Hemorrhage control of liver injury by short electrical pulses

Abstract

Trauma is a leading cause of death among young individuals globally and uncontrolled hemorrhage is the leading cause of preventable death. Controlling hemorrhage from a solid organ is often very challenging in military as well as civilian setting. Recent studies demonstrated reversible vasoconstriction and irreversible thrombosis following application of microseconds-long electrical pulses. The current paper describes for the first time reduction in bleeding from the injured liver in rat and rabbit model in-vivo. We applied short (25 and 50 µs) electrical pulses of 1250 V/cm to rats and rabbit liver following induction of standardized penetrating injury and measured the amount of bleeding into the abdominal cavity one hour post injury. We found a 60 and 36 percent reduction in blood volume in rats treated by 25 µs and 50 µs, respectively (P<0.001). Similar results were found for the rabbit model. Finite element simulation revealed that the effect was likely non-thermal. Histological evaluation found local cellular injury with intravascular thrombosis. Further research should be done to fully explore the mechanism of action and the potential use of short electric pulses for hemorrhage control.

Figure 1. Experimental setup of rat (a) and rabbit (b) liver.

(a) Injured rat liver (long arrows) was treated with two parallel plate electrodes (short arrows) mounted on a hand caliper adjusting for liver thickness. (b) Rabbit liver injury was treated by fix parallel plates electrodes (7.2 mm apart) (short arrows) positioned at two sides of the wound (dotted line).

Figure 2. Normalized bleeding weight in all animal groups (rats and rabbits).

Control groups were not treated. EPT50 and EPT 25 were treated by 200 pulses of 50 and 25 µs, respectively, in a repetition rate of 1 Hz. Bars represents standard error. Unpaired t-test results for various comparisons are as follows: (*) p<0.001, (**) p = 0.43, (***) p = 0.025, (****) p = 0.004.

Figure 3. Calculated mean temperature versus time of rat liver treated by 200 pulses of 25 and 50 µs at pulse potential of 500 V with repetition rate of 1 Hz.

Following a mild increase in temperature, there is a rapid relaxation of temperature to baseline.

Figure 4. Simulation results of electric field around the liver cut (white line) following pulsing with 4 mm electrodes spaced apart by 7.2 mm.

Figure 5. H&E staining of rat (A,B) and rabbit (C,D) livers treated with short electrical pulses following injury.

Figure A shows a sharp demarcation line between normal and treated areas (arrows) in rat liver treated with 200 pulses of 50 microseconds with electrical field of 1250 V/cm. B Higher magnification of the same. C. Rabbit liver treated with 100 pulses of 500 volts at pulse duration of 25 µs shows similar changes as in A,B with distinct border between treated area (left to arrows) to untreated area. D. Higher magnification of the same area depicts eosinophilic cellular discoloration, picnotic nuclei in many of hepatocytes and extensive extravasation of RBC's due to clogging of blood vessels.