Blood flow

About: Blood flow is a research topic. Over the lifetime, 27604 publications have been published within this topic receiving 735527 citations.

Lipo-prostaglandin E1 increases immediate arterial maximal flow velocity of free flap in patients undergoing reconstructive surgery.

Abstract: Background In free flap surgery, the maintenance of proper blood flow after anastomosis of flap pedicle vessels is important. Lipo-prostaglandin E1 (lipo-PGE1) has been empirically administered to prevent blood flow insufficiency in a free flap reconstruction. We tested our hypothesis that lipo-PGE1 administration increases the arterial inflow of free flap. We also evaluated lipo-PGE1-related haemodynamic changes and complications. Methods Thirty-seven patients who underwent free flap reconstruction were analysed. Lipo-PGE1 was administered 10 minutes after the vascular anastomosis of the free flap. The maximal blood flow velocity was measured at the free flap pedicle artery before and 30 minutes after lipo-PGE1 administration using duplex ultrasonography. The primary outcome was the difference in the maximal blood flow velocity before and 30 minutes after lipo-PGE1 administration. The arterial blood pressure, heart rate, cardiac output, stroke volume variation, and pulse pressure variation were measured simultaneously. Lipo-PGE1-related complications such as hypotension, bradycardia, hypothermia, facial flushing, diarrhoea, apnoea, and seizure were also investigated. Results The maximal blood flow velocity was significantly increased at 30 minutes after lipo-PGE1 administration compared to the level before lipo-PGE1 administration (mean (standard deviation): 26.3 (8.7) cm/s vs 22.5 (8.0) cm/s, P = 0.002). The haemodynamic variables were not significantly different before and 30 minutes after lipo-PGE1 administration. No lipo-PGE1-related complications occurred. Conclusions Lipo-PGE1 significantly increases the maximal blood flow velocity without complications in patients undergoing free flap reconstruction and may be an effective and safe method of maintaining adequate blood flow in these cases.

Waveform analysis of human retinal and choroidal blood flow with laser Doppler holography

Abstract: Laser Doppler holography was introduced as a full-field imaging technique to measure blood flow in the retina and choroid with an as yet unrivaled temporal resolution. We here investigate separating the different contributions to the power Doppler signal in order to isolate the flow waveforms of vessels in the posterior pole of the human eye. Distinct flow behaviors are found in retinal arteries and veins with seemingly interrelated waveforms. We demonstrate a full field mapping of the local resistivity index, and the possibility to perform unambiguous identification of retinal arteries and veins on the basis of their systolodiastolic variations. Finally we investigate the arterial flow waveforms in the retina and choroid and find synchronous and similar waveforms, although with a lower pulsatility in choroidal arteries. This work demonstrates the potential held by laser Doppler holography to study ocular hemodynamics in healthy and diseased eyes.

Pulsed Doppler: determination of blood velocity and volume flow in normal and diseased common carotid arteries in man

Abstract: A pulsed Doppler velocimeter with an adjustable range gated time system and a double transducer probe has been used to measure volume blood flow in 50 normal and 50 diseased common carotid arteries A significant difference in mean volume flow between normal and diseased arteries was found (P<00001) On-line audio-frequency display of velocity signals were evaluated in each of the arteries together with angiographic description of the diseased arteries Disturbance of the velocity profile develops before significant changes in volume flow or angiogram occur Volume flow results and angiogram appearance relate best when the angiogram description is either of minimal disease or severe disease Determination of dynamic flow conditions from structural appearance of arteries are not consistently dependable

Studies on haematocrit in peripheral arterial disease.

Abstract: Haematocrit is often elevated in peripheral arterial disease, and is an important determinant of blood viscosity and of platelet behaviour. We have studied the relationships of haematocrit to claudication, smoking habit, calf blood flow, platelet aggregation in whole blood, and the late complications of aortic bifurcation grafts. In 31 claudicants, blood viscosity, haematocrit and fibrinogen levels were significantly higher compared to 50 controls (p less than 0.01). However this was largely explained by a higher prevalence in claudicants of cigarette-smoking, which is associated with increased blood viscosity, haematocrit and fibrinogen levels. In 8 stable claudicants with high-normal haematocrit (mean 0.50), venesection reduced haematocrit to low-normal levels (mean 0.44). Resting calf blood flow was unchanged: peak flow increased slightly (17%) but oxygen delivery (peak flow X haemoglobin concentration) was unchanged. Spontaneous platelet aggregation in whole blood was studied using a single platelet counting method: the increase in haematocrit in patients with claudication was not associated with a significant increase in aggregation, and a negative association of haematocrit and aggregation was observed. In a preliminary retrospective study of patients with late complications of aortic bifurcation grafts, significantly higher haematocrits prior to operative were found compared to controls who had not returned to the clinic. Further prospective studies are required to assess the significance of haematocrit in peripheral arterial disease, and to determine whether any adverse effects are due to associations with smoking, rheology or platelet behaviour.