A systematic review of human and veterinary applications of noninvasive tissue oxygen monitoring

Abstract

Tissue oxygen monitoring is most commonly performed utilizing a noninvasive, portable monitor, which provides real-time, continuous, repeatable StO2 measurements. A decline in StO2 is an early indicator of shock in both human and veterinary patients. Low StO2 values in human patients are associated with increased morbidity, mortality, and length of hospitalization, as well as the development of multiple organ system dysfunction and surgical site infections.

Evaluation of tissue oxygen saturation in naturally occurring canine shock patients

“…Alternatively, a lower average StO 2 may have been identified in our study due to the inclusion of a variety of etiologic causes of clinical shock. StO 2 can be variable in human patients with septic shock . This has been theorized to occur due to a wide array of microvascular disturbances including functional arteriovenous shunting, endothelial barrier dysfunction, microthrombi formation, closed capillaries, decreased flow, and vasomotor paralysis.…”

“…The THI is a value based on the total amount of measured hemoglobin in the tissue and is an indicator of signal strength. A THI ≥5.0 indicates sufficient hemoglobin present to obtain an accurate StO 2 value in people …”

“…Tissue oxygen saturation (StO 2 ) measured using near‐infrared spectroscopy (NIRS) may be of clinical utility for the diagnosis of shock in canine patients. NIRS is a noninvasive, continuous technique for monitoring oxygen saturation at the tissue level and is thought to be a surrogate for oxygen delivery . It is based on the low absorption of near‐infrared light (700–1,000 nm) in biological tissues and is capable of providing a percentage of oxygen saturation of hemoglobin in blood vessels <1 mm in diameter.…”

Tissue oxygen saturation in dogs with acute hemorrhage

“…There are some precautions that must be taken to ensure accurate NIRS measurements. The probe comes with a sensor shield as excessive ambient light can lead to inaccurate measurements . Placement of the probe over bone, areas of skin with excessive pigmentation, or hematomas should be avoided, as this may alter the accuracy of measurements .…”

“…The probe comes with a sensor shield as excessive ambient light can lead to inaccurate measurements . Placement of the probe over bone, areas of skin with excessive pigmentation, or hematomas should be avoided, as this may alter the accuracy of measurements . In a study determining StO 2 in healthy dogs, the body condition score affected the measurements, with moderately to severely overweight dogs having significantly lower StO 2 values .…”