Alterations In Hemodynamic Responses Research Articles

Cortical Hemodynamic Response and Connectivity Modulated by Sub-threshold High-Frequency Repetitive Transcranial Magnetic Stimulation.

Repetitive transcranial magnetic stimulation (rTMS) at sub-threshold intensity is a viable clinical strategy to enhance the sensory and motor functions of extremities by increasing or decreasing motor cortical excitability. Despite this, it remains unclear how sub-threshold rTMS modulates brain cortical excitability and connectivity. In this study, we applied functional near-infrared spectroscopy (fNIRS) to investigate the alterations in hemodynamic responses and cortical connectivity patterns that are induced by high-frequency rTMS at a sub-threshold intensity. Forty high-frequency (10 Hz) trains of rTMS at 90% resting motor threshold (RMT) were delivered through a TMS coil placed over 1–2 cm lateral from the vertex. fNIRS signals were acquired from the frontal and bilateral motor areas in healthy volunteers (n = 20) during rTMS administration and at rest. A significant reduction in oxygenated hemoglobin (HbO) concentration was observed in most defined regions of interest (ROIs) during the stimulation period (p < 0.05). Decreased functional connectivity within prefrontal areas as well as between symmetrical ROI-pairs was also observed in most participants during the stimulation (p < 0.05). Results suggest that fNIRS imaging is able to provide a reliable measure of regional cortical brain activation that advances our understanding of the manner in which sub-threshold rTMS affects cortical excitability and brain connectivity.

Noninvasive measurements of hemodynamic, autonomic and endothelial function as predictors of mortality in sepsis: A prospective cohort study.

Background and aimSepsis is associated with marked alterations in hemodynamic responses, autonomic dysfunction and impaired vascular function. However, to our knowledge, analysis of noninvasive markers to identify greater risk of death has not yet been investigated. Thus, our aim was to explore the prognostic utility of cardiac output (CO), stroke volume (SV), indices of vagal modulation (RMSSD and SD1), total heart rate variability (HRV) indices and FMD of brachial artery (%FMD), all measured noninvasively, in the first 24 hours of the diagnosis of sepsis.Methods60 patients were recruited at ICU between 2015 and 2017 and followed by 28 days. CO, SV, RR intervals were measurement. Doppler ultrasound was used to assess brachial artery FMD and the hyperemic response were obtained (%FMD). Patients were divided by survivors (SG) and nonsurvivors groups (NSG).ResultsA total of 60 patients were analysed (SG = 21 and NSG = 39). Survivors were younger (41±15 years vs. 55±11 years) and used less vasoactive drugs. As expected, APACHE and SOFA scores were lower in NSG compared to SG. In addition, higher SD1, triangular index, % FMD, velocity baseline and hyperemia flow velocity as well as lower HR values were observed in the SG, compared to NSG (P<0.05). Interestingly, RMSSD and SD1 indices were independent predictors of %FMD, ΔFMD and FMDpeak. RMSSD threshold of 10.8ms and %FMD threshold of -1 were optimal at discriminatomg survivors and nonsurvivors.ConclusionNoninvasive measurements of autonomic and endotelial function may be important markers of sepsis mortality, which can be easily obtained in the early stages of sepsis at the bedside.

Alterations in Hemodynamic Response to Laryngoscopy and Intubation by Lidocaine, Esmolol, and Nitroglycerin-A comparative study

Alterations in Hemodynamic Response to Laryngoscopy and Intubation by Lidocaine, Esmolol, and Nitroglycerin-A comparative study

Re-examine tumor-induced alterations in hemodynamic responses of BOLD fMRI: implications in presurgical brain mapping

Blood oxygenation level dependent (BOLD) fMRI is used for presurgical functional mapping of brain tumor patients. Abnormal tumor blood supply may affect hemodynamic responses and BOLD fMRI signals. To perform a multivariate and quantitative investigation of the effect of brain tumors on the hemodynamic responses and its impact on BOLD MRI signal time course, data analysis in order to better understand tumor-induced alterations in hemodynamic responses, and accurately mapping cortical regions in brain tumor patients. BOLD fMRI data from 42 glioma patients who underwent presurgical mapping of the primary motor cortex (PMC) with a block designed finger tapping paradigm were analyzed, retrospectively. Cases were divided into high grade (n = 24) and low grade (n = 18) groups based on pathology. The tumor volume and distance to the activated PMCs were measured. BOLD signal time courses from selected regions of interest (ROIs) in the PMCs of tumor affected and contralateral unaffected hemispheres were obtained from each patient. Tumor-induced changes of BOLD signal intensity and time to peak (TTP) of BOLD signal time courses were analyzed statistically. The BOLD signal intensity and TTP in the tumor-affected PMCs are altered when compared to that of the unaffected hemisphere. The average BOLD signal level is statistically significant lower in the affected PMCs. The average TTP in the affected PMCs is shorter in the high grade group, but longer in the low grade tumor group compared to the contralateral unaffected hemisphere. Degrees of alterations in BOLD signal time courses are related to both the distance to activated foci and tumor volume with the stronger effect in tumor distance to activated PMC. Alterations in BOLD signal time courses are strongly related to the tumor grade, the tumor volume, and the distance to the activated foci. Such alterations may impair accurate mapping of tumor-affected functional areas when using conventional fixed models.

Comparison of hemodynamic responses to orotracheal intubation between using Airtraq(R) laryngoscope and Macintosh laryngoscope

bjective To compare the hemodynamic responses to orotracheal intubation between Airtraq(R)laryngoscope and Macintosh laryngoscope. Methods 40 patients scheduled for surgery under general anesthesia requiting orotracheal intubation were randomly allocated to undergo intubation using Airtraq (R)(group A, n=20) or Macintosh(group M, n=20) laryngoscope. The following data were recorded and analyzed: glottic exposure time, tracheal intubation time, blood pressure(BP) and heart rate(HR) before and after anesthetic induction, at intubation and thereafter at 1 and 3 min. The rate pressure product (RPP) at each measuring time point was calculated. Results There was no significant difference in the glottic exposure time between the two groups,but the intubation time in M group (10±4) s were significantly longer than that in A group (6±4) s. Compared with base value preinduction, BP, HR and RPP were significantly decreased in both groups.Glottic exposure and tracheal intubation caused significant increases in BP, HR,and RPP as compared with postinduction values. In group M, BP, HR and RPP at 3 min after indubation [SBP (106±17) mm Hg,DBP (65±10) mm Hg,MAP (78±19) nun Hg,HR (92±12) beat/min,RPP (9748±2072)]were significant higher than that with postinduction values [SBP (93±15) mm Hg,DBP(54±9) mm Hg,MAP(67±10) mm Hg,HR(85±12) beat/min,RPP(8117±1886)].But both A and M group,BP,HR and RPP at 5 min after indubation were no significant with postinduction values. Conclusion In comparison to the Macintosh laryngoscope, tracheal intubation with the Airtraq(R)laryngoscope resulted in less alterations in hemodynamic responses. Key words: Airtraq (R) laryngoscope; Macintosh laryngoscope; Orotracheal intubation hemodynamic responses

Renal hemodynamic changes during serial seizures in rats

Renal blood flow (RBF) and mean arterial blood pressure (MABP) were measured during serially induced seizures in anesthetized paralyzed rats to investigate possible alterations in hemodynamic responses during experimental status epilepticus. During initial seizures, MABP increased from 143 to 193 mmHg, and RBF decreased from 4.8 to 1.5 ml/min. In contrast, MABP fell from 124 to 100 mmHg and RBF dropped from 3.6 to 2.8 ml/min during late seizures. The large decreases in RBF during initial seizures were blocked by renal denervation or bilateral adrenalectomy. During the period of late seizures, both the increase in MABP and the decrease in RBF in response to intravenous boluses of norepinephrine fell to 55% of the preseizure value. Our data indicate that the marked decreases in RBF during early seizures can be mediated by either the renal nerves or the adrenal glands. Furthermore, decreased sensitivity of the vasculature to norepinephrine likely contributes to the diminution of both MABP and RBF responses during later seizures.