Effect of cryotherapy duration on experimentally induced connective tissue inflammationin vivo

Abstract

Objectives This study tested the hypothesis that cryotherapy duration influences lipopolysaccharide (LPS)-induced inflammation in a rat model. Materials and Methods Six Wistar rats ( Rattus norvegicus albinus ) were used. Five sites were selected per animal and divided into 5 groups: a negative control group (NC), 2 positive control groups (PC1 and PC2), and 2 experimental groups (E1 and E2). Cryotherapy was applied for 1 minute (E1) or 5 minutes (E2). An acute inflammatory response was induced in the PC and E groups via subcutaneous administration of 0.5 mL/kg. In the PC2 group, a catheter was inserted without additional treatment. For the E1 and E2 groups, 2.5°C saline solution was administered through the implanted catheters for 1 and 5 minutes, respectively. The rats were sacrificed, and samples were obtained and processed for histological analysis, specifically examining the presence of polymorphonuclear neutrophils and hemorrhage. The χ 2 test was used to compare the presence of acute inflammation across groups. Dependent variables were compared using the linear-by-linear association test. Results Inflammation and hemorrhage varied significantly among the groups ( p = 0.001). A significantly higher degree of acute inflammation was detected ( p = 0.0002) in the PC and E1 samples than in the E2 group, in which cryotherapy was administered for 5 minutes. The PC and E1 groups also exhibited significantly greater numbers of neutrophils ( p = 0.007), which were essentially absent in both the NC and E2 groups. Conclusions Cryotherapy administration for 5 minutes reduced the acute inflammation associated with LPS and catheter implantation.