Performance of Near-Infrared Spectroscopy in Detecting Acute Tourniquet-Induced Upper-Extremity Ischemia Across Different Skin Phenotypes

Skin Pigmentation Affects ViOptix T.Ox Performance in Variably Pigmented Preclinical Model of Flap Ischemia and Congestion

“…Although Gary et al 9 found decreased baseline StO 2 (−8.6%) in pigmented fingertips compared with nonpigmented fingertips, our study found no significant StO 2 difference in adjacent areas of nonpigmented and pigmented tissue during normoxemia despite being powered to detect a difference as small as 3%. Contrastingly, both studies found that the T.Ox device was less dynamic in the presence of darker skin tones.…”

“…Contrastingly, both studies found that the T.Ox device was less dynamic in the presence of darker skin tones. 9 With regard to the contrasting findings during normoxemia, we would argue that the current experiment using adjacent areas of contrasting skin in the same organism is better suited to make this assessment than any design using separate individuals, in which factors such as skin thickness, comorbidities, and/ or variable perfusion could confound the comparison.…”

“…This adjunctive objective measurement of tissue oxygenation is particularly important in patients with dark skin because pigmentation compromises the clinical assessment of tissue perfusion. 3,7 Because the evidence mounts that the NIRS devices may perform differently in the presence of skin pigmentation, 9,[19][20][21] it is critical to understand how this variable may impact function of the T.Ox device used for flap monitoring. In this study, we have established an internally controlled preclinical model to directly assess the impact of skin pigmentation on T.Ox performance while controlling for all other physiological parameters.…”

“…Although the prior literature on T.Ox and skin pigmentation is quite limited, 3,9 there has been much more work on how pigmentation impacts pulse oximetry, which is another widely used application of NIRS. Recent work has found that pulse oximeters are more likely to provide falsely normoxemic StO 2 in hypoxemic patients who self-identify as Black.…”

“…Recent reports have raised concerns as to whether the T.Ox device performs equally well across a diverse range of skin tones. 9 Specifically, Gary et al 9 subjected volunteers to tourniquet-induced upper extremity ischemia while monitoring tissue oxygenation using the ViOptix T.Ox NIRS probe placed on fingertip. In all participants, NIRS T.Ox was able to successfully detect the acute onset of digital ischemia, but those with subjectively darker skin tones had a lower starting StO 2 and smaller change in StO 2 .…”