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Biomedical subjects

M Kleen

Publications and source records attributed to M Kleen.

At least 19 recordsLinked to original sources
PubMed2004

Fluid resuscitation from severe hemorrhagic shock using diaspirin cross-linked hemoglobin fails to improve pancreatic and renal perfusion.

BACKGROUND: Fluid resuscitation from hemorrhagic shock is intended to abolish microcirculatory disorders and to restore adequate tissue oxygenation. Diaspirin cross-linked hemoglobin (DCLHb) is a hemoglobin-based oxygen carrier (HBOC) with vasoconstrictive properties. Therefore, fluid resuscitation from severe hemorrhagic shock using DCLHb was expected to improve perfusion pressure and tissue perfusion of kidneys and pancreas. METHODS: In 20 anesthetized domestic pigs with an experimentally induced coronary stenosis, shock (mean arterial pressure 45 mmHg) was induced by controlled withdrawal of blood and maintained for 60 min. Fluid resuscitation (replacement of the plasma volume withdrawn during hemorrhage) was performed with either 10% DCLHb (DCLHb group, n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group, n = 10). Completion of resuscitation was followed by a 60-min observation period. Regional blood flow to the kidneys and the pancreas was measured by use of the radioactive microspheres method at baseline, after shock and 60 min after fluid resuscitation. RESULTS: All animals (10/10) resuscitated with DCLHb survived the 60-min observation period, while 5/10 control animals died within 20 min due to persisting subendocardial ischemia. In contrast to HSA survivors, pancreas and kidneys of DCLHb-treated animals revealed lower total and regional organ perfusion and regional oxygen delivery. Renal and pancreatic blood flow heterogeneity was higher in the DCLHb group. CONCLUSION: DCLHb-induced vasoconstriction afforded superior myocardial perfusion, but impaired regional perfusion of the kidneys and the pancreas.

Algorithms↗
PubMed2003

[The roentgenmorphologic aspects of symptomatic calcifications in patients with calcifying tendinitis of the shoulder: determination of intra- and interobserver variabilities of Gärtner's classification].

AIM OF THE STUDY: The roentgenologic morphology of symptomatic calcified deposits of the rotator cuff can be classified according Gärtner. This classification influences therapeutic procedures and prognosis of clinical outcome in these patients. In the present study intraoberserver-reproducibility and interobserver-reliability of Gärtner's classification were tested. METHODS: Plane radiographs of 100 patients with calcifications of the supraspinatus tendon were classified according the criteria of Gärtner by 6 independent observers twice within 4 months. Intraoberserver-reproducibility and interobserver-reliability were calculated by means of Cohen's kappa-index. RESULTS: kappa-values of intraoberserver-reproducibility had a mean of 0.4208 (SD 0.1299), kappa-values of interobserver-reliability were 0.490 for the first and 0.474 for the second classification. CONCLUSIONS: Determination of intraoberserver-reproducibility gave insufficient to satisfactory results, interobserver-reliability was sufficient. The clinical use of Gärtner's classification to plan therapeutic procedures or to determine clinical prognosis in patients with calcifying tendinitis can be recommended only with limitations.

Adult↗
PubMed2003

Hyperoxic ventilation at the critical haematocrit.

OBJECTIVE: During normovolaemic haemodilution arterial O(2)-content decreases exponentially. Nevertheless, tissue oxygenation is first maintained initially by increased organ perfusion and O(2)-extraction. As soon as these compensatory mechanisms are exhausted, myocardial ischaemia and tissue hypoxia occur at an individual 'critical' haematocrit (Hct) value. This study was conducted in order to assess whether tissue hypoxia at the critical Hct is reversed by hyperoxic ventilation with 100% O(2). METHOD: Eighteen anaesthetized pigs were ventilated with room air and were hemodiluted by 1:1 exchange of blood with 6% pentastarch to their individual critical Hct (onset of myocardial ischaemia; significant ECG changes). At the critical Hct, hyperoxic ventilation was initiated. In nine complete datasets, global O(2) delivery and consumption, local tissue O(2) partial pressure (tpO(2)) (MDO-Electrode, Eschweiler, Kiel, Germany) and organ blood flow (microsphere method) in skeletal muscle were analyzed at baseline, after haemodilution to the critical Hct and after 15 min of hyperoxic ventilation. RESULTS: At the critical Hct (7.2+/-1.2%), tpO(2) was reduced from 23+/-3 to 10+/-2 Torr with 50% of all values in the hypoxic range (<10 Torr, all P<0.05). During hyperoxic ventilation, contribution of physically dissolved O(2) to the O(2) delivery and O(2) consumption increased by 400 and 563% (P<0.05) and instantly restored tpO(2) to 18+/-2 Torr, (hypoxic values 25%, P<0.05). CONCLUSION: Hyperoxic ventilation reversed tissue hypoxia at the critical Hct due to preferential utilization of plasma O(2) and allowed temporary preservation of tissue oxygenation. During haemodilution, hyperoxic ventilation might offer an effective bridge until red cells are ready for transfusion.

Animals↗
PubMed2003

New mathematical model for the correct prediction of the exchangeable blood volume during acute normovolemic hemodilution.

BACKGROUND: The blood volume that has to be exchanged for crystalloids and/or colloids during acute normovolemic hemodilution (ANH) in order to reach a preset target hemoglobin concentration (hb) is usually predicted by the Bourke and Smith formula developed in 1974. This formula systematically overestimates the 'true' exchangeable blood volume (EBV), a fact that may potentially endanger patients because the target hb will be missed and the normovolemic anemia might turn out to be more severe than a priori intended. Our objective was to develop a more accurate mathematical model of hemodilution kinetics and to validate this new model in animals and in patients undergoing ANH. METHODS: Twenty-two anesthetized beagle dogs and 18 patients under balanced anesthesia underwent isovolemic hemodilution with hydroxyethyl starch (HAES 6%, 200 000) to a target hb of 7 g dl-1 or 9 g dl-1, respectively. Exchangeable blood volume predicted by use of the different mathematical models was compared with the blood volume actually exchanged to meet the preset target hb. RESULTS: Calculation of EBV by the Bourke and Smith formula (EBVB + S) systematically overestimated the volume actually exchanged (overestimation: dogs 15%, patients 20%), whereas our new iterative model predicted EBV (EBViterative) more reliably (overestimation: dogs 1%, patients 8%). In both cases EBVB + S differed significantly from the EBViterative. CONCLUSION: Exchangeable blood volume is predicted more accurately by the new iterative model than by the Bourke and Smith formula. The iterative model leads to an improvement in patient safety and provides a physiologically adequate basis for future studies investigating the efficacy of ANH in reducing allogenic blood transfusions.

Algorithms↗
PubMed2002

Calculation is unsuitable for determination of O2-consumption (VO2) in case of O2-supply-dependency.

BACKGROUND: When O2-delivery to tissues is critically reduced, O2-consumption becomes dependent on O2-delivery and starts to decline, which reflects tissue hypoxia. In order to timely detect tissue hypoxia prior to organ damage, O2-consumption may be calculated or measured from respiratory gases. We have assessed reproducibility of calculated and measured O2-consumption-data and their agreement during O2-supply-dependency. METHOD: Data of 31 anesthetized, ventilated pigs were analysed retrospectively. Animals had undergone either controlled hemorrhage ("shock") or isovolemic exchange of blood with colloids (extreme hemodilution, "HD") until O2-consumption had become dependent on O2-delivery. O2-consumption was calculated from the Fick equation and measured simultaneously with a DELTATRAC II metabolic monitor. Repeatability was determined for (1) calculated and (2) for measured.VO2 -values and (3) for input variables of the Fick equation (i.e. cardiac index (CI) and arteriovenous O2-content difference (CaO2-CvO2)). Bias between calculated and measured data and precision of calculation were assessed from paired O2-consumption-values obtained before and after induction of O2-supply-dependency via hemorrhage or extreme hemodilution. RESULTS: Repeatability of the reversed Fick method was inferior to repeatability of measurement (27 vs 15%) due to error propagation from CI and (CaO2-CvO2). Between-method-bias at baseline ("BL") was 3%, and changed in case of O2-supply-dependency (shock -15%; HD -31%, both p<0.05 vs BL), precision of the reversed Fick method deteriorated (BL 32%; shock 60%; HD 60%) due to variability of CI (CV: 16%; shock 27%; HD 41%). CONCLUSION: In anesthetized pigs calculated and measured O2-consumption values are in agreement, while in presence of O2-supply-dependency the reversed Fick method (1) grossly underestimates true O2-consumption and (2) precision deteriorates not allowing to verify or reject the presence of tissue hypoxia.

Animals↗
PubMed2001

Three-dimensional visualization of lung blood flow heterogeneity based on fluorescent microsphere technique and fractal dimension: The Blood Flow Analysis System - BFA System.

The heterogeneity of regional pulmonary blood flow (RPBF) can be assessed by fractal analysis. The fractal dimension (FD) is a scale-independent measure of spatial heterogeneity of blood flow. The relative dispersion (RD) is often used to obtain the heterogeneity of RPBF but it is influenced by the resolution of measurement. The Blood Flow Analysis (BFA) System was developed in Delphi to represent the three-dimensional structure of lung blood flow and calculates statistics of FD, RD, spatial correlation of neighbored tissue samples and shows histograms of blood flows at diverse time points during different experiments. The BFA System reads a text file with flows, measured with fluorescent microsphere technique, and constructs the lung anatomy with volumetric pixels showing the flows with a color schema. It is possible to rotate the lungs into two axis (XY) and the statistics are shown with 3D graphics. The System maintains a database with data from various studies at same time. The BFA System was validated with four data sets from previous experiments. The BFA System has shown consistency and it is a new tool to help researchers during lung perfusion studies.

Animals↗
PubMed2001

Physiology of pulmonary perfusion: new concepts.

Regional pulmonary perfusion is spatially heterogeneous. The classic assumption has been that this is due to the influence of gravity. In the past decade, a new concept has emerged, stressing the fractal geometric properties of the pulmonary vascular tree. Studies that support the gravitational concept tend to have been elaborated using a lower resolution of measurement whereas experiments with high resolution measurements often yield results that contradict the gravitational hypothesis.

Journal Article↗
PubMed2000

[Acute normovolemic hemodilutin (ANH). Effects of ANH on the diastolic function of the left ventricle].

Ischemia-induced changes of diastolic leftventricular (LV) properties commonly precede corresponding ECG-changes. In the present experimental study the consequences of acute normovolemic hemodilution (ANH) induced dilutional anemia (hematocrit, hct 20%) for LV diastolic function were investigated. A total of 22 anaesthetized, splenectomized beagle dogs breathing room air were hemodiluted with isooncotic hydroxyethylstarch solution (6% HAES 200,000/0.5) until a hct value of 20% was reached. Before and after ANH intravascular blood volume (indocyaningreen dilution technique), global and regional myocardial blood flow (radioactive microspheres technique) and the following parameters reflecting LV diastolic properties were ascertained: 1) the maximum rate of LV pressure decrease (LVdp/dtmin), 2) slope and intercept of the enddiastolic pressure-volume relationship (EDPVR, conductance technique) and 3) the time-constant of isovolumic LV pressure decline "tau". After ANH to hct 20% diastolic LV function was found unchanged. Particularly the load-independent parameters (EDPVR-slope and tau) remained constant. The decrease of LV dp/dtmin (-2724 +/- 479 vs. -2388 +/- 408 mmHg.sek-1; p < 0.05) reflects ANH induced changes of LV pre- and afterload. Signs of subendocardial perfusion mismatch were not encountered. Presumed that the coronary vascular system is intact ANH to hct 20% does not provoque changes of LV diastolic function. Moreover neither myocardial perfusion and oxygenation nor myocardial function are endangered by this degree of dilutional anemia.

Animals↗
PubMed2000

Diaspirin-crosslinked hemoglobin reduces mortality of severe hemorrhagic shock in pigs with critical coronary stenosis.

OBJECTIVE: To evaluate the effects of resuscitation with a 10% diaspirin-crosslinked hemoglobin (DCLHb) solution on global hemodynamic variables, systemic and myocardial oxygen transport and tissue oxygenation, and contractile function of the left ventricle in an experimental model of severe hemorrhagic shock and critical stenosis of the left anterior descending coronary artery (LAD). DESIGN: Prospective, placebo-controlled, randomized study. SETTING: Experimental animal laboratory. SUBJECTS: A total of 20 anesthetized pigs. INTERVENTIONS: After implementation of a permanent critical LAD stenosis (ie, maintenance of basal blood flow but absence of reactive hyperemia after a 10-sec complete vessel occlusion), hemorrhagic shock (target mean aortic pressure, 45 mm Hg) was induced within 15 mins by programmed withdrawal of blood and maintained for 60 mins. Subsequently, the volume of plasma lost during hemorrhage was replaced by either a balanced electrolyte solution containing 10 g/dL DCLHb (DCLHb group; n = 10) or an 8 g/dL human albumin solution (HSA) oncotically matched to DCLHb (HSA group; n = 10). Data were collected immediately after the infusion of the different solutions and again after 60 mins had elapsed. MEASUREMENTS AND MAIN RESULTS: Although five of ten HSA-treated animals died of acute left ventricular failure within the first 20 mins after complete fluid resuscitation, all of the DCLHb-treated animals survived the 60-min observation period after resuscitation (p < .05). This significant difference in mortality is explained by higher coronary perfusion pressure in DCLHb-treated animals (75 +/- 17 vs. 27 +/- 17 torr DCLHb vs. HSA group; p < .05) and persistence of subendocardial ischemia and hypoxia (radioactive microspheres method) in HSA-treated animals on resuscitation particularly affecting the LAD-supported myocardium (subendocardial oxygen delivery: 20 +/- 11 vs. 3 +/- 1 mL oxygen x g(-1) x min(-1), DCLHb vs. HSA group; p < .05). Except for enhanced myocardial contractility immediately on infusion of DCLHb (maximal left ventricular pressure increase: 2373 +/- 782 vs. 1730 +/- 543 torr x sec(-1) DCLHb vs. HSA group; p < .05), no differences were detected between groups concerning the variables of systemic oxygen transport, tissue oxygenation, and regional contractile function of the myocardium (determined with microsonometry). CONCLUSIONS: Fluid resuscitation with 10% DCLHb solution completely reverses hemorrhagic shock-induced subendocardial ischemia and hypoxia in the presence of compromised coronary circulation and thereby prevents early death after resuscitation.

Animals↗
PubMed2000

Effects of primary resuscitation from shock on distribution of myocardial blood flow.

Hemorrhagic shock alters heterogeneity of regional myocardial perfusion (RMP) in the presence of critical coronary stenosis in pigs. Conventional resuscitation has failed to reverse these effects. We hypothesized that improvement of the resuscitation regime would lead to restoration of RMP heterogeneity. Diaspirin-cross-linked hemoglobin (10 g/dl; DCLHb) and human serum albumin (8.0 g/dl; HSA) were used. After baseline, a branch of the left coronary artery was stenosed; thereafter, hemorrhagic shock was induced. Resuscitation was performed with either DCLHb or HSA. At baseline, the fractcal dimension (D) of subendocardial myocardium was 1.31 +/- 0.083 (HSA) and 1.35 +/- 0.106 (DCLHb) (mean +/- SD). Coronary stenosis increased subendocardial D slightly but consistently only in the DCLHb group (1.39 +/- 0.104; P < 0.05). Shock reduced subendocardial D: 1.21 +/- 0.093 (HSA; P = 0.10), 1.25 +/- 0.092 (DCLHb; P < 0.05). Administration of DCLHb increased subendocardial D in 7 of 10 animals (1.31 +/- 0.097; P = 0.066). HSA was ineffective in this respect. DCLHb infusion restored arterial pressure and increased cardiac index (CI) to 80% of baseline values. Administration of HSA left animals hypotensive (69 mmHg) and increased CI to 122% of the average baseline value. Shock-induced disturbances of the distribution of RMP were improved by administration of DCLHb but not by HSA.

Animals↗
PubMed1999

Response to inhaled nitric oxide (NO) is not associated with changes of plasma cGMP levels in patients with acute lung injury.

BACKGROUND: A clinically relevant increase of PaO subset2 or decrease of pulmonary vascular resistance (PVR) upon inhalation of NO (iNO) does occur in only 60 to 80% of patients with acute lung injury. The mechanisms for divergent responses of different patients have not yet been fully elucidated. Since NO mediates its pulmonary effects by stimulating soluble guanylate cyclase, thereby increasing levels of cyclic guanosinemonophosphate (cGMP), we hypothesized that pulmonary cGMP production upon iNO might be suppressed in patients not responding to iNO treatment. METHODS: After approval by the local ethical committee and after informed consent had been obtained, both arterial and mixed-venous cGMP levels were analyzed in 13 patients in whom iNO was administered to treat pulmonary hypertension and/or hypoxemia due to acute respiratory distress syndrome (n = 11) or reperfusion injury following lung transplantation (n = 2). Both cardiorespiratory variables and cGMP concentrations were documented simultaneously at baseline, 15 min after inhalation of 8 ppm of NO, and 15 min after withdrawal of NO, respectively. RESULTS: Inhaled NO resulted in a significant increase in PaO(2)/FiO(2) and a decrease in PVR. Arterial and mixed venous concentration of cGMP (median) also increased significantly upon iNO from 2.5 to 6.5 nM (p <0.05) and from 3.0 to 5.7 nM (p <0.05), respectively. Theses effects were fully reversible after withdrawal of iNO. No gradients between arterial and mixed venous cGMP concentrations were detected (p = 0.12). Regression analysis showed no relationship between baseline arterial cGMP concentrations and changes of either PaO(2)/FiO(2) (p = 0. 62) or PVR (p = 0.91). Similarly, no relationship was found between the rise of arterial cGMP concentration subsequent to iNO and corresponding changes of PaO(2) (p = 0.40) or PVR (p = 0.74), respectively. CONCLUSION: Inhalation of NO significantly stimulates soluble guanylate cyclase within the lungs in patients with acute lung injury. However, neither baseline cGMP nor its rise during treatment with inhaled NO can predict the clinical efficacy of iNO in humans. Furthermore, the fact that increased cGMP concentrations were detected during administration of iNO in mixed venous blood (i.e. pulmonary inflow) strongly suggest that the pharmacological effects of iNO are not fully selective for the lungs, but may also affect extrapulmonary organs.

Acute Disease↗
PubMed1999

Effect of acute normovolemic hemodilution on distribution of blood flow and tissue oxygenation in dog skeletal muscle.

Acute normovolemic hemodilution (ANH) is efficient in reducing allogenic blood transfusion needs during elective surgery. Tissue oxygenation is maintained by increased cardiac output and oxygen extraction and, presumably, a more homogeneous tissue perfusion. The aim of this study was to investigate blood flow distribution and oxygenation of skeletal muscle. ANH from hematocrit of 36 +/- 3 to 20 +/- 1% was performed in 22 splenectomized, anesthetized beagles (17 analyzed) ventilated with room air. Normovolemia was confirmed by measurement of blood volume. Distribution of perfusion within skeletal muscle was determined by using radioactive microspheres. Tissue oxygen partial pressure was assessed with a polarographic platinum surface electrode. Cardiac index (3.69 +/- 0.79 vs. 4.79 +/- 0.73 l. min-1. m-2) and muscle perfusion (4.07 +/- 0.44 vs. 5.18 +/- 0.36 ml. 100 g-1. min-1) were increased at hematocrit of 20%. Oxygen delivery to skeletal muscle was reduced to 74% of baseline values (0.64 +/- 0.06 vs. 0.48 +/- 0.03 ml O2. 100 g-1. min-1). Nevertheless, tissue PO2 was preserved (27.4 +/- 1.3 vs. 29.9 +/- 1. 4 Torr). Heterogeneity of muscle perfusion (relative dispersion) was reduced after ANH (20.0 +/- 2.2 vs. 13.9 +/- 1.5%). We conclude that a more homogeneous distribution of perfusion is one mechanism for the preservation of tissue oxygenation after moderate ANH, despite reduced oxygen delivery.

Animals↗
PubMed1999

[Artificial oxygen carriers. Alternatives to homologous blood transfusion?].

The expected explosion of costs in transfusion medicine due to the shortfall of healthy donors and the more frequent treatment of transfusion-associated complications (chronic hepatitis, cirrhosis, wound infection, tumor recurrence) increases the socio-economic importance of the development of safe and effective synthetic oxygen carriers as an alternative to the transfusion of homologous red blood cells. Currently two types of artificial oxygen carriers are experimentally and clinically investigated for their capacity to ensure adequate tissue oxygenation in the case of severe anemia. In addition to their oxygen transport capacity solutions based on free human or bovine hemoglobin provide vasoconstrictor properties. Their hyperoncotic properties make them particularly attractive for the treatment of severe hemorrhagic shock. Perfluorocarbon (PFC) emulsions allow an increase of the physically dissolved portion of arterial oxygen content. Due to their particulate nature (emulsion droplets) PFC may only be infused in low doses. Otherwise there is risk of overload and malfunction of phagocytic cells of the reticulo-endothelial system. In the case of an intraoperative blood-loss in preoperatively hemodiluted patients, bolus infusion of PFC represents an effective means to avoid immediate retransfusion of autologous blood and allows for further, extreme hemodilution without risking tissue hypoxia.

Animals↗
PubMed1999

Toxicity of high PaO2.

There is no mammalian life without oxygen. At the same time, oxygen can be toxic. This paper focuses on extrapulmonary manifestations of oxygen toxicity. Hyperbaric and normobaric applications of oxygen are relevant to the anesthesiologist and carry different risks of oxygen toxicity. Normobaric O2 is tolerated for relatively long periods and has no acute sequelae. Chronic exposure to normobaric O2 will increase the concentration of oxygen radicals in the tissues and produce organ damage. This has to be weighed against the risk of withholding possibly life-saving oxygen therapy. High FiO2 can be used to increase plasma dissolved oxygen to offset low hemoglobin based oxygen transport capacity of blood during acute pre- or intraoperative normovolemic hemodilution with the aim of reducing allogeneic transfusion requirements. Administration of hyperbaric oxygen can be followed by a spectrum of neurologic disturbances leading to frank convulsions. The mechanism leading to cerebral seizure activity is not fully understood but is possibly linked to oxygen radical production and the L-Arginine-NO system.

Anesthesia↗
PubMed1998

Recombinant human interleukin-10 attenuates TNFalpha production by porcine monocytes.

BACKGROUND: Human recombinant interleukin-10 (rhIL-10) has been found to inhibit endotoxin-induced production of several proinflammatory cytokines including tumor necrosis factor alpha (TNFalpha) from human monocytes. The exogenous therapeutic administration of rhIL-10 in acute and chronic hyperinflammatory conditions has been discussed. For none of the large animal species that have been used to study the role and effects of various mediators during septicemia, crossreactivity of rhIL-10 has been shown so far. Therefore, the aim of the present investigation was to evaluate the crossreactivity of rhIL-10 in a porcine model. METHODS: To determine the effects of rhIL-10 on endotoxin-challenged porcine monocytes, we incubated porcine peripheral blood monocytes from five donors with three different concentrations of rhIL-10 (500 ng/ml, 1000 ng/ml and 2000 ng/ml, respectively) either simultaneously with, or two hours prior to lipopolysaccharide (LPS) administration. RESULTS: As compared to incubation with LPS (1 microg/ml) alone, coincubation with LPS and rhIL-10 (500 ng/ml, 1000 ng/ml and 2000 ng/ml) (n = 5) for four hours resulted in a marked and uniform reduction of immunoreactive TNFalpha. For preincubation (n = 5), only the addition of 500 ng/ml rhIL-10 led to a homogeneous decrease of TNFalpha levels in each sample. There was no consistent reduction in TNFalpha after preincubation with 1000 and 2000 ng/ml rhIL-10. Our results indicate crossreactivity of recombinant human interleukin-10 in porcine peripheral blood monocytes. Further investigations on the potential therapeutical role of exogenously administered rhIL-10 are thus possible in porcine models.

Adjuvants, Immunologic↗
PubMed1998

IV perflubron emulsion versus autologous transfusion in severe normovolemic anemia: effects on left ventricular perfusion and function.

Intact cardiac compensatory mechanisms are necessary to maintain adequate tissue oxygenation during acute normovolemic hemodilution (ANH). Left ventricular (LV) perfusion, oxygenation and function were analyzed in an experimental whole-body model of profound ANH (Hct 9%) and effectiveness of a perfluorocarbon-based oxygen carrier in maintaining myocardial oxygenation and function was evaluated. A total of 22 anesthetized dogs were hemodiluted to Hct 20% followed by a simulated, controlled blood-loss phase in which dogs were randomized to either: (1) 1:1 exchange of lost blood with autologous red blood cells (RBC-group), (2) 1:1 exchange with a colloid (control-group) and (3) 1:1 exchange with a colloid after a single dose of 1.8 g/kg BW perflubron i.v. (PFC-group). Myocardial oxygen delivery and consumption as well as endocardial perfusion were determined using radioactive microspheres. LV myocardial contractility (LV MC) was assessed from: (1) the relationship between maximum rate of LV pressure increase (LVdp/dtmax) and LV enddiastolic volume (LVEDV) and (2) analysis of the LV endsystolic pressure volume relationship (ESPVR). LV diastolic properties were reflected by (1) minimum rate of LV pressure increase (LVdp/dtmin), (2) slope and intercept of the enddiastolic pressure-volume relationship (EDPVR) and (3) the time-constant of isovolumic LV pressure decline "tau 1/2". Full sets of LV MC data were obtained from 18 dogs (n = 6 per group). LV MC (LVdp/dtmax-LVEDV relation) increased after perflubron administration. At the lowest Hct level, all parameters reflecting LV MC as well as LVdp/dtmin were significantly higher in the PFC-group than in the control-group. After profound normovolemic hemodilution (Hct 9%) superiority of LV MC and LV diastolic properties was found, when myocardial oxygenation was supported by i.v. perflubron emulsion, a temporary O2 carrier.

Anemia↗
PubMed1998

Programs for assessment of spatial heterogeneity of regional organ blood flow.

Regional organ blood flow (RBF) is spatially heterogeneous. Relative dispersion (standard deviation S.D./mean) is often used to assess heterogeneity of RBF. Relative dispersion is a global measure of heterogeneity and is strongly influenced by the tissue sample size making comparisons between research groups inappropriate. Spatial correlation (s.c.) of blood flow is, on the other hand, averaged local self similarity. Both parameters change oppositely secondary to interventions. Fractal dimension (D) is a scale-independent measure of spatial heterogeneity and thus facilitates comparison of data. Programs for calculation of s.c. and D have not been published. We present two portable computer programs written in C+2 for calculating s.c. and D. The programs were validated with six computer generated data sets of known heterogeneity. The results were in agreement with data from the literature: we conclude that the programs accurately calculate spatial correlation and fractal dimension of 1-, 2-, or 3-dimensional perfusion matrices.

Humans↗