Hemodynamic Changes In Response Research Articles

Initial orthostatic hypotension among patients with unexplained syncope: An overlooked diagnosis?

BackgroundInitial orthostatic hypotension (IOH) is a clinical syndrome of transient orthostatic hypotension that is defined as a drop in blood pressure of >40 mm Hg systolic and/or >20 mm Hg diastolic within 15 s after standing, accompanied by symptoms of cerebral hypoperfusion, but without sustained orthostatic hypotension (blood pressure decrease >20/10 mm Hg after 1–3 min of standing). As the etiology of syncope remains unknown in a large proportion of patients, we hypothesized that IOH is highly prevalent among patients with unexplained syncope. MethodsWe studied 250 consecutive outpatients with unexplained syncope that were evaluated in the syncope-unit of our tertiary referral hospital. We measured hemodynamic changes in response to active standing using a beat-to-beat blood pressure measurement device, first after lying supine for >5 min and then after squatting for 30 s. Results11.2% of the patients were diagnosed with syncope due to IOH, with a mean fall in blood pressure of 47.4 ± 12.5/29.0 ± 10.7 mm Hg within 15 s after standing up. Therefore, IOH was the second commonest cause of syncope in our cohort. 46.2% of the patients diagnosed with syncope due to IOH used antihypertensive drugs, mostly betablockers (41.6%) and/or tamsulosin (24.9%). The squatting-to-standing-test in addition to the lying-to-standing-test resulted in only 3 additional patients diagnosed with syncope due to IOH. ConclusionsIOH is highly prevalent among patients with previously unexplained syncope. Therefore, beat-to-beat blood pressure measurement should be considered in patients with unexplained syncope.

Correlation of changes in hemodynamic response as measured by cerebral optical spectrometry with subjective pain ratings in volunteers and patients: a prospective cohort study.

PurposeNoninvasive cerebral optical spectrometry is a promising candidate technology for the objective assessment physiological changes during pain perception. This study’s primary objective was to test if there was a significant correlation between the changes in physiological parameters as measured by a cerebral optical spectrometry-based algorithm (real-time objective pain assessment [ROPA]) and subjective pain ratings obtained from volunteers and laboring women. Secondary aims were performance assessment using linear regression and receiver operating curve (ROC) analysis.Patients and methodsProspective cohort study performed in Human Pain Laboratory and Labor and Delivery Unit. After institutional review board approval, we evaluated ROPA in volunteers undergoing the cold pressor test and in laboring women before and after epidural or combined spinal epidural placement. Linear regression was performed to measure correlations. ROCs and corresponding areas under the ROCs (AUC), as well as Youden’s indices, as a measure of diagnostic effectiveness, were calculated.ResultsCorrelations between numeric rating scale or visual analog scale and ROPA were significant for both volunteers and laboring women. AUCs for both volunteers and laboring women with numeric rating scale and visual analog scale subjective pain ratings as ground truth revealed at least good (AUC: 70%–79%) to excellent (AUC >90%) distinction between clinically meaningful pain severity differentiations (no/mild–moderate–severe).ConclusionCerebral Optical Spectrometry-based ROPA significantly correlated with subjectively reported pain in volunteers and laboring women, and could be a useful monitor for clinical circumstances where direct assessment is not available, or to complement patient-reported pain scores.

Roles and mechanism of protein kinase D in vasoconstriction

Protein kinase D (PKD) is known to be implicated in a variety of cellular processes and physiological functions, including cell motility, cardiac contraction, angiogenesis and smooth muscle contraction through regulation of multiple molecules. Although these regulations are presumed to be closely associated with vasomotor activity, role of PKD in vascular function is unknown. Then, we investigated the role of PKD in systemic circulation and contraction of aorta in in rats. We also investigated precise role s of PKD isoforms using human aortic smooth muscle cells (HASMCs) with RNA interference.Material and methodsSystemic blood pressure (SBP) through femoral artery, cardiac output (CO) and systemic vascular resistances (SVR) were measured in Sprague‐Dawley rats. The hemodynamic changes in response to intravenous injections of PKD inhibitor, CRT0066101 were recorded. Isometric tension of aorta ring samples was measured to examine inhibitory effect of CRT0066101 on norepinephrine (NE)‐induced contraction. To explore mechanisms of PKD in vasomotor activity, phosphorylations of PKD, myosin targeting subunit‐1 (MYPT1), CPI‐17, regulatory myosin light chain (RLC) and heat shock protein 27 (HSP27) stimulated with NE were measured as an index of activation of the pathways in aorta rings. In HASMCs, simultaneous measurements of intracellular calcium concentrations and cell shortening with NE stimulation were performed. PKD1, 2, and 3 were knocked down by their specific siRNA respectively in HASMCs for measurements of phosphorylation of PKD, MYPT1, CPI‐17 and RLC and actin polymerization.ResultsInjection of CRT0066101 decreased SBP and SVR. CRT0066101 also inhibited NE‐induced contraction in aorta rings dose‐dependently. In the rings, NE increased phosphorylations of PKD, MYPT1, RLC and CPI‐17, which were attenuated by pretreatment of CRT0066101 except CPI‐17. NE did not increase HSP27 phosphorylation in the rings. In HASMCs, CRT0066101 inhibited NE‐induced cell shortening without affecting increased calcium concentrations. In HASMCs, increased phosphorylations of MYPT1 and RLC with NE were significantly inhibited by PKD1 but not PKD2, 3 knock down. NE did not affect actin polymerization in the cells. Collectively, attenuation of NE‐induced contraction of aorta rings with CRT0066101 was associated with decreased phosphorylations of MYPT1 and RLC, but not CPI‐17 and HSP27. In HASMCs, PKD1 knocked down or PKD inhibition attenuated NE‐induced phosphorylation of MYPT1 and RLC without affecting actin polymerization and intracellular calcium regulation.ConclusionsPKD1 may play roles in contraction of aorta and systemic circulation. The regulation of vasomotor activity by PKD1 may be associated with phosphorylation of MYPT1. Understanding of PKD may lead to novel regulation of circulation.Support or Funding InformationThis work was supported by Grant‐in‐Aid for Scientific Research (C) 17K11058 from Japan Society for the Promotion of ScienceThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sex differences in hemodynamic responses and long-term survival to optimal medical therapy in patients with pulmonary arterial hypertension

It is widely known that the incidence of pulmonary arterial hypertension (PAH) is higher in female, whereas prognosis is poorer in male patients. However, sex differences in hemodynamic response to and long-term prognosis with PAH-targeted treatment in the modern era remain to be fully elucidated. We examined the long-term prognosis of 129 consecutive PAH patients (34 males and 95 females) diagnosed in our hospital from April 1999 to October 2014, and assessed hemodynamic changes in response to PAH-targeted therapy. Female patients had better 5-year survival compared with male patients (74.0 vs. 53.4%, P = 0.003); however, higher age quartiles in females were associated with poor outcome. Follow-up examination after medical treatment showed significant decreases in mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), and pulmonary arterial capacitance (PAC) in both sexes (both P < 0.05), whereas only females had a significant improvement in right ventricular end-diastolic pressure (RVEDP), right atrial pressure (RAP), cardiac index, and mixed venous oxygen saturation (SvO2) (all P < 0.05). Baseline age significantly correlated with the hemodynamic changes only in female patients; particularly, there were significant sex interactions in RVEDP and RAP (both P < 0.10). The multivariable analysis showed that SvO2 at baseline and mPAP and SvO2 at follow-up were significant prognostic factors in males, whereas the changes in mPAP, PVR, and PAC and use of endothelin-receptor antagonist in females. These results indicate that female PAH patients have better long-term prognosis than males, for which better improvements of right ventricular functions and hemodynamics may be involved.

Using Functional Near-Infrared Spectroscopy to Measure Effects of Delta 9-Tetrahydrocannabinol on Prefrontal Activity and Working Memory in Cannabis Users.

Intoxication from cannabis impairs cognitive performance, in part due to the effects of Δ9-tetrahydrocannabinol (THC, the primary psychoactive compound in cannabis) on prefrontal cortex (PFC) function. However, a relationship between impairment in cognitive functioning with THC administration and THC-induced change in hemodynamic response has not been demonstrated. We explored the feasibility of using functional near-infrared spectroscopy (fNIRS) to examine the functional changes of the human PFC associated with cannabis intoxication and cognitive impairment. Eighteen adult regular cannabis users (final sample, n = 13) performed a working memory task (n-back) during fNIRS recordings, before and after receiving a single dose of oral synthetic THC (dronabinol; 20–50 mg). Functional data were collected using a continuous-wave NIRS device, in which 8 Sources and 7 detectors were placed on the forehead, resulting in 20 channels covering PFC regions. Physiological changes and subjective intoxication measures were collected. We found a significant increase in the oxygenated hemoglobin (HbO) concentration after THC administration in several channels on the PFC during both the high working memory load (2-back) and the low working memory load (0-back) condition. The increased HbO response was accompanied by a trend toward an increased number of omission errors after THC administration. The current study suggests that cannabis intoxication is associated with increases in hemodynamic blood flow to the PFC, and that this increase can be detected with fNIRS.

Changes in hemodynamic responses during movements of the upper extremities in the acute phase after stroke: A fNIRS study

The acute phase of stroke is accompanied by functional changes and interplay of both hemispheres. However little is known on how the time course of functional motor recovery is related to the progression of symmetry in the motor areas of the brain. This study aimed to assess the time course of both hemodynamic patterns of cortical motor areas using functional near infrared spectroscopy (fNIRS) and functional recovery during the first months after stroke. Unaffected upper limb movements-related contralateral motor areas activity showed no significant changes. Eight right-handed first ischemic/hemorrhagic stroke patients (60 ± 8 yrs, 3 female and 5 men) with mild to severe hemiparesis were examined with fNIRS measurements and functional motor recovery (Fugl-Meyer score) tests every two weeks during two months (five sessions). We investigated hemodynamic changes over the contralateral and ipsilateral motor areas with a 2 × 8-channel fNIRS system (Oxymon MkIII ® ) during a unilateral intermittent isometric forearm task (1 Hz) at self-selected submaximal force levels. Laterality index (LI) was computed to evaluate the asymmetry of hemodynamic changes from the two hemispheres. Affected upper limb movements were associated early with a bilateral cortical activity before shifting to contralateral patterns ( P < 0.01). Progressive lateralization was observed with LI increases over the first 4 sessions (from −0.24 ± 0.18 to 0.36 ± 0.27, P < 0.05) prior to level off (session 5, 0.25 ± 0.39), as did the Fugl-Meyer score. These findings suggest that cortical reorganization monitoring with fNIRS during the first weeks after stroke should be considered further when assessing functional motor recovery in stroke rehabilitation services.

Physiological changes of pneumoperitoneum during laproscopic cholecystectomy

Background: Recently, the frequency and indication for laparoscopic surgery have increased, and laparoscopic cholecystectomy has been widely accepted as an alternative to laparotomy.To carry out the laparoscopic procedure, a pressure gas, most commonly co2 is used. It is important to know the pathophysiological changes that are caused by an increase in intra-abdominal pressure and by the absorption of co2 from an co2 pneumoperitoneum. Aim this study; aims to estimate some physiological changes that caused by pneumoperitoneum during laparoscopic cholecystectomy. Patients and methods: one hundred patients were included in this study randomly selected and consisted of (80 females) and (20 males) their ages were between 19-65 years. Those patients were underwent elective aparoscopic cholecystectomy. we measured some clinical and biochamical parameters (pulmonary function tests, liver function tests, serum urea and creatinine) 24hr before operation as control and 24hr after operation , also we measured end tidal co2(ETCO2),serum aldosterone, potassium and sodium before insufflation of CO2(as control)and at the end of insufflation ,blood pressure and heart rate recorded at different time throughout the operation.&#x0D; Results: there is a statistically significant changes in haemodynamic responses (systolic, diastolic and heart rate) after pneumoperitoneum and changes in position; Pulmonary function tests (VC, FVC, FEV1, FEV1/FVC) show highly significant decrease (p&lt;0.01) ,highly significant increase (p&lt;0.01) in serum level of ALT and AST enzymes 24hrs post-operative . There was highly significant increase (p&lt;0.01) in ETCO2, serum aldosterone and serum potassium level . Serum sodium, urea and creatinine show no significant changes.Conclusion: we concluded that laparoscopic cholecystectomy causes notable physiological alteration intraoperatively and postoperatively, caused mainly by pneumoperitoneum and change in position.

Comparative Effects of Fentanyl, Medazolam, Lignocaine and Propranolol on Controlling the Hemodynamic Pressor Response during Laryngoscopy and Intubation

Laryngoscopy and tracheal intubation are considered the most invasive stimuli in anesthesia. They provoked cardiovascular responses that include hypertension, tachycardia and dysrhythmias. Various pharmacological approaches have been used to blunt or attenuate such pressor responses. The present study was designed to evaluate the effect of medazolom, lignocaine and propranolol as a valuable adjuvant to fentanyl in attenuating hemodynamic responses to endotracheal intubation in normotensive patients. Thirty two patient with physical status I or II according to the score of American Society of Anesthesiologist (ASA), scheduled for elective surgery under standard general anesthesia, were randomly allocated into four groups (8 patients in each group), assigned as F, M, L and P groups. Each patient in the four groups received 1 µg/kg i.v fentanyl. Patients in groups M, L and P are treated with 0.2 mg/kg i.v medazolam, 1.5mg/kg i.v lignocaine and 0.01mg/kg i.v propranolol respectively. Induction of anesthesia was then accomplished with 2mg/kg thiopental sodium followed by1.5mg/kg succinylcholine. Tracheal intubation was performed 2 minutes after induction of anesthesia. Heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure and rate pressure product were measured before induction, after induction and at 2, 4, 6 and 8 minutes after intubation. The results indicated no significant variation in the hemodynamic pressor response in all four groups with tracheal intubation. In conclusion, a minimum effective dose of i.v pre-medications (fentanyl, medazolom, lignocaine and propranolol) were found to be individually successful in attenuating and providing a reliable control of all hemodynamic response changes accompanied the process of laryngoscopy and intubation. Therefore, all are proved effective premedication and no one being superior.&#x0D; Key words: fentanyl, medazolom, lignocaine, propranolol, endotracheal intubation, hemodynamic response.

Non-Invasive Respiratory Impedance Enhances Cerebral Perfusion in Healthy Adults.

Optimization of cerebral blood flow (CBF) is the cornerstone of clinical management in a number of neurologic diseases, most notably ischemic stroke. Intrathoracic pressure influences cardiac output and has the potential to impact CBF. Here, we aim to quantify cerebral hemodynamic changes in response to increased respiratory impedance (RI) using a non-invasive respiratory device. We measured cerebral perfusion under varying levels of RI (6 cm H2O, 9 cm H2O, and 12 cm H2O) in 20 healthy volunteers. Simultaneous measurements of microvascular CBF and middle cerebral artery mean flow velocity (MFV), respectively, were performed with optical diffuse correlation spectroscopy and transcranial Doppler ultrasound. At a high level of RI, MFV increased by 6.4% compared to baseline (p = 0.004), but changes in cortical CBF were non-significant. In a multivariable linear regression model accounting for end-tidal CO2, RI was associated with increases in both MFV (coefficient: 0.49, p < 0.001) and cortical CBF (coefficient: 0.13, p < 0.001), although the magnitude of the effect was small. Manipulating intrathoracic pressure via non-invasive RI was well tolerated and produced a small but measurable increase in cerebral perfusion in healthy individuals. Future studies in acute ischemic stroke patients with impaired cerebral autoregulation are warranted in order to assess whether RI is feasible as a novel non-invasive therapy for stroke.

Abstract WP432: Non-invasive Respiratory Impedance Enhances Cerebral Perfusion

Background: Optimization of cerebral blood flow is the cornerstone of clinical management in a number of neurologic diseases, most notably ischemic stroke. Intra-thoracic pressure influences cardiac output and has the potential to impact cerebral blood flow (CBF). Here we aim to quantify cerebral hemodynamic changes in response to increased respiratory impedance using a non-invasive respiratory device. Methods: Cerebral perfusion was measured under varying levels of respiratory impedance (6cm H 2 0, 9cm H 2 0, and 12 cm H 2 0) in 20 healthy volunteers. Simultaneous measurements of microvascular CBF and middle cerebral artery mean flow velocity (MFV), respectively, were performed with optical diffuse correlation spectroscopy (DCS) and transcranial Doppler ultrasound (TCD). Results: At the high level of respiratory impedance, mean flow velocity increased by 6.4% compared to baseline (p=0.004), but changes in cortical CBF were smaller and non-significant (Figure). Heart rate, cardiac output, respiratory rate, and end tidal CO 2 remained stable during all levels of respiratory impedance. There was small increase in mean arterial blood pressure, 1.7% (p=0.006), at the high level of respiratory impedance. In a multivariable linear regression model accounting for end tidal CO 2 and individual variability, respiratory impedance was associated with increases in both mean flow velocity (coefficient: 0.49, p&lt;0.001) and cortical CBF (coefficient: 0.13, p&lt;0.001). Conclusions: Manipulating intrathoracic pressure via non-invasive respiratory impedance was well tolerated and produced a small but measurable increase in cerebral perfusion in healthy individuals. Future studies in acute ischemic stroke patients with impaired cerebral autoregulation is warranted in order to assess whether respiratory impedance is feasible as a novel non-invasive therapy for stroke.

Hemodynamic changes in response to the stimulated visual quadrants : A study with 24-channel near-infrared spectroscopy( Brain Imaging and Psychonomic Science)

Hemodynamic changes in response to the stimulated visual quadrants : A study with 24-channel near-infrared spectroscopy( Brain Imaging and Psychonomic Science)

Effect of Aerobic Fitness on Hemodynamic Responses to Upright Tilting

The purpose of this study was to examine the influence of aerobic fitness on heart rate, systolic and diastolic blood pressure, mean arterial pressure, and pulse pressure responses to upright tilting in 10 below-average (BA Group) and 10 above-average (AA Group) aerobically fit adults. Aerobic fitness levels were predicted using the Astrand and Ryhming submaximal exercise test. Mean predicted maximal aerobic capacities were significantly higher (p less than .05) for the AA Group (46.0 +/- 6.0 mL.kg-1.min-1) compared with the BA Group (31.0 +/- 4.8 mL.kg-1.min-1) subjects. Heart rate and blood pressure responses were obtained at rest (supine position for 30 minutes) and during 5 minutes of upright tilting to 70 degrees (electric tilt table). A two-factor analysis of variance indicated that the increase in heart rate to upright tilting was significant (p less than .05) (significant treatment effect). More importantly, the study revealed a significant treatment x group interaction (p less than .05), indicating that the heart rate response for the BA Group was significantly greater than for the AA Group. Similar results occurred for blood pressure responses. A separate analysis of variance demonstrated significant changes in hemodynamic responses to upright tilting and significant treatment x group interactions. These results demonstrated significantly smaller (p less than .05) changes in blood pressure and heart rate to upright tilting for the AA Group compared with the BA Group. The results, therefore, indicate that reflex responses to central hypovolemia are different between above-average and below-average aerobically fit adults.

Persistence of impulsivity in pediatric and adolescent patients with obsessive-compulsive disorder.

Increasing clinical evidence points to impulsivity as a symptom of obsessive-compulsive disorder (OCD). However, little is known about its persistence over time. In this study, we evaluated the performance of 12 pediatric patients with OCD on the Stroop color-word task, which assesses impulsivity, and compared this with age- and sex-matched controls. In parallel, we measured changes in hemodynamic responses during the task, using near-infrared spectroscopy. As patients in the OCD group were naïve to treatment, we compared results before and after 3-year medication with serotonin reuptake inhibitors. We report that, compared with controls, the OCD group had significantly poorer performance and less activation in the prefrontal cortex during the Stroop color-word task. Surprisingly, while serotonin-reuptake-inhibitors treatment reduced OCD symptomology, it did not improve the diminished hemodynamic responses or task performance of these patients. Our findings suggest that a persistent deficit exists in the inhibitory control of pediatric patients with OCD; they also provide insight into the pathophysiology of OCD.

Photoacoustic microscopy of electronic acupuncture (EA) effect in small animals.

Acupuncture has been an effective treatment for various pain in China for several thousand years. However, the mechanisms underlying this mysterious ancient healing are still largely unknown. Here we applied photoacoustic microscopy (PAM) to investigate brain hemodynamic changes in response to electronic acupuncture (EA) at ST36 (Zusanli). Due to the high optical absorption of blood at 532nm, PAM could sensitively probe changes in hemoglobin concentration (HbT, i.e., cerebral blood volume [CBV]) of cortical regions in high resolution. Six healthy mice were stimulated at the acupoint and three healthy mice were stimulated at sham points. Remarkable CBV changes in sensorimotor and retrosplenial agranular cortex were observed. Results showed the potential of PAM as a visualization tool to study the acupuncture effect on brain hemodynamics in animal models. (a) Schematic showing the stimulation points. (b) B-scan images overlaid with mouse atlas. (c) & (d) Statistical results of CBV changes from cortical regions.

Cortical plasticity in patients with median nerve lesions studied with MEG

We have previously shown age- and time-dependent effects on brain activity in the primary somatosensory cortex (SI), in a functional magnetic resonance imaging (fMRI) study of patients with median nerve injury. Whereas fMRI measures the hemodynamic changes in response to increased neural activity, magnetoencephalography (MEG) offers a more concise way of examining the evoked response, with superior temporal resolution. We therefore wanted to combine these imaging techniques to gain additional knowledge of the plasticity processes in response to median nerve injury. Nine patients with median nerve trauma at the wrist were examined with MEG. The N1 and P1 responses at stimulation of the injured median nerve at the wrist were lower in amplitude compared to the healthy side (p < .04). Ulnar nerve stimulation of the injured hand resulted in larger N1 amplitude (p < .04). The amplitude and latency of the response did not correlate with the sensory discrimination ability. There was no correlation between N1 amplitude and size of cortical activation in fMRI. There was no significant difference in N1 latency between the injured and healthy median nerve. N1 latency correlated positively with age in both the median and ulnar nerve, and in both the injured and the healthy hand (p < .02 or p < .001). It is concluded that conduction failure in the injured segment of the median nerve decreases the amplitude of the MEG response. Disinhibition of neighboring cortical areas may explain the increased MEG response amplitude to ulnar nerve stimulation. This can be interpreted as a sign of brain plasticity.

Abstract PR060

Background & Objectives: Application of positive end expiratory pressure (PEEP) is known to induce hemodynamic instability particularly in patients with hypovolemia (1). Under constant elastic wall properties of large arteries, pulse pressure (PP) changes predominantly reflect stroke volume changes. Accordingly, we hypothesized that PEEP-induced percent changes of PP (PiPPP) predict circulatory volume (CV) conditions determined by the stroke volume variation (SVV). Materials & Methods: With approval of the IRB, we recruited 80 ASA PS I-II adult patients undergoing major surgeries requiring continuous arterial pressure monitoring with a Vigileo/FloTracTM (Edwards Lifesciences, Irvine, CA). Exclusion criteria included 1) BMI > 35, 2) ejection fraction < 40%, 3) SV index < 30 ml/m2 on zero end-expiratory pressure (ZEEP), 4) systolic blood pressure < 80 mmHg on ZEEP, 5) arrhythmia and 6) COPD. All patients were mechanically ventilated under general anesthesia and paralysis (tidal volume = 10 ml/kg, respiratory rate = 10 breaths/min, I/E ratio = 1:2). Hemodynamic parameters including SVV and PP were measured during ZEEP and 10 cm H2O PEEP application. PiPPP was calculated as (PPZEEP – PPPEEP) / (PPZEEP) %. Correlation analysis between SVV on ZEEP and PiPPP was performed by Spearman rank order test and P < 0.05 was considered significant. Results: We observed variable hemodynamic changes in response to PEEP application and significant dependence of the PiPPP on CV conditions (R = 0.66, P < 0.01). For different CV conditions determined by the SVV values at ZEEP (non-normovolemia: SVV > 10 %, severe hypovolemia: SVV > 13 %), we found a high positive predictive value (PPV) for non-normovolemic condition (83 %) and a high negative predictive value (NPV) for severe hypovolemic condition (93 %) when PiPPP > 15% is considered positive (2). This study demonstrated dependence of PiPPP on SVV on ZEEP while significant association between PEEP-induced SV changes and SVV on ZEEP was previously reported (3). Our results suggest potential usefulness of pulse pressure measurements before and during 10 cm H2O PEEP for determining CV conditions in anaesthetized and mechanically ventilated patients. Clinical usefulness of the PiPPP, a simple hemodynamic parameter, should be assessed by accuracy of fluid responsiveness prediction in a large sample size in the future.Conclusion: PEEP-induced pulse pressure changes predict stroke volume variation and possibly serve to optimal fluid management.

A temperature-controlled glove with non-invasive arterial pulse sensing for active neuro-vascular assessment.

A non-invasive, active neuro-vascular assessment system was developed using a modified temperature-controlled glove and feedback techniques. The glove incorporates local heating and cooling of the hand using multi-point skin temperature measurements as feedback, and thereby induces local and central mechanisms involved in thermoregulation. Electrocardiogram (ECG), photoplethysmogram (PPG) and non-invasive finger-cuff based blood pressure (BP) measurements were used to monitor electrophysiology and hemodynamic changes in response to temperature modulation. Then, the triggered neuro-vascular mechanisms associated with thermoregulation were quantified by extracting parameters from the measured waveforms, specifically heart rate variability (HRV), vascular tone, and BP. The system was tested on six young, healthy individuals with no history of microvascular diseases. During heating, vasodilation, decrease in systolic BP, and a decrease in parasympathetic tone were observed, while during cooling, vasoconstriction and increased BP were observed. While such changes are expected physiologically using passive experiments, the ability to modulate the physiology non-invasively with a controlled, quantitative, and inexpensive instrument can potentially enable serial assessments of neuro-vascular control outside of clinical settings.

Effective Bolus Dose of Sufentanil to Attenuate Cardiovascular Responses in Laryngoscopic Double-Lumen Endobronchial Intubation.

BackgroundSufentanil is a potent opioid analgesic frequently used in clinical anesthesia. Double-lumen endobronchial intubation induces profound cardiovascular responses in comparison with ordinary endotracheal intubation because of the larger tube diameter and direct irritation of the carina.ObjectivesThe purpose of this study was to determine the effective bolus dose of sufentanil to attenuate hemodynamic changes in response to laryngoscopic double-lumen endobronchial intubation.Patients and MethodsWe randomly assigned 72 patients aged 18 - 65 years and with an American Society of Anesthesiologists physical status of 1 or 2 to one of four sufentanil dose groups: NS, S0.1, S0.2, or S0.3. The respective doses for the groups were as follows: normal saline, 0.1 mcg/kg of sufentanil, 0.2 mcg/kg of sufentanil, and 0.3 mcg/kg of sufentanil. Blood pressure and heart rate were recorded during the pre-anesthesia period at baseline, pre-intubation, immediate post-intubation, and every minute during 5 minutes after intubation.ResultsBaseline mean arterial pressures in the NS, S0.1, S0.2, and S0.3 groups were 89.8 ± 12.1, 89.2 ± 10.9, 88.8 ± 13.6, and 90.7 ± 11.1, respectively. At immediate post-intubation, the mean arterial pressures in the NS, S0.1, S0.2, and S0.3 groups were 129.7 ± 14.7, 120.7 ± 14.2, 120.8 ± 17.2, and 96.7 ± 10.4, respectively. At immediate post-intubation, the mean arterial pressure in the NS, S0.1, and S0.2 groups significantly increased from baseline (P < 0.001), but the S0.3 group showed no difference. In the time point comparison at immediate post- intubation, the S0.3 group had a significantly lower mean arterial pressure than did the NS, S0.1, and S0.2 groups (P < 0.001).ConclusionsWe found that 0.3 mcg/kg of sufentanil attenuates cardiovascular responses to double-lumen endobronchial intubation without adverse effects.

Cocaine-Induced Abnormal Cerebral Hemodynamic Responses to Forepaw Stimulation Assessed by Integrated Multi-Wavelength Spectroimaging and Laser Speckle Contrast Imaging

Simultaneous imaging of cerebral hemodynamic changes in response to functional activation during drug intoxication provides a valuable strategy to assess cocaine induced neurovascular dysfunction. However, this requires tools with sufficient spatiotemporal resolution and adequate signal to noise ratio (SNR). Though several technologies have been developed to address this demand during functional brain activation, their spatiotemporal resolution has been compromised to preserve SNR. In this study, we combine spatiotemporal-domain laser speckle contrast analysis and image correlation techniques to integrate multi-wavelength spectroimaging and laser speckle contrast imaging (MW-LSCI). Experimental results show that optimized spatiotemporal resolution with enhanced SNR were achieved that enabled simultaneous measurement of multiple hemodynamic responses (i.e., ΔHbO2, ΔHbR, ΔHbT and ΔCBF) during cocaine administration. Specifically, cocaine-induced functional cerebral hemodynamic changes were accessed by measuring the activation responses to forepaw electrical stimulation at different times after cocaine administration. With improved spatiotemporal resolution and SNR, the system was able to differentiate the heterogeneity of cocaine's effects on the cerebral vasculature and on tissue metabolism, demonstrating the unique capability of MW-LSCI for various brain functional and pharmacological studies.

Neural substrates of sexual arousal in heterosexual males: event-related fMRI investigation.

BackgroundSexual behavior is an important role for the survival of species. The advancement of brain imaging methods has enabled the understanding of the brain mechanism related to sexual arousal. The previous studies on the brain mechanism related to sexual arousal have mostly conducted on block design paradigm.MethodsDespite its requirement for stricter experimental control, the event-related paradigm is known to be more efficient in detecting instant emotional and cognitive responses. The paradigm also enables the observation of hemodynamic responses through time. Therefore, this study used the event-related fMRI to examine the brain activation in various areas associated with sexual arousal as well as changes in hemodynamic responses with time.ResultsStrong activations were observed in the various areas associated with sexual arousal comprised of various factors: (1) activation areas related to cognitive factors: the occipital lobe and parietal lobe; (2) activation areas related to emotional factors: the thalamus and amygdala; (3) activation areas related to motivational factors: the anterior cingulate gyrus, orbitofrontal cortex, and insula; and (4) activation areas related to physiological factors: the precentral gyrus, putamen, and globus pallidus. We also identified the activation of the putamen and globus pallidus that were not well observed in previous block design studies. In the result of the hemodynamic response, the neural activity in those areas showed more transient aspects of the hemodynamic responses relative to the neural activity of other areas.ConclusionsThese results suggested that the event-related paradigm is better at detecting the neural activity of the brain regions, which tend to appear suddenly, but disappear soon.