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Results for “PERFUSION”

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At least 19 recordsLinked to original sources

PubMed2000

Perfusate lactate dehydrogenase level and intrarenal resistance could not be adequate markers of perfusion quality during isolated kidney perfusion.

The main goal of this work was to study the influence of perfusion pressure and flow waveform during kidney perfusion, and the relationship between renal vascular resistance (RVR) and lactate dehydrogenase (LDH) concentration in the perfusate. Simultaneous constant pressure kidney perfusions were performed with either pulsatile or continuous flow at either 30 or 80 mm Hg of constant perfusion pressure. Mean flow, pressure, and RVR were displayed online during perfusion. Perfusate samples for LDH, creatine phosphatase kinase (CPK), and alkaline phosphatase (AP) determinations were taken. At the end of the perfusion, 2 ml of Evans blue was injected into the circuit to obtain images of perfusate distribution, and the kidneys were weighed. Also, hematoxylin/eosine studies were performed, showing more Bowman's space and tubular dilation in kidneys perfused with high pressure. We did not find differences in RVR between kidneys perfused at 30 and 80 mm Hg; nevertheless, perfusate distribution was better in the 80 mm Hg perfusions. We did not find any correlation between enzyme release and RVR in kidneys perfused with different mean pressures. These findings suggest that vascular resistance and LDH concentration cannot be independently considered as adequate markers of perfusate distribution.

Alkaline Phosphatase↗

PubMed1989

Prostanoid release from ex vivo perfused canine arteries and veins: effects of prolonged perfusion, intermittent perfusion, as well as exposure to exogenous arachidonic acid, thrombin and bradykinin.

Regulation of prostanoid release from ex vivo perfused vessel segments is not fully understood. A series of perfusion experiments were performed with canine arteries and veins to define certain regulatory phenomena. Arteries were perfused with pulsatile flow of 90 ml/min at a pressure of 100 mmHg, and veins with nonpulsatile flow of 90 ml/min at a pressure of 7 mmHg. Segments were perfused with Hanks' balanced salt solution for five 15-min periods with the perfusate exchanged after each study period. With onset of perfusion, there was an initial burst of prostacyclin release to 127 +/- 40 pg/mm2, declining to 32 +/- 10 pg/mm2 after 60 minutes (p less than 0.005). If perfusion continued for 5.5 hours, there was a stable release period between 1 and 3 hours, followed by a very slow decline. At that time addition of arachidonic acid (AA) increased prostacyclin release six-fold (p less than 0.01). Vessels perfused for 1 hour and then rested for another hour, responded to reperfusion at the second onset of flow with a two-fold increase in prostacyclin release (p less than 0.01). Vessels perfused with thrombin, bradykinin or AA (either added to each perfusate or only to the last perfusate) exhibited greater prostacyclin release than did control segments. Release of thromboxane steadily declined with time in all parts of the study, and only increased with the addition of AA to the perfusate.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗

PubMed2002

Perfusion abnormalities in pulmonary embolism studied with perfusion MRI and ventilation-perfusion scintigraphy: an intra-modality and inter-modality agreement study.

PURPOSE: To compare perfusion magnetic resonance imaging (MRI) and ventilation-perfusion scintigraphy (V-P scan) in the study of perfusion abnormalities in pulmonary embolism (PE) and to compare the PE results to the findings previously reported for pneumonia and chronic obstructive pulmonary disease (COPD), in terms of perfusion abnormalities. MATERIALS AND METHODS: Dynamic contrast-enhanced MR images and V-P scans of 20 patients with PE, 11 patients with acute pneumonia, and 13 patients with exacerbation of COPD were studied. Five categories of perfusion abnormalities within each imaging modality were defined. Intra- and inter-modality agreement (kappa values) in the evaluation of perfusion abnormalities were calculated, based on the two observers of each imaging modality (all blinded to each other and true diagnosis). Finally, three categories of perfusion MRI diagnosis (PE, pneumonia, and COPD) were also defined and the inter-observer agreement (kappa value) was calculated. RESULTS: For PE, the intra-modality agreement (kappa value) in the evaluation of perfusion abnormalities was 0.77 for MRI and 0.65 for V-P scan. The inter-modality agreement varied from 0.52 to 0.57, respectively, and was observer-dependent. For the pooled group of PE, pneumonia, and COPD, the intra-modality agreement of perfusion abnormalities was 0.76 for MRI and 0.65 for V-P scan, and the inter-modality agreement varied from 0.51 to 0.56. The kappa value for inter-observer agreement for MRI diagnosis was 0.92. CONCLUSION: Evaluation of perfusion abnormalities in PE, pneumonia, and COPD using perfusion MRI and V-P scan showed a high intra-modality agreement that was higher than the inter-modality agreement. Further studies are now needed in patients presenting with possible PE to evaluate the sensitivity and specificity of the method.

Acute Disease↗

PubMed2003

Incremental value of combined perfusion and function over perfusion alone by gated SPECT myocardial perfusion imaging for detection of severe three-vessel coronary artery disease.

OBJECTIVES: We hypothesized that combining functional assessment to perfusion enhances the ability of electrocardiographic gating Tc-99m sestamibi single photon emission computed tomography (gated SPECT) myocardial perfusion imaging (MPI) to detect defects in multiple vascular territories in patients with severe three-vessel coronary artery disease (3VD). BACKGROUND: In patients with 3VD, perfusion defects in multiple vascular territories may not always be evident due to globally reduced perfusion. METHODS: Gated SPECT MPIs were interpreted sequentially with perfusion first, followed by combined perfusion/function, in 143 patients with angiographic 3VD and a control group of 112 non-3VD patients. All patients underwent coronary arteriography within one month of MPI. RESULTS: In 3VD patients, combined perfusion/function analysis yielded significantly greater numbers of abnormal segments/patient (6.2 +/- 4.7 vs. 4.1 +/- 2.8, p < 0.001) and more defects in multiple vascular territories (60% vs. 46%, p < 0.05) than perfusion alone. In the control group, there were no differences between the combined perfusion/function and perfusion alone interpretations. Multivariate analysis of 15 different clinical, stress, and scintigraphic variables in all patients revealed age (p < 0.0001) and number of abnormal vascular territories by combined perfusion/function (p < 0.0001) to be the most powerful predictors of 3VD. Addition of functional data to clinical, stress, and perfusion yielded a significant increase in the predictive value of 3VD (global chi-square: 131.7 vs. 89.8, p < 0.00001). Specificity of combined perfusion/function analysis was not lower than perfusion alone (72% vs. 69%, p = NS). CONCLUSIONS; Adjunctive assessment of function with perfusion by gated SPECT MPI enhances the detection of defects in multiple vascular territories in patients with severe 3VD, without adversely affecting its specificity.

Aged↗

PubMedDate not supplied

Hepatic perfusion during hepatic artery infusion chemotherapy: evaluation with perfusion CT and perfusion scintigraphy.

The standard method for the evaluation of hepatic perfusion during hepatic artery infusion (HAI) chemotherapy is planar hepatic artery perfusion scintigraphy (HAPS). Planar HAPS was performed with 2 mCi of [99mTc] macroaggregated albumin infused at 1 ml/min and compared with single photon emission CT (SPECT) HAPS and with a new study, CT performed during the slow injection of contrast material through the HAI catheter (HAI-CT). Thirteen patients underwent 16 HAI-CT studies, 14 planar HAPS studies, and 9 SPECT HAPS studies. In 13 of 14 studies (93%) HAI-CT and planar HAPS were in complete agreement as to the perfusion pattern of intrahepatic metastases and normal liver. In nine studies where all modalities were performed, the findings identified by HAI-CT and planar HAPS agreed in all cases, whereas the results of two SPECT scans disagreed with the other studies. With respect to perfusion of individual metastases, 14 of 14 HAI-CT studies, 12 of 13 planar HAPS studies, and 9 of 9 SPECT HAPS studies correctly demonstrated the perfusion status of individual lesions as indicated by the pattern of changes in tumor size determined on CT obtained before and after the perfusion studies. Hepatic artery infusion CT was superior for delineation of individual metastases, particularly small lesions, and for the evaluation of nonperfused portions of the liver. Planar HAPS detected extrahepatic perfusion in four patients, and this was not detected by HAI-CT. We conclude that HAI-CT and scintigraphy are complementary techniques. Hepatic artery infusion CT has advantages for the evaluation of intrahepatic perfusion, and planar HAPS is superior to HAI-CT for the detection of extrahepatic perfusion.

Adult↗

PubMed1992

Kinin metabolism in the perfused ventilated rat lung. II: Influence of ventilation, perfusion, and perfusate composition variation on bradykinin metabolism in uninjured lung.

Bradykinin metabolism by peptidases of the pulmonary endothelium has been investigated in the previously uninjured, ventilated, and asanguinously perfused rat lung. The influence of short-duration (up to 20 min) abnormal ventilation and perfusion conditions on bradykinin metabolism was assessed. Neither variation of the oxygen concentration (0 to 45%) nor omission of carbon dioxide in the ventilatory gas altered bradykinin metabolism significantly. Tidal volume variation did not alter bradykinin metabolism, and exclusion of one lung from the perfusion circuit reduced the capacity to degrade bradykinin proportionately. Acidification of the perfusion medium to pH 5 did not alter bradykinin metabolism. Acetylsalicylic acid in the perfusate protected the lung from an otherwise irreversible pressure increase associated with high-dose bradykinin perfusion. Endotoxin and hydrogen peroxide in the perfusate did not alter bradykinin metabolism. However, ammonia in the ventilatory gas caused immediate pulmonary edema, diminished lung capacity to metabolize bradykinin and altered the pattern of bradykinin metabolic products. The pulmonary endothelium itself, in the absence of blood, maintains its capacity to metabolize bradykinin under an extraordinary range of conditions.

Amino Acid Sequence↗

PubMed1988

To perfuse or not to perfuse? A retrospective comparative study to evaluate the effect of adjuvant isolated regional perfusion in patients with stage I extremity melanoma with a thickness of 1.5 mm or greater.

The use of isolated regional perfusion in an adjuvant setting for stage I melanoma of the extremity continues to be controversial. The present retrospective study evaluates the past 20 years' experience by comparing 227 perfused patients from Groningen with 238 matched controls from five hospitals in The Netherlands and Westphalia (a region of West Germany bordering the Netherlands). All patients underwent wide local excision for a primary extremity melanoma of 1.5 mm or greater in thickness. A proportional hazards regression analysis for recurrence of disease and survival identified the significant prognostic factors, of which tumor thickness was the most important. Corrected for these factors, it was not possible to demonstrate a statistically significant effect for perfusion in terms of time to limb recurrence (P = .61), time to regional lymph node metastasis (P = .11), time to distant metastasis (P = .73), disease-free interval (P = .42), and survival (P = .90). No statistically significant differences were seen for adjuvant perfusion in any of the subgroups.

Adult↗

PubMed1985

Short-term kidney preservation: to perfuse or not to perfuse with the new Belzer perfusate.

Delayed graft function is ischaemically induced and the consequence of high energy phosphate depletion. A new perfusate, described by Belzer, has been used in 43 kidney preservations, 16 of which had prolonged cold ischaemia. The overall immediate function rate was 37 of 43 kidneys or 86 per cent. Of 18 kidneys cold-stored during the same period, only nine functioned immediately. Twenty-six of these patients received cyclosporine for immunosuppression without an increase in delayed graft function or evidence of increased nephrotoxicity because of ischaemic injury or prolonged preservation.

Adenosine Triphosphate↗

PubMed1995

Isolated single-lung perfusion: a study of the optimal perfusate and other pharmacokinetic factors.

BACKGROUND: Isolated single-lung perfusion with doxorubicin hydrochloride was shown to be effective in clearing experimental sarcoma lung metastases in the rat. The best perfusate to be used for isolated lung perfusion and factors affecting the final lung concentration of doxorubicin are the subject of the present study. METHODS: In experiment 1, 60 animals were randomized to undergo isolated left lung perfusion with doxorubicin with six different perfusates (n = 10 per group): saline, low-potassium-dextran, 5% albumin, 6% hetastarch, 5% buffered albumin, and 6% buffered hetastarch. Five animals served as negative controls. After perfusion, the lung wet to dry ratio and final lung doxorubicin concentration were determined. In experiment 2, 60 animals underwent isolated left lung perfusion with either 80 micrograms/mL or 320 micrograms/mL of doxorubicin. Animals were perfused at either 0.5 mL/min or 1 mL/min and for 2, 6, or 10 minutes. At the end of the perfusion period, the left lung doxorubicin concentration was measured. Statistical analysis included analysis of variance, the Duncan test for multiple comparisons, and multiple linear regression analysis. Significance was defined as a p value of less than 0.05. RESULTS: In experiment 1, perfusion with 6% buffered hetastarch resulted in the lowest lung wet to dry ratio, significantly different from all groups except the controls. Perfusion with low-potassium-dextran solution led to the highest final lung concentration of doxorubicin. In experiment 2, a model to predict final lung doxorubicin concentration was constructed: Log (final lung concentration) = 1.9 + 0.0071.P + 0.186.T, where P is the measured perfusate concentration of doxorubicin, and T is the time of perfusion in minutes. The R2 was 0.91 and p, less than 0.001. The dose of doxorubicin per kilogram of animal body weight, the dose of doxorubicin per square meter of body surface area, the total amount of doxorubicin delivered, and the rate of perfusion did not meet the criteria to enter the equation. CONCLUSIONS: Isolated lung perfusion experiments should use 6% buffered hetastarch as the perfusate. The perfusate doxorubicin concentration and the duration of perfusion are the only factors determining the final lung concentration of doxorubicin. In lung perfusion experiments, the dose of chemotherapy is not as important as the perfusate concentration and the duration of the perfusion. Animals should be perfused at a lower rate so the lungs are exposed to less doxorubicin without changing the final lung concentration.

Albumins↗

PubMed1985

Regulation of ammonia production by mouse proximal tubules perfused in vitro. Effect of luminal perfusion.

To investigate factors regulating ammonia (NH3) production by isolated defined proximal tubule segments, we examined the rates of total NH3 (NH3 + NH+4) production by individual proximal tubule segments perfused in vitro under a variety of perfusion conditions. Segments consisting of late convoluted and early straight portions of superficial proximal tubules were incubated at 37 degrees C in Krebs-Ringer bicarbonate (KRB) buffer containing 0.5 mM L-glutamine and 1.0 mM sodium acetate, pH 7.4. The rate of total ammonia production was calculated from the rate of accumulation of total NH3 in the bath. The total ammonia production rate by unperfused proximal segments was 6.0 +/- 0.2 (+/- SE) pmol/mm per minute, which was significantly lower than segments perfused at a flow rate of 22.7 +/- 3.4 nl/min with KRB buffer (21.5 +/- 1.4 pmol/mm per minute; P less than 0.001) or with KRB buffer containing 0.5 mM L-glutamine (31.9 +/- 2.5; P less than 0.001). The rate of NH3 production was higher in segments perfused with glutamine than in segments perfused without glutamine (P less than 0.01). The perfusion-associated stimulation of NH3 production was characterized further. Analysis of collected luminal fluid samples revealed that the luminal fluid total NH3 leaving the distal end of the perfused proximal segment accounted for 91% of the increment in NH3 production observed with perfusion. Increasing the perfusion flow rate from 3.7 +/- 0.1 to 22.7 +/- 3.4 nl/min by raising the perfusion pressure resulted in an increased rate of total NH3 production in the presence or absence of perfusate glutamine (mean rise in rate of total NH3 production was 14.9 +/- 3.7 pmol/mm per minute in segments perfused with glutamine and 7.8 +/- 0.9 in those perfused without glutamine). In addition, increasing the perfusion flow rate at a constant perfusion pressure increased the rate of luminal output of NH3. Total NH3 production was not affected by reducing perfusate sodium concentration to 25 mM and adding 1.0 mM amiloride to the perfusate, a condition that was shown to inhibit proximal tubule fluid reabsorption. These observations demonstrate that the rate of total NH3 production by the mouse proximal tubule is accelerated by perfusion of the lumen of the segment, by the presence of glutamine in the perfusate, and by increased perfusion flow rates. The increased rate of NH3 production with perfusion seems not to depend upon normal rates of sodium reabsorption. The mechanism underlying the stimulation of NH3 production by luminal flow is unknown and requires further study.

Absorption↗

PubMed2002

Use of a peripheral perfusion index derived from the pulse oximetry signal as a noninvasive indicator of perfusion.

OBJECTIVE: Peripheral perfusion in critically ill patients frequently is assessed by use of clinical signs. Recently, the pulse oximetry signal has been suggested to reflect changes in peripheral perfusion. A peripheral perfusion index based on analysis of the pulse oximetry signal has been implemented in monitoring systems as an index of peripheral perfusion. No data on the variation of this index in the normal population are available, and clinical application of this variable in critically ill patients has not been reported. We therefore studied the variation of the peripheral perfusion index in healthy adults and related it to the central-to-toe temperature difference and capillary refill time in critically ill patients after changes in clinical signs of peripheral perfusion. DESIGN: Prospective study. SETTING: University-affiliated teaching hospital. PATIENTS: One hundred eight healthy adult volunteers and 37 adult critically ill patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Capillary refill time, peripheral perfusion index, and arterial oxygen saturation were measured in healthy adults (group 1). Capillary refill time, peripheral perfusion index, arterial oxygen saturation, central-to-toe temperature difference, and hemodynamic variables were measured in critically ill patients (group 2) during different peripheral perfusion profiles. Poor peripheral perfusion was defined as a capillary refill time >2 secs and central-to-toe temperature difference > or = 7 degrees C. Peripheral perfusion index and arterial oxygen saturation were measured by using the Philips Medical Systems Viridia/56S monitor. In group 1, measurements were made before and after a meal. In group 2, two measurements were made, with the second measurement taken when the peripheral perfusion profile had changed. A total of 216 measurements were carried out in group 1. The distribution of the peripheral perfusion index was skewed and values ranged from 0.3 to 10.0, median 1.4 (inner quartile range, 0.7-3.0). Seventy-four measurements were carried out in group 2. A significant correlation between the peripheral perfusion index and the core-to-toe temperature difference was found (R2=.52; p <.001). A cutoff peripheral perfusion index value of 1.4 (calculated by constructing a receiver operating characteristic curve) best reflected the presence of poor peripheral perfusion in critically ill patients. Changes in peripheral perfusion index and changes in core-to-toe temperature difference correlated significantly (R =.52, p <.001). CONCLUSIONS: The peripheral perfusion index distribution in the normal population is highly skewed. Changes in the peripheral perfusion index reflect changes in the core-to-toe temperature difference. Therefore, peripheral perfusion index measurements can be used to monitor peripheral perfusion in critically ill patients.

Adult↗

PubMed1995

Effects of an increase in perfusion pressure and of the direction of flow on carbohydrate metabolism in the perfused rat liver.

The effects of increases in perfusion pressure and direction of perfusion flow (anterograde and retrograde) on hepatic carbohydrate metabolism were examined in the isolated perfused rat liver. Changing the direction of flow from anterograde (portal to caval vein) to retrograde (caval to portal vein) increased the rates of glycogenolysis and gluconeogenesis from sorbitol, lactate, pyruvate, and dihydroxyacetone. The extent of stimulation of gluconeogenesis by norepinephrine was higher during anterograde perfusion while stimulation by glucagon was higher during retrograde perfusion. Since the inflowing perfusion pressure was higher in retrograde perfusion (3.8 mmHg) than during anterograde perfusion (2.2 mmHg), we examined the effect of elevation in perfusion pressure on hepatic metabolism. In anterograde (portal to caval vein) perfusion, increases in perfusion pressure above the basal level (2.2 mmHg) caused increases in rates of glycogenolysis and gluconeogenesis with maximum rates at 4 mmHg. The extent of stimulation of gluconeogenesis by norepinephrine decreased and that by glucagon increased during perfusion at elevated pressure. At the same perfusion pressure (4 mmHg), there were no differences in rates of glycogenolysis and gluconeogenesis and in the responses to hormones between anterogradely and retrogradely perfused livers. The omission of Ca2+ ions from the perfusate abolished the effects of retrograde perfusion and of the elevation of perfusion pressure on carbohydrate metabolism. An infusion of A23187 (30 nM) induced an increase in both glycogenolysis and gluconeogenesis with unchanged perfusion pressure. The results suggest that elevated perfusion pressure during retrograde perfusion stimulates hepatic carbohydrate metabolism via a Ca(2+)-dependent process.

Animals↗

PubMed1996

Cardiac electrophysiological variables in blood-perfused and buffer-perfused, isolated, working rabbit heart.

Effects of crystalloid buffer and blood-buffer perfusates on cardiac electrophysiological parameters were compared in four groups of isolated, working rabbit hearts. Hearts were perfused with Krebs-Henseleit buffer or blood plus Krebs-Henseleit buffer (10% hematocrit) over a range of left ventricular afterload (30-100 cmH2O) and cardiac outputs (30-180 ml/min). Left ventricular monophasic action potential duration (APD) was significantly shorter at low afterload and high cardiac output in buffer-perfused (114 +/- 35 ms) compared with blood-perfused hearts (177 +/- 23 ms, P < 0.001). APD shortened in blood-perfused hearts after an increase in afterload to 100 cmH2O (P < 0.05), and APD was similar in blood-perfused (151 +/- 19 ms) compared with buffer-perfused hearts (142 +/- 24 ms, P = NS). Ventricular effective refractory period (VERP) was significantly shorter at low afterload in buffer-perfused (154 +/- 32 ms) compared with blood-perfused hearts (227 +/- 17 ms, P < 0.001). VERP shortened in blood-perfused hearts after an increase in afterload to 100 cmH2O (P < 0.05) and was similar in blood-perfused (166 +/- 26 ms) compared with buffer-perfused hearts (151 +/- 37 ms, P = NS). Determination of VERP was associated with induction of ventricular fibrillation in 10 of 15 buffer-perfused hearts, whereas ventricular fibrillation was not observed in blood-perfused hearts (P < 0.001). Thus significant differences in ventricular repolarization and cardiac hemodynamics are observed in working rabbit hearts perfused with a blood-buffer perfusate compared with a crystalloid buffer. Blood-perfused working hearts are electrophysiologically more stable.

Animals↗

PubMed2001

Assessment of myocardial perfusion and viability with stress Tc-99m-MIBI SPECT before surgical revascularisation. Correlation with postoperative perfusion improvement.

BACKGROUND: The immediate result of successful revascularisation of the myocardium is the improvement of perfusion (and in patients with depressed ventricular function, functional recovery is expected as an effect of coronary flow improvement). The main goal of the work was to assess the value of myocardial stress-rest MIBI perfusion scintigraphy in predicting myocardial perfusion state measured early (< 5 months) after CABG. MATERIAL AND METHODS: Forty-three patients (39 males, mean age 52 +/- 9 years) with chronic coronary artery disease underwent prerevascularisation and postrevascularisation stress-rest Tc-99m-MIBI SPECT studies. Eighty-one percent of patients had a history of myocardial infarction, the number of stenosed main coronary arteries was 2.3 +/- 0.6 per patient, and the left ventricle ejection fraction was 18-70% (mean 46 +/- 14%). Preoperative perfusion defects were considered as small, medium or severe (depending upon stress uptake deficiency) and as transient or persistent (depending upon uptake improvement in rest). Changes in perfusion defects (improvement, lack of changes or deterioration) were evaluated very early after CABG (mean 31 +/- 12 days) in all patients and additionally about 3 months later (mean 119 +/- 17 days after CABG) in 36 patients. RESULTS: In transient perfusion defects, the probability of early postoperative perfusion improvement was 80% (in small defects: 89%, CI(0,95) = 80-94%) and was significantly higher than in small persistent defects (51%) and than in medium-and-severe persistent defects (21%). In medium-and-severe persistent defects, the lack of changes in perfusion was observed in 76% of defects (in severe defects: 81%, CI(0,95)= 69-91%) and was significantly higher than in small persistent defects (37%), than in medium-and-severe transient defects (17%), and than in small transient defects (4%). The probability of later postoperative perfusion improvement was 78% in transient perfusion defects (in small defects: 85%, CI(0,95)=74-92%) and was significantly higher than in small, medium, and severe persistent defects (28%). In medium-and-severe persistent defects, the lack of changes in perfusion was observed in 71% of defects (in severe defects: 81%, CI(0,95)=66-91%) and was significantly higher than in small persistent defects (40%), and than in severe, medium, and small transient defects (11%). CONCLUSIONS: 1. The result of preoperative stress-rest Tc-99m-MIBI SPECT myocardial perfusion study is an exact predictor of the state of perfusion measured early (< 5 months) after CABG; the postoperative regional perfusion improvement is most dependent upon reversibility and also upon severity of stress defect. 2. In small persistent defects, changes in perfusion are different than in other types of defects - so they should not be considered together with transient defects (as "viable") or with persistent defects (as "nonviable"). 3. Preoperative viability assessment on the basis of Tc-99m-MIBI study performed solely in rest is unjustified: at the similar perfusion defect at rest, the presence of even minimal inducible ischaemia is associated with increased probability of perfusion improvement after CABG.

Journal Article↗

PubMed1993

A retrospective comparative study evaluating the results of a single-perfusion versus double-perfusion schedule with melphalan in patients with recurrent melanoma of the lower limb.

BACKGROUND: Forty-two patients with measurable recurrent melanoma of the lower limb were treated according to a double-perfusion schedule. METHODS: To assess the advantage of this schedule compared with that of a single-perfusion treatment, a retrospective study was done comparing the 42 patients with 45 patients who had undergone a single-perfusion procedure. Both groups were well balanced with respect to patient and tumor characteristics. For patients treated with a double schedule, the dose of melphalan given in the first perfusion was low (6 mg/l; 1 hour; normothermic conditions) to make it possible to perform a second perfusion (9 mg/l; 1 hour; normothermic conditions) with a planned short interval of 3-4 weeks. In the single-perfusion group, a normothermic perfusion with 10 mg melphalan/l was performed. RESULTS: The toxicity did not differ between the two treatment modalities. The response rate was significantly higher in the double-perfusion group (90% versus 68%; P = 0.007) because of a higher complete remission rate (76% versus 48%; P = 0.006). In both groups, approximately half of the patients with complete remission experienced disease recurrence in the perfused area (50% versus 52%). No significant differences were seen in the two groups in the regional node recurrence rate (33% in the double-perfusion group versus 20% in the single-perfusion group), distant recurrence rate (50% in the double-perfusion group versus 58% in the single-perfusion group), and their corresponding recurrence-free intervals. The overall 3-year survival rate was 46% in both groups. CONCLUSION: In the patient groups studied, the double-perfusion schedule shows a better complete remission benefit than does the single-perfusion procedure. No differences are seen in limb, regional node, and distant recurrence rates in the two groups. Thus, additional improvement of the perfusion methodology is warranted.

Adult↗

PubMed1996

Extracorporeal plasma perfusion of cultured hepatocytes: effect of intermittent perfusion on hepatocyte function and morphology.

The most promising approaches to developing a temporary bioartificial liver support system involve incorporating cultured primary hepatocytes into an extracorporeal perfusion device. As a result, it is important to characterize both the phenotypic response of these cells during extracorporeal perfusion and the critical factors involved in maintaining differentiated cell function over extended periods of perfusion. In this study, hepatocytes cultured in a collagen sandwich configuration were connected to a rat via a hollow fiber plasma separator and perfused with plasma on line. Perfusions were either continuous for 48 hr or intermittent for up to 174 hr with 6 hr per day of extracorporeal plasma perfusion alternating with 18 hr of culture medium perfusion. During perfusion cell morphology was continuously monitored by time-lapse video microscopy. After the procedure, hepatocytes were returned to static culture and function was evaluated by measuring the rates of urea synthesis daily for 7 days. During plasma perfusion all hepatocytes accumulated cytoplasmic lipid droplets in a time dependent manner. Urea synthesis was maintained at initial levels for up to 20 hr of continuous plasma perfusion. However, urea synthesis rates were reduced by 31 and 52% after 30 and 48 hr of continuous plasma exposure, respectively. With intermittent perfusions, as well as with control cells perfused with culture medium only, urea synthesis rates did not decrease for at least 78 hr of total perfusion. There was no difference between the urea synthesis rates after 48 hr of cumulative plasma exposure time between cells subjected to continuous and intermittent plasma perfusion. These results suggest that cultured hepatocytes may be exposed to plasma for at least 20 hr with no significant reduction in liver-specific function. Furthermore, an intermittent plasma perfusion schedule can be used to divide the useful plasma perfusion time over several days with no adverse effects on cell function.

Animals↗

PubMed1985

Isolated hindlimb perfusion in dogs: the effect of perfusion pressures on the oxygen supply (ptO2 histogram) to the skeletal muscle.

During regional isolated perfusion, neoplasms in extremities are treated with high doses of chemotherapeutic drugs by means of an extracorporeal circuit. The question is whether optimal tissue perfusion, which is essential for the therapy, is obtained by regulation of the extracorporeal circuit on an adequate perfusion flow or on an adequate perfusion pressure. To determine which perfusion pressure is needed to maintain adequate tissue perfusion, hindlimbs of six dogs were perfused at perfusion pressures 0, 15, 25, and 50 mm Hg below systemic mean arterial pressure. A multiwire polarographic oxygen electrode placed on the sartorius muscle permitted quantitative evaluation of tissue oxygenation by means of ptO2 histograms. Our results indicated that the perfusion pressure must be equal to or within 15 mm Hg below systemic mean arterial pressure to obtain optimal tissue perfusion. To maintain this perfusion pressure, high perfusion flows of about five to 10 times control femoral flows were needed. At a perfusion pressure 50 mm Hg below systemic mean arterial pressure, perfusion flow was normal, but tissue perfusion was severely impaired.

Animals↗

PubMed1997

Tissue and perfusate pharmacokinetics of melphalan in isolated perfused rat hindlimb.

Melphalan is commonly used as a cytotoxic agent in isolated limb perfusion for locally recurrent malignant melanoma. The time course of melphalan concentrations in perfusate and tissues during a 60-min melphalan perfusion and 30-min drug-free washout in the single-pass perfused rat hindlimb was examined using a physiologically based pharmacokinetic model. The rat hindlimbs were perfused with Krebs-Heinseleit buffer containing 4.7% bovine serum albumin (BSA) or 2.8% dextran 40 at a constant rate of 3.8 ml/min. The concentration of melphalan in perfusate and tissues was determined by high-performance liquid chromatography. The tissue concentrations of melphalan were significantly higher with the perfusate containing dextran than BSA during the 60-min perfusion. During the washout period, the melphalan concentration in the perfusates decreased rapidly in first few minutes, followed by a slower monoexponential decline. The estimated half life (t1/2) for melphalan removal from skin and fat was 59 +/- 2 min for both BSA and dextran perfusates. However, the estimated t1/2 for melphalan removal from muscle was 79 and 96 min for BSA and dextran washout perfusates, respectively. The predicted concentration-time profiles obtained for melphalan with BSA and dextran perfusates appear to correspond closely to the observed data. This study showed that the uptake of melphalan into perfused tissues is impaired by the use of perfusates in which melphalan is highly bound. Melphalan washout from muscle, but not skin and fat, was facilitated by the use of perfusates in which melphalan is highly protein bound.

Adipose Tissue↗