Examination of Lower Limb Microcirculation in Diabetic Patients with and without Intermittent Claudication.

Intermittent claudication is a frequent complaint in lower extremity artery disease, but approximately two thirds of patients are asymptomatic, most of which are diabetic patients. Non-invasive angiological and microrheological tests on diabetic subjects with and without intermittent claudication were performed in the present study. In total, 98 diabetic patients were included and divided into two groups: 20 patients (63.5 ± 8.8 years, 55% men, 45% women) had intermittent claudication, 78 patients (65.5 ± 9.3 years, 61.5% men, 38.5% women) were asymptomatic. Hand-held Doppler ultrasound examination, transcutaneous tissue partial oxygen pressure (tcpO2) measurement, Rydel-Seiffer tuning fork tests, and 6-min walk tests were performed, and erythrocyte aggregation was investigated. Ankle-brachial index (p < 0.02) and tcpO2, measured during provocation tests (p < 0.003) and the 6-min walk test (p < 0.0001), significantly deteriorated in the symptomatic group. A higher erythrocyte aggregation index and faster aggregate formation was observed in claudication patients (p < 0.02). Despite the statistically better results of the asymptomatic group, 13% of these patients had severe limb ischemia based on the results of tcpO2 measurement. Claudication can be associated with worse hemodynamic and hemorheological conditions in diabetic patients; however, severe ischemia can also develop in asymptomatic subjects. Non-invasive vascular tests can detect ischemia, which highlights the importance of early instrumental screening of the lower limbs.

Lower limb ischemia and microrheological alterations in patients with diabetic retinopathy.

BACKGROUND: Diabetes mellitus is frequently associated with vascular pathologies and hemorheological disorders. METHODS: 105 patients with diabetic retinopathy (DRP) (mean age 64.64±9.01 years, 56 males, 49 females), 35 age-matched non-diabetic (mean age 61.65±7.6 years, 14 males and 21 females) and 42 young healthy volunteers (mean age 25.52±3.32 years, 22 males, 20 females) were recruited. Lower extremity artery disease (LEAD) and microcirculatory alterations were screened by hand-held Doppler, transcutaneous partial tissue oxygen tension (tcpO2), tuning fork test, 6-minute walk test, erythrocyte aggregation and deformability. RESULTS: High prevalence of LEAD was detected in diabetic population: 55.3% fulfilled the criteria of LEAD based on ankle-brachial index; severely impaired tcpO2 was measured in 18.6%. The results of non-invasive measurements of the diabetic patients were significantly worse than those of the control groups (p < 0.05). Hemorheological disturbances could be characterized by the significantly higher erythrocyte aggregation (p < 0.05) and lower erythrocyte deformability (p < 0.05) in the diabetic population. CONCLUSION: Macro- and microcirculatory lower limb disorders could be revealed at high prevalence in diabetic patients with retinopathy. Measurement of tcpO2 and hemorheological variables could be useful to discover patients at higher risk for diabetic foot complications.

Viscometer validation studies for routine and experimental hemorheological measurements.

BACKGROUND: Viscosity measurement is challenging due to the internal properties of blood and the artifacts deriving from the various viscometer systems. OBJECTIVE: We aimed to determine the pitfalls of a cone-plate viscometer (Brookfield DV-III Ultra LV) before starting measurements and compare it to our capillary type model (Hemorex Hevimet 40). Effects of sample storage and thermal calibration were assessed as well. METHODS AND RESULTS: Intra-observer variability was studied by 10 replicate measurements of 7 blood samples, mean coefficients of variation were less than 5%. Instruments were compared by measuring 26 blood samples, an average difference of 7% in WBV and 10% in PV was observed. 9 blood samples were stored at 4°C, 22°C and 37°C up to 48 hours to study the effect of storage on viscosity values. WBV at 50 and 100 s-1 became significantly lower after 3 hours at 37°C (p < 0.05). WBV at higher shear rates and PV remained constant at all temperatures. To evaluate the possibility of measuring one sample at different temperatures, 8 blood samples were measured at 40°C with the device calibrated both at 20°C and 40°C; no significant difference was observed. CONCLUSIONS: Thorough validation studies are required before starting experimental and routine viscosity measurements.

The relationship between hemorheological parameters and mortality in critically ill patients with and without sepsis.

PURPOSE: The prognostic scoring systems for mortality of intensive care patients estimate clinical outcome using several physiological and biochemical parameters. In altered hemodynamic conditions of critically ill patients, hemorheological variables may play a significant role in appropriate tissue perfusion. We investigated if hemorheological parameters are altered in critical status and if they could be markers of mortality. METHODS: 112 patients (67.8 ± 12 years, 58 males, 54 females) treated in intensive care unit with different non-surgical diseases were investigated. Routine laboratory parameters and prognostic scores were determined and hemorheological variables (hematocrit, plasma and whole blood viscosity, red blood cell aggregation and deformability) were measured on the 1st and the 2nd day after admission. RESULTS: ICU scores predicted 35.2-41.3% mortality rate, real mortality in intensive care unit was 37.5%, while 30-day mortality was 46.6%. Whole blood viscosity (WBV) and red blood cell (RBC) deformability were lower, red blood cell aggregation was higher in septic than in nonseptic patients (p < 0.05). In septic patients calcium was increased, osmolality was decreased, while in nonseptic patients WBV and RBC aggregation were higher in nonsurvivors compared to survivors (p < 0.05). Worsening of RBC deformability from day 1 to day 2 predicted higher mortality (p < 0.05). CONCLUSION: Calcium and osmolality level were associated with outcome in sepsis. Whole blood viscosity, red blood cell aggregation and change in red blood cell deformability could predict mortality in nonseptic patients and they may add prognostic information over the ICU scores. Further investigations are needed to evaluate the benefit of our findings in clinical practice.

Hemorheological alterations in carotid artery stenosis.

BACKGROUND: Carotid artery stenosis (CAS) is not only an important risk factor of cerebrovascular events but it can also indicate generalized atherosclerosis. Hemorheological parameters are altered in CAS and in chronic cerebrovascular disorders as well, but it is controversial if hemorheological parameters could be markers of stenosis or atherosclerosis. METHODS: 107 patients were investigated, 40% of them had stroke or TIA in case history and 48% had CAS. Routine lab parameters were determined and hemorheological variables were measured: hematocrit, plasma viscosity, whole blood viscosity, red blood cell aggregation, and deformability. RESULTS: In the stenotic group whole blood viscosity and red blood cell aggregation were deteriorated (p < 0.05). Whole blood and plasma viscosity were higher and red blood cell deformability was lower in the symptomatic group (p < 0.05). Plasma viscosity and red blood cell deformability were altered in the evolving atherosclerosis group and the CAS groups compared to patients having no signs of stenosis (p < 0.05), but there was no difference among the CAS groups. CONCLUSION: Although hemorheological parameters are impaired both in CAS and chronic cerebrovascular disorders, the severity of stenosis cannot be detected based on hemorheological parameters. Our investigation suggests that alteration of hemorheological parameters could indicate carotid atherosclerosis.