Detection of hypoxia by near-infrared spectroscopy and pulse oximetry: a comparative study

SIGNIFICANCE: Pulse oximetry is widely used in clinical practice to monitor changes in arterial oxygen saturation ([Formula: see text]). However, decreases in [Formula: see text] can be delayed relative to the actual clinical event, and near-infrared spectroscopy (NIRS) may detect alterations in oxygenation earlier than pulse oximetry, as shown in previous cerebral oxygenation monitoring studies. AIM: We aim to compare the response of transcutaneous muscle NIRS measures of the tissue saturation index with pulse oximetry [Formula: see text] during hypoxia. APPROACH: Episodes of acute hypoxia were induced in nine anesthetized Yucatan miniature pigs. A standard pulse oximeter was attached to the ear of the animal, and a transcutaneous NIRS sensor was placed on the hind limb muscle. Hypoxia was induced by detaching the ventilator from the animal and reattaching it once the pulse oximeter reported 70% [Formula: see text]. RESULTS: Twenty-four episodes of acute hypoxia were analyzed. Upon the start of hypoxia, the transcutaneous NIRS measures changed in [Formula: see text] , whereas the pulse oximetry measures changed in [Formula: see text] ([Formula: see text]). CONCLUSIONS: Transcutaneous muscle NIRS can detect the effects of hypoxia significantly sooner than pulse oximetry in the Yucatan miniature pig. A transcutaneous NIRS sensor may be used as an earlier detector of oxygen saturation changes in the clinical setting than the standard pulse oximeter.