Changes In Blood Velocity Research Articles

Changes in skin blood flow and body temperatures during climacteric hot flushes

Blood velocity changes in the radial, temporal and lateral thoracic arteries have been measured quantitatively during climacteric hot flushes by means of an ultrasonic velocity meter. In the radial artery the median increase in velocity was 6 times greater than the basal velocity (range 4–10); in both the temporal and the lateral thoracic arteries the median increase was 1.5 (1.5–3). Simultaneous temperature measurements showed a fairly high increase in finger temperatures. An initial increase in temperature on the forehead was followed by a decrease. The core temperature measured on the tympanic membrane decreased. The pattern of blood velocity which increases during hot flushes, is identical to the pattern seen when someone is transferred to an uncomfortably high temperature. This similarity points to the hot flush as a time in which a heat loss occurs. As temperature measurements show no accumulation of heat prior to the flushes, it is reasonable to assume that hot flushes are the result of a central disorder of temperature regulation.

Qualitative estimation of blood velocity changes in human umbilical arteries after delivery

Qualitative doppler shift ultrasound estimations of blood velocity were made from umbilical arteries of 17 neonates for 90 sec after delivery using a 10 MHz doppler instrument. The mean maximum doppler shift frequency at 10 sec was 1.5 kHz ± 0.3 (SE) reducing to 0.5 ± 0.1 kHz at 60 sec after delivery. This indicates that flow velocity cannot be quantified. The initial mean pulsatility index was 10.6 suggesting that either constrictions were occurring in the arteries by 10 sec after delivery or that the placenta has a high impedance or both.

Mode of action of Xanthinol-Nicotinate on the human ERG

To determine if arterial stiffness is associated with age-related differences in cerebrovascular conductance and reactivity, twenty-eight apparently healthy sedentary young (25 ± 1 years; n = 15) and older (67 ± 1 years; n = 13) adults were studied. Brachial-ankle pulse wave velocity (baPWV) was measured as an index of arterial stiffness. Cerebrovascular reactivity was determined by measuring changes in mean blood velocity in the middle cerebral artery under normocapnic, hypocapnic and hypercapnic conditions. Mean baPWV was greater (p < 0.05) in older compared with young adults. At baseline, mean cerebral blood flow velocity and cerebrovascular conductance index were lower (p < 0.05) in older compared with young adults under normocapnic, hypocapnic and hypercapnic conditions. There were no significant group differences in cerebrovascular reactivity when they were adjusted for stimuli (i.e., end-tidal CO2 concentrations) in most perturbation conditions except for the normocapnia to hypercapnia condition. baPWV was negatively associated with cerebrovascular conductance index at all conditions (all p < 0.05). We concluded that arterial stiffness was associated with age-related differences in cerebrovascular conductance and that there were no apparent age-associated differences in cerebrovascular reactivity.

Pulsatile aspects of coronary sinus blood flow in closed-chest dogs

Phasic aspects of the velocity of coronary sinus blood flow were studied in closed-chest dogs by means of an electromagnetic flow measuring device located at the tip of a cardiac catheter. In agreement with observations in open-chest dogs, it was noted that flow was predominantly systolic, and the wave form was characterized by marked variability. Peak flow velocity occurred at various phases of systole. Small presystolic reversals of coronary sinus flow seemed to occur occasionally in some dogs. Cyclic respiratory changes of coronary sinus blood velocity were not infrequently observed. This study demonstrates a suitable method for the measurement of the velocity of flow within the coronary sinus of closed-chest animals, and perhaps, more importantly, demonstrates a method potentially applicable to human subjects.

Cerebral blood flow and oxygen consumption in man.

Cerebral blood flow and oxygen consumption in man.

On the relation of changes in blood velocity and volume flow of blood to change of posture: Bock, A. V., Dill, D. B., and Edwards, H. T.: J. Clin. Investigation 8: 533, 1930

On the relation of changes in blood velocity and volume flow of blood to change of posture: Bock, A. V., Dill, D. B., and Edwards, H. T.: J. Clin. Investigation 8: 533, 1930

On the use of the double eye-piece in the determination of the personal equation

To investigate whether the respiratorychanges in peak velocity (Vpeak) of aortic blood flow could be relatedto the effects of volume expansion on cardiac index.Prospective clinical study.Medical ICUs of a university hospital (20 beds)and of a nonuniversity hospital (15 beds).Nineteen sedated septic shock patients who were receiving mechanicalventilation and who had preserved left ventricular (LV) systolicfunction.Volume expansion.Analysis of aortic blood flow bytransesophageal echocardiography allowed beat-to-beat measurement of Vpeak before and after volume expansion. Maximum values of Vpeak(Vpeakmax) and minimum values of Vpeak (Vpeakmin) were determined overone respiratory cycle. The respiratory changes in Vpeak (ΔVpeak) werecalculated as the difference between Vpeakmax and Vpeakmin divided bythe mean of the two values and were expressed as a percentage. Theindexed LV end-diastolic area (EDAI) and cardiac index were obtained atthe end of the expiratory period. The volume expansion-induced increasein cardiac index was ≥ 15% in 10 patients (responders) and < 15%in 9 patients (nonresponders). Before volume expansion, ΔVpeak washigher in responders than in nonresponders (20 ± 6% vs 10 ± 3%;p < 0.01), while EDAI was not significantly different between thetwo groups (9.7 ± 3.7 vs 9.7 ± 2.4cm2/m2). Before volume expansion, a ΔVpeakthreshold value of 12% allowed discrimination between responders and nonresponders with a sensitivity of 100% and a specificity of 89%. Volume expansion-induced changes in cardiac index closely correlatedwith the ΔVpeak before volume expansion(r2 = 0.83; p < 0.001).Analysis of respiratory changes in aortic bloodvelocity is an accurate method for predicting the hemodynamic effectsof volume expansion in septic shock patients receiving mechanicalventilation who have preserved LV systolic function.