Monitoring of autoregulation using laser Doppler flowmetry in patients with head injury

1997 ◽  
Vol 86 (3) ◽  
pp. 438-445 ◽  
Author(s):  
Joseph M. K. Lam ◽  
John N. K. Hsiang ◽  
Wai S. Poon
Keyword(s):  
Cerebral Cortex ◽  
Laser Doppler Flowmetry ◽  
Rapid Change ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Content Type ◽  
Good Outcome ◽  
Arterial Blood ◽  
Transient Loss ◽  
Fine Print

✓ The authors studied 31 comatose head-injured patients to assess the clinical usefulness of laser Doppler flowmetry (LDF) in continuous autoregulation monitoring. The LDF probes were placed on the surface of the cerebral cortex. Data on LDF, intracranial pressure (ICP), and arterial blood pressure (ABP) were recorded and continuously entered into a computer. The data were broken down into multiple segments of 15 minutes' duration (epochs). Epochs showing rapid change in cerebral perfusion pressure (CPP), change in CPP of less than 10 mm Hg, LDF values of less than five arbitrary units, and loss of ABP/ICP waveform were excluded from further analysis. A linear relationship between LDF and CPP in individual epochs was used as an indicator of loss of autoregulation. The relationship between LDF and CPP changed with time, indicating improvement or deterioration in autoregulation. Longitudinal analysis of all the epochs measured in a patient revealed three patterns of progress: 1) intact autoregulation; 2) transient loss; and 3) persistent loss of autoregulation. All five patients with intact autoregulation had a good outcome. Ten patients experienced transient loss of autoregulation; of these four had a good outcome, five were moderately disabled, and one was severely disabled. Transient impairment of autoregulation did not always indicate poor outcome, provided the impaired autoregulation responded to treatment. In 11 patients who had persistent loss of autoregulation, nine died and two were severely disabled. In five cases the LDF probe lost contact with the cerebral cortex and no useful information was obtained. Real-time measurement of autoregulation using LDF and CPP monitors was achieved and the findings were related to outcome in these patients.

Estimation of laser-Doppler flux biological zero using basilar artery flow velocity in the rabbit

1995 ◽  
Vol 268 (1) ◽  
pp. H213-H217 ◽  
Author(s):  
H. K. Richards ◽  
M. Czosnyka ◽  
P. J. Kirkpatrick ◽  
J. D. Pickard
Keyword(s):  
Flow Velocity ◽  
Laser Doppler Flowmetry ◽  
Basilar Artery ◽  
Maximum Flow ◽  
Laser Doppler ◽  
Absolute Difference ◽  
Doppler Flowmetry ◽  
Arterial Blood ◽  
Artery Flow ◽  
Doppler Flux

Laser-Doppler flowmetry has potential for continuous cerebral blood flow (CBF) measurement in man and experimental animals. However, laser-Doppler flux (LDFx) measured when perfusion is absent (the biological zero, 0biol) does not necessarily coincide with the instrument's electrical zero. To evaluate laser-Doppler flowmetry further we have compared LDFx in rabbits with continuous measurement of the maximum flow velocity (FVx) in the basilar artery using Doppler ultrasonography. Arterial blood pressure (ABP), FVx, and LDFx were measured continuously in anesthetized New Zealand White rabbits. ABP was altered by controlled hemorrhage with subsequent reinfusion. 0biol was estimated from regression analysis of FVx vs. LDFx and compared with 0biol obtained after death. There was a strong linear relationship between LDFx and FVx (r = 0.94). The absolute difference between estimated 0biol and true 0biol was 5.24% of control prehemorrhage LDFx. Variations in 0biol (range 4-409) suggest that percent changes in LDFx must be related to 0biol if results between individual animals are to be compared.

scholarly journals Sex features of cutaneous microvasculature in healthy working-age people

2022 ◽  
Vol 20 (8) ◽  
pp. 3111
Author(s):  
K. V. Omelyanenko ◽  
A. Yu. Gorshkov ◽  
A. A. Fedorovich ◽  
A. I. Korolev ◽  
V. A. Dadaeva ◽  
...  
Keyword(s):  
Laser Doppler Flowmetry ◽  
Augmentation Index ◽  
Pulse Amplitude ◽  
Capillary Density ◽  
Laser Doppler ◽  
Sex Characteristics ◽  
Doppler Flowmetry ◽  
Arterial Blood ◽  
Healthy Working ◽  
Working Age

Aim. To study sex characteristics of cutaneous microvascular structure and function in a cohort of healthy working-age people without cardiovascular diseases.Material and methods. The study included 35 healthy men (42±4 years) and 34 women (41 ±5 years). The cardiovascular system was assessed in all patients. The microcirculatory bed of the skin was investigated by the following non-invasive methods: 1) computerized video capillaroscopy; 2) laser Doppler flowmetry; 3) photoplethysmography.Results. According to computerized video capillaroscopy in men, compared with women, there was a smaller number of both functioning capillaries (78 vs 86 capillaries/mm2, respectively (p<0,05)) and their total number (100 vs 120 capillaries/mm2, respectively (p<0,001)). Against the background of a decrease in capillary density in men, there was a higher skin interstitial hydration — 113 vs 96 gm (p<0,005) in men than in women. At the level of precapillary arterioles, where humoral tone regulation prevails. Laser Doppler flowmetry revealed lower pulse amplitude in men than in women — 0,87 vs 1,02 pf, respectively (p<0,05), which indicates a lower arterial blood inflow to exchange microvessels. Against this background, the constrictor response of precapillary arterioles to a sympathetic nervous system stimulation in men is higher than in women — 45% vs 40%, respectively (p<0,05). At the level of large arterioles, where neural tone regulation prevails, photoplethysmography revealed lower augmentation index standardized at a heart rate in men (-4,6 vs 1,7%, respectively, p<0,05), which indicates lower rigidity of muscular vessels in men.Conclusion. In working-age healthy people, sex differences are noted at all cutaneous microvascular levels, which must be taken into account when planning studies.

scholarly journals Cerebral haemodynamics during experimental intracranial hypertension

2016 ◽  
Vol 37 (2) ◽  
pp. 694-705 ◽  
Author(s):  
Joseph Donnelly ◽  
Marek Czosnyka ◽  
Spencer Harland ◽  
Georgios V Varsos ◽  
Danilo Cardim ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Intracranial Pressure ◽  
Intracranial Hypertension ◽  
Flow Velocity ◽  
Arterial Blood Pressure ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Wall Tension ◽  
Doppler Flowmetry ◽  
Arterial Blood

Intracranial hypertension is a common final pathway in many acute neurological conditions. However, the cerebral haemodynamic response to acute intracranial hypertension is poorly understood. We assessed cerebral haemodynamics (arterial blood pressure, intracranial pressure, laser Doppler flowmetry, basilar artery Doppler flow velocity, and vascular wall tension) in 27 basilar artery-dependent rabbits during experimental (artificial CSF infusion) intracranial hypertension. From baseline (∼9 mmHg; SE 1.5) to moderate intracranial pressure (∼41 mmHg; SE 2.2), mean flow velocity remained unchanged (47 to 45 cm/s; p = 0.38), arterial blood pressure increased (88.8 to 94.2 mmHg; p < 0.01), whereas laser Doppler flowmetry and wall tension decreased (laser Doppler flowmetry 100 to 39.1% p < 0.001; wall tension 19.3 to 9.8 mmHg, p < 0.001). From moderate to high intracranial pressure (∼75 mmHg; SE 3.7), both mean flow velocity and laser Doppler flowmetry decreased (45 to 31.3 cm/s p < 0.001, laser Doppler flowmetry 39.1 to 13.3%, p < 0.001), arterial blood pressure increased still further (94.2 to 114.5 mmHg; p < 0.001), while wall tension was unchanged (9.7 to 9.6 mmHg; p = 0.35).This animal model of acute intracranial hypertension demonstrated two intracranial pressure-dependent cerebroprotective mechanisms: with moderate increases in intracranial pressure, wall tension decreased, and arterial blood pressure increased, while with severe increases in intracranial pressure, an arterial blood pressure increase predominated. Clinical monitoring of such phenomena could help individualise the management of neurocritical patients.

scholarly journals Laminar Analysis of Cerebral Blood Flow in Cortex of Rats by Laser-Doppler Flowmetry: A Pilot Study

1997 ◽  
Vol 17 (12) ◽  
pp. 1326-1336 ◽  
Author(s):  
Martin Fabricius ◽  
Nuran Akgören ◽  
Ulrich Dirnagl ◽  
Martin Lauritzen
Keyword(s):  
Blood Flow ◽  
Cerebral Cortex ◽  
Real Time ◽  
Optical Fibers ◽  
Laser Doppler Flowmetry ◽  
Laser Light ◽  
Laser Doppler ◽  
Flow Measurements ◽  
Doppler Flowmetry ◽  
Artificial Brain

Laser-Doppler flowmetry (LDF) is a reliable method for estimation of relative changes of CBF. The measurement depth depends on wavelength of the laser light and the separation distance of transmitting and recording optical fibers. We designed an LDF probe using two wavelengths of laser light (543 nm and 780 nm), and three separation distances of optical fibers to measure CBF in four layers of the cerebral cortex at the same time. In vitro comparison with electromagnetic flow measurements showed linear relationship between LDF and blood flow velocity at four depths within the range relevant to physiologic measurements. Using artificial brain tissue slices we showed that the signal for each channel decreased in a theoretically predictable fashion as a function of slice thickness. Application of adenosine at various depths in neocortex of halothane-anesthetized rats showed a predominant CBF increase at the level of application. Electrical stimulation at the surface of the cerebellar cortex demonstrated superficial predominance of increased CBF as predicted from the distribution of neuronal activity. In the cerebellum, hypercapnia increased CBF in a heterogeneous fashion, the major increase being at apparent depths of approximately 300 and 600 μm, whereas in the cerebral cortex, hypercapnia induced a uniform increase. In contrast, the CBF response to cortical spreading depression in the cerebral cortex was markedly heterogeneous. Thus, real-time laminar analysis of CBF with spatial resolution of 200 to 300 μm may be achieved by LDF. The real-time in depth resolution may give insight into the functional organization of the cortical microcirculation and adaptive features of CBF regulation in response to physiologic and pathophysiologic stimuli.

scholarly journals Laser Doppler Flowmetry to Differentiate Arterial From Venous Occlusion in Free Tissue Transfer

2019 ◽  
Vol 27 (4) ◽  
pp. 297-304
Author(s):  
Emre Gazyakan ◽  
Huang-Kai Kao ◽  
Ming-Huei Cheng ◽  
Holger Engel
Keyword(s):  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Free Tissue Transfer ◽  
Venous Occlusion ◽  
Laser Doppler ◽  
Arterial Blood Flow ◽  
Probe Laser ◽  
Doppler Flowmetry ◽  
Arterial Blood ◽  
Tissue Transfer

Purpose: The differentiation of arterial versus venous occlusion in free tissue transfers has rarely been described. This study investigated changes in blood flow caused by arterial and venous occlusion and the potential for laser Doppler flowmetry to distinguish between these 2 conditions for better clinical assessment and management of free tissue transfer. Methods: Six patients with a mean age of 43.5 years underwent microsurgical free tissue transfer. The venous and arterial blood flow of the vessels and skin flap were monitored using laser Doppler flowmetry with high-frequency pulsed Doppler transducers for vessels and skin before, during, and after clamping the vessels for 10 minutes. Results: The average decreases in blood flow in the artery and vein caused by clamping were 94.4% and 93.8%, respectively. On average, arterial occlusion demonstrated a sudden drop of 67.7% and venous occlusion caused a decrease of 26.6% on laser Doppler flowmetry in free tissue skin. Conclusion: Using a vessel-holding probe, laser Doppler flowmetry could be used to differentiate between arterial and venous occlusion in free tissue transfer, thereby aiding decision-making for better clinical management.

Intraoperative Measurement of Cerebral and Tumor Blood Flow with Laser-Doppler Flowmetry

Neurosurgery ◽  
1989 ◽  
Vol 24 (2) ◽  
pp. 166-170 ◽  
Author(s):  
E. Arbit ◽  
G. R. DiResta ◽  
R. F. Bedford ◽  
N. K. Shah ◽  
J. H. Galicich
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Normal Brain ◽  
Blood Gas ◽  
Doppler Flowmetry ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
A New Technique

Abstract A new technique, laser-Doppler flowmetry, has been used intraoperatively to measure blood flow responses in normal brain tissue and brain tumor to blood pressure and arterial blood gas alterations. We have observed that blood flow is reduced in most cerebral tumors, and that most tumors retain the normal response to changes in arterial blood gas; however, these responses are varied. One group of tumors in our study demonstrated an autoregulatory capacity; a second behaved passively—that is, blood flow changes followed blood pressure—while a third showed no response.

The response of skin perfusion and of rheological and immunological variables to intravenous prostanoid administration in Raynaud’s phenomenon secondary to collagenosis

VASA ◽  
2005 ◽  
Vol 34 (4) ◽  
pp. 243-249 ◽  
Author(s):  
Drinda ◽  
Neumann ◽  
Pöhlmann ◽  
Vogelsang ◽  
Stein ◽  
...  
Keyword(s):  
Laser Doppler Flowmetry ◽  
Raynaud’S Phenomenon ◽  
Raynaud's Phenomenon ◽  
Plasma Viscosity ◽  
Laser Doppler ◽  
Erythrocyte Aggregation ◽  
Control Group ◽  
Long Term Effects ◽  
Doppler Flowmetry

Background: Prostanoids are used in the treatment of Raynaud’s phenomenon and acral perfusion disorders secondary to collagenosis. In subjective terms, intravenous administration of these agents produces success in more than 50% of patients. The therapeutic outcome of clinical administration of alprostadil or iloprost may vary from individual to individual. Patients and methods: The following variables were analysed in a cross-over study in 27 patients with collagenosis and Raynaud’s phenomenon: plasma viscosity and erythrocyte aggregation (rheological variables), partial pressure of oxygen and laser Doppler flowmetry in the finger region, and lymphocyte phenotyping and interleukin (IL) determinations (immunological variables). Results: Laser Doppler flowmetry revealed significant differences between patients with secondary Raynaud’s phenomenon and a control group of 25 healthy subjects. Laser Doppler readings did not change significantly as a result of the treatments. Therapy with iloprost produced a reduction in IL-1beta, L-selectin (CD 62 L) and IL-6. Conclusion: The change in immunological variables due to iloprost may explain the long-term effects of prostaglandins in the treatment of Raynaud’s phenomenon. From our results it is not possible to infer any preference for iloprost or alprostadil.

Sign in / Sign up

Export Citation Format

Share Document