slurry into the body via the vascular system for the purpose of tissue cooling. Of the catheters tested the insulated catheter performs best under internal body temperatures compared to room temperature conditions.
Description
2025
License
Attribution 4.0 International