Schematic presentation of thenar skeletal muscle StO2 before, during and after the vascular occlusion tests. Before the vascular occlusion, the StO2 is measured in the resting period (1, basal StO2). During the vascular occlusion, the StO2 gradually decreases. The rate of this decrease is determined from the curve as the downslope StO2 (2; %/min), as a surrogate of the tissue oxygen consumption. After reaching the predetermined minimum StO2, present here as 40% StO2 (3), the vascular occlusion is released, and the StO2 begins to rise again. The rate of this increase is determined from the curve as the upslope StO2 (4; %/min), as a surrogate marker of the microcirculatory reactivity. After the release of the occlusion, the StO2 increases to higher values compared to the basal StO2 due to post-ischaemic vasodilatation (5, maximum StO2). The StO2 then slowly returns to the basal StO2.
Table 1
Demographics, laboratory, haemodynamic and skeletal muscle NIRS variables of the patients before the RBC transfusions
| Characteristic | All patients (n = 28) |
| Demographics | |
| Female [n (%)] | 13 (46) |
| Age (years) | 65 ±12 |
| Laboratory data | |
| Haemoglobin (g/L) | 77.9 ± 12.4 |
| Haematocrit (%) | 0.23 ± 0.04 |
| Haemodynamics | |
| Systolic blood pressure (mm Hg) | 122 ± 19 |
| Diastolic blood pressure (mm Hg) | 68 ± 10 |
| Heart rate (beats/min) | 78 ± 17 |
| Thenar skin temperature (°C) | 35.6 ± 0.6 |
| NIRS in resting conditions | |
| Basal StO2, % | 53 ± 7 |
| Tissue haemoglobin (g/L) | 1.13 ± 0.14 |
| NIRS: during vascular occlusion test | |
| Downslope StO2 (%/min) | -9.4 ± 4.6 |
| Minimum StO2 (%) | 39 ± 5 |
| Upslope StO2 (%/min) | 78 ± 51 |
| Maximum StO2 (%) | 59 ± 10 |
Data are means ± SD
Effects of the age of the RBCs for the transfusions on the basal StO2. (A) Regression/analysis of variance. (B) Roc analysis, interactive dot diagram for optimal effect separation.
Prediction line (solid lines); 95% confidence line (dashed lines)
Effects of the age of the RBCs for the transfusions on the upslope StO2. (A) Regression/analysis of variance. (B) ROC analysis, interactive dot diagram for optimal effect separation.
Prediction line (solid lines); 95% confidence line (dashed lines
Effects of the age of the RBCs for the transfusions on the maximum StO2. (A) Regression/analysis of variance. (B) ROC analysis, interactive dot diagram for optimal effect separation
Prediction line (solid lines); 95% confidence line (dashed lines)