Histological and ultra-structural effects of rapid muscle expansion through intramuscular administration of carbon dioxide: an intra-operative study in an animal model.

INTRODUCTION: Carbon dioxide (CO2) therapy refers to trans-cutaneous or sub-cutaneous administration of CO2 for therapeutic purposes, and recent studies have pointed out that it produces a vasodilation effect after it is locally injected, which helps amplify the reconstructive potentiality of an expanded-muscle flap. MATERIALS AND METHODS: Thirty male Wistar rats, weighting between 350 and 400 g, were randomly divided into three groups of 10. In the first group, single intra-operative rapid expansion was carried out under the right latissimus dorsi muscle. In the second group, for five days prior to surgery, a pre-treatment with intramuscular injections of CO2 was performed. The third group served as controls. For each group, the latissimus dorsi muscle was fixed as soon possible after mice died, and ultrathin sections of it examined with transmission electron microscope. RESULTS: In the treated group, the majority of expanded muscles showed a normal striation pattern, whereas a few fibers showed mild disorganization of the myo-filaments in the sarcomeres, which appeared overstretched (average 2.37 µm). CONCLUSIONS: This evidence could demonstrate a greater capacity of muscle recovery after treatment by CO2 expansion.