The results of designing a new prototype device and algorithm in closed method intraperitoneal hyperthermia model in rats

BACKGROUND

There is currently no standard medical device and method available for hyperthermic intraperitoneal therapy studies in rats. In this study, we present our designed device and algorithm that operates based on our own protocol for hyperthermic intraperitoneal treatment in rats. The aim was to demonstrate the effectiveness of the designed device, algorithm, and hyperthermia protocol by showing that the device can achieve the desired temperature inside the rat's abdomen, does not cause rat loss due to complications, operates autonomously, and provides warnings to the operator in case of emergencies.

METHODS

A closed method for intraperitoneal hyperthermia protocol was established for 6 female 8-week-old (280-310 g) albino Wistar rats. Fluid inlet and outlet tubes and a temperature probe were inserted through a 1 cm vertical incision between the xiphoid and bladder in the rat's abdomen, and the skin was sutured in a circular manner. A protocol for intraperitoneal hyperthermic treat-ment was established using a saline solution at a flow rate of 100 mL/min for 60 min, maintaining a temperature of 41°C±0.5 inside the rat's abdomen.

RESULTS

During the study, a temperature of 41°C±0.5 was successfully achieved in the abdomen of all rats at a flow rate of 100 mL/min±5 for 60 min. Due to three rats reaching a rectal temperature above 38.5°C during the hyperthermia protocol, external cooling was applied to the rat's tail base using ice. There were no losses until the postoperative 72nd h, and the study was successfully completed.

CONCLUSION

Our designed device and algorithm, which prioritize animal welfare, operate rapidly, safely, and with high accuracy sensitivity, have been successful in hyperthermic intraperitoneal treatment studies in rats. We believe that they can be used as a stan-dard method and approach in hyperthermic intraperitoneal studies in rats.

Pseudomyxoma Peritonei: Presentation of Two Cases and Challenging Issues in the Literature

Pseudomyxoma peritonei (PMP) is a rather uncommon syndrome in oncology with a unique biological behavior and an estimated incidence of one to two cases per million per year. Clinically, it usually presents with a variety of unspecific signs and symptoms including abdominal pain and distention, ascites, or even bowel obstruction. Despite its intimidating clinical manifestation, PMP is characterized by satisfactory survival rates when treated with cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC). We present two interesting cases of PMP deriving from the appendix with a rather atypical presentation, which was successfully treated with cytoreduction and HIPEC. In addition, we intend to raise clinical suspicion on the diagnosis of PMP and comment on several challenging issues concerning the origin and classification of PMP.