No description available.

The purpose of this study was to examine the consistency of near-infrared spectroscopy (NIRS) measures associated with a 10 minute vascular occlusion of the thigh during 5 consecutive days. A secondary purpose was to examine if the repeated daily occlusions modify the vascular response to such occlusions. The NIRS chromophores of oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (HHb), total hemoglobin (tHb), hemoglobin difference (HbDiff), and total saturation index (TSI) were monitored at the vastus lateralis muscle during each testing session. Participants were female (age 18-30 yrs) and were randomly assigned to one of two groups. The Test Group (age 23 ± 2yrs) completed an occlusion test every day for 5 consecutive days while the Control Group (age 21 ±1.6yrs) was tested on days 1, 3 and 5. Each testing session involved 10 minutes rest in a supine position, 10 minutes of femoral artery occlusion (preset at 250mmHg), 10 minutes of recovery. At onset of occlusion, the rapid cuff inflation system inflated in 0.3 seconds to the preset 250mmHg. Following the 10 minutes of occlusion, the cuff was deflated in 0.3 seconds. Heart rate was monitored throughout all testing sessions and mean arterial pressure was calculated and compared between groups. There were no significant group or day main effects found, nor any significant interactions for the following hemoglobin chromophores measures: HbO2, HHb, HbDiff, and TSI. In all participants, the NIRS response pattern to rest, occlusion and recovery was consistent for all testing days regardless of group. The response pattern to the occlusion initiated by the rapid cuff inflation was as follows: HbO2, tHb, HbDiff, and TSI decreased then slowly plateaued over the 10 minutes while HHb increased initially and then plateaued. Following the rapid cuff deflation, HbO2, tHb, HbDiff and TSI increased to their maximum reperfusion levels and then plateaued over the remainder of the 10 minutes of recovery. During that same period, HHb decreased initially upon reperfusion and then plateaued. Unlike the other measures, TSI and tHb demonstrated inconsistencies in their response pattern regardless of group or day. The consistency of hemoglobin chromophores response pattern to daily 10 minute vascular leg occlusions over 5 consecutive days is an important finding of this study. This response indicates that there is no apparent change in vascular response to repeated occlusions and has implications for exercise studies that use occlusion in their methodology. The study also emphasizes the inconsistency of tHb and TSI as primary hemoglobin response measures to occlusion. Similarly, the results demonstrate the potential misinterpretation of results if only relying on one hemoglobin measure during occlusion. / Graduate

Purpose: The purpose of this study was to investigate the blood flow/pressure relationship (linear or nonlinear) in the superficial femoral artery when seated, as well as to investigate blood flow changes with exercise using varying cuff pressures and a preexercise (PE) condition. The presence of venous outflow with occlusion at rest and exercise was also investigated.Methods: Twenty-three subjects visited the lab on 3 occasions. First to determine linearity of blood flow using 0% to 90% arterial occlusion pressure (AOP), and venous outflow at rest and during exercise with cuff inflated to 40% AOP. Subsequent visits compared blood flow between rest and PE conditions to determine average blood flow, heart rate, systolic and diastolic blood pressure changes in response to a blood flow-restricted (BFR) exercise protocol. Results: Blood flow/pressure relationship is nonlinear at the superficial femoral artery (p < 0.01). No significant differences in average blood flow, conductance or mean arterial pressure (MAP) were found between 30% to 80% AOP (p = 1.0 to .08). Blood flow is not significantly different between rest and PE groups (p = 0.49) although initial 40% AOP and 40% exercise arterial occlusion pressure (EAOP) values were different between rest and PE groups. (p < 0.01). Conclusion: The nonlinear relationship at the superficial femoral artery demonstrates higher cuff pressures are not necessary to reduce blood flow in BFR exercise of the lower extremity. Furthermore, PE or warm-up is not necessary prior to determining EAOP as it does not alter blood flow responses during BFR exercise. We found evidence of venous outflow above the cuff both at rest and during exercise at 40% AOP.

PURPOSE: This study comparted arterial occlusion pressure (AOP) of the superficial femoral artery (SFA) between the dominant and nondominant legs and the relationship between blood flow and occlusion pressure at rest and during muscle contractions in males and females. METHODS: The AOP of the SFA was measured using Doppler ultrasound in the dominant and nondominant legs of 35 (16 males, 19 females) apparently healthy, normotensive young adults. Blood flow in the SFA was measured in the resting state (REST) and during plantar flexion exercise (EXC) at occlusion pressures ranging from 0% to 100% of AOP. ANOVA was used to compare AOP between the dominant and nondominant legs and between males and females. Regression analysis was used to evaluate the influence of relevant variables on AOP. A mixed model was used to evaluate the relationship between blood flow and occlusion pressure at REST and during EXC. RESULTS: There was a significant difference in the AOP between the dominant and nondominant legs in males (230 ± 41 vs 209 ± 37 mmHg) and females (191 ± 27 vs 178 ± 21 mmHg), respectively. There was also a significant sex difference in the AOP in the dominant (230 ± 41 vs 191 ± 27 mmHg; p = 0.002) and nondominant (209 ± 37 vs 178 ± 21 mmHg; p = 0.004) legs, respectively. Regression analysis revealed that after accounting for leg circumference, age, sex, blood pressure, and skinfold thickness were not independent predictors of AOP. At REST and during EXC, there was a linear relationship between relative blood flow and occlusion pressure. CONCLUSIONS: Differences in leg circumference contribute to a portion of the differences in AOP between the dominant and nondominant legs and between sexes. The linear relationship between relative blood flow and occlusion pressure suggests that occlusion pressures during blood flow restriction exercise should be chosen carefully. A large variance in blood flow measurements at different occlusion pressures suggests the need for evaluating the reliability of blood flow measurements and standardization of methods.

O sistema cardiovascular está estrutural e funcionalmente disposto de modo “circular”. Situações de obstrução do fluxo sanguíneo determinam o aparecimento de mecanismos que visam suplantar tais interrupções e manter a circularidade íntegra. À nível molecular, o principal elemento envolvido nestes mecanismos é o Vascular Endothelial Growth Factor (VEGF). A expressão do VEGF quando há oclusão arterial está bem documentada, faltando elementos com relação à oclusão venosa. Neste estudo objetivamos verificar se a oclusão à nível arterial determina uma expressão do VEGF diferente daquela que ocorre se a oclusão acontecer à nível venoso. Para isso randomizamos dois grupos de ratos de experimentação. Em um grupo realizamos a oclusão da aorta infra-renal e em outro a oclusão da veia cava infra-renal. Posteriormente medimos a expressão do VEGF através da contagem do número de células marcadas imunoistoquimicamente no omento destes ratos. O resultado demonstrou que a expressão do VEGF, quando analisada pelo método proposto foi igual no grupo da oclusão venosa e no grupo da oclusão arterial. / The cardiovascular system is structurally and functionally circular. Situations in which there is obstruction to blood flow trigger mechanisms to bypass these blockages and maintenance the integrity of the circularity. At the molecular level the main factor involved is the Vascular Endothelial Growth Factor (VEGF). The VEGF expression associated with arterial occlusion is well documented but is lacking evidence when venous occlusion occurs. This study aimed to verify if the expression of VEGF when an occlusion occurs at venous level is the same or different from that caused at the arterial level. Two groups of rats were randomized by infra-renal aortic occlusion or inferior vena cava occlusion. VEGF was measured by counting the immunohistochemistry method marked cells at the omentum level. It was demonstrated that the VEGF expression is the same in the venous group obstruction as the arterial obstruction group.

O sistema cardiovascular está estrutural e funcionalmente disposto de modo “circular”. Situações de obstrução do fluxo sanguíneo determinam o aparecimento de mecanismos que visam suplantar tais interrupções e manter a circularidade íntegra. À nível molecular, o principal elemento envolvido nestes mecanismos é o Vascular Endothelial Growth Factor (VEGF). A expressão do VEGF quando há oclusão arterial está bem documentada, faltando elementos com relação à oclusão venosa. Neste estudo objetivamos verificar se a oclusão à nível arterial determina uma expressão do VEGF diferente daquela que ocorre se a oclusão acontecer à nível venoso. Para isso randomizamos dois grupos de ratos de experimentação. Em um grupo realizamos a oclusão da aorta infra-renal e em outro a oclusão da veia cava infra-renal. Posteriormente medimos a expressão do VEGF através da contagem do número de células marcadas imunoistoquimicamente no omento destes ratos. O resultado demonstrou que a expressão do VEGF, quando analisada pelo método proposto foi igual no grupo da oclusão venosa e no grupo da oclusão arterial. / The cardiovascular system is structurally and functionally circular. Situations in which there is obstruction to blood flow trigger mechanisms to bypass these blockages and maintenance the integrity of the circularity. At the molecular level the main factor involved is the Vascular Endothelial Growth Factor (VEGF). The VEGF expression associated with arterial occlusion is well documented but is lacking evidence when venous occlusion occurs. This study aimed to verify if the expression of VEGF when an occlusion occurs at venous level is the same or different from that caused at the arterial level. Two groups of rats were randomized by infra-renal aortic occlusion or inferior vena cava occlusion. VEGF was measured by counting the immunohistochemistry method marked cells at the omentum level. It was demonstrated that the VEGF expression is the same in the venous group obstruction as the arterial obstruction group.

O sistema cardiovascular está estrutural e funcionalmente disposto de modo “circular”. Situações de obstrução do fluxo sanguíneo determinam o aparecimento de mecanismos que visam suplantar tais interrupções e manter a circularidade íntegra. À nível molecular, o principal elemento envolvido nestes mecanismos é o Vascular Endothelial Growth Factor (VEGF). A expressão do VEGF quando há oclusão arterial está bem documentada, faltando elementos com relação à oclusão venosa. Neste estudo objetivamos verificar se a oclusão à nível arterial determina uma expressão do VEGF diferente daquela que ocorre se a oclusão acontecer à nível venoso. Para isso randomizamos dois grupos de ratos de experimentação. Em um grupo realizamos a oclusão da aorta infra-renal e em outro a oclusão da veia cava infra-renal. Posteriormente medimos a expressão do VEGF através da contagem do número de células marcadas imunoistoquimicamente no omento destes ratos. O resultado demonstrou que a expressão do VEGF, quando analisada pelo método proposto foi igual no grupo da oclusão venosa e no grupo da oclusão arterial. / The cardiovascular system is structurally and functionally circular. Situations in which there is obstruction to blood flow trigger mechanisms to bypass these blockages and maintenance the integrity of the circularity. At the molecular level the main factor involved is the Vascular Endothelial Growth Factor (VEGF). The VEGF expression associated with arterial occlusion is well documented but is lacking evidence when venous occlusion occurs. This study aimed to verify if the expression of VEGF when an occlusion occurs at venous level is the same or different from that caused at the arterial level. Two groups of rats were randomized by infra-renal aortic occlusion or inferior vena cava occlusion. VEGF was measured by counting the immunohistochemistry method marked cells at the omentum level. It was demonstrated that the VEGF expression is the same in the venous group obstruction as the arterial obstruction group.