Non-invasive monitoring of canine tissue hemodynamics undergoing a hyperbaric chamber treatment (HBO2) by time domain near infrared spectroscopy

A novel technique to treat different diseases from inflammation to poisonous bites from snakes on small animals is the hyperbaric chamber treatment [1]. Non-invasive and real-time hemodynamic monitoring of patient's tissue could be useful to quantify the effect of oxygen therapy on the patient. In this pilot study, we explored the possibility of noninvasively detecting canine tissues optical properties by Time Domain Near-Infrared Spectroscopy (TD-NIRS) and then retrieving hemodynamic parameters (deoxygenated and oxygenated hemoglobin molar concentration and tissue oxygen saturation) on different tissues (Triceps Brachii, Biceps Femoralis, and Head) of dogs. Four dogs with different hair length and color undergoing to hyperbaric chamber treatment were measured before and after the treatment, on each of the three sites and on both sides of the animal. In Triceps Brachii and Biceps Femoralis we found an increase in the absorption coefficient for both wavelengths after the treatment, meaning that the total concentration of blood has increased. Different results were obtained in the head, where the total hemoglobin concentration is decreased. The use of TD-NIRS oximetry technology seems a clinically feasible means to assess tissue oxygenation in most of dogs, thanks to a sufficiently high signal-to-noise ratio that allows to evaluate the optical parameters and consequently the physiological parameters of the area under investigation. Moreover, the presence of hair and dark skin did not prevent the possibility of obtaining robust readings.