Alterations In Regional Perfusion Research Articles

Motor asymmetry related cerebral perfusion patterns in Parkinson's disease: An arterial spin labeling study.

Persisting asymmetry of motor symptoms are characteristic of Parkinson's disease (PD). We investigated the possible lateralized effects on regional cerebral blood flow (CBF), CBF‐connectivity, and laterality index (LI) among PD subtypes using arterial spin labeling (ASL). Forty‐four left‐sided symptom dominance patients (PDL), forty‐eight right‐sided symptom dominance patients (PDR), and forty‐five matched HCs were included. Group comparisons were performed for the regional normalized CBF, CBF‐connectivity and LI of basal ganglia (BA) subregions. The PDL patients had lower CBF in right calcarine sulcus and right supramarginal gyrus compared to the PDR and the HC subjects. Regional perfusion alterations seemed more extensive in the PDL than in the PDR group. In the PDL, correlations were identified between right thalamus and motor severity, between right fusiform gyrus and global cognitive performance. None of correlations survived after multiple comparisons correction. The significantly altered CBF‐connectivity among the three groups included: unilateral putamen, unilateral globus pallidus, and right thalamus. LI score in the putamen was significantly different among groups. Motor‐symptom laterality in PD may exhibit asymmetric regional and interregional abnormalities of CBF properties, particularly in PDL patients. This preliminary study underlines the necessity of classifying PD subgroups based on asymmetric motor symptoms and the potential application of CBF properties underlying neuropathology in PD.

Saturación tisular de oxígeno en el paciente crítico

Hemodynamic resuscitation seeks to correct global macrocirculatory parameters of pressure and flow. However, current evidence has shown that despite the normalization of these global parameters, microcirculatory and regional perfusion alterations can persist, and these alterations have been independently associated with a poorer patient prognosis. This in turn has lead to growing interest in new technologies for exploring regional circulation and microcirculation. Near infra-red spectroscopy allows us to monitor tissue oxygen saturation, and has been proposed as a noninvasive, continuous and easy-to-obtain measure of regional circulation. The present review aims to summarize the existing evidence on near infra-red spectroscopy and its potential clinical role in the resuscitation of critically ill patients in shock.

Skeletal Muscle Oxygen Saturation (StO2) Measured by Near-Infrared Spectroscopy in the Critically Ill Patients

According to current critical care management guidelines, the overall hemodynamic optimization process seeks to restore macrocirculatory oxygenation, pressure, and flow variables. However, there is increasing evidence demonstrating that, despite normalization of these global parameters, microcirculatory and regional perfusion alterations might occur, and persistence of these alterations has been associated with worse prognosis. Such observations have led to great interest in testing new technologies capable of evaluating the microcirculation. Near-infrared spectroscopy (NIRS) measures tissue oxygen saturation (StO2) and has been proposed as a noninvasive system for monitoring regional circulation. The present review aims to summarize the existing evidence on NIRS and its potential clinical utility in different scenarios of critically ill patients.

Gastrointestinal Monitoring Using Measurement of Intramucosal PCO2

Gastrointestinal Monitoring Using Measurement of Intramucosal PCO2

Adrenergic mechanisms contribute to alterations in regional perfusion during normotensive E. coli bacteremia.

The complex role of adrenergic mechanisms in the pathogenesis of sepsis and shock remains incompletely understood. Recent reports have suggested that adrenergic mechanisms may play an important modulatory role in arachidonate metabolism during early sepsis, specifically in the synthesis of the vasoactive metabolites thromboxane A2 and prostacyclin. The purpose of the present set of experiments was to evaluate the extent to which adrenergic mechanisms contribute to early alterations in regional perfusion during Gram-negative bacteremia, using the mixed alpha adrenergic receptor antagonist phenoxybenzamine hydrochloride. Male Sprague-Dawley rats received a 3-hour continuous intraarterial infusion of either saline (n = 7) or 6.6 +/- 0.4 x 10(8) live E. coli colony forming units (n = 7), after which regional perfusion was determined using 51Cr-labelled microspheres (16.5 +/- 0.1 micron). Significant reductions (p less than 0.05) in blood flows to the renal, gastric, cecal, pancreatic, and splenic beds, as well as a reduction (p less than 0.05) in the calculated portal venous flow, were observed in the bacteremic group while mean arterial blood pressure remained unchanged. Further experiments conducted in 14 rats with preexisting alpha adrenergic receptor blockade revealed relative preservation of renal, gastric, cecal, and portal venous blood flows during bacteremia. These data identify alterations in regional perfusion during early E. coli bacteremia occurring before changes in systemic arterial blood pressure, and indicate that adrenergic mechanisms participate in the modulation of such.

Complications of Multiple Trauma

Patients who acquire sepsis, ARDS, ARF, or MSOF subsequent to multiple trauma have a high mortality rate. The pathophysiology of these complications is complex and is thought to involve ischemia, the generation of mediators, alterations in regional perfusion, and cellular oxygen use. Because of the critical nature of the patient with these complications, nursing care requires indepth knowledge as well as competent nursing management, necessitating use of both the art and science of nursing.

Nitrogen-13-labeled ammonia for myocardial imaging

Cyclotron-produced nitrogen-13 (half-life 10 min), as labeled ammonia (13NH4+), has been evaluated as a myocardial perfusion imaging agent. The regional myocardial uptake of 13NH4+ has been shown to be proportional to regional tissue perfusion in animal studies. Intravenously administered 13NH4+ is rapidly cleared from the circulation, being extracted by the liver (15%), lungs, myocardium (2%-4%), brain, kidney, and bladder. Myocardial ammonia is metabolized mainly to glutamine via the glutamine synthetase pathway. Pulmonary uptake is substantial, but usually transient, except in smokers where clearance may be delayed. The position annihilation irradiation (511 keV) of 13N may be imaged with a scintillation camera, using either a specially designed tungsten collimator or a pinhole collimator. After early technical problems with collimation and the production method of 13NH4+ were overcome, reproducible high quality myocardial images were consistently obtained. The normal myocardial image was established to be of a homogeneous "doughnut" configuration. Imaging studies performed in patients with varying manifestations of ischemic and valvular heart disease showed a high incidence of localized perfusion defects, especially in patients with acute myocardial infarction. Sequential studies at short intervals in patients with acute infarction showed correlation between alterations in regional perfusion and the clinical course of the patient. It is concluded that myocardial imaging with 13NH4+ and a scintillation camera provides a valid and noninvasive means of assessing regional myocardial perfusion. This method is especially suitable for sequential studies of acute cardiac patients at short intervals. Coincidence imaging of the 511 keV annihilation irradiation provides a tomographic and potentially quantitative assessment of the regional myocardial uptake of 13NH4+.