Doppler Monitoring Research Articles

Does Sustained Epinephrine Release Trigger a Hypoxia-Neovascularization Cascade?

Recent data regarding the long-term local administration of epinephrine to soft tissues for the purpose of inducing prolonged vasoconstriction have yielded promising results. These studies postulated that long-term release of epinephrine by a microsphere/drug delivery system caused continuous vasoconstriction and subsequent vascular augmentation. The goal of this study was to test the hypothesis that epinephrine induces a hypoxia-neovascularization cascade and plays a primary role in vascular proliferation within soft tissues. Thirty male New Zealand White rabbits were randomly grouped as follows: group I, control (n = 10); group II, saline-loaded microsphere/drug delivery system injection (n = 10); and group III, epinephrine-loaded microsphere/drug delivery system injection (n = 10). A 2 x 1-cm rectangle was marked on the dorsal surface of the left ear of each rabbit. No solutions were injected in the control group, whereas 1 ml of saline-loaded and epinephrine-loaded microspheres was injected into groups II and III, respectively. A laser Doppler device was used to measure tissue blood volume and tissue blood flow. Laser Doppler monitoring in tissue blood flow yielded a distinct difference between the epinephrine-loaded microsphere-injected group and the other two groups (p < 0.05). The ability of epinephrine-loaded microspheres to augment the vascular network in vivo is the result of sustained vasoconstriction with consequent tissue hypoxia and subsequent neovascularization. Data extracted from the present study, first, might be applied to improve hemostasis for operations typically plagued by serious intraoperative blood loss. Second, the ability to intentionally augment the vascularity of certain flaps before elevation should result in their increased survival. Radiation-injured tissues may also derive great benefit from this treatment.

Speed of tPA-Induced Clot Lysis Predicts DWI Lesion Evolution in Acute Stroke

We sought to evaluate the impact of the speed of recanalization on the evolution of diffusion- weighted imaging (DWI) lesions and outcome in stroke patients treated with tissue-type plasminogen activator (tPA). We evaluated 113 consecutive stroke patients with a middle cerebral artery occlusion who were treated with intravenous tPA. All patients underwent multiparametric magnetic resonance imaging studies, including DWI and perfusion-weighted imaging before and 36 to 48 hours after administration of a tPA bolus. Patients were continuously monitored with transcranial Doppler during the first 2 hours after tPA administration. The pattern of recanalization on transcranial Doppler was defined as sudden (<1 minute), stepwise (1 to 29 minutes), or slow (>30 minutes). During transcranial Doppler monitoring, 13 (12.3%) patients recanalized suddenly, 32 (30.2%) recanalized in a stepwise manner, and 18 (17%) recanalized slowly. Baseline clinical and imaging parameters were similar among recanalization subgroups. At 36 to 48 hours, DWI lesion growth was significantly (P=0.001) smaller after sudden (3.23+/-10.5 cm(3)) compared with stepwise (24.9+/-37 cm(3)), slow (46.3+/-38 cm(3)), and no (51.7+/-34 cm(3)) recanalization. The slow pattern was associated with greater DWI growth (P=0.003), lesser degree of clinical improvement (P=0.021), worse 3-month outcome (P=0.032), and higher mortality (P=0.003). The speed of tPA-induced clot lysis predicts DWI lesion evolution and clinical outcome. Unlike sudden and stepwise patterns, slow recanalization is associated with greater DWI lesion growth and poorer short- and long-term outcomes.

Site of Arterial Occlusion Identified by Transcranial Doppler Predicts the Response to Intravenous Thrombolysis for Stroke

The objective of this study was to examine clinical outcomes and recanalization rates in a multicenter cohort of stroke patients receiving intravenous tissue plasminogen activator by site of occlusion localized with bedside transcranial Doppler. Angiographic studies with intraarterial thrombolysis suggest more proximal occlusions carry greater thrombus burden and benefit less from local therapy. Using validated transcranial Doppler criteria for specific arterial occlusion (Thrombolysis in Brain Ischemia flow grades), we compared the rate of dramatic recovery (National Institutes of Health Stroke Scale score < or =2 at 24 hours) and favorable outcomes at 3 months (modified Rankin Scale < or =1) for each occlusion site. We determined the likelihood of recanalization at various occlusion sites and its predictors. Then, stepwise logistic regression was used to determine predictors of complete recanalization. Three hundred thirty-five patients had a mean age 69+/-13 years and 48.5% were women (median baseline National Institutes of Health Stroke Scale score 16 [range, 3 to 32], mean time to transcranial Doppler 140+/-84 minutes, and mean time to intravenous tissue plasminogen activator 145+/-68 minutes). Distal middle cerebral artery occlusion had an OR of 2 for complete recanalization (50 of 113 [44.2%], 95% CI: 1.1 to 3.1, P=0.005), proximal middle cerebral artery 0.7 (49 of 163 [30%], 95% CI: 0.4 to 1.1, P=0.13), terminal internal carotid artery 0.1 (one of 17 [5.9%], 95% CI: 0.015 to 0.8, P=0.015), tandem cervical internal carotid artery/middle cerebral artery 0.7 (6 of 22 [27%], 95% CI: 0.3 to 1.9, P=0.5), and basilar artery 0.96 (3 of 10 [30%], 95% CI: 0.2 to 4, P=0.9). Prerecombinant tissue plasminogen activator National Institutes of Health Stroke Scale score, systolic blood pressure, glucose, and Thrombolysis in Brain Ischemia flow grade at the occlusion site were the negative independent predictors for complete recanalization in the final model. There were no associations among time to treatment, stroke mechanisms, or recanalization rate. Patients with no flow (Thrombolysis in Brain Ischemia 0) at the occlusion site had less probability of complete recanalization than patients with dampened flow (Thrombolysis in Brain Ischemia 3) (OR(adj): 0.256, 95% CI: 0.11 to 0.595, P=0.002). Continuous transcranial Doppler monitoring (exposure to ultrasound) was a positive predictor for complete recanalization (OR(adj): 3.02, 95% CI: 1.396 to 6.514, P=0.005). National Institutes of Health Stroke Scale score < or =2 at 24 hours was achieved in 66 of 305 patients (22%): distal middle cerebral artery 33% (35 of 107), tandem cervical internal carotid artery/middle cerebral artery 24% (5 of 21), proximal middle cerebral artery 16% (24 of 155), basilar artery 25% (2 of 8), and none of the patients with terminal internal carotid artery had dramatic recovery (0%, n=14; P=0.003). Modified Rankin Scale score < or =1 was achieved in 90 of 260 patients (35%): distal middle cerebral artery 52% (50 of 96), proximal middle cerebral artery 25% (33 of 131), tandem cervical internal carotid artery/middle cerebral artery 21% (3 of 14), terminal internal carotid artery 18% (2 of 11), and basilar artery 25% (2 of 8) (P<0.001). Patients with distal middle cerebral artery occlusion were twice as likely to have a good long-term outcome as patients with proximal middle cerebral artery (OR: 2.1, 95% CI: 1.1 to 4, P=0.025). Clinical response to thrombolysis is influenced by the site of occlusion. Patients with no detectable residual flow signals as well as those with terminal internal carotid artery occlusions are least likely to respond early or long term.

Is cerebral autoregulation impaired in Parkinson's disease? A transcranial Doppler study

Orthostatic hypotension (OH) is one of the many autonomic disturbances observed in Parkinson's disease (PD). It has been debated whether an additional impairment of cerebral autoregulation (CA) in PD patients may exacerbate the consequences of OH upon brain perfusion. We assessed CA in PD patients and the potential influence of dopaminergic agents. CA was determined by means of transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) at rest and during a thigh cuff release test inducing a systemic blood pressure (BP) drop. Fourteen patients were investigated when taking their usual dopaminergic medication and after drug discontinuation for 12 h. A control group was composed of 11 age-matched subjects (CS). In comparison with PD patients, CS presented a significantly higher increase of the mean cerebral blood flow velocities in the MCA after the BP drop. Mean velocities were increased above the initial values in all CS, whereas a flattened curve was observed in PD patients. No significant differences could be further observed between the PD patients regarding the BP, the cerebrovascular resistance, the heart rate and the pulsatility index. These results provide evidence of an impaired cerebral autoregulation in PD patients which appears independent of dopaminergic treatment.

Measuring aortic diameter improves accuracy of esophageal Doppler in assessing fluid responsiveness

Fluid responsiveness requires the accurate measurement of cardiac output that can be approached by aortic blood flow (ABF) as measured by esophageal Doppler monitoring (EDM). EDM devices may either include an echo-determination of aortic diameter or estimate aortic diameter from nomograms and thus consider it as constant. However, it is unclear if measuring aortic diameter increases the accuracy of EDM to identify fluid responsiveness. Aortic diameter varies with arterial pressure such that its measure could be essential for assessing the changes in ABF during acute circulatory failure. We attempted to demonstrate that measuring aortic diameter improved the accuracy of EDM to assess fluid responsiveness. Prospective study. University hospital intensive care unit. Seventy-six patients with acute circulatory failure in whom a fluid challenge was given. Rapid volume expansion (500 mL of NaCl 0.9%). We measured aortic velocity and area by EDM before and after fluid loading and evaluated the effects of fluid challenge on ABF, either measured after fluid infusion (measured ABFafter) or estimated assuming an unchanging aortic area (estimated ABFafter). If measured ABFafter was used for assessing fluid response, it was increased above 15% compared with ABF at baseline in 41 patients (responders). Conversely, estimated ABFafter increased above 15% from ABF at baseline in 27 patients only; that is, the effects of the challenge were underestimated in 14 patients. In these 14 patients, the relative change in mean arterial pressure during volume expansion was of greater magnitude than in patients who were classified as nonresponders by considering measured ABFafter. Monitoring the changes in aortic diameter improves the accuracy of EDM in assessing the hemodynamic effects of a fluid challenge, especially if it induces a large increase in arterial pressure. Estimating rather than measuring the aortic diameter may lead to underestimation of fluid responsiveness.

Validation of esophageal Doppler for noninvasive hemodynamic monitoring under pneumoperitoneum

Commonly used perioperative measurements of hemodynamics, such as Swan-Ganz catheter assessment, are invasive and may not be reliable under pneumoperitoneum. The purpose of this study was to validate the use of esophageal Doppler for noninvasive hemodynamic monitoring under pneumoperitoneum in an experimental pig model. Eight female pigs were submitted to two 30-min study periods, one each for the baseline (no interventions) and pneumoperitoneum (12-mmHg carbon dioxide pneumoperitoneum) conditions. One pig was excluded because of tachycardia (>140 at baseline). A Swan-Ganz pulmonary artery catheter was used to measure cardiac output (CO-SG) and pulmonary capillary wedge pressure (PCWP). An esophageal Doppler probe was inserted to record cardiac output (CO-ED) and corrected flow time (FTc), an index of preload. Transthoracic echocardiography was used to measure left ventricular end-diastolic diameter (LVEDD) and cardiac output (CO-TTE). Pearson correlation was used to assess individual associations between the measured hemodynamic parameters. There was good correlation between CO-ED and CO-SG (r = 0.577; p < 0.001) and excellent correlation between CO-ED and CO-TTE (r = 0.815; p < 0.001). There was no correlation between FTc and LVEDD or PCWP. These relationships were consistent when analyzed separately at baseline and during pneumoperitoneum. Esophageal Doppler monitoring is a valid noninvasive method of estimating cardiac output at baseline and during pneumoperitoneum in a porcine model. Corrected flow time did not correlate with other estimates of preload at baseline or during pneumoperitoneum.

Pocket Guide to Perioperative and Critical Care Echocardiography

This pocket guide on perioperative echocardiography discusses various issues on echocardiography and Doppler imaging, a diagnostic and monitoring technique that is used increasingly in the perioperative and intensive care unit setting. The setup of the pocket guide is clear and straightforward. The sequence of the different topics is built up logically and step by step. Each chapter begins with learning objectives, informing the reader immediately what is to be found in that chapter. The first chapter deals with general views on how to use and implement echocardiography in a perioperative setting. The following two sections encompass the technology of the echocardiograph and probes. Quality of imaging and organization of echo-imaging is the topic of another chapter. The authors provide careful instruction to the reader on what different anatomical characteristics are, how they can be obtained and how these features should be viewed in terms of a three-dimensional construction from two-dimensional images. Transoesophageal imaging and transthoracic echocardiographic imaging are discussed in separate chapters, which also provide the official terminology. The chapter on Doppler imaging provides an overview of such basic issues as the Doppler effect and rapidly progresses to information on how to assess pressures with Doppler. This section forms the basis for the following chapter, on the assessment of haemodynamics. Various self-explanatory schemes guide the reader through decision making in this difficult issue. In addition, tables are well organized to illustrate decision making on hypovolaemia, assessment of fluid responsiveness and evaluation of ventricular function. Ventricular function is also covered later, encompassing both systolic and diastolic function of the left ventricle. Again, various diagrams provide illustrative information. Subsequent chapters discuss the most frequent problems of valvular pathology and provide information on problems with great vessels, and a further chapter discusses pericardial pathology from an echocardiographic point of view. In particular, the important issue of pericardial tamponade is elaborated extensively in clear diagrams. Regional anaesthesia and vascular access – two hot topics at the moment – are included in the book's later sections, and the information presented is important for general anaesthetists. Both issues are exemplified in several schemes. The final chapter discusses which items should be included when training and accreditation is organized. The booklet includes a small CD-Rom including several clips of most important issues, sorted by chapter. The pocket guide does not have the aim of including all facets of echocardiography. For example, tissue Doppler imaging is discussed only very briefly. In addition, other issues such as valvular pathology are summarized, although the most important problems are discussed. Some iconography could have been more specific and illustrative, as modern echographs often offer pretty visualizations. Real images could have replaced the presented schematic representations in the chapter on regional anaesthesia and vascular access. In summary, this booklet is a good pocket guide for anaesthetists or critical care physicians who deal with echocardiography and an echographic approach to haemodynamic follow-up and problem solving.

Esophageal Doppler-guided fluid management decreases blood lactate levels in multiple-trauma patients: a randomized controlled trial

IntroductionEsophageal Doppler was confirmed as a useful non-invasive tool for management of fluid replacement in elective surgery. The aim of this study was to assess the effect of early optimization of intravascular volume using esophageal Doppler on blood lactate levels and organ dysfunction development in comparison with standard hemodynamic management in multiple-trauma patients.MethodsThis was a randomized controlled trial. Multiple-trauma patients with blood loss of more than 2,000 ml admitted to the intensive care unit (ICU) were randomly assigned to the protocol group with esophageal Doppler monitoring and to the control group. Fluid resuscitation in the Doppler group was guided for the first 12 hours of ICU stay according to the protocol based on data obtained by esophageal Doppler, whereas control patients were managed conventionally. Blood lactate levels and organ dysfunction during ICU stay were evaluated.ResultsEighty patients were randomly assigned to Doppler and 82 patients to control treatment. The Doppler group received more intravenous colloid during the first 12 hours of ICU stay (1,667 ± 426 ml versus 682 ± 322 ml; p < 0.0001), and blood lactate levels in the Doppler group were lower after 12 and 24 hours of treatment than in the control group (2.92 ± 0.54 mmol/l versus 3.23 ± 0.54 mmol/l [p = 0.0003] and 1.99 ± 0.44 mmol/l versus 2.37 ± 0.58 mmol/l [p < 0.0001], respectively). No difference in organ dysfunction between the groups was found. Fewer patients in the Doppler group developed infectious complications (15 [18.8%] versus 28 [34.1%]; relative risk = 0.5491; 95% confidence interval = 0.3180 to 0.9482; p = 0.032). ICU stay in the Doppler group was reduced from a median of 8.5 days (interquartile range [IQR] 6 to16) to 7 days (IQR 6 to 11) (p = 0.031), and hospital stay was decreased from a median of 17.5 days (IQR 11 to 29) to 14 days (IQR 8.25 to 21) (p = 0.045). No significant difference in ICU and hospital mortalities between the groups was found.ConclusionOptimization of intravascular volume using esophageal Doppler in multiple-trauma patients is associated with a decrease of blood lactate levels, a lower incidence of infectious complications, and a reduced duration of ICU and hospital stays.

Use of the esophageal echo-Doppler to guide intensive care unit resuscitations: A retrospective study

Purpose: The esophageal Doppler monitoring (EDM) has emerged as an alternative to the pulmonary artery catheter (PAC). The purpose of this study is to better define its role in the ICU. Materials and Methods: Retrospective review of Hemosonic™ 100 EDM probe use between 2003 and 2005. Patient- and EDM-related characteristics, indications, complications, resuscitation end points (lactate, base excess - BE, left ventricular ejection time - LVET) were recorded. Comparisons between EDM and PAC were made. Results: Thirty-nine patients were monitored using the EDM. EDM-guided interventions resulted in significantly improved lactate, BE and LVET (all, P P Conclusions: EDM may be most helpful in ventilated/sedated patients requiring short-term hemodynamic monitoring. When compared to PAC, the EDM tends to underestimate CO in the lower range and overestimate CO in the upper range of measurements. We recommend EDM use concurrently with end-points of resuscitation.

Transcranial doppler monitoring during language tasks in stroke patients with aphasia

Purpose. To investigate the pattern of hemispheric activation, according to cerebral blood flow changes, as measured by Transcranial Doppler Ultrasonography (TCD) during language tasks in stroke patients with aphasia.Method. Prospective study investigating results of TCD monitoring during language naming and recognition tasks in ischemic stroke patients (n = 32) with and without aphasia and 5 control subjects.Results. Delta mean flow velocity (MFV) in the left Middle Cerebral Artery (MCA) was found to be much lower in aphasia patients as compared to healthy subjects. Negative statistical correlation was found between the improvement of language ability and the blood flow velocity parameters in the left hemisphere. Aphasia patients with good language ability showed much higher MFV in the right MCA during the first test. Left hemispheric blood flow velocity shift was found to be higher during speech tasks in the patients with poor language ability.Conclusions. Our study suggests that the performance of language tasks in aphasia patients during early recovery after stroke is associated with relatively high right hemisphere activation. High blood flow velocity in the right MCA of aphasia patients was found to be a good prognostic sign for better language ability. Arterial blood flow that shifted towards the left hemisphere during speech tasks was associated with poor language ability.

Utility of Esophageal Doppler and the Hemodynamic Effect of Nicardipine during a Laparoscopic Cholecystectomy

Background: We performed this study to investigate the hemodynamic effect of nicardipine using an esophageal Doppler monitor (EDM) during a laparoscopic cholecystectomy. Methods: Forty patients scheduled to undergo a laparoscopic cholecystectomy, were divided into two groups; the control group (Group C) and the nicardipine group (Group N). Pneumoperitoneum was initiated by CO2 gas and the intraperitoneal pressure was kept under 12 mmHg. Hemodynamic parameters at critical points were measured by the use of EDM: before skin incision (T1), 5, 10 and 15 min after the initiation of pneumoperitoneum (T2, T3 and T4), and 5 min after deflation (T5). Results: The mean arterial pressure (MAP) was significantly lower in the Group N patients when compared to the Group C patients 5, 10 and 15 min after the initiation of pneumoperitoneum (T2, T3 and T4), and 5 min after deflation (T5)(P ＜ 0.05). There was no significant differences in heart rate (HR) between patients in the two groups. The cardiac output (CO) was significantly increased in the Group N patients when compared to the Group C patients 5 min after the initiation of pneumoperitoneum (T2)(P ＜ 0.05). The peak velocity (PV) was significantly increased in the Group N patients when compared to the Group C patients 5 and 10 min after the initiation of pn eumoperitoneum (T2 and T3)(P ＜ 0.05). The corrected flow time (FTC) was significantly increased in the Group N patients when compared to the Group C patients 5 min after the initiation of pneumoperitoneum (T2)(P ＜ 0.05). Conclusions: We conclude that nicardipine continuous infusion with 0.5-2.0μg/kg/min is effective in attenuating the hemodynamic change after pneumoperitoneum during a laparoscopic cholecystectomy. (Korean J Anesthesiol 2007; 53: 304～10)

Esophageal Doppler monitoring predicts fluid responsiveness in critically ill ventilated patients

Esophageal Doppler monitoring predicts fluid responsiveness in critically ill ventilated patients

Hemodynamic Changes using Partial CO2Rebreathing Method and Esophageal Doppler Monitor during Bilateral Total Knee Replacement Arthroplasty

Background: We studied hemodynamic changes using a noninvasive partial CO2 rebreathing cardiac output method (NICO) and esophageal Doppler monitor (EDM), and metabolic changes in elderly patients undergoing bilateral total knee replacement arthroplasty (BTKA). Methods: Twenty patients undergoing BTKA were studied. Hemodynamic and metabolic parameters were measured before tourniquet inflation (TI), 0, 3, 6, 9, 15, 30, 45 min after TI, and 0, 3, 6, 9, 15, 30 min after tourniquet deflation (TD) and skin suture. Stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were measured using NICO and EDM. Results: Mean blood pressure (MBP), central venous pressure (CVP), and SVR had significant increases in TI, and decreases in TD compared with value measured before TI (baseline value). Especially, MBP had higher decrease in the second tourniquet compared with first tourniquet, SV and CO were decreased in TI, and increased in TD compared with baseline value, HR had significant increases in the TD of second tourniquet. pH and lactate were shown significantly lower values at the second tourniquet compared with the first tourniquet (P ＜ 0.05). The bias and precision derived from CO between EDM and NICO was 0.27 ± 0.41 L/min, and CO by NICO was smaller than that by EDM. The correlation coefficient between NICO and EDM was calculated to be 0.43. Conclusions: MBP, SV, CO, pH and lactate were shown to be higher in the second tourniquet in BTKA. NICO showed lower CO compared with EDM after TD in patients undergoing BTKA, but statistically insignificant at most measurement. (Korean J Anesthesiol 2007; 53: 615～23)

Exploring measurement biases associated with esophageal Doppler monitoring in critically ill patients in intensive care unit

BACKGROUND:Esophageal Doppler monitoring (EDM) is utilized in numerous clinical settings. This study examines the relationship between pulmonary artery catheter (PAC) and EDM-derived hemodynamic parameters, concentrating on gender- and age-related EDM measurement biases.MATERIALS AND METHODS:Prospective study of EDM use in ventilated surgical ICU patients. Parameters examined included demographics, diagnosis, resuscitation endpoints, cardiac output (CO) and stroke volume from both devices, number of personnel and time needed to place equipment, time to data acquisition, duration of use, complications of placement.RESULTS:Fifteen patients (11 men, 4 women, mean age 47 years) were included. Most common diagnoses included trauma (7/15) and sepsis (4/15). Insertion time and time to data acquisition were shorter for EDM than for PAC (P<0.001). The EDM required an average of 1.1 persons to place (2.4 for PAC, P=0.002). Mean EDM utilization time was 12.4 h. There was a fair CO correlation between EDM and PAC (r = 0.647, P<0.001). Overall, the EDM underestimated CO relative to PAC (bias -1.42 ± 2.08, 95% CI: -5.58-2.74), with more underestimation in women (mean bias difference of -1.16, P<0.001). No significant age-related measurement bias differences between PAC and EDM were noted. Significant reductions in lactate and norepinephrine requirement were noted following EDM monitoring periods.CONCLUSIONS:This study found that the EDM significantly underestimated cardiac output in women when compared to PAC. Clinicians should be aware of this measurement bias when making therapeutic decision based on EDM data. Significant reductions in lactate and norepinephrine requirement during EDM monitoring periods support the clinical usefulness of EDM technology.

Noninvasive cardiac output: accuracy between the ultrasound cardiac output monitor and the esophageal Doppler monitor

The hypothesis is that measurement of the cardiac index (CI) is accurate between the ultrasound cardiac output monitor (USCOM) and the esophageal Doppler monitor (EDM). The EDM is a minimally invasive device that has demonstrated strong correlation with cardiac output measurements obtained by thermodilution. A disadvantage of the EDM is the need for probe placement in the esophagus, effectively limiting its use to mechanically ventilated patients. The USCOM, in contrast, can measure cardiac hemodynamics by use of a CW Doppler probe placed on the skin to measure blood flow across either the aortic or pulmonic valve.

Prediction of early cerebral outcome by transcranial Doppler monitoring in carotid bifurcation angioplasty and stenting

Prediction of early cerebral outcome by transcranial Doppler monitoring in carotid bifurcation angioplasty and stenting

Orthostatic hypotension and cerebral blood flow velocity in the rehabilitation of stroke patients

The objective of this study was to investigate the results of transcranial Doppler monitoring during tilt table tests in stroke patients with and without orthostatic hypotension. In stroke patients without orthostatic hypotension, the mean flow velocity was almost similar in both middle cerebral arteries and was stable during the test. In patients with orthostatic hypotension symptoms, a significant difference was found between the two hemispheres. Mean flow velocity in the damaged middle cerebral artery was lower in the supine position and stayed almost the same at 80 degrees standing. In the non-damaged middle cerebral artery, however, the mean flow velocity was much higher when supine and dropped in the standing position. These findings suggest that the appearance of orthostatic hypotension symptoms may be associated in post-stroke patients with decreased blood velocity in the damaged middle cerebral artery. Those patients are at a high risk of developing syncopal reactions and should be treated on the tilt table with caution, especially at the beginning of the rehabilitation.

Cerebral autoregulatory changes in hypertensive states assessed by beat to beat cerebral blood velocity changes

BY BEAT TO BEAT CEREBRAL BLOOD VELOCITY CHANGES KEITH WILLIAMS, FRANCE GALERNEAU, MARIA SMALL, Yale University, Obstetrics & Gynecology, New Haven, Connecticut, Yale University, Obstetrics and Gynecology, New Haven, Connecticut, Yale University, New Haven, Connecticut OBJECTIVE: Recent studies have identified significant changes in cerebral autoregulation in preeclampsia (PET). We chose to examine pulsatile fluctations in in the Middle Cerebral Blood Flow Velocity. (MCBFV) by assessing the beat to beat systolic variation with changes in RR interval and Systolic MCBFV Variability. This study investigates the usefulness as a test of cerebral autoregulation the beat-to-beat changes in MCBFV with changes in RR intervals. STUDY DESIGN: Transcranial Doppler monitoring of the middle cerebral artery (MCA) was performed for 2 minutes on 20 normotensive, 10 PET, 5 chronic hypertensive and 7 Pregnancy Induced Hypertension (PIH) patients were assessed. We measured beat-to-beat systolic, diastolic, and mean MCBFV velocity and RR intervals. Offline using software we calculated the beat-to-beat change in Systolic MCBFV associated with changes RR in each of the groups. In addition the Systolic MCBFV variability was calculated as the square root of the mean of the sum of the squares of differences in Systolic MCBFV between adjacent RR intervals. All continuous data was compared between the four groups using ANOVA with Bonferroni correction. RESULTS: We identified a significant difference the Systolic MCBFV change with the RR interval among the normotensive PET, Chronic Hypertensive and PIH groups (33.6G14.6, vs 16G10.2, vs, 44G14.8, vs 31.9G17.8)(P!.004) There was no significant difference in Systolic MCBFV variability (1.96G63, vs 1.63G.49, vs1.91G.52, vs 1.58G.29)(P!.30). CONCLUSION: We evaluated cerebral function in various pregnant hypertensive states by examining spontaneous fluctuations and rythmicity of RR interval and systolic MCBFV. Our data suggest that in PET unlike chronic hypertension acts to diminish spontaneous beat to beat oscillations in MCBFV. The loss of the dynamic complexity of the variability signal may be an indication of loss of vessel adaptability to continuously changing environmental requirements.

Vascular reactivity at different sites in preeclampsia-is there a correlation?

ObjectivePreeclampsia (PET) is associated with a disordered circulatory changes in the brain and the peripheral circulation as evidenced by changes in brachial artery Flow Mediated Vascular Dilation (FMVD) and estimated Cerebral Perfusion Pressure (eCPP). This study investigates whether the peripheral circulatory changes correlate with changes in the central cerebral circulation.Study design20 normotensive, 10 PET patients were assessed. Transcranial Doppler monitoring of the middle cerebral artery in the mother was performed and we recorded Mean and Diastolic Blood Presure and Mean and Diastolic Middle Cerebral Blood Flow Velocity (MCBFV). We calculated the eCPP according to the following equation eCPP = Vmean/(Vmean-Vdiastolic) × (BPmean – BPdiastolic). Following this FMVD of the brachial artery was measured post cuff release. We assessed the maximum brachial artery dilatation in each patient. The means were compared between the groups using student t tests and Correlation coefficient between FMVD and eCPP was measured in each of the 2 groups.ResultseCPP was significantly higher in the PET vs. the normotensive group (91.4±15.7 vs 56.9±11.5) P<.001). FMVD was significantly lower in the PET than the normotensive group (5.0±2.7 vs 8.2±2.9)(P<.022). There was poor correlation between FMVD and eCPP in the 2 groups. PET (R=.546), Normotensive (R=.498)ConclusionPreeclampsia is a multisystem disorder of generalized vasculopathy with multiple organ systems being affected. This study identifies that the peripheral vascular bed (FMVD) and cerebral circulation (eCPP) undergo significant changes in preeclampsia but these changes are independent components of the disease process. Vascular dysfunction occurring in one organ system cannot be used to predict dysfunction in another organ system. ObjectivePreeclampsia (PET) is associated with a disordered circulatory changes in the brain and the peripheral circulation as evidenced by changes in brachial artery Flow Mediated Vascular Dilation (FMVD) and estimated Cerebral Perfusion Pressure (eCPP). This study investigates whether the peripheral circulatory changes correlate with changes in the central cerebral circulation. Preeclampsia (PET) is associated with a disordered circulatory changes in the brain and the peripheral circulation as evidenced by changes in brachial artery Flow Mediated Vascular Dilation (FMVD) and estimated Cerebral Perfusion Pressure (eCPP). This study investigates whether the peripheral circulatory changes correlate with changes in the central cerebral circulation. Study design20 normotensive, 10 PET patients were assessed. Transcranial Doppler monitoring of the middle cerebral artery in the mother was performed and we recorded Mean and Diastolic Blood Presure and Mean and Diastolic Middle Cerebral Blood Flow Velocity (MCBFV). We calculated the eCPP according to the following equation eCPP = Vmean/(Vmean-Vdiastolic) × (BPmean – BPdiastolic). Following this FMVD of the brachial artery was measured post cuff release. We assessed the maximum brachial artery dilatation in each patient. The means were compared between the groups using student t tests and Correlation coefficient between FMVD and eCPP was measured in each of the 2 groups. 20 normotensive, 10 PET patients were assessed. Transcranial Doppler monitoring of the middle cerebral artery in the mother was performed and we recorded Mean and Diastolic Blood Presure and Mean and Diastolic Middle Cerebral Blood Flow Velocity (MCBFV). We calculated the eCPP according to the following equation eCPP = Vmean/(Vmean-Vdiastolic) × (BPmean – BPdiastolic). Following this FMVD of the brachial artery was measured post cuff release. We assessed the maximum brachial artery dilatation in each patient. The means were compared between the groups using student t tests and Correlation coefficient between FMVD and eCPP was measured in each of the 2 groups. ResultseCPP was significantly higher in the PET vs. the normotensive group (91.4±15.7 vs 56.9±11.5) P<.001). FMVD was significantly lower in the PET than the normotensive group (5.0±2.7 vs 8.2±2.9)(P<.022). There was poor correlation between FMVD and eCPP in the 2 groups. PET (R=.546), Normotensive (R=.498) eCPP was significantly higher in the PET vs. the normotensive group (91.4±15.7 vs 56.9±11.5) P<.001). FMVD was significantly lower in the PET than the normotensive group (5.0±2.7 vs 8.2±2.9)(P<.022). There was poor correlation between FMVD and eCPP in the 2 groups. PET (R=.546), Normotensive (R=.498) ConclusionPreeclampsia is a multisystem disorder of generalized vasculopathy with multiple organ systems being affected. This study identifies that the peripheral vascular bed (FMVD) and cerebral circulation (eCPP) undergo significant changes in preeclampsia but these changes are independent components of the disease process. Vascular dysfunction occurring in one organ system cannot be used to predict dysfunction in another organ system. Preeclampsia is a multisystem disorder of generalized vasculopathy with multiple organ systems being affected. This study identifies that the peripheral vascular bed (FMVD) and cerebral circulation (eCPP) undergo significant changes in preeclampsia but these changes are independent components of the disease process. Vascular dysfunction occurring in one organ system cannot be used to predict dysfunction in another organ system.

Spontaneous recanalization at subacute phase of stroke may be dramatic: A case report

Spontaneous recanalization of the occluded cerebral arteries has occasionally occurred in an acute phase of stroke patients. We report a stroke patient with recanalization at 7 days of onset detected by using continuous transcranial Doppler (TCD) monitoring. After the presence of microembolic signals on TCD display, dynamic flow changes of the middle cerebral artery (MCA) occurred, which represented recanalization of the occluded MCA.