Examiner’s finger-mounted near-infrared spectroscopy (NIRS) is feasible to analyze cerebral and skeletal muscle oxygenation in conscious Chihuahuas
Keisuke Hiwatashi1,2, Kimiaki Doi3, Risuke Mizuno4 and Makoto Yokosuka1
1Laboratory of Comparative Medicine, School of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-Cho, Musashino, Tokyo 180-8602 Japan, 2Animal Medical Center of Gotemba Inter, 383-1, Niihashi, Gotemba, 412-0043, Japan, 3Doi Pet Clinic, 1-4-23, Aoba, Fujieda, 426-0066, Japan, 4Department of Medical Technology, Faculty of Health Sciences, Tsukuba International University, 6-20-1, Manabe, Tsuchiura, Ibaraki, 300-0051, Japan

To measure regional saturation of oxygen (rSO2) of hemoglobin and total hemoglobin index (HbI) in the brain (through the molera of the head) and skeletal muscle (musculus gracilis) of conscious Chihuahua dogs using an examiner’s finger-mounted near-infrared spectroscopy (NIRS) device, Toccare. We investigated brain and skeletal muscle NIRS in forty-eight Chihuahuas without severe disease. To measure rSO2 and total HbI, a Toccare probe was placed on the molera of the head and musculus gracilis of each dog for real-time recording. Stable NIRS values were obtained within 10 seconds. We also examined the effect of anesthesia on rSO2 and total HbI of a Chihuahua. Cerebral rSO2 values (59 ± 7%) were significantly lower than those obtained at femoral regions (67 ± 6%), whereas total HbI values in the brain (0.38 ± 0.09) were significantly higher than those of the musculus gracilis (0.20 ± 0.05). Sedation with a combination of medetomidine and ketamine decreased cerebral rSO2 along with a corresponding reduction in heart rate. Sevoflurane anesthesia with 100% O2 maintained rSO2 in the brain with an even lower heart rate. In conclusions, we measured brain and skeletal muscle rSO2 of hemoglobin in conscious Chihuahuas using a newly developed NIRS device, Toccare, and found that changes in cerebral oxygenation levels were associated with administration of anesthetics.