Role of injection pressure, flow and sclerosant viscosity in causing cutaneous ulceration during sclerotherapy.

The objective of the study is to evaluate the viscosity of popular sclerosants and their flow hydrodynamics through a syringe/needle to further discuss Miyake's old, venous-capillary reflux theory, using additional objective data. The following sclerosing agents were tested in the study: 75% dextrose (D75%); 50% dextrose (D50%); 5% ethanolamine oleate (Etha5%); 0.5% laureth-9 (Aet0.5%) and 0.1% sodium tetradecyl sulphate (STS0.1%). Using 5 mL syringes and 27G needles, the resulting pressures and flows for each sclerosant agent were measured. To do this, a three-way stopcock was connected between the syringe and the needle so that an arm of the stopcock could be used to measure injection pressures with a digital monitor in 1 mmHg increments. Two trials were performed: in trial 1, the syringe was attached to a Samtronic 680 infusion pump and in trial 2, the solutions were injected manually. The observed sclerosant viscosities were as follows: D75%: 0.28 Poise; D50%: 0.12 Poise; Etha5%: 0.10 Poise; Aet0.5%: 0.07 Poise; and STS0.1%: 0.04 Poise. In trial 1 (constant flow), it was observed that D75%, which had the highest viscosity of the sclerosants tested, had the highest pressure readings. In trial 2 (constant pressure), the flow obtained with the D75% solution was lower than the flow of the other solutions. In conclusion, based on the rabbit study theory, vessel size and sclerosant viscosity and strength, not extravasation, play a role in causing ulceration from injection sclerotherapy. As a result, they all affect the potential of venous-capillary reflux being caused by sclerotherapy injection and, thus, the risk of postsclerotherapeutic cutaneous ulceration.