1. 2014;17;197-202Acquiring the Optimal Time for Hyperbaric Therapy in the Rat Model of CFA Induced Arthritis
   Controlled Animal Study
   Sung Tae Koo, KMD, PhD, Chang-Hyung Lee, MD, PhD, Yong Il Shin, MD, PhD, Hyun Yoon Ko, MD, PhD, Da Young Lee, MS, and Han-Sol Jeong, KMD, PhD.

BACKGROUND: We previously published an article about the pressure effect using a rheumatoid animal model. Hyperbaric therapy appears to be beneficial in treating rheumatoid arthritis (RA) by reducing the inflammatory process in an animal model. In this sense, acquiring the optimal pressure-treatment time parameter for RA is important and no optimal hyperbaric therapy time has been suggested up to now.

OBJECTIVE: The purpose of our study was to acquire the optimal time for hyperbaric therapy in the RA rat model.

STUDY DESIGN: Controlled animal study.

METHODS: Following injection of complete Freund’s adjuvant (CFA) into one side of the knee joint, 32 rats were randomly assigned to 3 different time groups (1, 3, 5 hours a day) under 1.5 atmospheres absolute (ATA) hyperbaric chamber for 12 days. The pain levels were assessed daily for 2 weeks by weight bearing force (WBF) of the affected limb. In addition, the levels of gelatinase, MMP-2, and MMP-9 expression in the synovial fluids of the knees were analyzed.

RESULTS: The reduction of WBF was high at 2 days after injection and then it was spontaneously increased up to 14 days in all 3 groups. There were significant differences of WBF between 5 hours and control during the third through twelfth days, between 3 hours and control during the third through fifth and tenth through twelfth days, and between 3 hours and 5 hours during the third through seventh days (P < 0.05). The MMP-9/MMP-2 ratio increased at 14 days after the CFA injection in all groups compared to the initial findings, however, the 3 hour group showed a smaller MMP-9/MMP-2 ratio than the control group.

LIMITATION: Although enough samples were used for the study to support our hypothesis, more samples will be needed to raise the validity and reliability.

CONCLUSION: The effect of hyperbaric treatment appears to be dependent upon the elevated therapy time under 1.5 ATA pressure for a short period of time; however, the long-term effects were similar in all pressure groups. Further study will be needed to acquire the optimal pressure-treatment parameter relationship in various conditions for clinical application.