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PubMed1988

Elevation of tissue PO2 with improvement of tissue perfusion by topically applied CO2.

Local absorption of CO2 was examined, by tissue gas analysis with medical mass spectrometry, in rabbits placed in a bath. The results obtained clearly showed that (1) Elevation of subcutaneous tissue PO2 was followed by elevation of PCO2 in the subcutaneous tissue. (2) Local absorption of CO2 through skin was confirmed by elevation of the levels of subcutaneous PO2 and PCO2 at the site exposed to CO2. (3) Tissue perfusion during the CO2 bath was moderately higher than that observed with tap water bathing. The mechanism of oxygen release into the tissue by CO2 bathing is thought to involve increased [H+] and PCO2 in the red blood cells, which shifts the hemoglobin dissociation curve to the right, thus facilitating oxygen release at the tissue level. There is, therefore a good possibility, that the improved tissue perfusion together with the increased oxygen in the tissue will favourably affect wound healing and chronic degenerative disorders, thus facilitating rehabilitation.

Animals↗
PubMed1991

NMR measurements of different tissue perfusion parameters.

The traditional perfusion rate is based on the amount of fluid flowing longitudinally down the capillaries, often given in ml/100 g tissue/min. In principle, fluid flowing radially out of or into the capillaries can be measured as well. Radial and longitudinal perfusion have the same units but independent values. If spins leave and reenter a capillary several times during a transit, radial perfusion can exceed longitudinal perfusion and it probably does. Radial perfusion measures capillary wall function. Progressively increasing the time between two gradient pulses in a proposed radial perfusion imaging sequence allows more magnetization to move into the vasculature to be dephased or removed. Progressive decreases in gradient strength keep diffusion effects constant allowing isolation of the desired perfusion effects.

Blood↗
PubMed2000

Influence of positive end-expiratory pressure ventilation on peripheral tissue perfusion evaluated by measurements of tissue gases and pH. An experimental study in pigs with oleic acid lung injury. .

UNLABELLED: Measurements of subcutaneous oxygen tension (PscO(2)), subcutaneous carbon dioxide tension (PscCO(2)) and subcutaneous pH (pHsc) were used for evaluation of peripheral oxygenation in pigs subjected to oleic acid-induced lung injury during ventilation with increasing levels of positive end-expiratory pressure (PEEP). Lung injury resulted in a decrease of arterial oxygen tension (PaO(2)) from 93 to 37 mm Hg (p<0.01) with maintained cardiac output. PscO(2) decreased from 45 to 17 mm Hg (p<0.01) and pHsc from 7.47 to 7.39 (p<0.05), and PscCO(2) increased from 46 to 59 mm Hg (p<0.05). Increase of PEEP level between 5 and 20 cm H(2)O resulted in a continuous increase of PaO(2) from 45 to 145 mm Hg and a decrease of cardiac output from 4.1 to 2.0 liters/min (p<0.01). PscO(2) increased up to a PEEP level of 15 cm H(2)O, reaching 26 mm Hg. Further increase of PEEP level up to 20 cm H(2)O resulted in an increase of PscCO(2) from 65 to 71 mm Hg (p<0.05) and a decrease of pHsc from 7.31 to 7.29 (p<0.05). IN CONCLUSION: measurements of tissue gases and pH can be used to evaluate optimum peripheral tissue oxygenation during titration of PEEP level. Whether these measurements can be used as the only indicator to guide therapy in an individual case remains to be studied.

Animals↗
PubMed1987

Tissue perfusion during normovolemic hemodilution investigated by a hydraulic model of the cardiovascular system.

Normovolemic hemodilution on a whole body basis is studied by means of a steady flow, hydraulic analogue simulation of the cardiovascular system, based on the Casson's model and current hemodynamic and rheological data. The vasculature is divided into serially connected compartments whose hydraulic resistance is characterized by the average diameter, length, number of vessels, and the corresponding rheological properties of blood formulated by Dintenfass (1971) and Lipowsky et al. (1980). This model computes the pressure distributions in all compartments, where the calculated venous pressure modulates the cardiac function according to the Starling mechanism for cardiac performance. The alterations of flow induced by the action of the heart are added to the effects due to changes in peripheral vascular resistance as a result of hematocrit variation. This model shows that when the response of heart to the changes of venous pressure is impaired, the maximum oxygen carrying capacity occurs at 40% hematocrit (H) where it is 1% higher than normal hematocrit (H = 44%). The normal cardiac response to the changes of venous pressure, causes the maximum oxygen carrying capacity to occur at 32% H where it is 12% greater than that at normal hematocrit. Mean arteriolar pressure and capillary pressure increase while venular pressure is slightly reduced during normovolemic hemodilution.

Blood Pressure↗
PubMed2003

A multivessel model describing replenishment kinetics of ultrasound contrast agent for quantification of tissue perfusion.

To improve the quantification of tissue perfusion using intermittent sonography, a new model describing replenishment kinetics of microbubbles is proposed. The new approach takes into account the variability of blood flow velocities found in vivo, especially in tumors, and consistently describes the refilling process of microbubbles. Based upon this model, blood volume, blood velocity, blood flow and perfusion in 17 experimental tumors were calculated, and compared with the results obtained with the established, phenomenologically derived exponential kinetic model. In contrast to the existing model, our approach describes tissue vascularization more physiologically and allows deduction of a consistent new hyperbolic model for quantification of intermittent sonography. Blood volume and mean blood velocity did significantly correlate between both the new and the established model (k=0.99; k=0.94, both p<0.001). However, mean tumor blood velocity was lower (-19%, p<0.01) with the established model compared to the newly developed model. In addition, the range and distribution of blood flow velocities found in vivo can be estimated with the new model. Furthermore, it uses simpler mathematical fitting routines and allows easier data acquisition, which may allow a more practicable clinical application of intermittent sonography. In conclusion, a more valid, detailed and accurate calculation of perfusion parameters, especially of tumors, can be derived in vivo with the new multivessel model of intermittent sonography.

Animals↗
PubMedDate not supplied

Interaction of swainsonine with lymphoid and highly perfused tissues: a pharmacokinetics explanation for sustained immunomodulation.

The kinetics of inhibition of metastasis by the immunomodulator swainsonine (SW) is effective 1 to 3 days after administration. It is likely that SW's prolonged antimetastatic effect is due to its mitogenic property (spleenocytes isolated from animals treated with SW for 42-72 hours stimulated DNA synthesis that remained elevated for up to 3 days after removal of the drug from the drinking water). An analysis of SW in lymphoid (spleen and thymus) and highly perfused tissues was undertaken to determine if SW's sustained antimetastatic effect could be correlated to its retention. C57BL/6 mice received [3H]SW in drinking water for 24-72 hours and thereafter, received SW-free drinking for 24, 48, and 72 hours. Lymphoid and highly perfused tissues were analyzed for [3H]SW. At 24, 48, and 72 hours, spleen SW levels are, respectively, at least 2.33, 2.25, and 2.00 times greater than the perfused tissue; and thymus are, respectively, 1.44, 1.50, and 1.77 as great as the perfused tissue (kidney) with the highest SW level. These studies suggest that SW is predominantly retained for at least 72 hours, in lymphoid tissue. The targeting and retention of SW for lymphoid tissue days after removal of SW from animal drinking water is consistent with a) the immunomodulatory/mitogenic property and b) the sustained antimetastatic effect attributed to SW.

Adjuvants, Immunologic↗
PubMed1986

Nuclear magnetic resonance of perfused tissue.

The effect of perfusion on the NMR signal observed in NMR imaging is studied in a phantom and in two isolated perfused canine lungs. It is observed that perfusion in tissue has little effect on longitudinal relaxation times. Transverse relaxation rates are observed to correlate linearly with rates of perfusion, in accordance with a model presented.

Animals↗
PubMed2000

Nitric oxide inhibition improved myocardial metabolism independent of tissue perfusion during ischemia but not during reperfusion.

Nitric oxide (NO) is one of the important regulators of cardiac metabolism and function as well as of tissue perfusion. Myocardial NO formation is increased during ischemia and reperfusion. We investigated the roles of endogenous NO in myocardial metabolism during ischemia and reperfusion independent of tissue perfusion changes. In an open-chest pig model, a bolus infusion of 20 mg/kg of N(G)-nitro l -arginine methyl ester (l -NAME), a NO synthase inhibitor, did not alter the regional myocardial perfusion compared with a control saline injection, as measured by colored microsphares. Using(31)P-nuclear magnetic resonance spectroscopy, we showed that the tissue levels of pH and adenosine triphosphate (ATP) but not those of creatine phosphate were significantly preserved in the l -NAME group compared with the placebo group during the subsequent 15-min regional ischemia. Thus, l -NAME reduced myocardial ATP utilization during ischemia, and the mechanism underlying these effects is independent of tissue perfusion changes. However, l -NAME did not accelerate the recovery of ATP levels following reperfusion, suggesting distinct roles of endogenous NO during reperfusion.

Animals↗
PubMed2006

Importance of improving tissue perfusion during treatment of hypertension.

Experimental and clinical studies have established a link between end-organ damage in hypertensive patients and the severe impairment of tissue perfusion and microcirculation structure and function. Microvascular rarefaction is constantly observed in hypertension, and probably contributes to higher systemic resistance and lower tissue perfusion. Endothelial dysfunction leading to impaired arteriolar reactivity is also characteristic of the microvascular dysfunction in hypertensive patients. The effective lowering of blood pressure while maintaining optimal tissue perfusion is therefore one of the major goals of antihypertensive therapy, in order to improve the cardiovascular prognosis of hypertensive patients.

Blood Pressure↗
PubMed2005

Effect of clopidogrel plus aspirin on tissue perfusion and coronary flow in patients with ST-segment elevation myocardial infarction: a new reperfusion strategy.

BACKGROUND: Current reperfusion strategies may fail to achieve optimal tissue perfusion in ST-elevation myocardial infarction (STEMI). We investigated the effect of clopidogrel plus aspirin on tissue perfusion and coronary flow in infarct patients treated with fibrinolytic agents. METHODS: Consecutive 78 patients with STEMI were randomized to receive clopidogrel plus aspirin (clopidogrel group, n = 42) or placebo plus aspirin (placebo group, n = 36) before streptokinase. Maximum and total ST-segment resolutions (sumSTR) were calculated at 90 minutes after fibrinolysis. TIMI flow grade and corrected TIMI frame count in infarct-related artery were evaluated at predischarge. Inhospital ischemic and hemorrhagic events were also analyzed. RESULTS: Baseline characteristics were comparable in both groups. Both mean maximum ST-segment resolution (54.5 +/- 21.3% vs 44.6 +/- 22.0%, P = .047 ) and sumSTR (52.7 +/- 21.1% vs 42.8 +/- 20.7%, P = .041) were slightly higher in the clopidogrel group than placebo group. The rate of complete sumSTR 70% was significantly higher in the clopidogrel group compared with placebo group (31% vs 11%, P = .021). TIMI flows were similar in both groups, but corrected TIMI frame count was significantly lower in the clopidogrel group compared with placebo group (25.5 +/- 10.5 vs 33.5 +/- 11.8 frames, P = .027). Clinical events were comparable in 2 groups; however, there were 1 death caused by heart failure and moderate bleeding in the clopidogrel group. CONCLUSION: Our results suggest that clopidogrel plus aspirin compared with aspirin alone may improve myocardial tissue perfusion and coronary flow in STEMI patients receiving streptokinase.

Aged↗
PubMed2003

Blockade of the platelet P2Y12 receptor by AR-C69931MX sustains coronary artery recanalization and improves the myocardial tissue perfusion in a canine thrombosis model.

OBJECTIVE: Reperfusion therapy for myocardial infarction is limited by a significant reocclusion rate and less optimal myocardial tissue perfusion due to excessive platelet accumulation and recruitment at the sites of vascular injury. We assessed the influence of a selective P2Y(12)-receptor antagonist (AR-C69931MX), in conjunction with thrombolytic therapy, on the prevention of platelet aggregation and thrombus formation. METHODS AND RESULTS: A canine coronary electrolytic injury thrombosis model was used. Tissue-type plasminogen activator (t-PA; 1 mg/kg in phase I, 0.5 mg/kg in phase II in the AR-C69931MX group, and 1 mg/kg in the placebo group in phase I and II) was administered 30 minutes after thrombus formation; either saline or AR-C69931MX (4 micro g x kg(-1) x min(-1)) was given to all animals intravenously 10 minutes before t-PA administration for a total of 2 hours. All animals received heparin (80 U/kg) as an intravenous bolus followed by a continuous infusion of 17 U x kg(-1) x h(-1). Myocardial tissue perfusion was evaluated by use of the colored microsphere technique and real-time myocardial contrast echocardiography. The incidences of reocclusion and cyclic flow variation were significantly decreased in the AR-C69931MX group (P<0.05). Myocardial tissue flow with AR-C69931MX treatment improved significantly at 20 and 120 minutes after reflow, whereas tissue flow with placebo remained at a level similar to that during occlusion (P<0.05). CONCLUSIONS: The adjunctive administration of AR-C69931MX blocked ADP-mediated platelet aggregation and recruitment and prevented platelet-mediated thrombosis, resulting in prolongation of reperfusion time and a decrease in reocclusion and cyclic flow variations. Importantly, myocardial tissue perfusion was significantly improved in the P2Y(12) antagonist group.

Adenosine Monophosphate↗
PubMed2005

Non-blood contacting electro-hydraulic artificial myocardium (EHAM) improves the myocardial tissue perfusion.

Artificial heart (AH) and ventricular assist devices (VAD) are widely used in the clinical setting to assist severe heart failure patients. The concept of direct cardiac compression (DCC) has been in use for several decades and has advantages over intravascular VAD. The process involves compressing the dysfunctional heart from its epicardial surface to avoid the thromboembolic events and decrease the complications and mortality. An Electro-hydraulic Artificial Myocardium (EHAM) system was designed and fabricated by Tohoku University. This system may assist cardiac contraction and create pulsatile blood flow. The aim of this study was to clearly define the hemodynamic efficiency of the EHAM system in myocardial tissue perfusion during its application in acute animal experiment. Eight healthy adult goats were used; left lateral thoracotomy was performed and the chest was opened by the resection of the 4th and 5th ribs. Hemodynamic parameters including ECG, blood pressure and cardiac output were continuously monitored. Myocardial tissue perfusion was measured by using Omega flow laser fiber attached to the surface of the heart. During the EHAM compression, and increase in blood pressure and myocardial tissue perfusion was observed in all animals when compared with pre-assisted mode. To conclude, EHAM effectively improves myocardial tissue perfusion and increases the pressure on the initiation of direct cardiac compression immediately. Thus it can be a potentially valuable adjunct in the management of severe heart failure.

Animals↗
PubMed1987

Deuterium nuclear magnetic resonance measurements of blood flow and tissue perfusion employing 2H2O as a freely diffusible tracer.

The use of deuterium oxide (2H2O) is proposed as a freely diffusible nuclear magnetic resonance (NMR) blood flow and tissue perfusion tracer of potential clinical utility. Deuterium is a stable, nonradiative isotope commercially available as 2H2O at enrichment levels of essentially 100%--i.e., 110 molar equivalent deuterium. This high concentration, together with the short relaxation time of the spin 1 (quadrupole) deuterium nuclide, provides substantial sensitivity for NMR spectroscopy. As a result, when 2H2O is administered in a bolus fashion to a specific tissue or organ in vivo, the deuterium NMR intensity time course can be analyzed, using mathematical models developed by others for radiolabeled tracers, to measure the rate of blood flow and tissue perfusion. Such an application is demonstrated herein at a static magnetic field of 8.5 tesla. Using single-compartment flow modeling, hepatic blood flow and tissue perfusion in fasted (18 hr) male Sprague-Dawley rats was determined to be 61 +/- 17 (mean +/- SD) ml/100 g per min (n = 5).

Animals↗
PubMed1989

Effect of indomethacin on peripheral tissue perfusion after coronary artery bypass surgery.

The effect of indomethacin on peripheral tissue perfusion in the early phase after coronary artery bypass grafting (CABG) was investigated in ten patients randomly allocated to receive indomethacin 25 mg i.v. or placebo 'double-blind'. The patients were coupled to a respirator with FiO2 30 v/v %. Central haemodynamics, intrapulmonary shunt and blood gases showed no significant change in either group during the 2-hour study period. The thromboxane A2 metabolite P-TXB2 decreased significantly (p less than 0.05) in the indomethacin group, but the prostacyclin metabolite P-6-K PGF1 alpha showed no significant change in either group. The PtcO2 index (transcutaneous oxygen tension/arterial PO2), measured in the upper extremity, rose (p less than 0.05) after indomethacin infusion, but was almost unchanged in the controls. The mean subcutaneous tissue oxygen tension and the laser-Doppler skin red-cell flux underwent no significant change. The data thus suggested that indomethacin administered intravenously post-CABG may exert beneficial effects on peripheral tissue perfusion and oxygenation, possibly mediated by improvements in prostacyclin-thromboxane balance and microcirculation.

Coronary Artery Bypass↗
PubMed2002

Sinusoidal heating method to noninvasively measure tissue perfusion.

Noninvasively measuring the tissue blood perfusion has been an important however difficult problem in the biomedical engineering field. Based on the newly developed phase-shift principle, an improved sinusoidal heating method to estimate the perfusion was proposed in this paper to replace the original heating algorithm. The phase shift between the sinusoidal heat flux and the surface temperature response was both theoretically and experimentally revealed to be a time-dependent value which however will approach a constant value after a sufficiently long time. Only using this constant phase shift can the perfusion be properly estimated. Following the theory, an instrument consisting of low-frequency sinusoidal signal generator, power amplifier, heating plate, temperature and heat flux monitoring unit, as well as the data-acquisition system was carefully constructed. It allows generating a high-quality sinusoidal heat flux whose frequency and magnitude can be easily regulated. An auxiliary heat-conducting plate was introduced to simultaneously measure the surface temperature and the heat flux, which are hard to do otherwise. Experiments on human bodies were performed and the forearm perfusion was estimated and then validated through a constant surface heating experiment. Several issues related to the instrument integration and perfusion measurement were discussed. The instrument was also tested through experiments on nonperfused materials and good results were obtained. These efforts will help to build a compact device for noninvasively measuring the human perfusion, which may have significant applications in future clinics.

Algorithms↗
PubMed2005

Continuous noninvasive monitoring of cardiac performance and tissue perfusion in pediatric trauma patients.

PURPOSE: The aim of this study was to assess the accuracy of a continuous survival probability prediction using noninvasive measures of cardiac performance and tissue perfusion in severely injured pediatric patients. METHODS: Review of all patients entered into a prospective noninvasive monitoring protocol. Cardiac index (CI) was measured using a thoracic bioimpedance device and tissue perfusion was assessed by transcutaneous carbon dioxide (Ptcco(2)) tension and oxygen tension indexed to the fraction of inspired oxygen (Ptco(2)/Fio(2)). Survival probability (SP) was continuously calculated using a stochastic analysis program. RESULTS: There were 45 patients with a total of 953 data sets. The mean age was 11 years (range, 1-16 years) with a mean Injury Severity Score of 24 (+/-16). There was no difference between survivors (n = 32) and nonsurvivors (n = 13) at study entry for heart rate, blood pressure, CI, or pulse oximetry (all P > .05). However, survivors demonstrated higher Ptcco(2) (45 vs 35), higher Ptco(2)/Fio(2) (236 vs 156), and higher predicted SP (89% vs 62%) compared with nonsurvivors at study entry and throughout the monitoring period (all P < .01). For the entire data set, the strongest independent predictors of survival were Ptco(2)/Fio(2) and SP. The area under the receiver operating characteristic curve for mortality prediction was 0.83 for SP and 0.71 for Ptco(2)/Fio(2), compared with 0.6 for heart rate, 0.51 for blood pressure, and 0.53 for CI. Similar hemodynamic patterns were observed for all injury patterns with the exception of those with severe brain injury. CONCLUSIONS: Thoracic bioimpedance and transcutaneous monitoring give critical real-time hemodynamic and tissue perfusion data that can provide early identification of pathologic flow patterns and accurately predict survival.

Adolescent↗
PubMed1990

[The effects of pulsatile pumping on tissue perfusion and renal function during deep hypothermic low flow perfusion].

The effects of pulsatile pumping on tissue perfusion and renal function during deep hypothermic low flow perfusion were compared with non-pulsatile pumping. Twelve dogs were classified into 2 groups by the perfusion technique used. Animals were core cooled to 20 degrees C esophageal temperature with 80 ml/kg/min perfusion rate and maintained at the level for 2 hours with low flow perfusion (LFP) (30 ml/kg/min), then rewarmed to 35 degrees C with 80 ml/kg/min flow rate. As compared with the non-pulsatile group, pulsatile group demonstrated greater urine output during rewarming (p less than 0.05) and greater lymph flow during core cooling (p less than 0.05). The non-pulsatile group showed higher lymph/plasma protein concentration ratio (Lc/Pc) during LFP and rewarming (p less than 0.05), and greater plasma protein clearance during rewarming (p less than 0.05), and much higher increase of interstitial fluid pressure. The lesser water retention during bypass was also noted in the pulsatile group (28.6 +/- 27.6 ml/kg vs 85.4 +/- 52.1 ml/kg, p less than 0.05). These findings have suggested that the pulsatile perfusion may be useful for the infant cardiopulmonary bypass reducing tissue edema and preserving better renal function.

Animals↗