Vascular dysfunction detected by a simplified venous occlusion test in NIDDM patients

Measuring reactive hyperemia in the lower limb using near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) has been used to measure reactive hyperemia following a vascular occlusion. However, the procedures and methods of analysis used have varied. The purpose of the present study is to identify reproducible methods for measuring reactive hyperemia using HbO2 NIRS signals in the calf and foot. Healthy participants (10 male, 10 female) aged 19 to 28 years performed one of two tests: reproducibility trials or elevation protocol (30 and 60 cm limb elevation above the heart). The time to 50% reperfusion (T1/2) and the second (R2q) quartile rates of reperfusion were found to be the most reproducible parameters (coefficient of variation= 7.12 to 14.1%). The time to 95% reperfusion (T95) was 12.7% more reproducible on average than the previously reported parameter of time to peak hyperemia. Measures of reperfusion time and rate slowed with increasing limb elevation. Correlations were identified between the calf and foot in the measurements of R2q (R2 = 0.713, p = 0.021), T1/2 (R2 = 0.673, p = 0.033), and T95 (R2 = 0.792, p = 0.006). Half and 95% recovery times and second and third quartile rates expressed good reproducibility and sensitivity to change with reduced perfusion pressure. NIRS measures of reactive hyperemia have the potential to evaluate microvascular perfusion in clinical populations.

Relationship between cerebral injury and inflammatory responses in patients undergoing cardiac surgery with cardiopulmonary bypass

This study was performed to evaluate whether cytokines, adhesion molecules, ghrelin and S-100B are useful markers in predicting the cerebral infarction after cardiac surgery with cardioplumomary bypass (CPB). The patients (n=20) were classified into two groups; group A (n=4) showed postoperative organized cerebral damage, while group B (n=16) consisted of patients without occurrence of postoperative strokes. Before CPB, serum levels of S-100B in both groups A and B were low (<0.5 ng/mL), while ghrelin concentrations in group A (all patients had history of strokes) were much higher than those in group B. After CPB, when serum levels of S-100B in group A at 24h were higher than those in group B, ghrelin in group A at same time point showed high levels in comparison to group B. At 12 and 24h after CPB, levels of tumor necrosis factor (TNF)-alpha, interleukin-10 and soluble TNF-receptor I in group A were significantly higher than those in group B. In conclusion, it is considered that ghrelin as well as S-100B can be a useful marker for the prediction of stoke after CPB. Increase of TNF-alpha, interleukin-10 and soluble TNF-receptor I after CPB may be involved in the pathogenesis of stroke after CPB.

Stability and reproducibility of brachial artery flow-mediated dilation

PURPOSE

Brachial artery flow-mediated dilation (BAFMD) is a noninvasive technique, which has been suggested as a potential means of identifying patients with early atherosclerosis and therefore has enormous clinical appeal. Despite this, the stability and reproducibility of this technique are not yet clear. Therefore, the purpose of this study was to establish the stability and reproducibility of BAFMD after 5 min of forearm occlusion and to produce power calculations to aid in clinical trial design.

METHODS

Twenty-six healthy volunteers underwent high-resolution ultrasonographic brachial artery assessments before, during, and after 5 min of forearm occlusion. The study design involved three scans on 2 d, performed by two ultrasonographers and analyzed by two readers. All subjects were tested between 7 and 11 a.m. after refraining from food and exercise. The nondominant arms were scanned, in longitudinal view, approximately 4 cm proximal to the olecranon process, in the anterior/medial plane. Blood draws were performed on each visit. The SAS MIXED restricted maximum likelihood (REML) procedure for an unbalanced design was used to calculate variance components and provide power calculations.

RESULTS

Average baseline artery diameter for all studies was 3.48 +/- 0.53 mm. This increased to 3.71 +/- 0.57 mm (6.58 +/- 4.15%) at peak dilation. Intraclass correlation coefficients (ICCC) for days, testers, and readers were 0.92, 0.94, and 0.90, respectively. To detect a difference in vasoreactivity of 60% (two-tailed), e.g., 5% vasodilation versus 8% vasodilation, at 90% power, 23 and 10 subjects would be required for cross-sectional and pre-post designs, respectively.

CONCLUSIONS

These data indicate adequate stability and reproducibility of the BAFMD technique under controlled conditions. Additionally, BAFMD appears useful to differentiate between groups, although its prognostic value for the examination of individuals is unclear.