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At least 19 recordsLinked to original sources
PubMed1979

Effects of ether anesthesia and surface-induced hypothermia on regional blood flow.

Regional blood flow and distribution of cardiac output (CO) were evaluated by the radioactive microsphere technique in seven rhesus monkeys prior to anesthesia, following the induction of deep ether anesthesia and throughout the cooling course during surface-induced hypothermia to temperatures of 20 degrees C. As given, deep ether anesthesia alone significantly decreased CO 10% to 15% and output fraction (Qt) was decreased to the carcass, increased to the splanchnic circulation (although not statistically significant), and unchanged to other organs, while total vascular (TVR) and organ resistances were reduced. With the addition of cooling, CO progressively decreased. Individual organ Qt's, however, did not change from anesthetized normothermic values; thus organ flows decreased parallel to the reduction of CO as cooling progressed. TVR and organ vascular resistances increased to levels in excess of 150% of anesthetized precooling values, apparently as the result of viscosity rather than vascular changes.

Anesthesia, Inhalation↗
PubMed2001

Influence of equianaesthetic concentrations of nitrous oxide and isoflurane on regional cerebral blood flow, regional cerebral blood volume, and regional mean transit time in human volunteers.

Nitrous oxide and isoflurane have cerebral vasodilatory effects. The use of isoflurane in neuroanaesthesia is widely accepted, whereas the use of nitrous oxide in neuroanaesthesia is still the subject of debate. In the present study, contrast-enhanced magnetic resonance (MR) perfusion measurement was used to compare the effects of 0.4 MAC nitrous oxide (n=9) and 0.4 MAC isoflurane (n=9) on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and regional mean transit time (rMTT) in spontaneously breathing human volunteers. Nitrous oxide increased rCBF and rCBV in supratentorial regions more than did isoflurane. Isoflurane, by contrast, increased rCBF and rCBV in basal ganglia more than did nitrous oxide. An increased rMTT was caused by a relatively greater increase in rCBV than in rCBF supratentorially by isoflurane and infratentorially by nitrous oxide. In conclusion, nitrous oxide increases rCBF and rCBV predominantly in supratentorial grey matter, whereas isoflurane increases rCBF and rCBV predominantly in infratentorial grey matter.

Adult↗
PubMed1986

Sequential assessment of regional cerebral blood flow, regional cerebral blood volume, and blood-brain barrier in focal cerebral ischemia: a case report.

Regional CBF (rCBF) and regional cerebral blood volume (rCBV) were evaluated by N,N,N'-trimethyl-N'-(2)-hydroxy-3-methyl-5-[123I]iodobenzyl-1, 3-propanediamine-2 HCl- and 99mTC-labeled red blood cells, respectively, and single-photon emission computerized tomography (SPECT) in a patient with focal cerebral ischemia. Sequential transmission computerized tomography (TCT) and SPECT functional data were compared with clinical findings to monitor the pathophysiological events occurring in stroke. A lack of correlation between rCBF-rCBV distributions and blood-brain barrier (BBB) breakdown was found in the acute phase. In the face of more prolonged alteration of BBB, as seen by TCT enhancement, a rapid evolution of transient phenomena such as luxury perfusion was shown by SPECT studies. Follow-up of the patient demonstrated a correlation between the neurological recovery and a parallel relative improvement of the cerebral perfusion.

Adult↗
PubMed1984

Regional blood flow during cardiopulmonary resuscitation with abdominal counterpulsation in dogs.

The addition of abdominal counterpulsation to standard cardiopulmonary resuscitation (AC-CPR) during ventricular fibrillation has been shown to improve cardiac output, oxygen uptake, and central arterial blood pressure in dogs. The present study was performed to determine the effect of AC-CPR on regional blood flow. Regional blood flow was measured with radioactively labeled microspheres during sinus rhythm and during alternate periods of AC-CPR and standard CPR (STD-CPR) in nine dogs anesthetized with pentobarbital. Blood pressures and oxygen uptake were measured continuously. As in previous studies, diastolic arterial pressure was higher (30.8%) during AC-CPR than during STD-CPR, as were cardiac output (24.5%) and oxygen uptake (37.5%). Whole brain and myocardial blood flow increased 12.0% and 22.7%, respectively, during AC-CPR. Blood flow to abdominal organs was not changed appreciably in response to abdominal compression, and postmortem examination revealed no gross trauma to the abdominal viscera. The AC-CPR technique is simple and is easily added to present basic life support procedures. In light of the improvements observed in myocardial and cerebral blood flow, AC-CPR could significantly improve the outcome of CPR attempts.

Abdomen↗
PubMed2006

Microsphere maps of regional blood flow and regional ventilation.

Systematically mapped samples cut from lungs previously labeled with intravascular and aerosol microspheres can be used to create high-resolution maps of regional perfusion and regional ventilation. With multiple radioactive or fluorescent microsphere labels available, this methodology can compare regional flow responses to different interventions without partial volume effects or registration errors that complicate interpretation of in vivo imaging measurements. Microsphere blood flow maps examined at different levels of spatial resolution have revealed that regional flow heterogeneity increases progressively down to an acinar level of scale. This pattern of scale-dependent heterogeneity is characteristic of a fractal distribution network, and it suggests that the anatomic configuration of the pulmonary vascular tree is the primary determinant of high-resolution regional flow heterogeneity. At approximately 2-cm(3) resolution, the large-scale gravitational gradients of blood flow per unit weight of alveolar tissue account for <5% of the overall flow heterogeneity. Furthermore, regional blood flow per gram of alveolar tissue remains relatively constant with different body positions, gravitational stresses, and exercise. Regional alveolar ventilation is accurately represented by the deposition of inhaled 1.0-microm fluorescent microsphere aerosols, at least down to the approximately 2-cm(3) level of scale. Analysis of these ventilation maps has revealed the same scale-dependent property of regional alveolar ventilation heterogeneity, with a strong correlation between ventilation and blood flow maintained at all levels of scale. The ventilation-perfusion (VA/Q) distributions obtained from microsphere flow maps of normal animals agree with simultaneously acquired multiple inert-gas elimination technique VA/Q distributions, but they underestimate gas-exchange impairment in diffuse lung injury.

Aerosols↗
PubMedDate not supplied

Theoretical analysis of regional blood flow studies.

Regional blood flow measurements were analyzed using a two-compartment model. The distribution of injected tracer between blood and tissue was assumed to be in equilibrium only at the beginning of the experiment. Equations for the determination of the partition coefficient of injected radionuclides from in vivo measurements were derived. These equations can also be used for estimation of the relative blood content of a tumor or an organ. The results were applied to experiments, where three diffusible radionuclides were injected simultaneously into patients with diagnosed tumors.

Argon↗
PubMed1991

Arteriovenous shunting and regional blood flow in myocutaneous island flaps: an experimental study in pigs.

In eight pigs, total blood flow, regional capillary blood flow distribution, and arteriovenous (AV) shunting were studied during the first 4 postoperative hours after elevation of a myocutaneous rectus abdominis island flap. Capillary blood flow and AV shunting were measured using radioactive microspheres before flap creation and 1 and 4 hours after surgery. Total blood flow, measured continuously as venous outflow, increased in the first postoperative hour (p less than 0.05). Elevation of the flap caused a slight decrease in skin capillary blood flow (p less than 0.05), whereas muscular capillary blood flow increased (p less than 0.01). AV shunting accounted for 50 percent of the total flap blood flow, whereas it was negligible in the abdominal wall prior to flap elevation. Thus stalk blood flow, skin appearance, and skin temperature may be poor indicators of nutritional capillary perfusion. However, the clinical and nutritional consequences of these findings remain to be established.

Analysis of Variance↗
PubMed2002

The influence of hyperoxia on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and cerebral blood flow velocity in the middle cerebral artery (CBFVMCA) in human volunteers.

Conflicting results reported on the effects of hyperoxia on cerebral hemodynamics have been attributed mainly to methodical and species differences. In the present study contrast-enhanced magnetic resonance imaging (MRI) perfusion measurement was used to analyze the influence of hyperoxia (fraction of inspired oxygen (FiO2) = 1.0) on regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) in awake, normoventilating volunteers (n = 19). Furthermore, the experiment was repeated in 20 volunteers for transcranial Doppler sonography (TCD) measurement of cerebral blood flow velocity in the middle cerebral artery (CBFV(MCA)). When compared to normoxia (FiO2 = 0.21), hyperoxia heterogeneously influenced rCBV (4.95 +/- 0.02 to 12.87 +/- 0.08 mL/100g (FiO2 = 0.21) vs. 4.50 +/- 0.02 to 13.09 +/- 0.09 mL/100g (FiO2 = 1.0). In contrast, hyperoxia diminished rCBF in all regions (68.08 +/- 0.38 to 199.58 +/- 1.58 mL/100g/min (FiO2 = 0.21) vs. 58.63 +/- 0.32 to 175.16 +/- 1.51 mL/100g/min (FiO2 = 1.0)) except in parietal and left frontal gray matter. CBFV(MCA) remained unchanged regardless of the inspired oxygen fraction (62 +/- 9 cm/s (FiO2 = 0.21) vs. 64 +/- 8 cm/s (FiO2 = 1.0)). Finding CBFV(MCA) unchanged during hyperoxia is consistent with the present study's unchanged rCBF in parietal and left frontal gray matter. In these fronto-parietal regions predominantly fed by the middle cerebral artery, the vasoconstrictor effect of oxygen was probably counteracted by increased perfusion of foci of neuronal activity controlling general behavior and arousal.

Adult↗
PubMed1996

Cardiac output and urea kinetics in dialysis patients: evidence supporting the regional blood flow model.

The regional blood flow model predicts that urea sequestration occurs in organs rather than cells, and that post-dialysis urea rebound is a function of both cardiac index (CI) and regional blood flow distribution to muscle. We measured cardiac output (CO) in 100 randomly selected dialysis patients using bioelectric impedance three times during a single dialysis. Mean CO was 5.8 +/- 2.1 liter/min and CI averaged 3.1 +/- 1.1 liter/min/M2. CI was negatively correlated with age (r = -0.48, P < 0.01). CI was strongly affected by vasodilator ingestion (yes, N = 36, CI = 3.5 +/- 1.2; no, N = 64, CI = 2.88 +/- 0.92, P < 0.006). CI was not associated with systolic, diastolic, or mean blood pressures, nor with Hct, although very few severely anemic patients were in the cohort. Repeat intra-dialytic CO measurements two to three months later in 15 patients with low CI (2.59 +/- 0.59 liter/min/M2) and in 13 patients with high CI (5.00 +/- 0.9, P < 0.001) during a urea kinetic modeling session including 30 minutes post-dialysis rebound, sampling showed highly reproducible values for CO, with a mean absolute value % difference between CO values measured several months apart of 9.0 +/- 17%, r = 0.92. Urea rebound expressed as the difference (delta Kt/V30) between equilibrated and single-pool Kt/V was lower in the high CI group (-0.099 +/- 0.07) than in the low CI group (-0.16 +/- 0.06, P = 0.026), and delta KT/V30 as well as delta Kt/V30 divided by K/V correlated with CI (r = 0.48 and 0.48, respectively, P < 0.01). The RBF model was used to compute a group mean predicted delta Kt/V30 for the low CI and high CI groups based on measured group mean values for CI and K/V. The predicted delta Kt/V30 values for the high CI group (-0.097) and the low CI group (-0.183) agreed closely with measured values. RBF modeled values of CO (7.46 +/- 2.96 liter/min) were not significantly different from impedance-derived CO (6.93 +/- 2.70 liter/min), and the two CO measures correlated significantly (r = 0.63, P = 0.0003). The results provide support for the regional blood flow model of urea kinetics.

Adult↗
PubMed1985

Transient heat clearance method for regional blood flow measurements.

A method for assessing regional blood flow by transient heat clearance is described. A probe at room temperature is attached to the tissue which is to be investigated and the temperature of the probe is thereby decreased. The time constants which describe the increases in tissue temperature as the temperature approaches equilibrium temperature are related to blood flow. Regional blood flow can be determined by the method of transient heat clearance without calibration.

Body Temperature Regulation↗
PubMed1992

Effects of temperature and flow rate on regional blood flow and metabolism during cardiopulmonary bypass.

Eleven dogs were subjected to a 150-minute period of cardiopulmonary bypass that consisted of a high-flow, normothermic phase, a high-flow, hypothermic phase, a low-flow, hypothermic phase, and then a high-flow, rewarming phase. Regional blood flow and oxygen consumption to the brain, intestines, kidney, and hind limb were determined at baseline and at 10-minute intervals during cardiopulmonary bypass. Blood flow to the carotid artery, superior mesenteric artery, and renal artery declined significantly with hypothermic cardiopulmonary bypass whereas blood flow to the femoral artery increased significantly. Although total body oxygen consumption returned to baseline values at the end of the rewarming phase, oxygen consumption for these regions differed somewhat from their baseline values. We conclude that blood flow during hypothermic cardiopulmonary bypass is shunted to skeletal muscle, particularly with high pump flows. Additionally, the return of total body oxygen consumption to baseline after rewarming is not necessarily reflected at the regional level.

Animals↗
PubMed1990

Noninvasive measurement of regional blood flow in man.

Regional blood flow in man is ideally measured by techniques that are noninvasive, accurate, and can measure flow repetitively with comparative ease. Although numerous noninvasive techniques are available, no single method records blood flow accurately in every location. The neophyte investigator is often faced with a confusing array of methods and can spend considerable time searching for the ideal one. This paper presents current methods available to the clinical or metabolic researcher and comments on the strengths and limitations of each method. It is hoped that this will allow more rapid selection of a flow measurement method that is tailored to each individual's need.

Blood Flow Velocity↗
PubMed1979

Effect of intracerebral vasculitis on regional cerebral blood flow.

Regional cerebral blood flow was measured by the xenon 133-inhalation method in a 40-year-old man during an acute exacerbation of intracranial vasculitis. Neurologic function was quantitated by the Halstead-Reitan Neuropsychological test battery. The patient was also studied during remission that was induced by steroid therapy. Vasculitis produced a diffuse encephalopathy with generalized reduction in cerebral blood flow. During remission, only local symptoms secondary to a small cerebral infarction remained and regional cerebral blood flow returned to the normal range. There seems to be a close correlation between the severity of symptoms in cerebral vasculitis and reduction of flow through diseased vessels.

Adult↗
PubMedDate not supplied

Cortical organization of voluntary motor activity as revealed by measurement of regional cerebral blood flow.

Regional cerebral blood flow (rCBF) was measured in conjunction with carotid angiography using the intra-arterial xenon-133 injection method. Measurements were made in 9 patients in the left hemisphere and in 6 patients in the right hemisphere. It was confirmed that there was no significant differences in the blood flow, in either the right or the left hemisphere, between measurements taken while patients carried out various types of voluntary activity and preceding measurements of total mean hemisphere blood flow taken during rest. However, the pattern of flow distribution changed significantly during various types of voluntary motor activity, In general, the contralateral Rolandic motor and sensory areas were activated during execution of voluntary movements. The supplementary motor area appears to play a major role in the integration of information from various cortical regions; such integration is, of course, necessary in the preparation of the ultimate motor action.

Adult↗
PubMed1985

Dextroamphetamine-induced changes in regional cerebral blood flow.

Regional cerebral blood flow (CBF), blood pressure, pulse rate, respiratory rate, end-tidal carbon dioxide and mood states were measured before and after IV injections of 15 mg dextroamphetamine sulfate or saline in 22 physically and mentally healthy normal volunteers. Amphetamine administration was associated with significant increases in systolic blood pressure and vigor and decrease in end-tidal carbon dioxide. There were no significant differences between the amphetamine and saline groups on CBF changes. However, there was a non-significant trend towards a post-amphetamine CBF reduction, even after the flow values were corrected for the acute changes in CO2.

Adult↗