Common Carotid Artery Blood Flow Research Articles

Global REACH 2018: The carotid artery diameter response to the cold pressor test is governed by arterial blood pressure during normoxic but not hypoxic conditions in healthy lowlanders and Andean highlanders.

What is the central question of this study? What is the impact of oxygen on the circulatory responses to an isocapnic cold pressor test (CPT) in lowlanders and Andean highlanders? What is the main finding and its importance? Overall, the circulatory responses to an isocapnic CPT were largely unaltered with acute normobaric hypoxia and chronic hypobaric hypoxia exposure in lowlanders. However, the relationship between mean arterial pressure and common carotid artery diameter was dampened in hypoxic conditions. Furthermore, there were no differences in the circulatory responses to the CPT between lowlanders and Andean highlanders with lifelong exposure to high altitude. The impact of oxygen on the circulatory responses to a cold pressor test (CPT) in lowlanders and Andean highlanders remains unknown. Our hypotheses were as follows: (i) in lowlanders, acute normobaric and hypobaric hypoxia would attenuate the common carotid artery (CCA) diameter response to the CPT compared with normobaric normoxia; (ii) Andean highlanders would exhibit a greater CCA diameter response compared with lowlanders; and (iii) a positive relationship between CCA diameter and blood pressure in response to the CPT would be present in both lowlanders and highlanders. Healthy lowlanders (n=13) and Andean highlanders (n=8) were recruited and conducted an isocapnic CPT, which consisted of a 3min foot immersion into water at 0-1°C. Blood pressure (finger photoplethysmography) and CCA diameter and blood flow (Duplex ultrasound) were recorded continuously. The CPT was conducted in lowlanders at sea level in isocapnic normoxic and hypoxic conditions and after 10 days of acclimatization to 4300m (Cerro de Pasco, Peru) in hypoxic and hyperoxic conditions. Andean highlanders were tested at rest at high altitude. The main findings were as follows: (i) in lowlanders, normobaric but not hypobaric hypoxia elevated CCA reactivity to the CPT; (ii) no differences in response to the CPT were observed between lowlanders and highlanders; and (iii) although hypobaric hypoxaemia reduced the relationship between CCA diameter and blood pressure compared with normobaric normoxia (P=0.132), hypobaric hyperoxia improved this relationship (P=0.012), and no relationship was observed in Andean highlanders (P=0.261). These data demonstrate that the circulatory responses to a CPT were modified by oxygen in lowlanders, but were unaltered with lifelong hypoxic exposure.

Venous and Arterial Responses to Partial Gravity.

Introduction: Chronic exposure to the weightlessness-induced cephalad fluid shift is hypothesized to be a primary contributor to the development of spaceflight-associated neuro-ocular syndrome (SANS) and may be associated with an increased risk of venous thrombosis in the jugular vein. This study characterized the relationship between gravitational level (Gz-level) and acute vascular changes.Methods: Internal jugular vein (IJV) cross-sectional area, inferior vena cava (IVC) diameter, and common carotid artery (CCA) flow were measured using ultrasound in nine subjects (5F, 4M) while seated when exposed to 1.00-Gz, 0.75-Gz, 0.50-Gz, and 0.25-Gz during parabolic flight and while supine before flight (0-G analog). Additionally, IJV flow patterns were characterized.Results: IJV cross-sectional area progressively increased from 12 (95% CI: 9–16) mm2 during 1.00-Gz seated to 24 (13–35), 34 (21–46), 68 (40–97), and 103 (75–131) mm2 during 0.75-Gz, 0.50-Gz, and 0.25-Gz seated and 1.00-Gz supine, respectively. Also, IJV flow pattern shifted from the continuous forward flow observed during 1.00-Gz and 0.75-Gz seated to pulsatile flow during 0.50-Gz seated, 0.25-Gz seated, and 1.00-Gz supine. In contrast, we were unable to detect differences in IVC diameter measured during 1.00-G seated and any level of partial gravity or during 1.00-Gz supine. CCA blood flow during 1.00-G seated was significantly less than 0.75-Gz and 1.00-Gz supine but differences were not detected at partial gravity levels 0.50-Gz and 0.25-Gz.Conclusions: Acute exposure to decreasing Gz-levels is associated with an expansion of the IJV and flow patterns that become similar to those observed in supine subjects and in astronauts during spaceflight. These data suggest that Gz-levels greater than 0.50-Gz may be required to reduce the weightlessness-induced headward fluid shift that may contribute to the risks of SANS and venous thrombosis during spaceflight.

Endothelial Shear Stress In The Common Carotid Artery During Boxing Training

PURPOSE: Endothelial function is highly regulated by the interaction between blood flow and the endothelium. Endothelial shear stress (ESS) is defined as the dragging force generated by this interaction and it has been reported that low ESS affects nitric oxide bioavailability which in turn might increase blood pressure. Exercise programs are one of the best suited approaches to prevent high blood pressure, however, there are no studies describing changes on ESS in the common carotid artery during specific modalities of exercise, such as boxing training. Therefore, the purpose of this study was to quantify ESS in the common carotid artery during maximal and submaximal boxing training in normotensive and pre-hypertensive subjects. METHODS: A cohort of 5 healthy normotensive and 5 pre-hypertensive subjects matched by age, gender, height, and weight were recruited for this study. All 10 subjects performed two boxing tests. The first was a graded maximal boxing test to estimate their maximal oxygen uptake (VO₂max). The second one, performed 48 hours after the first evaluation, was a 2-workload steady-state boxing test at 60%VO2max and at 95%VO2max for 3 minutes each. A high-definition Doppler ultrasound recorded common carotid artery diameters and blood flow velocities throughout each steady-state condition. ESS was estimated using Womersley’s approximation. RESULTS: There was a significant increase in antegrade ESS with higher workloads in both groups (p < 0.05 for all). No difference were found in anterograde ESS at baseline (Normotensive: 33.9±13.9 dynes/cm2, Pre-HTA: 34.7±5.5 dynes/cm2; p = 0.936), at 60%VO₂max (Normotensive: 51.3±19.1 dynes/cm2, Pre-HTA: 49.6±7.6 dynes/cm2; p = 0.894, and at 95%VO₂max (Normotensive: 72.9±30.9 dynes/cm2 , Pre-HTA: 85.2±12.5 dynes/cm2; p = 0.560) between both groups. Meanwhile, no retrograde blood flow was present at baseline for either groups, but it was identified at 60%VO₂max (Normotensive: 8.1±0.7 dynes/cm2, Pre-HTA: 7.8±7.8 dynes/cm2; p = 0.971) and 95%VO₂max (Normotensive: 22.5±18.9 dynes/cm2 , Pre-HTA: 20.8±5.6 dynes/cm2; p = 0.891). CONCLUSIONS: ESS increases in an exercise-intensity manner during boxing training in normotensive and prehypertensive population. Boxing training might be beneficial in high blood pressure prevention due to increments on ESS.

Moderate hypothermia with remote ischaemic preconditioning improves cerebral protection compared to deep hypothermia: a study using a surviving porcine model.

The optimal temperature management of hypothermic circulatory arrest is still controversial. Moderate hypothermia preserves cerebral autoregulation and shortens cardiopulmonary bypass (CPB) duration. However, moderate hypothermia alone has inferior organ protection to deep hypothermia, so adjuncts that increase the ischaemic tolerance are needed. Thus, we hypothesized that a combination of remote ischaemic preconditioning (RIPC) and moderate hypothermia would be superior to deep hypothermia alone. Sixteen pigs were randomized to either RIPC or control groups (8 + 8). The RIPC group underwent 4 cycles of transient hind limb ischaemia. The RIPC group underwent cooling with CPB to 24°C, and the control group underwent cooling with CPB to 18°C, followed by a 30-min arrest period and subsequent rewarming to 36°C. Measurements of cerebral metabolism were made from sagittal sinus blood samples and common carotid artery blood flow. The permissible periods of hypothermic circulatory arrest were calculated based on these measurements. Neurological recovery was evaluated daily during a 7-day follow-up, and the brain was harvested for histopathological analysis. Six pigs in the RIPC group reached normal neurological function, but none in the control group reached normal neurological function (P = 0.007). The composite neurological score of all postoperative days was higher in the RIPC group than in the control group [55 (52-58) vs 45 (39-51), P = 0.026]. At 24°C, the estimated permissible periods of hypothermic circulatory arrest were 21 (17-25) min in the RIPC group and 11 (9-13) min in the control group (P = 0.007). RIPC combined with moderate hypothermia provides superior cerebral protection.

Endothelial shear stress in the common carotid artery during boxing training in prehypertension

PURPOSEEndothelial function is highly regulated by the friction between blood flow and the endothelium. Endothelial shear stress (ESS) is defined as the dragging force generated by this interaction and it has been reported that low ESS affects nitric oxide bioavailability which in turn might increase blood pressure. Exercise programs are one of the best suited approaches to treat high blood pressure, however, there are no studies describing changes on ESS in the common carotid artery during upper‐body exercise, such as boxing training. Therefore, the purpose of this study was to quantify ESS in the common carotid artery during 60% and 95% of the maximal boxing exercise capacity in normotensive and pre‐hypertensive subjects.METHODSA total of 5 healthy normotensive and 5 pre‐hypertensive subjects matched by age, gender, height, and weight were recruited for this study. All 10 subjects performed two boxing exercise tests. The first was a graded maximal boxing test to estimate their maximal oxygen uptake (VO2max). The second one, performed 48 hours after the first evaluation, was a 2‐workload steady‐state boxing test at 60%VO2max and at 95%VO2max for 3 minutes each. A high‐definition Doppler ultrasound recorded common carotid artery diameters and blood flow velocities throughout each steady‐state condition. ESS was estimated using Womersley’s approximation.RESULTSThere was a significant increase in antegrade ESS with higher workloads in both groups (p &lt; 0.05 for all). No difference were found in anterograde ESS at baseline (Normotensive: 33.9±13.9 dynes/cm2, Pre‐HTA: 34.7±5.5 dynes/cm2; p = 0.936), at 60%VO2max (Normotensive: 51.3±19.1 dynes/cm2, Pre‐HTA: 49.6±7.6 dynes/cm2; p = 0.894, and at 95%VO2max (Normotensive: 72.9±30.9 dynes/cm2, Pre‐HTA: 85.2±12.5 dynes/cm2; p = 0.560) between both groups. Meanwhile, no retrograde blood flow was present at baseline for either groups, but it was identified at 60%VO2max (Normotensive: 8.1±0.7 dynes/cm2, Pre‐HTA: 7.8±7.8 dynes/cm2; p = 0.971) and 95%VO2max (Normotensive: 22.5±18.9 dynes/cm2, Pre‐HTA: 20.8±5.6 dynes/cm2; p = 0.891).CONCLUSIONESS increases in an exercise‐intensity manner during boxing training in normotensive and prehypertensive population. Boxing training might be beneficial in high blood pressure prevention due to increments on ESS.

Emergency department non-invasive cardiac output study (EDNICO): an accuracy study

BackgroundThere is little published data investigating non-invasive cardiac output monitoring in the emergency department (ED). We assess here the accuracy of five non-invasive methods in detecting fluid responsiveness in the ED: (1) common carotid artery blood flow, (2) suprasternal aortic Doppler, (3) bioreactance, (4) plethysmography with digital vascular unloading method, and (5) inferior vena cava collapsibility index. Left ventricular outflow tract echocardiography derived velocity time integral is the reference standard. This follows an assessment of feasibility and repeatability of these methods in the same cohort of ED patients.MethodsThis is a prospective observational study of non-invasive methods for assessing fluid responsiveness in the ED. Participants were non-ventilated ED adult patients requiring intravenous fluid resuscitation. Sensitivity and specificity of each method in determining the fluid responsiveness status of participants is determined in comparison to the reference standard.ResultsThirty-three patient data sets were included for analysis. The specificity and sensitivity to detect fluid responders was 46.2 and 45% for common carotid artery blood flow (CCABF), 61.5 and 63.2% for suprasternal artery Doppler (SSAD), 46.2 and 50% for bioreactance, 50 and 41.2% for plethysmography vascular unloading technique (PVUT), and 63.6 and 47.4% for inferior vena cava collapsibility index (IVCCI), respectively. Analysis of agreement with Cohen’s Kappa − 0.08 for CCABF, 0.24 for SSAD, − 0.04 for bioreactance, − 0.08 for PVUT, and 0.1 for IVCCI.ConclusionIn this study, non-invasive methods were not found to reliably identify fluid responders. Non-invasive methods of identifying fluid responders are likely to play a key role in improving patient outcome in the ED in fluid depleted states such as sepsis. These results have implications for future studies assessing the accuracy of such methods.

Effects of Stellate Ganglion Blockade on Muscle Blood Flow During Hypercapnia.

This study investigated the effects of a unilateral stellate ganglion block (SGB) on ipsilateral and contralateral masseter muscle blood flow during permissive hypercapnia. Eight male Japanese white rabbits were anesthetized with isoflurane. Observed variables included heart rate (HR), blood pressure (BP), left common carotid artery blood flow (LCBF), left and right masseter muscle tissue blood flow (LMBF and RMBF), and left femoral quadriceps muscle tissue blood flow (LQBF). Variable measurements were taken at a baseline end-tidal carbon dioxide tension (EtCO2) of 40 mm Hg and repeated at an elevated EtCO2 of 60 mm Hg prior to and after administration of a left SGB. HR decreased, while systolic BP was elevated during hypercapnia and after the SGB. LCBF increased during hypercapnia and after the SGB. LMBF and RMBF decreased to 75% and LQBF decreased to 60% of their respective baseline values during hypercapnia. After the SGB, LMBF was restored, reapproximating its baseline, but RMBF and LQBF further decreased to 55 and 45% of their respective baseline values. In conclusion, unilateral SGB restored the ipsilateral masseter muscle blood flow that had been reduced during hypercapnia. In contrast, the SGB exacerbated the hypercapnia-induced reduction in blood flows in the contralateral masseter muscle and the femoral quadriceps muscle.

Intermittent Exercise ｗith Vocalization Increases Common Carotid Artery Blood Flow

Intermittent Exercise ｗith Vocalization Increases Common Carotid Artery Blood Flow

Use of resuscitative balloon occlusion of the aorta in a swine model of prolonged cardiac arrest

AimWe examined the use of a Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) catheter during cardiopulmonary resuscitation (CPR) after cardiac arrest (CA) to assess its effect on haemodynamics such as coronary perfusion pressure (CPP), common carotid artery blood flow (CCA-flow) and end-tidal CO2 (PetCO2) which are associated with increased return of spontaneous circulation (ROSC). MethodsSix male swine were instrumented to measure CPP, CCA-Flow, and PetCO2. A 7Fr REBOA was advanced into zone-1 of the aorta through the femoral artery. Ventricular fibrillation was induced and untreated for 8 min. CPR (manual then mechanical) was initiated for 24 min. Continuous infusion of adrenaline (epinephrine) was started at minute-4 of CPR. The REBOA balloon was inflated at minute-16 for 3 min and then deflated/inflated every 3 min for 3 cycles. Animals were defibrillated up to 6 times after the final cycle. Animals achieving ROSC were monitored for 25 min. ResultsData showed significant differences between balloon deflation and inflation periods for CPP, CCA-Flow, and PetCO2 (p < 0.0001) with an average difference (SD) of 13.7 (2.28) mmHg, 15.5 (14.12) mL min−1 and −4 (2.76) mmHg respectively. Three animals achieved ROSC and had significantly higher mean CPP (54 vs. 18 mmHg), CCA-Flow (262 vs. 135 mL min−1) and PetCO2 (16 vs. 8 mmHg) (p < 0.0001) throughout inflation periods than No-ROSC animals. Aortic histology did not reveal any significant changes produced by balloon inflation. ConclusionREBOA significantly increased CPP and CCA-Flow in this model of prolonged CA. These increases may contribute to the ability to achieve ROSC.

Emergency department non-invasive cardiac output study (EDNICO): a feasibility and repeatability study

BackgroundThere is little published data investigating non-invasive cardiac output monitoring in the emergency department (ED). We assessed six non-invasive fluid responsiveness monitoring methods which measure cardiac output directly or indirectly for their feasibility and repeatability of measurements in the ED: (1) left ventricular outflow tract echocardiography derived velocity time integral, (2) common carotid artery blood flow, (3) suprasternal aortic Doppler, (4) bioreactance, (5) plethysmography with digital vascular unloading method, and (6) inferior vena cava collapsibility index.MethodsThis is a prospective observational study of non-invasive methods of assessing fluid responsiveness in the ED. Participants were non-ventilated ED adult patients requiring intravenous fluid resuscitation. Feasibility of each method was determined by the proportion of clinically interpretable measurements from the number of measurement attempts. Repeatability was determined by comparing the mean difference of two paired measurements in a fluid steady state (after participants received an intravenous fluid bolus).Results76 patients were recruited in the study. A total of 207 fluid responsiveness measurement sets were analysed. Feasibility rates were 97.6% for bioreactance, 91.3% for vascular unloading method with plethysmography, 87.4% for common carotid artery blood flow, 84.1% for inferior vena cava collapsibility index, 78.7% for LVOT VTI, and 76.8% for suprasternal aortic Doppler. The feasibility rates difference between bioreactance and all other methods was statistically significant.ConclusionOur study shows that non-invasive fluid responsiveness monitoring in the emergency department may be feasible with selected methods. Higher repeatability of measurements were observed in non-ultrasound methods. These findings have implications for further studies specifically assessing the accuracy of such non-invasive cardiac output methods and their effect on patient outcome in the ED in fluid depleted states such as sepsis.

Feasible study of carotid artery Doppler ultrasound blood flow measurement during chest compression cardiopulmonary resuscitation

To determine the feasibility of ultrasound to measure blood flow on patients with chest compression cardiopulmonary resuscitation (CPR), and to find out a real-time, noninvasive hemodynamic evaluation method. A prospective study was conducted. All adult patients undergoing CPR admitted to Department of Emergency and intensive care unit (ICU) of Zhengzhou People's Hospital from May 2016 to November 2018 were enrolled. The blood flow over the right carotid arteries during chest compressions was recorded with a bedside ultrasound machine. The peak systolic flow velocity (PSV) and end diastolic flow velocity (EDV) of carotid artery were recorded at 1 minute after the start of CPR and 1 minute before the end of CPR. The mean compression frequency during the whole recovery period was recorded, the rate of compression reaching the standard was evaluated by ultrasound (the rate of compression 100-120 times/min was defined as up to standard), and the interruption time of compression was calculated retrospectively according to the ultrasound image data recorded during CPR. Thirty-nine patients were enrolled, and 21 patients were successfully rescued, with a successful rate of 53.8%, the time of restoration of spontaneous circulation (ROSC) was (10.9±5.3) minutes. The time from CPR to retrieve an ultrasound image was 1.1-4.9 minutes, with an average of (2.5±1.2) minutes. Satisfactory ultra-sonographic images were obtained in 28 patients during the whole course of chest compression. The acquisition rate was 71.8% (28/39). In the process of compression, if the frequency of compression was less than 100 times/min or the velocity of carotid artery dropped (PSV < 30 cm/s), the chest compressors should be reminded and corrected in time. The PSV at 1 minute after CPR start of 28 patients with satisfactory ultrasound images was (62.9±18.5) cm/s, and the EDV was (13.9±3.5) cm/s, the PSV at 1 minute before the end of CPR was (55.4±18.4) cm/s, and the EDV was (12.9±3.7) cm/s. There was no significant difference in above parameters between the two time points (both P > 0.05), suggesting that satisfactory resuscitation effect was achieved in the whole process of CPR. The compression frequency of 28 patients was 100-149 times/min with an average of (117±47) times/min. The rate of compression with standard was 85.7% (24/28), and the total interruption time of compression accounted for 4.4% of all compression time (25.9 minutes/587.2 minutes). Ultrasound measurement of common carotid artery blood flow during CPR has the advantage of real-time and non-invasive, and it is feasible in clinical work.

Abstract 359: Use of Resuscitative Balloon Occlusion of the Aorta in a Swine Model of Prolonged Cardiac Arrest

Introduction: Despite advancements in CPR, survival to hospital discharge remains low for in- and out-of-hospital cardiac arrest (CA). Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is an evolving tool for temporary control of non-compressible truncal hemorrhage. In this investigation, we examined whether REBOA use during non-traumatic CA would produce favorable hemodynamic changes associated with return of spontaneous circulation (ROSC). Hypothesis: We hypothesized that REBOA use during CPR would result in higher coronary perfusion pressure (CPP) and common carotid artery blood flow (C-Flow) in a prolonged model of CA. Methods: Six male swine were anesthetized and instrumented to measure and monitor CPP, and C-Flow. A REBOA catheter (Prytime Medical Devices) was advanced into zone 1 of the aorta through the femoral artery. Ventricular fibrillation was electrically induced and untreated for 8 minutes. CPR was started manually at minute-8, then changed to mechanical CPR at minute-12 for the duration of the experiment. Continuous infusion of epinephrine (0.0024mg/kg/min) was simultaneously started with mechanical CPR. The REBOA balloon was inflated beginning at minute-16 for 3 minutes then deflated for 3 minutes for a total of 6 cycles. At the end of the final cycle (REBOA inflation), CPR was stopped (after 33 minutes of total arrest time) and animals were defibrillated using 200 J biphasic shocks, repeated up to 6 times. Animals achieving ROSC were monitored for an additional 25 minutes. Results: Analysis using repeated measure ANOVA showed significant differences between balloon deflation and inflation periods for CPP (p&lt;0.0001) with mean difference(SD) of 14(2.6) (Range: 17 to 42) mmHg and for C-Flow (p&lt;0.0001) with mean difference(SD) 16(23) (Range: 115 to 269) mL/min across all animals. Three animals achieved ROSC and had significantly higher CPP (48 vs. 24mmHg, p&lt;0.0001) and C-Flow (249 vs. 168mL/min) by t-test (p&lt;0.0001). Post-mortem aortic histology did not reveal any changes produced by balloon inflation. Conclusion: REBOA significantly increased CPP and C-Flow in this swine model of prolonged CA. These increases may have contributed to the ability to achieve ROSC after greater than 30 min of CA.

OR-022 Effects of aerobic exercise on the hemodynamics and structure of the common carotid artery in obese adolescents

Objective With the population of obese adolescents increases dramatically, a series of cardiovascular diseases, especially atherosclerotic, are triggered by obese which seriously threatens the life and health of teenagers. The aim of this study is to investigate the effects of aerobic exercise intervention on the hemodynamics and structure of the common carotid artery in obese adolescents.&#x0D; Methods Forty obese adolescents (18 ± 2years) were randomly assigned into the experimental group (EG; n = 20) and control group (CG; n = 20). EG undertook 12 weeks of aerobic exercise training (AET), CG had not any exercise intervention. The carotid artery of both CG and EG were examined and compared. Carotid artery responses were assessed in both groups. Color doppler ultrasound was used to determine the tube diameter and axial flow of the common carotid before and after exercise intervention. The heart rate, systolic and diastolic blood pressure were simultaneously measured on the left brachial artery by a sphygmomanometer.&#x0D; Results Compared with CG, there were improvements of EG in peripheral resistance (22.90±6.70 VS 29.58±8.71. p＜0.01) and Systolic blood pressure (123.57±7.36 VS 130.25±6.79. p＜0.05) were verified after AET, except diastolic blood pressure. Following AET, blood flow velocity (0.28±0.05 VS 0.21±0.05. p＜0.01) and wall shear stress (6.25±0.90 VS 4.97±1.54. p＜0.05) increased prominently, which were also significant differences only in EG. In contrast, the vascular diameter demonstrated consistently upper compared with CG, but no differences between EG and CG.&#x0D; Conclusions Regular aerobic exercise lasting 12 weeks could effectively change the dynamic parameters of the common carotid artery in obese adolescents, but no changes in arterial diameter. These findings indicated that 12 weeks of aerobic exercise can induce some changes of the common carotid artery blood flow within the circulation function in a short time. But the changing in common carotid arteries structure is needed after a long-term blood flow to the stimulation.

Carotid and femoral Doppler do not allow the assessment of passive leg raising effects

BackgroundThe hemodynamic effects of the passive leg raising (PLR) test must be assessed through a direct measurement of cardiac index (CI). We tested whether changes in Doppler common carotid blood flow (CBF) and common femoral artery blood flow (FBF) could detect a positive PLR test (increase in CI ≥ 10%). We also tested whether CBF and FBF changes could track simultaneous changes in CI during PLR and volume expansion. In 51 cases, we measured CI (PiCCO2), CBF and FBF before and during a PLR test (one performed for CBF and another for FBF measurements) and before and after volume expansion, which was performed if PLR was positive.ResultsDue to poor echogenicity or insufficient Doppler signal quality, CBF could be measured in 39 cases and FBF in only 14 cases. A positive PLR response could not be detected by changes in CBF, FBF, carotid nor by femoral peak systolic velocities (areas under the receiver operating characteristic curves: 0.58 ± 0.10, 0.57 ± 0.16, 0.56 ± 0.09 and 0.64 ± 10, respectively, all not different from 0.50). The correlations between simultaneous changes in CI and CBF and in CI and FBF during PLR and volume expansion were not significant (p = 0.41 and p = 0.27, respectively).ConclusionDoppler measurements of CBF and of FBF, as well as measurements of their peak velocities, are not reliable to assess cardiac output and its changes.

Noninvasive assessment of the common carotid artery hemodynamics with increasing exercise work rate using wave intensity analysis.

Noninvasively determined local wave speed (c) and wave intensity (WI) parameters provide insights into arterial stiffness and cardiac-vascular interactions in response to physiological perturbations. However, the effects of incremental exercise and subsequent recovery on c and WI have not been fully established. We examined the changes in c and WI parameters in the common carotid artery (CCA) during exercise and recovery in eight young, healthy male athletes. Ultrasound measurements of CCA diameter and blood flow velocity were acquired at rest, during five stages of incremental exercise (up to 70% maximum work rate), and throughout 1 h of recovery, and noninvasive WI analysis [diameter-velocity (DU) approach] was performed. During exercise, c increased (+136%), showing increased stiffness with work rate. All peak and area of forward compression, backward compression, and forward expansion waves increased during exercise (+452%, +700%, and +900%, respectively). However, WI reflection indexes and CCA resistance did not significantly change from rest to exercise. Furthermore, wave speed and the magnitude of all waves returned to baseline within 5 min of recovery, suggesting that the effects of exercise in the investigated parameters of young, healthy individuals were transient. In conclusion, incremental exercise was associated with an increase in local CCA stiffness and increases in all wave parameters, indicative of enhanced ventricular contractility and improved late-systolic blood flow deceleration.NEW & NOTEWORTHY We examined hemodynamics of the common carotid artery using noninvasive application of wave intensity analysis during exercise and recovery. The hemodynamic adjustments to exercise were associated with increases in local common carotid artery stiffness and all waves’ parameters, with the latter indicating enhanced ventricular contractility and improved late systolic blood flow deceleration.

Investigation of EEG Activity Compared with Mean Arterial Blood Pressure in Extremely Preterm Infants

Cerebral electrical activity in extremely preterm infants is affected by various factors including blood gas and circulatory parameters. To investigate whether continuously measured invasive mean arterial blood pressure (BP) is associated with electroencephalographic (EEG) discontinuity in extremely preterm infants. This prospective observational study examined 51 newborn infants born <29 weeks gestation in the first 3 days after birth. A single channel of raw EEG was used to quantify discontinuity. Mean BP was acquired using continuous invasive measurement and Doppler ultrasound was used to measure left ventricular output (LVO) and common carotid artery blood flow (CCAF). Median gestation and birthweight were 25.6 weeks and 760 g, respectively. Mean discontinuity reduced significantly between days 1 and 3. EEG discontinuity was significantly related to gestation, pH and BP. LVO and CCAF were not associated with EEG discontinuity. Continuously measured invasive mean arterial BP was found to have a negative relationship with EEG discontinuity; increasing BP was associated with lower EEG discontinuity. This did not appear to be mediated by surrogates of systemic or cerebral blood flow. Infants receiving inotropic support had significantly increased EEG discontinuity on the first day after birth.

Remifentanil decreases oral tissue blood flow while maintaining internal carotid artery blood flow during sevoflurane anesthesia in rabbits.

The aim of this study was to investigate the effect of remifentanil infusion on oral tissue blood flow including submandibular gland tissue blood flow (SBF) and internal carotid artery blood flow (ICBF) in rabbits during sevoflurane anesthesia. Twelve male Japan White rabbits were anesthetized with sevoflurane and remifentanil. Remifentanil was infused at 0.2 and 0.4 µg/kg/min. Measurements included circulatory variables, common and external carotid artery blood flow (CCBF, ECBF), ICBF, tongue mucosal blood flow (TMBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue blood flow (BBF), tongue muscle tissue blood flow (TBF) and SBF. Vascular resistances for each tissue, including the tongue mucosa, masseter muscle, mandibular bone marrow, tongue muscle and submandibular gland, were calculated by dividing the mean arterial pressure by the respective tissue blood flow. Remifentanil infusion decreased oral tissue blood flow and circulatory variables. CCBF, ECBF and ICBF did not change. The calculated vascular resistance in each oral tissue, except for the tongue mucosa, increased in an infusion-rate-dependent manner. These results showed that remifentanil infusion reduced TMBF, MBF, BBF, TBF and SBF in an infusion-rate-dependent manner without affecting ICBF under sevoflurane anesthesia.

Intervention effect of total flavonoids of ilex pubesceus on tolerant rat models under cerebral anoxia.

Objective: To observe the intervention effect of total flavonoid of ilex pubesceus on animal models of cerebral ischemic tolerance. Methods: A rat model of global-focal cerebral ischemic tolerance was established by blocking bilateral common carotid artery blood flow and occluding left middle cerebral artery using thread-occlusion method. After the first operation, the Ginaton group and large-dosage, medium-dosage and small-dosage groups of total flavonoid of ilex pubesceus were given intragastric administration of corresponding drugs. The sham-operated group, pretreatment model group and ischemia-reperfusion group were given intragastric administration of the same volume of normal saline, 1 time a day, and administrated for 4d. At 24 h after the second operation, the neurological deficit was assessed, the whole blood viscosity, plasma viscosity, iNOS activity as well as NO level, IL-1β content and TNF-α content in the brain tissue of the rats were determined, and the morphological changes of brain tissue of the rats were observed by HE staining. Results: All the rat models of cerebral ischemic tolerance were established successfully. The total flavonoid of ilex pubesceus can obviously or significantly reduce the neurological deficit score, whole blood viscosity and plasma viscosity, obviously or significantly increase the NO level in the brain tissue of the rats, and significantly reduce the pathological damage of brain tissue of the rats. But compared with the ischemia-reperfusion group, the total flavonoid of ilex pubesceus can significantly or obviously increase the iNOS activity, IL-1β content and TNF-α content in the brain tissue of the rats.

Methods in hemorheology and their clinical applications1.

The lecture was presented during the Fåhraeus award ceremony for 2016 at the University of Lisbon. It summarizes the main results and some of the more important hemorheological contributions achieved in the Laboratory of Biodynamics and Biorheology of the Institute of Mechanics to BAS and in collaboration with other laboratories of the research group, involved in many studies explaining hemorheological disturbances in various clinical conditions. An original method for the study of microstructural changes in the biological fluids by measuring the electrical conductivity simultaneously with the the rheological properties of red blood cells (RBC) in the whole blood and red blood cell suspensions in a viscometric flow was suggested. The influence of the disturbed hemorheological parameters on the common carotid artery and cerebral blood flow was studied. Analysis of blood flow in the common carotid artery bifurcation with stenosis was done. This lecture does not claim to be a comprehensive review, and many important studies were not cited. The author would like to acknowledge the valuable collaboration of all those cited in the reference list.

Behavioral phenotyping in rats during the experimental modeling of chronic cerebral circulation disorder

To describe motor, adaptive and cognitive disorders in rats with chronic cerebral circulatory deficiency caused by partial stenosis of the common carotid arteries (CCA). A study was performed on 20 white outbred male rats. This manipulation led to 40-45% and 50-60% reduction of blood flow in CCA and in the brain, respectively. Twenty days after operation, animal's condition was assessed in the following tests: open field test, rotarod performance test, marble burying test and novel object recognition. After 20 days of experimental CCA stenosis, animals demonstrated several signs of neuropsychiatric deficiency including coordination disorders, a decrease in locomotor activity as well as in explorative and protective behavior. The model of CCA partial stenosis could be used during further studies of the pathophysiology and pharmacology of chronic cerebral circulatory deficiency.