In Vivo Effects of Dexmedetomidine on Laser-Doppler Flow and Pial Arteriolar Diameter 

1998 ◽  
Vol 88 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Pragati Ganjoo ◽  
Neil E. Farber ◽  
Antal Hudetz ◽  
Jeremy J. Smith ◽  
Enric Samso ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Measurement Techniques ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
The Mean ◽  
Arteriolar Diameter

Background The alpha2-adrenergic agonist dexmedetomidine alters global cerebral blood flow (CBF). However, few studies have investigated the action of dexmedetomidine on the cerebral microcirculation. This investigation examined the effects of dexmedetomidine on (1) regional CBF in the rat cerebral cortex using laser-Doppler flowmetry and (2) on pial arteriolar diameter. Methods Halothane-anesthetized rats were fitted with instruments to measure CBF as determined by laser-Doppler flow (CBFldf) or to measure pial arteriolar diameter by preparing a cranial hollow deepened until a translucent plate of skull remained, thereby maintaining the integrity of the cranial vault. In both groups, 20 microg/kg dexmedetomidine was infused intravenously. Thirty minutes later, the mean arterial pressure was restored to control values with an infusion of phenylephrine (0.5 to 5 microg/kg/min). Results Administration of dexmedetomidine was associated with decreases in end-tidal and arterial carbon dioxide. The CBFldf and pial arteriolar diameter were measured during normocapnia (controlled carbon dioxide) and during dexmedetomidine-induced hypocapnia. Intravenous administration of dexmedetomidine significantly decreased systemic arterial pressure concurrent with a decrease in CBFldf (22% in normocapnic animals, 36% in hypocapnic animals). Restoration of mean arterial pressure increased CBFldf in normocapnic but not in hypocapnic animals. Similarly, dexmedetomidine significantly reduced pial vessel diameter in both normocapnic (9%) and hypocapnic animals (17%). However, vessel diameters remained decreased in the normocapnic and hypocapnic animals after the mean arterial pressure was restored. Conclusions These results suggest a modulation of cerebral vascular autoregulation by dexmedetomidine which may be mediated, in part, by alterations in carbon dioxide. Dexmedetomidine may have a direct action on the cerebral vessels to reduce the CBF during normo- or hypocapnia. The differences between CBFldf and pial arteriole responses to restoration of mean arterial pressure may reflect the difference in measurement techniques because laser-Doppler measurements reflect the net effect of several arterial segments on microvascular perfusion, whereas diameter measurements specifically examined individual pial arterioles, suggesting that dexmedetomidine vasoconstriction in the cerebral vasculature may be differentially and regionally mediated.

scholarly journals COMPARATIVE CHARACTERISTICS OF THE DYNAMICS OF CARDIOVASCULAR AND RESPIRATORY EFFECTS OF PNEUMOPERITONEUM BASED ON CARBON DIOXIDE AND ARGON IN LAPAROSCOPIC CHOLECYSTECTOMY

2021 ◽  
pp. 90-95
Author(s):  
O. L. Tkachuk ◽  
R. L. Parakhoniak ◽  
S. V. Melnyk ◽  
O. O. Tkachuk-Hryhorchuk
Keyword(s):  
Carbon Dioxide ◽  
Heart Rate ◽  
Cardiac Output ◽  
Laparoscopic Cholecystectomy ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Negative Impact ◽  
Abdominal Pressure ◽  
The Mean ◽  
Respiratory Systems

Pneumoperitoneum is one of the most critical components of laparoscopic surgery, which has a negative effect on gas exchange and stress to circulatory buffering system. One of the top priorities of laparoscopic technologies is to minimize the impact on the respiratory and cardiovascular systems, metabolic dynamics and compensatory abilities of homeostasis. The main goal of this research work is to compare the effects of carboxyperitoneum and argonoperitoneum on the intraoperative dynamics of CO2 concentration as well as cardiovascular and respiratory characteristics in patients undergoing laparoscopic cholecystectomy for various forms of cholelithiasis. Materials and methods. Four experimental groups involved patients based on their nosological form of cholelithiasis and the gas used to induce pneumoperitoneum. All patients underwent laparoscopic cholecystectomy by means of standard procedure. Either medical carbon dioxide or medical argon was used to induce pneumoperitoneum. Intraoperative monitoring of blood carbon dioxide levels PaCO2 was performed by taking venous blood every 15 minutes. Capnometry was performed by means of mainstream analysis using “BIOMED” BM1000C modular patient monitor by recording the discrete values of PetCO2 every 15 minutes, as well as by analyzing photocopies of capnography curves every 15 minutes. Intraoperative echocardiography was performed to identify the mean arterial pressure (MAP), heart rate (HR) and cardiac output (CO) in order to assess the effects of different types of pneumoperitoneum on the cardiovascular system. Results. The obtained data confirm the expected difference in the indices of cardiorespiratory functions between patients with acute cholecystitis and cholelithiasis without signs of inflammation. The investigation revealed that under the influence of pneumoperitoneum, heart rate and mean arterial pressure increase, while the cardiac output decreases. The respiratory pressure marker depends more on the intra-abdominal pressure and presumably the patient’s body type than on the presence of inflammatory syndrome. Argon insufflation has a slight negative impact on the cardiovascular system. Particularly, the mean arterial pressure and heart rate increase, while the cardiac output marker is less decreased as compared to the use of carbon dioxide. Abdominal pressure has a significant effect on the cardiovascular and respiratory systems regardless of the used type of gas. The combination of high intra-abdominal pressure with the elevated head end of the operating table, which is a common practise during cholecystectomy, has especially great influence on cardiovascular and respiratory functions. Operation which is carried out at decreased pressure allows reducing the deviations of practically all indices. Conclusions. Thus, the cardiovascular and respiratory systems adapt under the influence of pneumoperitoneum, providing compensation for the negative effects of mechanical and resorptive-metabolic character. Compensatory-adaptive abilities of the cardiovascular and respiratory systems increase with the decrease of intra-abdominal pressure. The use of argon as a working gas for insufflation into the abdominal cavity during laparoscopy reduces the negative impact of pneumoperitoneum on the cardiovascular and respiratory systems, providing a greater reserve of homeostatic and buffer systems of the body.

scholarly journals Simultaneous Measurements of Pial Arteriolar Diameter and Laser-Doppler Flow during Somatosensory Stimulation

1995 ◽  
Vol 15 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Al C. Ngai ◽  
Joseph R. Meno ◽  
H. Richard Winn
Keyword(s):  
Blood Flow ◽  
Sciatic Nerve ◽  
Laser Doppler ◽  
Similar Response ◽  
Somatosensory Stimulation ◽  
Laser Doppler Flow ◽  
Cortical Blood Flow ◽  
Doppler Flow ◽  
Cranial Window ◽  
Arteriolar Diameter

We simultaneously measured pial arteriolar diameter and changes in cortical blood flow during activation of the somatosensory cortex by sciatic nerve stimulation. The pial vasculature was visualized with a closed-cranial window technique in chloralose-anesthetized rats ( n = 13). Local blood flow was monitored with laser-Doppler flowmetry. During stimulation of the sciatic nerve (0.2 V, 5 Hz, 20 s), vascular diameter and laser-Doppler flow consistently displayed similar response profiles. With 0.5-ms stimulation pulses, the responses showed an initial peak followed by a smaller but sustained plateau dilation. In contrast, 5-ms pulses evoked a monotonically rising response. Our results support the concept that pial arteriolar diameter changes reflect cortical blood flow responses during somatosensory stimulation.

CEREBROCORTICAL LASER DOPPLER FLOW RESPONSE TO CARBON DIOXIDE

1994 ◽  
Vol 81 (SUPPLEMENT) ◽  
pp. A691
Author(s):  
J. J. Smith ◽  
A. G. Hudetz ◽  
J. G. Lee ◽  
Z. J. Bosnjak ◽  
J. P. Kampine
Keyword(s):  
Carbon Dioxide ◽  
Laser Doppler ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Flow Response

Effects of Short-term Fenoldopam Infusion on Gastric Mucosal Blood Flow in Septic Shock

2004 ◽  
Vol 101 (3) ◽  
pp. 576-582 ◽  
Author(s):  
Andrea Morelli ◽  
Monica Rocco ◽  
Giorgio Conti ◽  
Alessandra Orecchioni ◽  
Andrea De Gaetano ◽  
...  
Keyword(s):  
Septic Shock ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Laser Doppler ◽  
Mucosal Barrier ◽  
Short Term ◽  
Mucosal Permeability ◽  
Doppler Flowmetry ◽  
Mucosal Perfusion ◽  
Gastric Mucosal Perfusion

Background Inadequate splanchnic perfusion in septic shock is associated with increased morbidity and mortality. As result of splanchnic ischemia, mucosal permeability increases. Considering the implication of improved mucosal perfusion in terms of maintenance of mucosal barrier integrity, dopamine-1 receptor stimulation could be helpful in septic shock. The goal of the current study was to determine the effects of fenoldopam on systemic hemodynamic parameters and gastric mucosal perfusion in patients with septic shock. Furthermore, the authors tested the hypothesis that the addition of fenoldopam (0.1 microg x kg(-1) x min(-1)) to a combination of norepinephrine and dobutamine (5 microg x kg(-1) x min(-1)) may improve gastric mucosal perfusion in septic shock. Methods Patients with septic shock were randomized to a double-blind 2-h infusion of fenoldopam (n = 20) or placebo (n = 20). Each group received dobutamine (5 microg x kg(-1) x min(-1)), and the dosage of norepinephrine was adjusted to achieve a mean arterial pressure between 70 and 80 mmHg. A laser-Doppler probe and tonometer were introduced into the gastric lumen. Results A significant increase in gastric mucosal perfusion, detected by laser-Doppler flowmetry, was observed in the group treated with fenoldopam (P < 0.05). In addition, this increase in microcirculatory flow occurred despite the fact that systemic flow remained unchanged. Differences in gastroarterial partial pressure of carbon dioxide values were not statistically significant in the fenoldopam and placebo groups. Conclusions The study showed that, for the same mean arterial pressure, short-term fenoldopam infusion increased gastric mucosal perfusion in patients with septic shock.

Evaluation of laser-Doppler flowmetry as a measure of tissue blood flow

1986 ◽  
Vol 61 (2) ◽  
pp. 666-672 ◽  
Author(s):  
G. J. Smits ◽  
R. J. Roman ◽  
J. H. Lombard
Keyword(s):  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Electromagnetic Flowmeter ◽  
Laser Doppler ◽  
Tissue Blood Flow ◽  
Organ Blood Flow ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow

In this study the technique of laser-Doppler flowmetry was evaluated for the measurement of tissue blood flow by comparing laser-Doppler flow (LDF) signal in the renal cortex, gracilis muscle, and cremaster muscle of anesthetized rats to whole-organ blood flow measured with an electromagnetic flowmeter or radioactive microspheres. In vitro, LDF signal was closely correlated (r = 0.99) to changes in erythrocyte velocity generated with a rotating wheel. Although individual LDF readings varied in situ, mean LDF signal calculated from multiple readings on the tissue surface were significantly correlated (r = 0.74–0.95) with tissue blood flows measured at various perfusion pressures. However, significant differences in the slope of the LDF signal vs. blood flow relationship were observed in different tissues and with different methods of measurement in the same tissue. This study indicates that mean laser-Doppler flow signal provides a good estimate of tissue blood flow, provided a sufficient number of points is scanned. However, there appears to be no universal calibration factor for the method.

scholarly journals Ten days of repeated local forearm heating does not affect cutaneous vascular function

2017 ◽  
Vol 123 (2) ◽  
pp. 310-316 ◽  
Author(s):  
Michael A. Francisco ◽  
Vienna E. Brunt ◽  
Krista Nicole Jensen ◽  
Santiago Lorenzo ◽  
Christopher T. Minson
Keyword(s):  
Blood Flow ◽  
Young Adults ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Function ◽  
Forearm Blood Flow ◽  
Local Heating ◽  
Laser Doppler ◽  
Vascular Conductance ◽  
Doppler Flowmetry

The aim of the present study was to determine whether 10 days of repeated local heating could induce peripheral adaptations in the cutaneous vasculature and to investigate potential mechanisms of adaptation. We also assessed maximal forearm blood flow to determine whether repeated local heating affects maximal dilator capacity. Before and after 10 days of heat training consisting of 1-h exposures of the forearm to 42°C water or 32°C water (control) in the contralateral arm (randomized and counterbalanced), we assessed hyperemia to rapid local heating of the skin ( n = 14 recreationally active young subjects). In addition, sequential doses of acetylcholine (ACh, 1 and 10 mM) were infused in a subset of subjects ( n = 7) via microdialysis to study potential nonthermal microvascular adaptations following 10 days of repeated forearm heat training. Skin blood flow was assessed using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated as laser-Doppler red blood cell flux divided by mean arterial pressure. Maximal cutaneous vasodilation was achieved by heating the arm in a water-spray device for 45 min and assessed using venous occlusion plethysmography. Forearm vascular conductance (FVC) was calculated as forearm blood flow divided by mean arterial pressure. Repeated forearm heating did not increase plateau percent maximal CVC (CVCmax) responses to local heating (89 ± 3 vs. 89 ± 2% CVCmax, P = 0.19), 1 mM ACh (43 ± 9 vs. 53 ± 7% CVCmax, P = 0.76), or 10 mM ACh (61 ± 9 vs. 85 ± 7% CVCmax, P = 0.37, by 2-way repeated-measures ANOVA). There was a main effect of time at 10 mM ACh ( P = 0.03). Maximal FVC remained unchanged (0.12 ± 0.02 vs. 0.14 ± 0.02 FVC, P = 0.30). No differences were observed in the control arm. Ten days of repeated forearm heating in recreationally active young adults did not improve the microvascular responsiveness to ACh or local heating. NEW & NOTEWORTHY We show for the first time that 10 days of repeated forearm heating is not sufficient to improve cutaneous vascular responsiveness in recreationally active young adults. In addition, this is the first study to investigate cutaneous cholinergic sensitivity and forearm blood flow following repeated local heat exposure. Our data add to the limited studies regarding repeated local heating of the cutaneous vasculature.

scholarly journals Influence of the Endothelial Glycocalyx on Cerebral Blood Flow in Mice

2000 ◽  
Vol 20 (11) ◽  
pp. 1571-1578 ◽  
Author(s):  
J. Vogel ◽  
M. Sperandio ◽  
A.R. Pries ◽  
O. Linderkamp ◽  
P. Gaehtgens ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Endothelial Glycocalyx ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Cerebral Capillaries ◽  
Saline Treatment

The endothelial surface layer (glycocalyx) of cerebral capillaries may increase resistance to blood flow. This hypothesis was investigated in mice by intravenous administration of heparinase (2500 IU/kg body weight in saline), which cleaves proteoglycan junctions of the glycocalyx. Morphology was investigated by transmission electron microscopy. Cerebral perfusion velocity was recorded before and during heparinase or saline treatment using laser–Doppler flowmetry. In addition, cerebral blood flow (CBF) was measured 10 minutes after heparinase or saline treatment using the iodo[14C]antipyrine method. Laser–Doppler flowmetry and CBF measurements were performed during normocapnia and severe hypercapnia (Pco2: 120 mm Hg). After heparinase, morphology showed a reduced thickness of the glycocalyx in cortical microvessels by 43% ( P < 0.05) compared with saline-treated controls. Under normocapnic conditions, a 15% ( P < 0.05) transient increase of cerebral flow velocity occurred 2.5 to 5 minutes after heparinase injection. Laser–Doppler flow and CBF returned to control values ten minutes after the injection. However, during severe hypercapnia, heparinase treatment resulted in a persisting increase in laser–Doppler flow (6%, P < 0.05) and CBF (30%, P < 0.05). These observations indicate the existence of a flow resistance in cerebral capillaries exerted by the glycocalyx. The transient nature of the CBF increase during normocapnia may be explained by a vascular compensation that is exhausted during severe hypercapnia.

Relationship of Laser-Doppler-Flow and coronary perfusion and a concise update on the importance of coronary microcirculation in donor heart machine perfusion

2021 ◽  
Vol 79 (1) ◽  
pp. 121-128
Author(s):  
Lars Saemann ◽  
Anne Großkopf ◽  
Fabio Hoorn ◽  
Gábor Veres ◽  
Yuxing Guo ◽  
...  
Keyword(s):  
Laser Doppler ◽  
Control Group ◽  
Coronary Perfusion ◽  
Machine Perfusion ◽  
Donor Heart ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Ischemia Group ◽  
Coronary Microvascular Function

BACKGROUND: Machine perfusion (MP) is a novel method for donor heart preservation. The coronary microvascular function is important for the transplantation outcome. However, current research on MP in heart transplantation focuses mainly on contractile function. OBJECTIVE: We aim to present the application of Laser-Doppler-Flowmetry to investigate coronary microvascular function during MP. Furthermore, we will discuss the importance of microcirculation monitoring for perfusion-associated studies in HTx research. METHODS: Porcine hearts were cardioplegically arrested and harvested (Control group, N = 4). In an ischemia group (N = 5), we induced global ischemia of the animal by the termination of mechanical ventilation before harvesting. All hearts were mounted on an MP system for blood perfusion. After 90 minutes, we evaluated the effect of coronary perfusion pressures from 20 to 100 mmHg while coronary laser-doppler-flow (LDF) was measured. RESULTS: Ischemic hearts showed a significantly decreased relative LDF compared to control hearts (1.07±0.06 vs. 1.47±0.15; p = 0.034). In the control group, the coronary flow was significantly lower at 100 mmHg of perfusion pressure than in the ischemia group (895±66 ml vs. 1112±32 ml; p = 0.016). CONCLUSIONS: Laser-Doppler-Flowmetry is able to reveal coronary microvascular dysfunction during machine perfusion of hearts and is therefore of substantial interest for perfusion-associated research in heart transplantation.

scholarly journals Correlation of rheoencephalography and laser Doppler flow: a rat study

2019 ◽  
Vol 7 (1) ◽  
pp. 55-58 ◽  
Author(s):  
Michael Bodo ◽  
Ryan Sheppard ◽  
Aaron Hall ◽  
Martin Baruch ◽  
Melissa Laird ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Characteristic Curve ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Laser Doppler Flow ◽  
Doppler Flow ◽  
Cerebral Blood Flow Autoregulation ◽  
Rat Study

Abstract Measuring brain electrical impedance (rheoencephalography) is a potential technique for noninvasive, continuous neuro-monitoring of cerebral blood flow autoregulation in humans. In the present rat study, we compared changes in cerebral blood flow autoregulation during CO2 inhalation measured by rheoencephalography to changes measured by laser Doppler flowmetry, an invasive continuous monitoring modality. Our hypothesis was that both modalities would reflect cerebral blood flow autoregulation. Male Sprague-Dawley rats (n=28; 28 control and 82 CO2 challenges) were measured under anesthesia. The surgical preparation involved implantation of intracerebral REG electrodes and an LDF probe into the brain. Analog waveforms were stored in a computer. CO2 inhalation caused transient, simultaneous increases in the signals of both laser Doppler flow (171.99 ± 46.68 %) and rheoencephalography (329.88 ± 175.50%). These results showed a correlation between the two measured modalities; the area under the receiver operating characteristic curve was 0.8394. The similar results obtained by measurements made with laser Doppler flowmetry and rheoencephalography indicate that rheo-encephalography, like laser Doppler flowmetry, reflects cerebral blood flow autoregulation. Rheoencephalography therefore shows potential for use as a continuous neuro-monitoring technique.

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