Articles: blood-flow-velocity.
-
We analyzed the association between hematologic factors and blood velocity of the middle cerebral artery in 42 healthy ambulatory subjects aged 63-86 years. We found a significant inverse association between mean velocity and both hematocrit (r = -0.37, p less than 0.02) and fibrinogen concentration (r = -0.42, p less than 0.005). These two variables are independently associated with velocity and together explain 29% of the variance in mean velocity. Both hematocrit and fibrinogen concentration should be considered in the interpretation of transcranial Doppler findings in this population.
-
Anasth Intensivther Notfallmed · Oct 1990
[The effect of positive end expiratory pressure on the blood flow velocity in the basal cerebral arteries during general anesthesia].
The effects of incremental positive end-expiratory pressure (PEEP) on middle cerebral artery (MCA) blood flow velocity and pulsatility index were studied in 20 patients scheduled for minor elective surgery. Transcranial Doppler sonography (TCD) was used to measure systolic (Vsyst) and mean flow velocity (Vmean) and the pulsatility index (PI). Heart rate (HR), mean arterial blood pressure (MAP), end-tidal CO2(PetCO2) and TCD parameters were recorded at control (PEEP = O) and following PEEP of 5 cm H2O, 10 cm H2O and 15 cm H2O for a period of 5 minutes for each PEEP level. ⋯ PI increased stepwise in response to each PEEP level. MAP decreased with PEEP 10 and 15 while HR and PetCO2 remained constant over time. These data suggest that PEEP-induced decreases in MCA blood flow velocity may represent decreases in CBF due to impairment of the intracranial venous flow if the diameter of the insonated vascular segment remains constant.
-
J Neurosurg Anesthesiol · Sep 1990
Transcranial Doppler sonography as a supplement in the detection of cerebral circulatory arrest.
The effects of compromised cerebral hemodynamics on intracranial blood flow velocity patterns (BFV) were studied by noninvasive transcranial Doppler sonography (TCD). Pulsatility index (PI) as an estimation of peripheral cerebral vascular resistance was additionally analyzed. TCD patterns were determined in 19 mechanically ventilated brain dead patients (group A) and 8 resuscitated or severely head injured patients (group B) with intermittent elevated intracranial pressure (ICP). ⋯ In these patients, resistive Doppler signals with normal or reduced systolic peaks and decreased diastolic flow velocities were expressed as increases in PI. Noninvasive transcranial Doppler sonography appears to confirm cerebral circulatory arrest. Additionally, TCD may be of value for the early detection of impaired cerebral hemodynamics due to changes in intracranial compliance.
-
Doppler echocardiography can provide insight into the diastolic properties of the left ventricle. The hemodynamic origins of the diastolic mitral flow velocity profile are reviewed and Doppler information is compared to other measures of left ventricular diastolic function. Factors affecting the mitral diastolic flow velocity in both normal populations and pathologic conditions are discussed and the reported normal indexes of diastolic transmitral velocity are criticized.
-
The measurement of the pulse wave velocity (PWV) is widely used in clinical practice to assess the elasticity of the arterial system. It can be influenced by a number of factors. The present study was undertaken to assess the possible role of anthropometric factors, hemorheological parameters and blood pressure on this element. ⋯ The PWV-diastolic pressure relationship is well-known. In contrast, the effect of the hematocrit and body surface area has never been reported.(ABSTRACT TRUNCATED AT 250 WORDS)