On the way to pain-free diagnosis of compartment syndrome
The muscles of our body are located in closed spaces that are enclosed by connective tissue. These spaces are called muscle compartments. While volume changes are possible in some of these spaces, things get tight quickly – especially in our extremities, the arms and legs – when things get out of balance.
When tissue swells or the blood flow is impaired after an accidental injury, for example a severe contusion or fracture of the arm or leg bones, this can lead to severe permanent damage in the affected limb. Medicine refers to this as acute compartment syndrome. The lower legs and forearms are the most common sites affected by compartment syndrome – it occurs in about 2 to 9% of shin fractures.
Because the layer of fascia that defines the boundary of these compartments hardly stretches, a small amount of bleeding or swelling of the muscles within the muscle compartments can cause the pressure to rise sharply. Blood can then no longer enter the small vessels and becomes congested due to a collapse of the venous vessels. The tissue is no longer supplied with oxygen and dies. Rhabdomyolysis, i.e. degradation of the skeletal muscle, and subsequent kidney failure are also possible complications. The pressure must be relieved within a few hours, for example by cutting the fascia and skin, in order to avoid permanent consequential damage.
In addition to these potentially severe consequences, the diagnosis of compartment syndrome is difficult to make. It is mainly based on the symptoms of the affected person, first and foremost severe pain and numbness or tingling in the fingers or toes.
For this reason, the role of regional anaesthesia in delaying the diagnosis of compartment syndrome is being discussed. Some surgeons are concerned that if the pain sensation is deliberately switched off by regional nerve blocks, the diagnosis of compartment syndrome may be delayed. In the field of anaesthesia, there is no scientific evidence to support this. Studies from the USA show no difference in postoperative complications after leg fractures between regional or general anaesthesia. Both sides concede that there is a lack of data to draw firm conclusions one way or the other. In 2021, a publication by physicians from Austria, Germany and the Netherlands came to the unusual conclusion: “Frankly, our knowledge of the effects of regional anaesthetic blockade on delayed diagnosis of compartment syndrome is limited.”
The Ludwig Boltzmann Institute for Traumatology, the research centre in cooperation with AUVA, wants to counteract this. In a project funded by the FWF, scientists headed by Priv. Doz. Dr. Gerhard Fritsch, senior physician at the AUVA emergency hospital Salzburg, are specifically investigating the question of how regional anaesthesia affects the formation and recognition of compartment syndrome.
During the project, a laboratory model was established in which the compartment syndrome is artificially induced with the help of a balloon. The administration of an anaesthetic as a test group is contrasted with a control group that is administered only saline solution. The team of scientists then takes a close look at what happens to the tissue in both cases. Do more cells die? What does the histology say about the condition of the tissue – was it more or less squashed? Could the compartment syndrome have been detected without the patient complaining of pain?
Especially in the last question there lies great hope for the later clinical application of the new findings. No longer having to rely on the patient’s pain is a promising idea for both sufferers and practitioners. The scientists are investigating the concentration of systemic myoglobin, i.e. whether muscle degradation products are found in the blood, or lactate, a product of muscle acidity known from muscle soreness. The research project also uses a new diagnostic method. The so-called microperfusion makes it possible to measure substances directly in the muscle tissue, i.e. directly at the site of the event, which are produced in the course of cell death. Preliminary studies have shown that microperfusion reacts much more sensitively and quickly to a circulatory disorder in the muscle tissue than conventional measurements in the blood.
All this offers the possibility of diagnosing an incipient compartment syndrome more quickly and with greater diagnostic accuracy. The study can thus not only help settle the dispute between surgery and anaesthesia, but also jointly point out a way for better early detection of compartment syndrome.