Please see Bibliography of References for a list of abstracts, manuscripts and posters.

Other Studies

Characterization of tissue oxygen saturation (StO₂) and the vascular occlusion test (VOT): influence of measurement sites, probe sizes and deflation thresholds

Gomez H, Mesquida J, Simon P, Kim HK, Puyana JC, Ince C, Pinsky MR. American Thoracic Society International Conference; May 15-20, 2009; San Diego, CA.

Background: StO₂ and the VOT can identify tissue hypoperfusion in trauma and sepsis. However, the technique is neither standardized nor uses the same monitoring site. We hypothesized that baseline and VOT StO₂ would be different in forearm (F) and thenar eminence (TH) and that different minimal StO₂ values during VOT would result in different reoxygenation (ReO₂) rates.

Methods: StO₂ and its change during VOT (Gomez et al. Int Care Med, 2008;34:1600-07) were simultaneously measured in the F and TH, with 15 and 25 mm probes, using the 325 InSpectra monitor in 18 healthy, adult volunteers. Two VOTs were done to a threshold thenar StO₂ of 40% interchanging 15 and 25 mm probes between sites. Two additional VOTs were done to thresholds of 50% and 30%. Absolute StO₂, Deoxygenation rate (DeO₂) and ReO₂ (%/min) were compared between sites, probes and thresholds using non-parametric tests. Results are presented as mean SD (p value).

Results: Absolute StO₂, DeO₂ and ReO₂ values were different for TH vs. F, 15 vs. 25 mm. The ReO2 was also different between different thresholds. TH vs. F (15 mm probe): 89.1 5.1 vs. 84.6 6.8 (0.031), -14.1 3.8 vs. -9.1 4.0 (0.011), 278.9 61.8 vs. 90.8 64.1 (<0.0001); 25mm probe, 91.1 4.3 vs. 86.4 5.9 (0.016), -20.5 7.7 vs. -10.6 5.8 (<0.0001) and 415.2 120.7 vs. 252.1 173.3 (0.012) respectively. 15 vs. 25 mm probes (TH): Absolute StO₂ (p=0.020), DeO₂ (p<0.0001) and ReO₂ (p<0.0001). Threshold StO₂ values (15 mm probe): ReO₂, p=0.003, DeO₂, p=0.60. ReO₂ at 40 and 50% StO₂ thresholds, p=0.044.

Conclusion: Absolute StO₂, DeO₂ and ReO₂ were different when measured in different anatomical sites (F, TH), when measured by the 15 vs. 25 mm probe, and ReO₂ is different with differing DeO₂ release threshold values. Thus, standardization of site, probe and VOT challenge need to be stipulated when reporting these data.