Middle Cerebral Artery Velocity Research Articles

Assessment of Cerebrovascular Reserve in the Heart Failure Patients Supported with the HeartMate3

We previously showed that cerebrovascular reactivity (CVR) is reduced in heart failure (HF) patients and does not improve after left ventricular assist device (LVAD) HeartMate II (HMII) implantation, possibly because of low pulsatile physiology. Therefore, it is possible that the artificial pulse of the latest generation LVAD, the HeartMate3 (HM3), restores normal CVR. HM3 patients will have an increased CVR to a CO2-retention challenge compared with HF and HMII. A total of 79 subjects (17 healthy, 30 HF, 15 HMII and 17 HM3) underwent angle-corrected transcranial Doppler sonography. Middle cerebral artery (MCA) velocity profiles were recorded before and at the end of a 30s breath hold. Mean flow velocity (MFV), peak flow velocity (Vmax), minimal flow velocity (Vmin), Pulsatility Index (PI) and Resistance Index (RI) were quantified. Statistical differences were determined using 2-way ANOVA (Breathhold x group). At baseline, HF patients with and without LVAD implantation had a decreased Vmax, MFV, PI and RI compared to healthy (all P < 0.05). With CO2-retention the absolute and relative increase in MFV was highest in the HM3 group significantly compared with HMII (7.8±2.4 vs 1.6±2.1 cm/s; +16% vs +3%, p<0.01). HM3 and HF subjects exhibited similar absolute and relative changes in MFV and both were lower than health controls. Similar results were seen for Vmax and Vmin, however, there was no change PI or RI in any groups (Fig. 1). The change with MFV with breath-holding was not different when considering HF subjects on inotropes, or when comparing beats with and without artificial pulse in HM3 patients. HM3 patients have a significantly improved CVR to a CO2-retention challenge compared with HMII patients. However, the acute CVR is not altered by the artificial pulse. Since CVR of HM3 patients remains reduced compared with healthy controls, further research is needed to understand the pathophysiology of cerebrovascular complications in LVAD.

Clinical-hemodynamic features of ischemic stroke in patients of young age

58 patients with ischemic stroke were examined (29 young people — the main group and 29 middle-aged people — control group). Among the examined young patients, cardio embolic subtype of stroke prevailed (66 %), and among middle-aged patients was observed in 10 %. The athe rothrombotic subtype of stroke prevailed in middle-aged people (69 %), and among young people — 24 %. The lacunar subtype of stroke in young people was 3 %, and in middle-aged people — 21 %. Patients of young had such subtypes of strokes as hemodyna mic and hemorheological, which respectively equaled 3 %. In middle age these subtypes of strokes were not observed among the examined patients. In young people the proportion of vascular pools with ische mic stroke was: vertebrobasilar — 41 %, carotid prevailed to some extend — 59 %. In middle-aged people the proportion of strokes prevailed in the carotid pool — 64 %, in the vertebrobasilar it was 29 %. Middle-aged people also had a “combined stroke” (stroke that occurred in several pools at once), it amounted to 7 %. As a result, Doppler study of cerebral vessels proved that in young people linear velocity in the right middle cerebral artery was authentically higher compared with middle-aged patients. At the same time, the linear velocity in middle-aged patients was statistically greater in the left vertebral artery. Keywords: ischemic stroke subtypes, young age, hemodynamic parameters

Transient cerebral blood flow responses during microgravity

PurposeA number of studies has well described central cardiovascular changes caused by changing gravity levels as they occur e.g. during parabolic flight. limited data exists describing the effect of microgravity on the cerebrovascular system and brain perfusion. MethodsIn this study middle cerebral artery velocity (MCAv) of 16 participants was continuously monitored on a second-by-second basis during 15 consecutive parabolas (1G, 1,8G, 0G, 1,8G) using doppler ultrasound. Simultaneously central cardiovascular parameters (heart rate, mean arterial blood pressure, cardiac output) were assessed. ResultsResults revealed an immediate reaction of central cardiovascular parameters to changed gravity levels. In contrast, changes in MCAv only initially were in accordance with a normal cerebral autoregulation. Whereas all of the measured central cardiovascular parameters seemed to have reached a steady state after approximately 8 s of microgravity, MCAv, after an initial decrease with the onset of microgravity, increased again during the second half of the microgravity phase. ConclusionIt is concluded that this increase in MCAv during the second half of the microgravity period reflects a decrease of cerebrovascular resistance caused by a pressure driven increased venous outflow and/or a contraction of precapillary sphincters in order to avoid hyperperfusion of the brain.

Self-Reported Omega-3 Supplement Use Moderates the Association between Age and Exercising Cerebral Blood Flow Velocity in Older Adults.

Cerebral blood flow (CBF) decreases across the lifespan, and chronic conditions such as dementia and stroke accelerate this decline. Impaired CBF results in reduced delivery of oxygen and nutrients, which can damage the brain over time. Thus, there is a need to identify lifestyle interventions, including diet and exercise, to maintain CBF with aging and in the presence of chronic disease. In the present study, we used transcranial Doppler ultrasound to record middle cerebral artery velocity (MCAv), a surrogate measure of CBF, during moderate-intensity exercise in sedentary, cognitively normal older adults (n = 90). A multiple linear regression model (F(4, 85) = 3.21, p = 0.02) showed that self-reported omega-3 supplement use significantly moderated the association between age and mean exercising MCAv in these individuals (p = 0.01). Older age was associated with lower exercising MCAv in the group not taking omega-3 supplements, while exercising MCAv showed no decline with increasing age in the group who reported omega-3 supplement use. These findings suggest omega-3 supplementation may have an important role in the preservation of CBF with aging.

Neuropsychological Deficits in Patients with Electrical Status Epilepticus During Sleep: A Non-invasive Analysis of Neurovascular Coupling.

To evaluate the effects of electrical status epilepticus during sleep (ESES) on cerebral blood flow (CBF) and explore the associated neuro-vascular coupling and neuropsychological deficits. 19 ESES patients were recruited to undergo real-time transcranial doppler ultrasonography (TCD) and video-EEG monitoring (vEEG). Patients were grouped based on their cognitive functions or their EEG patterns. The mean cerebral blood flow velocity (CBFVm) of the unilateral middle cerebral artery was measured using TCD and was used to calculate various relevant parameters. The 19 patients participated in a total of 54 effective TCD-vEEG monitoring sessions. We found a significant effect of clinical severity for the following measurements: spike wave index (SWI), peak and average deep sleep stage (N3) CBFVm, peak, average and minimum deep sleep and awake CBFVm, and CBFVm oscillations during deep sleep. Nevertheless, CBFVm oscillations were not related to SWI. Furthermore, CBFVm oscillations revealed a statistically significant difference between the near-ESES and asymmetric-ESES groups. CBFVm oscillations may reflect the neuro-vascular coupling process associated with ESES disfunction. Understanding the relationship between CBFVm oscillations and epileptic activity will be important for assessing the neuropsychological damage associated with ESES and for developing treatment options for this and other diseases.

Study protocol for SFX-01 after subarachnoid haemorrhage (SAS): a multicentre randomised double-blinded, placebo controlled trial

IntroductionSubarachnoid haemorrhage (SAH) from a ruptured cerebral aneurysm carries high morbidity and mortality. Despite huge advances in techniques to secure the aneurysm, there has been little progress in the treatment...

Assessing Cerebrovascular Hemodynamics Using Transcranial Doppler in Patients with Mechanical Circulatory Support Devices.

Mechanical circulatory support (MCS) devices are commonly used in heart failure patients. These devices carry risk for presumably embolic and additionally hemorrhagic stroke. Alterations in blood flow play a key role in stroke pathophysiology, and we aimed to learn more about hemodynamic compromise. In this study, we used transcranial Doppler (TCD) ultrasound to define hemodynamics of commonly used nonpulsatile MCS devices, as well as pulsatile devices, with special attention to the total artificial heart (TAH). From 2/2013 through 12/2016, we prospectively enrolled patients with MCS who underwent TCD imaging. We analyzed TCD parameters, including peak systolic velocity, end-diastolic velocity, pulsatility indices (PIs), and number of high-intensity transient signals. Waveform morphologies were compared between various MCS devices. We performed 132 TCD studies in 86 MCS patients. Waveforms in patients supported by venoarterial-extracorporeal membrane oxygenation demonstrated continuous flow without clear systolic peaks with an average (±SD) PI of .43 (±.2). PIs were low in patients with continuous-flow left ventricular assist devices with a mean PI of .32 (±.13). Impella patients had morphologically distinct pulsatile waveforms and a higher mean PI of .65 (±.24). In intra-arterial balloon pump patients, mean PI was 1.01 (±.16) and diastolic upstrokes were pronounced. In TAH patients, mean middle cerebral artery velocity of 79.69 (±32.33) cm/seconds and PI of .74 (±.14) approached normal values. TCD can detect characteristic waveforms in patients supported by various MCS devices. These device-specific TCD patterns are recognizable and reproducible.

Dynamic cerebral autoregulation in anterior and posterior cerebral circulation during cold pressor test

We hypothesized that cerebral blood flow (CBF) regulation in the posterior circulation differs from that of the anterior circulation during a cold pressor test (CPT) and is accompanied by elevations in arterial blood pressure (ABP) and sympathetic nervous activity (SNA). To test this, dynamic cerebral autoregulation (dCA) in the middle and posterior cerebral arteries (MCA and PCA) were measured at three different conditions: control, early phase of the CPT, and the late phase of the CPT. The dCA was examined using a thigh cuff occlusion and release technique. The MCA and PCA blood velocities were unchanged at CPT compared with the control conditions despite an elevation in the ABP. The dCA in both the MCA and PCA remained unaltered at CPT. These findings suggest that CPT-induced elevations in the ABP and SNA did not cause changes in the CBF regulation in the posterior circulation compared with the anterior circulation.

The impact of acute remote ischaemic preconditioning on cerebrovascular function

PurposeRemote ischaemic preconditioning (RIPC) refers to the protection conferred to tissues and organs via brief periods of ischaemia in a remote vascular territory, including the brain. Recent studies in humans report that RIPC provides neuroprotection against recurrent (ischaemic) stroke. To better understand the ability of RIPC to improve brain health, the present study explored the potential for RIPC to acutely improve cerebrovascular function.MethodsEleven young healthy (females n = 6, age; 28.1 ± 3.7 years) and 9 older individuals (females n = 4, age 52.5 ± 6.7 years) at increased risk for stroke (cardiovascular disease risk factors) underwent assessments of cerebrovascular function, assessed by carbon dioxide (CO2) reactivity and cerebral autoregulation during normo- and hypercapnia (5% CO2) following 40 mins of bilateral arm RIPC or a sham condition. Squat-to-stand manoeuvres were performed to induce changes in blood pressure to assess cerebral autoregulation (0.10 Hz) and analysed via transfer function.ResultsWe found no change in middle cerebral artery velocity or blood pressure across 40 mins of RIPC. Application of RIPC resulted in no change in CO2 reactivity slopes (sham vs RIPC, 1.97 ± 0.88 vs 2.06 ± 0.69 cm/s/mmHg P = 0.61) or parameters of cerebral autoregulation during normocapnia (sham vs RIPC, normalised gain%, 1.27 ± 0.25 vs 1.22 ± 0.35, P = 0.46).ConclusionThis study demonstrates that a single bout of RIPC does not influence cerebrovascular function acutely in healthy individuals, or those at increased cardiovascular risk. Given the previously reported protective role of RIPC on stroke recurrence in humans, it is possible that repeated bouts of RIPC may be necessary to impart beneficial effects on cerebrovascular function.

A young woman with a transfusion-related pregnancy complication.

Individuals with the K0 phenotype are extremely rare. They may develop anti-Ku antibodies, which react with all antigens of the Kell blood group system, thereby leading to haemolytic transfusion reactions and haemolytic disease of the fetus and newborn. A primigravida who was transfused with one unit of red blood cells due to iron deficiency anaemia developed anti-Ku antibodies. The pregnancy was closely monitored by ultrasound and antibody titres. Maternal autologous blood collection was performed twice during the last trimester as back-up in case of maternal peripartum bleeding, and a few frozen K0 red blood cell units were provided in case of severe fetal anaemia. At gestational week 36+6, labour was induced due to increasing antibody titres and high blood velocities in the fetal middle cerebral artery during systole. The woman was delivered vaginally without need for transfusion. The infant was diagnosed with haemolytic disease of the fetus and newborn and treated with phototherapy, repeated infusions of intravenous immunoglobulin and iron supplements until normalisation of haemoglobin at three months of age. Iron deficiency anaemia should be treated primarily with iron supplementation before considering blood transfusions, which pose the risk of developing alloantibodies that can cause transfusion complications and haemolytic disease of the fetus and newborn.

Magnetic resonance angiography and transcranial Doppler ultrasound findings in patients with a clinical diagnosis of vertebrobasilar insufficiency

OBJECTIVE:To evaluate the findings of magnetic resonance angiography (MRA) and transcranial Doppler ultrasound (TCD) in patients with a clinical diagnosis of vertebrobasilar insufficiency (VBI).METHOD:From our outpatient neurotology clinic, we selected patients (using the criteria proposed by Grad and Baloh) with a clinical diagnosis of VBI. We excluded patients with any definite cause for vestibular symptoms, a noncontrolled metabolic disease or any contraindication to MRA or TCD. The patients in the study group were sex- and age-matched with subjects who did not have vestibular symptoms (control group). Our final group of patients included 24 patients (study, n=12; control, n=12).RESULTS:The MRA results did not demonstrate significant differences in the findings between our study and control groups. TCD demonstrated that the systolic pulse velocity of the right middle cerebral artery, end diastolic velocity of the basilar artery, pulsatility index (PI) of the left middle cerebral artery, PI of the right middle cerebral artery, and PI of the basilar artery were significantly higher in the study group than in the control group, suggesting abnormalities affecting the microcirculation of patients with a clinical diagnosis of VBI compared with controls.CONCLUSION:MRA failed to reveal abnormalities in patients with a clinical diagnosis of VBI compared with controls. The PI of the basilar artery, measured using TCD, demonstrated high sensitivity (91%) and specificity (91%) for detecting clinically diagnosed VBI.

Long-term Exercise Confers Equivalent Neuroprotection in Females Despite Lower Cardiorespiratory Fitness

Females are more prone to cognitive decline, stroke and neurodegenerative disease, possibly due to more marked reductions in cerebral blood flow and cerebrovascular reactivity to CO2 (CVRCO2HYPER) in later life. To what extent regular exercise confers selective neuroprotection in females remains unestablished. To examine this, 73 adults were prospectively assigned to 1 of 4 groups based on sex (male, ♂ vs. female, ♀) and physical activity status (trained, ≥150 min of moderate-vigorous intensity aerobic exercise/week; n = 18♂ vs. 18♀ vs. untrained, no formal exercise; n = 18♂ vs. 19♀). Middle cerebral artery velocity (MCAv, transcranial Doppler ultrasound), mean arterial pressure (MAP, finger photoplethysmography) and end-tidal CO2 (capnography) were assessed at rest during normocapnea and hypercapnea (5% CO2) enabling CVRCO2HYPER to be assessed. Cerebrovascular resistance/conductance indices (CVRi/CVCi) were calculated as MAP/MCAv and MCAv/MAP. Maximal oxygen uptake (VO2MAX) was determined during incremental semi-recumbent cycling ergometry to volitional exhaustion. Despite having a lower VO2MAX, females were characterized by selective elevations in MCAv, CVRCO2HYPER and lower CVRi (P < 0.05), but the training responses were similar across sexes. Linear relationships were observed between VO2MAX and CVRCO2HYPER (pooled untrained and trained data; ♂ r = 0.70, ♀ r = 0.51; both P < 0.05) with a consistent elevation in the latter equivalent to ∼1.50%.mmHg−1 compared to males across the spectrum of cardiorespiratory fitness. These findings indicate that despite having comparatively lower levels of cardiorespiratory fitness, the neuroprotective benefits of regular exercise translate into females and may help combat cerebrovascular disease in later life.

Ultrasound angiology reference standards of fetal cerebroplacental flow in normal Egyptian gestation: statistical analysis of one thousand observations

BackgroundDoppler velocity assessment is the most frequently used method in clinical practice to identify fetal well-being, as it is considered as a non-invasive estimation of the fetus and feto-placental circulation. The aim of the current study is to establish longitudinal reference ranges for MCA and UA Doppler velocities, systolic-to-diastolic (S/D) ratio, resistive index (RI) and PI, and cerebroplacental ratio. The current study was a multicentric longitudinal study of 428 singleton pregnancies and 1284 observations. Doppler ultrasound, middle cerebral artery (MCA) and umbilical artery (UA) peaked velocities, and pulsatility index (PI) were evaluated three times throughout a single session over gestational age range of 13–40 weeks.ResultsBased on 1284 observations, new longitudinal reference ranges for fetal middle cerebral peak systolic velocity (PSV), PI, RI, and S/D; reference ranges for umbilical artery PSV, PI, RI, and S/D; and reference ranges for cerebroplacental ratio PSV, PI, RI, and S/D were established. MCA PI, RI, PSV, and S/D curves are of parabolic pattern, and UA PI, RI, and S/D curves are decreased by age while UA PSV curve is of parabolic pattern; furthermore, cerebroplacental ratio (CPR) PI, RI, and S/D curves increased by age while CPR PSV curve decreased then increased by age. The reference ranges were at nearly variant from earlier studies and close to other studies.ConclusionsIn the Doppler data combining both umbilical and cerebral velocimetry, MCA/UA ratio incorporates information not only on placental station but also on fetal response; it is possibly more beneficial in anticipating perinatal outcome.

Cerebral blood flow responses to exercise are enhanced in left ventricular assist device patients after an exercise rehabilitation program.

Cerebral blood flow during exercise is impaired in patients with heart failure implanted with left ventricular assist devices (LVADs). Our aim was to determine whether a 3-mo exercise training program could mitigate cerebrovascular dysfunction. Internal carotid artery (ICA) blood flow and intracranial middle (MCAv) and posterior cerebral (PCAv) artery velocities were measured continuously using Doppler ultrasound, alongside cardiorespiratory measures at rest and in response to an incremental cycle ergometer exercise protocol in 12 LVAD participants (5 female, 53.6 ± 11.8 yr; 84.2 ± 15.7 kg; 1.73 ± 0.08) pre- (PreTR) and post- (PostTR) completion of a 3-mo supervised exercise rehabilitation program. At rest, only PCAv was different PostTR (38.1 ± 10.4 cm/s) compared with PreTR (43.0 ± 10.8 cm/s; P < 0.05). PreTR, the reduction in PCAv observed from rest to exercise (5.2 ± 1.8%) was mitigated PostTR (P < 0.001). Similarly, exercise training enhanced ICA flow during submaximal exercise (~8.6 ± 13.7%), resulting in increased ICA flow PostTR compared with a reduced flow PreTR (P < 0.001). Although both end-tidal partial pressure of carbon dioxide and mean arterial pressure responses during incremental exercise were greater PostTR than PreTR, only the improved was related to the improved ICA flow (R2 = 0.14; P < 0.05). Our findings suggest that short-term exercise training improves cerebrovascular function during exercise in patients with LVADs. This finding should encourage future studies investigating long-term exercise training and cerebral and peripheral vascular adaptation.NEW & NOTEWORTHY Left ventricular assist devices, now used as destination therapy in end-stage heart failure, enable patients to undertake rehabilitative exercise training. We show, for the first time in humans, that training improves cerebrovascular function during exercise in patients with left ventricular assist devices. This finding may have implications for cerebrovascular health in patients with heart failure.

The Effect of Stroke on Middle Cerebral Artery Blood Flow Velocity Dynamics During Exercise.

Previous work demonstrates that older adults have a lower response in the middle cerebral artery velocity (MCAv) to an acute bout of moderate-intensity exercise when compared with young adults. However, no information exists regarding MCAv response to exercise after stroke. We tested whether MCAv response to an acute bout of moderate-intensity exercise differed between participants 3 months after stroke and an age- and sex-matched control group of older adults (CON). A secondary objective was to compare MCAv response between the stroke- and non-stroke-affected MCAv. Using transcranial Doppler ultrasound, we recorded MCAv during a 90-second baseline (BL) followed by a 6-minute moderate-intensity exercise bout using a recumbent stepper. Heart rate (HR), end-tidal CO2 (PETCO2), and beat-to-beat mean arterial blood pressure (MAP) were additional variables of interest. The MCAv response measures included BL, peak response amplitude (Amp), time delay (TD), and time constant (τ). The Amp was significantly lower in the stroke-affected MCAv compared with CON (P < 0.01) and in the nonaffected MCAv compared with CON (P = 0.03). No between-group differences were found between TD and τ. No significant differences were found during exercise for PETCO2 and MAP while HR was lower in participants with stroke (P < 0.01). Within the group of participants with stroke, no differences were found between the stroke-affected and non-stroke-affected sides for any measures. Resolution of the dynamic response profile has the potential to increase our understanding of the cerebrovascular control mechanisms and test cerebrovascular response to physical therapy-driven interventions such as exercise.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A284).

P4518Cerebral blood flow is lower in heart failure patients with reduced ejection fraction

Abstract Purpose Heart and brain interaction is a well-known entity in heart failure (HF) and left ventricular systolic dysfunction poses an increased risk for stroke and cognitive impairment. Transcranial Doppler (TCD) provides valuable information on cerebral blood flow and detects microembolic signals that can be used to determine the risk of cerebrovascular events. However, less is known about cerebral blood flow in HF patients with reduced EF. So, we aimed to evaluate cerebral blood flow rates by means of TCD in HF patients with reduced ejection fraction (EF). Methods This study included 46 HF patients with an EF less than 35% (mean age 65.2±11 years, mean EF 20.1±3.8%) who underwent to TCD examination. In addition, 26 healthy individuals with sinus rhythm and EF &gt;50% (mean age 64.4±9.0 years, mean EF 63.5±2.38%) were included in the study as a control group. Minimum, maximum and mean flow velocities of the both right middle cerebral artery (RMCA) and left middle cerebral artery (LMCA) determined by TCD were analyzed. Results The average of RMCA maximum and mean flow velocities were found to be significantly lower in HF patients than those in control group (76,06±23,7 cm/s and 48,49±16,4 cm/s in HF group vs 87,84±14,5 cm/s and 56,41±10,7 cm/s in control group, p=0,025 and p=0,016, respectively). The average of LMCA maximum and mean flow velocities were also significantly lower in HF patients than those in control group (75,1±22,3 cm/s and 47,57±14.8 cm/s in HF group vs 88,73±17,7 cm/s and 57,15±12,4 cm/s in control group, p=0,009 and p=0,007, respectively). However, there was no significant difference in minimum RMCA or LMCA flow velocities between HF group and control groups (33,5±10,6 cm/s and 32,86±9,58 cm/s in HF group vs 36,34±9,2 cm/s and 36,53±10,4 cm/s in control group, p=0,226 and p=0,157, respectively). No significant microembolic signals were detected in HF and control groups. Conclusions The results of this study showed that HF patients with reduced EF have lower cerebral blood flow velocities as compared to healthy controls, which might be one of the explanations of the adverse interaction between heart and brain in HF.

Intrauterine Fetal Transfusion

1. A woman is pregnant at 31 weeks’ gestation with Rh (D)–negative, antibody-negative blood type. She develops a placental abruption, prompting delivery of a viable preterm infant with Rh (D)–positive blood type. Which of the following is recommended after delivery to prevent D-alloimmunization in the mother? 2. Unfortunately she does not receive the appropriate treatment. She then has a miscarriage while traveling and has an extremely elevated anti-D antibody titer in her next pregnancy 2 years later. She is diagnosed with fetal anemia at 22 weeks’ gestation and ultimately has a procedure ( Video 1). What procedure is being shown in this video? Video 1. Click here to view the video. Fetal intraperitoneal transfusion. Alloimmunization is the development of antibodies to foreign red blood cell antigens. Fetal red blood cell antigens are determined by maternal and paternal red blood cell phenotypes. If the fetus expresses antigens foreign to the pregnant woman, the woman can develop immunoglobulin G (IgG) antibodies to this …

Reduced cerebrovascular and cardioventilatory responses to intermittent hypoxia in elderly

BackgroundThe impact of aging on cerebrovascular function and tissue oxygenation during graded hypoxemia is incompletely known. This study compared the age effect on these variables during cyclic hypoxemia-reoxygenation. MethodsHypoxia-induced changes in arterial (SaO2) and cerebral tissue (ScO2) O2 saturation, middle cerebral arterial flow velocity (VMCA), estimated cerebral vascular conductance (CVC), heart rate (HR) and ventilation were compared between 12 elderly (71 ± 2 yr, 7 women) and 13 young (24 ± 3 yr, 5 women) adults during the first and fifth 5-min exposures to 10% O2. ResultsAlthough pre-hypoxia SaO2 did not differ between the groups, ScO2 was lower (P < 0.05) in the elderly (68.4 ± 1.2%) than young (73.8 ± 0.9%) adults, commensurate with a lower resting VMCA (P < 0.05). SaO2 fell less sharply (P < 0.05) in the elderly subjects during the first and fifth hypoxia exposures. Moreover, the responses of ScO2, VMCA, CVC, HR and breathing frequency to hypoxia were attenuated in the elderly subjects. Systolic and diastolic arterial pressures fell by 2–6 mmHg during hypoxia in both young and elderly. Thus, hypoxemia developed more gradually in elderly than young adults during normobaric hypoxia, concordant with a reduced metabolic demand in the elderly. ConclusionsThe elderly adults safely tolerated cyclic, moderate hypoxemia which lowered SaO2 by 20–25%, despite dampening of cerebrovascular and cardiac responses to hypoxemia.

Hemodynamic Surveillance of Unilateral Carotid Artery Stenting in Patients With or Without Contralateral Carotid Occlusion by TCD/TCCD in the Early Stage Following Procedure.

Objective: To evaluate the cerebral hemodynamic variations in patients with unilateral carotid artery stenosis and contralateral carotid occlusion (CCO) in hours following carotid artery stenting (CAS) by transcranial Doppler (TCD) or transcranial color-code Doppler (TCCD).Methods: Sixty-five consecutive patients who underwent unilateral CAS were enrolled. Among them, 14 patients had ipsilateral severe stenosis and CCO (CCO group) while the other 51 patients had only unilateral severe carotid stenosis without CCO (UCS group). All patients underwent TCD or TCCD monitoring before, at 1 and 3 h after CAS. We monitored bilateral middle cerebral artery (MCA) peak systolic velocity (PSV), pulsatility index (PI), and blood pressure (BP), and compared that data between two groups.Results: In UCS group, ipsilateral MCA PSV increased relative to baseline at 1 h (96 ± 30 vs. 85 ± 26 cm/s, 15%, P < 0.001) and 3 h (97 ± 29 vs. 85 ± 26 cm/s, 17%, P < 0.001) following CAS. Significant PI increases were observed at 1 and 3 h following CAS on the ipsilateral side. In CCO group, ipsilateral MCA PSV increased relative to baseline at 1 h (111 ± 30 vs. 83 ± 26 cm/s, 35%, P < 0.001) and 3 h (107 ± 28 vs. 83 ± 26 cm/s, 32%, P <0.001) following CAS. The magnitude of ipsilateral MCA PSV increase was significantly higher in CCO group compared with UCS group at 1 h (P = 0.002) and 3 h (P = 0.024) following CAS, while BP similarly decreased between the two groups. On the contralateral side, significant MCA PSV increases were observed following CAS in CCO group but not in UCS group. Bilateral MCA PSV increases were higher in patients with a stenosis degree of ≥90% than in patients with stenosis degree of 70–89% only in CCO group.Conclusion: The ipsilateral MCA PSV and PI increase moderately in the initial hours after unilateral CAS in patients without CCO. In patients with CCO, the ipsilateral, and contralateral MCA PSV increase significantly in the early stage following CAS. CCO is a factor of the increased blood flow velocity in ipsilateral MCA after unilateral CAS.

Early cardiovascular function and associated hemodynamics in adults with isolated moderate-severe traumatic brain injury: A pilot study

BackgroundWhile cardiac dysfunction has been described following traumatic brain injury (TBI), its association with systemic and cerebral hemodynamics is not known. We examined the contemporaneous relationship between early cardiac function with systemic and cerebral hemodynamic parameters after moderate-severe TBI. MethodsBedside transthoracic echocardiography (TTE) and transcranial Doppler (TCD) ultrasonography were performed within 24 h in patients > 18 years with isolated moderate-severe TBI. Systemic hemodynamic parameters were quantified using routine monitoring [heart rate and mean arterial pressures (MAP)] and calculation from echocardiographic data [stroke volume index (SVI), cardiac index (CI), and systemic vascular resistance index (SVRI)]. Systolic dysfunction was defined using TTE as global longitudinal strain (GLS) > -16%. Mean middle cerebral artery velocity (FVm) was the measure of cerebral hemodynamics and quantified using TCD. ResultsAmong 15 patients [mean age 43 ± 13 years, GCS 5 ± 3, 73% male], 15 TTE and 15 TCD exams were performed simultaneously. Five (33%) patients had systolic dysfunction, with significantly worse GLS (median [IQR] −12.1% [−14.1, −12] vs. −19.1% [−19.9, −17.7], p = 0.004). Median (IQR) MAP was 97 (89, 107) mmHg, SVI (29.0 [20.5, 31.0] mL m−2), and CI (2.83 [2.05, 3.10] L/min m−2) were low to normal, while SVRI (2704 dyne sec/cm5 m−2 [2210, 4084]) was normal to high. None of the patients had abnormal TCDs. Higher GLS (reduced systolic function) was associated with lower SVI (r2 = 0.274, p = 0.03) but not other parameters. ConclusionSystemic hemodynamic parameters were consistent with an early catecholamine-excess state. While reduced systolic function was associated with lower SVI, there was no relationship with reduced cerebral perfusion, possibly due to normal MAP.