Search results for "Autoregulation"
showing 10 items of 31 documents
Interactive effects of internalizing and externalizing problem behaviors on recurrent pain in children
2002
Objective: To examine, in children, relationships between self-reported recurrent pain and emotion regulation indicated by rated internalizing and externalizing problem behaviors and adjustment. Method: Finnish 11-12-year-old schoolchildren (N = 414) completed a questionnaire measuring recurrent pain. Emotion regulation was assessed by a Multidimensional Peer Nomination Inventory, Teacher Rating Form. Relationships between recurrent pain and emotion regulation were examined in logistic regression analyses, after controlling for past injuries and chronic illnesses. Results: Independent of injuries and chronic illnesses, externalizing and internalizing problem behaviors related to recurrent p…
Effects of Fenoldopam on Intracranial Pressure and Hemodynamic Variables at Normal and Elevated Intracranial Pressure in Anesthetized Pigs
1994
Fenoldopam (FE), a dopamine DA1-receptor agonist, has been introduced for treatment of arterial hypertension and heart failure and for preservation of renal function. Vasodilators are generally assumed to affect all vascular beds including the cerebral circulation. We have evaluated effects of FE-induced (4 micrograms.kg-1.min-1) arterial hypotension on intracranial pressure (ICP) and intraocular pressure (IOP) under conditions of normal and increased intracranial elastance. ICP and IOP responses to hypertension were tested by infusion of angiotensin II (15 micrograms.kg-1.min-1), and the response to hypercapnia was tested by elimination and reintegration of soda lime canisters in the breat…
Cerebral blood flow autoregulation during hypobaric hypotension assessed by laser Doppler scanning.
1994
Hypobaric hypotension was used to reduce systemic blood pressure in rats below the lower threshold of CBF autoregulation to evaluate a new laser Doppler (LD) “scanning” technique. Spontaneously breathing male Wistar Kyoto rats (n = 8) were anesthetized with chloral hydrate and the head fixed in a stereotaxic head holder. A cranial window with intact dura mater was introduced to assess local CBF (lCBF) by LD. One stationary probe served to detect rapid flow changes, whereas the second probe was used to sample lCBF recordings from many cortical locations by means of a stepping motor-controlled micromanipulator to obtain lCBF frequency histograms. Advantages are an improved spatial resolution…
Investigating the mechanisms of cardiovascular and cerebrovascular regulation in orthostatic syncope through an information decomposition strategy
2012
Some previous evidence suggests that postural related syncope is associated with defective mechanisms of cerebrovascular (CB) and cardiovascular (CV) control. We characterized the information processing in short-term CB regulation, from the variability of mean cerebral blood flow velocity (CBFV) and mean arterial pressure (AP), and in CV regulation, from the variability of heart period (HP) and systolic AP (SAP), in ten young subjects developing orthostatic syncope in response to prolonged head-up tilt testing. We exploited a novel information-theoretic approach that decomposes the information associated with a variability series into three amounts: the information stored in the series, the…
Time course of cerebrovascular autoregulation during extreme Trendelenburg position for robotic-assisted prostatic surgery
2013
Trendelenburg positioning in combination with pneumoperitoneum during robotic-assisted prostatic surgery possibly impairs cerebrovascular autoregulation. If cerebrovascular autoregulation is disturbed, arterial hypertension might induce cerebral hyperaemia and brain oedema, while low arterial blood pressure can induce cerebral ischaemia. The time course of cerebrovascular autoregulation was investigated during use of the Trendelenburg position and a pneumoperitoneum for robotic-assisted prostatic surgery using transcranial Doppler ultrasound. Cerebral blood flow velocity was correlated with arterial blood pressure and the autoregulation index (Mx) was calculated. In 23 male patients, Mx was…
Extended Granger causality: a new tool to identify the structure of physiological networks.
2015
Granger causality (GC) is a very popular tool for assessing the presence of directional interactions between two time series of a multivariate data set. In its original formulation, GC does not account for zero-lag correlations possibly existing between the observed time series. In the present study we compare the GC with a novel measure, termed extended GC (eGC), able to capture instantaneous causal relationships. We present a two-step procedure for the practical estimation of eGC based on first detecting the existence of zero-lag correlations, and then assigning them to one of the two possible causal directions using pairwise measures of non-Gaussianity. The proposed method was validated …
Cerebral haemodynamic changes during propofol-remifentanil or sevoflurane anaesthesia: transcranial Doppler study under bispectral index monitoring
2006
Background. Sevoflurane or propofol–remifentanil-based anaesthetic regimens represent modern techniques for neurosurgical anaesthesia. Nevertheless, there are potential differences related to their activity on the cerebrovascular system. The magnitude of such difference is not completely known. Methods. In total 40 patients, treated for spinal or maxillo-facial disorders, were randomly allocated to either i.v. propofol–remifentanil or inhalational sevoflurane anaesthesia. Transcranial Doppler was used to assess changes in cerebral blood flow velocity, carbon dioxide reactivity, cerebral autoregulation and the bispectral index to assess the depth of anaesthesia. Results. Time-averaged mean f…
Significance of resting and stimulated cerebral blood flow for predicting the risk of hemodynamic cerebral ischemia in a model of chronic hemodynamic…
2000
OBJECTIVE: It has been postulated that patients with a compromised cerebrovascular reserve capacity (RC), defined as cerebral blood flow (CBF) response to acetazolamide (ACZ) (by percent), are at higher risk for ischemic stroke. The value of CBF and RC for predicting the risk of hemodynamically induced impairment of cerebral function is examined. METHODS: Both common carotid arteries were occluded in 22 Wistar-Kyoto rats. Thirty-one days later, mean arterial blood pressure was reduced to 40 mm Hg for 30 minutes. Laser Doppler scanning of CBF at resting conditions and after intraperitoneal administration of ACZ (0.1 mg/g body weight) was performed 30 minutes and 28 days after occlusion as we…
Nonlinear effects of respiration on the crosstalk between cardiovascular and cerebrovascular control systems.
2016
Cardiovascular and cerebrovascular regulatory systems are vital control mechanisms responsible for guaranteeing homeostasis and are affected by respiration. This work proposes the investigation of cardiovascular and cerebrovascular control systems and the nonlinear influences of respiration on both regulations through joint symbolic analysis (JSA), conditioned or unconditioned on respiration. Interactions between cardiovascular and cerebrovascular regulatory systems were evaluated as well by performing correlation analysis between JSA indexes describing the two control systems. Heart period, systolic and mean arterial pressure, mean cerebral blood flow velocity and respiration were acquired…
Sevoflurane Impairs Cerebral Blood Flow Autoregulation in Rats: Reversal by Nonselective Nitric Oxide Synthase Inhibition
2005
UNLABELLED In this study, we investigated the effects of 1.0 and 2.0 minimum alveolar anesthetic concentration (MAC) sevoflurane on cerebral blood flow (CBF) autoregulation before and after nonselective inhibition of nitric oxide (NO) synthase in rats. Rats were randomly assigned as follows: Group 1 (n = 8): 1.0 MAC sevoflurane; Groups 2 and 3 (n = 8 per group): 2.0 MAC sevoflurane. Assessment of autoregulation within a mean arterial blood pressure range of 140-60 mm Hg was performed by graded hemorrhage before and after administration of l-arginine methyl ester (l-NAME, 30 mg/kg IV, Groups 1 and 2) or during hypocapnia (Group 3). In 10 additional animals, brain tissue NO(2)(-) concentratio…