The relation between blood viscosity and blood resistivity under the condition of large clinic samples is studied in this paper. Through processing and calculating the data of blood viscosity and blood resistivity, a ...The relation between blood viscosity and blood resistivity under the condition of large clinic samples is studied in this paper. Through processing and calculating the data of blood viscosity and blood resistivity, a quantitative equation between blood viscosity and blood resistivity can be regressed. Then, on the basis of this relation, the non invasive measurement of blood viscosity can be achieved by the means of plethysmography.展开更多
Blood viscosity, measurement is of great significance for diagnosing manydiseases. Traditional methods such as cone method, capillary method have manyshortcomings. In this paper, after establishing a model of blood mo...Blood viscosity, measurement is of great significance for diagnosing manydiseases. Traditional methods such as cone method, capillary method have manyshortcomings. In this paper, after establishing a model of blood movement in. capillaryat a non-steady state, we develop a new type of blood viscometer. The instrument canmeasure blood viscosity in vivo rapidly and accurately. Moreover, the results canreflect the non-Newton property of blood.展开更多
An inflatable cuff wrapped around the upper arm is widely used in noninvasive blood pressure measurement.However, the mechanical interaction between cuff and arm tissues, a factor that potentially affects the accuracy...An inflatable cuff wrapped around the upper arm is widely used in noninvasive blood pressure measurement.However, the mechanical interaction between cuff and arm tissues, a factor that potentially affects the accuracy of noninvasive blood pressure measurement, remains rarely addressed. In the present study, finite element（FE） models were constructed to quantify intra-arm stresses generated by cuff compression, aiming to provide some theoretical evidence for identifying factors of importance for blood pressure measurement or explaining clinical observations. Obtained results showed that the simulated tissue stresses were highly sensitive to the distribution of cuff pressure on the arm surface and the contact condition between muscle and bone. In contrast, the magnitude of cuff pressure and small variations in elastic properties of arm soft tissues had little influence on the efficiency of pressure transmission in arm tissues. In particular, it was found that a thickened subcutaneous fat layer in obese subjects significantly reduced the effective pressure transmitted to the brachial artery, which may explain why blood pressure overestimation occurs more frequently in obese subjects in noninvasive blood pressure measurement.展开更多
Objectives Nitroglycerine (NTG) enhances coronary blood flow to compromised myocardium is important in relieving ischemia. However, the mechanism for this increase in myocardial blood flow (MBF) is not well defined. I...Objectives Nitroglycerine (NTG) enhances coronary blood flow to compromised myocardium is important in relieving ischemia. However, the mechanism for this increase in myocardial blood flow (MBF) is not well defined. In small vessels and capillaries, relative blood viscosity plays a very important role in determining myocardial vascular resistance (MVR). MVR reduce is due partly to the increase in negative charge of erythrocyte surface. We therefore hypothesized that the enhancement of nutrient blood flow to zones of myocardial ischemia during NTG is partly secondary to reduced MVR and blood flow viscosity. The latter is affected by the negative charge of erythrocyte surface. Methods 6 dogs with LAD flow-limiting stenosis (group 1) and 6 dogs with LAD flow-limiting stenosis and LCx occmusion (group 2) were studied. At baseline and during intracoronary infusions of NTG (0.3-0.6 μg·kg-1·min-1), hemodynamics, MBF (mL·min-1·g-1), whole blood viscosity (WBη, mPa. S), elongation index (EI), eletrophoretic mobility of erythocytes (EME, [μ.s-1)/(V.cm-1)]) and percent wall thickening (%WT) were determined. MVR was calculated using driving pressure/MBF. Results As compared to baseline, no changes in hemodynamics were seen during NTG. MBF increased and MVR decreased significantly in normal bed, the central 25% and the entire of stenosed bed (P<0.05), with a decrease in WBη in both group 1 and group 2 dogs (18.6±9.7 % and 19.2±14.5 %, respectively). However, the % decrease in WBη was proportioned to the % increase in MBF or the % decrease in MVR only in the central 25% of stenosed bed (r=0.87, P<0.001), but not in the entire stenosed bed and normal bed. EI did not show statistically significant differences between during NTG and at baseline, but EME did increase. And the % decrease in WBη during NTG was related to the % increase in EME (r=0.83, P=0.01). Conclusions NTG reduced myocardial vascular resistance and blood viscosity due to the change of negative charge of erythrocyte surface may, in part, be the mechanism of the enhancement of nutrient blood flow to zones of myocardial ischemia. These results provide additional insights into the complex anti-ischemic effects of NTG.展开更多
基金The project is granted by Shandong Province Natural Science Fund and Plan Item
文摘The relation between blood viscosity and blood resistivity under the condition of large clinic samples is studied in this paper. Through processing and calculating the data of blood viscosity and blood resistivity, a quantitative equation between blood viscosity and blood resistivity can be regressed. Then, on the basis of this relation, the non invasive measurement of blood viscosity can be achieved by the means of plethysmography.
文摘Blood viscosity, measurement is of great significance for diagnosing manydiseases. Traditional methods such as cone method, capillary method have manyshortcomings. In this paper, after establishing a model of blood movement in. capillaryat a non-steady state, we develop a new type of blood viscometer. The instrument canmeasure blood viscosity in vivo rapidly and accurately. Moreover, the results canreflect the non-Newton property of blood.
基金supported in part by the National Natural Science Foundation of China (Grant 81370438)the SJTU Medical-Engineering Cross-cutting Research Project (Grant YG2015MS53)supported by the Hui-Chun Chin and Tsung-Dao Lee Chinese Undergraduate Research Program Endowment
文摘An inflatable cuff wrapped around the upper arm is widely used in noninvasive blood pressure measurement.However, the mechanical interaction between cuff and arm tissues, a factor that potentially affects the accuracy of noninvasive blood pressure measurement, remains rarely addressed. In the present study, finite element（FE） models were constructed to quantify intra-arm stresses generated by cuff compression, aiming to provide some theoretical evidence for identifying factors of importance for blood pressure measurement or explaining clinical observations. Obtained results showed that the simulated tissue stresses were highly sensitive to the distribution of cuff pressure on the arm surface and the contact condition between muscle and bone. In contrast, the magnitude of cuff pressure and small variations in elastic properties of arm soft tissues had little influence on the efficiency of pressure transmission in arm tissues. In particular, it was found that a thickened subcutaneous fat layer in obese subjects significantly reduced the effective pressure transmitted to the brachial artery, which may explain why blood pressure overestimation occurs more frequently in obese subjects in noninvasive blood pressure measurement.
文摘Objectives Nitroglycerine (NTG) enhances coronary blood flow to compromised myocardium is important in relieving ischemia. However, the mechanism for this increase in myocardial blood flow (MBF) is not well defined. In small vessels and capillaries, relative blood viscosity plays a very important role in determining myocardial vascular resistance (MVR). MVR reduce is due partly to the increase in negative charge of erythrocyte surface. We therefore hypothesized that the enhancement of nutrient blood flow to zones of myocardial ischemia during NTG is partly secondary to reduced MVR and blood flow viscosity. The latter is affected by the negative charge of erythrocyte surface. Methods 6 dogs with LAD flow-limiting stenosis (group 1) and 6 dogs with LAD flow-limiting stenosis and LCx occmusion (group 2) were studied. At baseline and during intracoronary infusions of NTG (0.3-0.6 μg·kg-1·min-1), hemodynamics, MBF (mL·min-1·g-1), whole blood viscosity (WBη, mPa. S), elongation index (EI), eletrophoretic mobility of erythocytes (EME, [μ.s-1)/(V.cm-1)]) and percent wall thickening (%WT) were determined. MVR was calculated using driving pressure/MBF. Results As compared to baseline, no changes in hemodynamics were seen during NTG. MBF increased and MVR decreased significantly in normal bed, the central 25% and the entire of stenosed bed (P<0.05), with a decrease in WBη in both group 1 and group 2 dogs (18.6±9.7 % and 19.2±14.5 %, respectively). However, the % decrease in WBη was proportioned to the % increase in MBF or the % decrease in MVR only in the central 25% of stenosed bed (r=0.87, P<0.001), but not in the entire stenosed bed and normal bed. EI did not show statistically significant differences between during NTG and at baseline, but EME did increase. And the % decrease in WBη during NTG was related to the % increase in EME (r=0.83, P=0.01). Conclusions NTG reduced myocardial vascular resistance and blood viscosity due to the change of negative charge of erythrocyte surface may, in part, be the mechanism of the enhancement of nutrient blood flow to zones of myocardial ischemia. These results provide additional insights into the complex anti-ischemic effects of NTG.
