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The influence of extracorporeal circulation on erythrocytes and flow properties of blood.

The influence of extracorporeal circulation on red blood cells and flow properties of blood was studied in 10 patients undergoing aorta-coronary bypass grafting. Blood samples were drawn on admission, under general anesthesia before the operation, during extracorporeal circulation, immediately after extracorporeal circulation, and 24 hours after extracorporeal circulation. Echinocytes were found during and shortly after extracorporeal circulation, but disappeared within 24 hours. Washing the cells in buffer restored the normal discocytic shape, which indicated that a plasma factor was responsible. Red cell membrane lipids were not affected. Analysis of the membrane proteins revealed a decrease of ankyrin after extracorporeal circulation, which was prevented by protease inhibitors during preparation. This suggests an increased proteolytic activity of the plasma after extracorporeal circulation. Red cell deformability was not altered. Plasma viscosity and hematocrit were markedly reduced by hemodilution with the priming solution. Their low levels resulted in a low blood viscosity during extracorporeal circulation, which was even lower at 26 degrees C than before or after the operation at 37 degrees C. We conclude that the red cell is affected by extracorporeal circulation. The flow properties of blood, however, are not impaired, but are improved by hemodilution.

Aged↗

Absence of urethral strictures with suprapubic urinary drainage during extracorporeal circulation.

Postoperative urethral strictures following extracorporeal circulation in open heart surgery are not uncommon. The etiology is not clear. Ischemia and pressure of the Foley catheter may cause a lesion that eventually leads to urethral stricture. We retrospectively analyzed 300 patients who had undergone open heart surgery. In 1 group the bladder was drained by a Foley catheter during extracorporeal circulation, while another group underwent suprapubic drainage. Strictures developed in 10 of 152 patients (6.6%) with an indwelling catheter. Conversely, no strictures occurred in the 148 patients treated with suprapubic urinary drainage. The use of suprapubic drainage during extracorporeal circulation greatly decreases the risk of postoperative urethral strictures.

Adolescent↗

Some experimental aspects of using lungs as biological oxygenator in extracorporal circulation.

Exposing problem of oxygenators in extracorporal circulation authors consider screen and membrane as the best, in spite of some disadvantages from which the haemolysis is the most cumbersome. In attempt to find the way of solution of this problem, authors have made a number of experiments in animals where they have conducted extracorporal circulation in such way that blood has been oxygenated in own lungs of an animals. Two types of bypass were examined as: right to right bypass (vv. cavae-pulmonary artery), right to right bypass as exposed with possibility of interconnection with classical extracorporal circulation, and finally bypass of the left and right heart. Exposing their experience and results authors consider that use of lungs as biological oxygenator in extracorporal circulation has its justification according to achieved results. In spite of some problems which need further elaboration such experiments are the motive for more work and reflexion in this type of problem.

Animals↗

Circulating endothelial cells demonstrate an attenuation of endothelial damage by minimizing the extracorporeal circulation.

OBJECTIVE: Detachment of endothelial cells may represent serious injury of the endothelium after cardiopulmonary bypass. We investigated whether the extent of endothelial injury is related to the type of cardiopulmonary bypass system used (conventional or minimized) and determined circulating endothelial cells as well as von Willebrand factor and soluble thrombomodulin. METHODS: Twenty patients scheduled for elective coronary bypass grafting were randomly assigned to either the minimal extracorporeal circulation system or the standard cardiopulmonary bypass. Ten healthy volunteers served as controls. Circulating endothelial cells per milliliter of full blood were perioperatively determined by immunomagnetic cell separation technique. Endothelial plasma markers were measured by enzyme-linked immunosorbent assay. RESULTS: Preoperative circulating endothelial cell numbers did not differ between the experimental groups, but were significantly higher than in the healthy controls (18.6 +/- 5.6 vs 7.2 +/- 3.8, P < .001). At 6 hours, circulating endothelial cell numbers increased significantly compared with baseline in both experimental groups and peaked at 12 hours after cardiopulmonary bypass initiation, each time with significantly lower values in the minimal extracorporeal circulation group (6 hours: 44.0 +/- 9.9 vs 29.6 +/- 9.8, P = .007; 12 hours: 48.1 +/- 6.8 vs 31.8 +/- 7.1, P < .001). Likewise, von Willebrand factor and soluble thrombomodulin postoperatively increased in both groups with a tendency toward lower levels in the minimal extracorporeal circulation group. Although circulating endothelial cells gradually declined, continually with lower numbers in the minimal extracorporeal circulation group, the endothelial plasma markers remained elevated during observation time. CONCLUSIONS: Circulating endothelial cells represent a novel marker of the intrinsic endothelial damage caused by cardiopulmonary bypass. Its analysis facilitates the evaluation of cardiopulmonary bypass modifications as the minimal extracorporeal circulation system could be proven to be less injurious to endothelium and myocardium.

Aged↗

Cytokine release during long-term extracorporeal circulation in an experimental model.

The objective of this study was to determine the degree of leukocyte activation, as measured by cytokine release, in circulating blood during experimental extracorporeal circulation. Complete in vitro extracorporeal membrane oxygenation (ECMO) circuits were used, and 9 experiments were performed. Whole blood stored at 37 degrees C was used as the control. Blood samples were withdrawn before the start of perfusion and at 24 h of perfusion. Statistically significant releases of interleukin (IL)-1beta, IL-8, and IL-1 receptor antagonist were observed in the perfusion circuits compared to both the control blood and baseline values. Also, increases in plasma tumor necrosis factor (TNF)alpha and IL-6 were seen after 24 h of perfusion although these changes did not reach statistical significance. These results indicate that extracorporeal circulation induced leukocyte activation and cytokine release. These reactions might, as an additional trauma, deteriorate the situation in an already severely ill patient. A search for methods to counteract this untoward activation seems warranted.

Adult↗

[Hypothermic retrograde cerebral perfusion for treatment of air embolism during extracorporeal circulation].

Air embolism during extracorporeal circulation is a life-threatening complication, requiring immediate response. During a recent case, brain damage was avoided using hypothermic retrograde cerebral perfusion, connecting the arterial line to superior vena cava cannula. Perfusion lasted 5 minutes at flow of 200ml/min. The patient had complete recovery and was discharged with normal neurologic status. The technique employed is described and steps for a face this accident are proposed.

Adult↗

[The effects of administration of haptoglobin for hemolysis by extracorporeal circulation].

It is well known that hemolysis by extracorporeal circulation is major cause of renal failure after open heart surgery. The purpose of this study is to investigate the effects of administration of haptoglobin (Hp) during extracorporeal circulation. The patients were divided into two groups: Group I 10 patients underwent open heart surgery for extracorporeal circulation; Group II 10 patients underwent open heart surgery for extracorporeal circulation with the administration of 4,000 IU of Hp. The serum level of total Hp was elevated in group II during bypass, and reduced at 1st day in both groups more than pre-operative level. The serum level of total Hb was elevated in both groups during bypass, and reduced at 1st day within normal limits. Free serum Hb was found in group I at 30 min after start bypass and increased during bypass and urinary Hb was also found. However, in group II free Hb was not found during and after bypass. Urinary NAG and alpha 1 Mg levels of group I were significantly higher than those of group II. The administration of Hp during extracorporeal circulation prevents the increment of serum free Hb and is effective for protection of renal function.

Acute Kidney Injury↗

[Changes in renal function in subjects undergoing an aortocoronary bypass with extracorporeal circulation].

It is well known that extracorporeal circulation (ECC) may determine an impaired renal function. The aim of our study was to identify those patients who, on the basis of the presence of cardiovascular risk factors such as diabetes mellitus, hypertension and hyperlipidemia, show more evident signs of such dysfunction. The study was conducted on 333 male patients, aged > 49 years, with normal renal function, who underwent coronary artery by-pass surgery in extracorporeal circulation. The results show that, among the cardiovascular risk factors, hypertension has a major influence on renal function after performing extracorporeal circulation, particularly on glomerular filtration rate and, when associated to diabetes mellitus, renal dysfunction may persist until the 9th post-operative day.

Coronary Artery Bypass↗

Effects of off-pump coronary surgery on the mechanics of the respiratory system, lung, and chest wall: Comparison with extracorporeal circulation.

OBJECTIVE: To compare the effects of cardiac surgery with and without extracorporeal circulation on the mechanics of the respiratory system, lung, and chest wall. We also determined the time course of those effects. DESIGN: Prospective, controlled study. SETTING: An eight-bed, cardiac-surgical intensive care unit at a university hospital. PATIENTS: Two groups of patients scheduled for elective coronary bypass surgery were studied: ten patients with extracorporeal circulation and 13 patients without extracorporeal circulation. INTERVENTIONS: Measurement of esophageal pressure after insertion of an esophageal balloon catheter to separate respiratory system mechanics into lung and chest wall components. Measurements were performed preoperatively after induction of anesthesia (control), immediately postoperatively at arrival in the intensive care unit (time 1), and after 3 hrs (time 2). In 12 of the 23 patients, measurements were also performed 6 hrs postoperatively (time 3). MEASUREMENTS AND MAIN RESULTS: No significant differences concerning demographics or surgical procedure were noticed between the two groups. Respiratory system, chest wall, and lung mechanics were obtained using the technique of rapid airway occlusion during constant-flow inflation. In both the group with and without extracorporeal circulation there was a significant increase in static and dynamic elastance of the respiratory system and lung at times 1 and 2, which tended to decrease again at time 3; chest wall elastance significantly increased at times 2 and 3 in the group without extracorporeal circulation, whereas the increase in chest wall elastance in the group with extracorporeal circulation occurred earlier (also at time 1). Additional resistance of the respiratory system and lung remained unchanged; chest wall resistance, however, significantly increased in both groups. Work of breathing significantly increased in both groups at times 1 and 2. There was a significant reduction in the Pao2/Fio2 ratio in both groups at times 2 and 3. No significant differences between the groups at any moment were noticed. CONCLUSIONS: Coronary bypass surgery with and without extracorporeal circulation results in dramatic impairment of respiratory system mechanics. Based on respiratory system mechanics, early extubation after coronary artery bypass grafting should be performed with caution, no matter whether the off-pump or cardiopulmonary bypass technique is used.

Aged↗

Inflammatory response during simulated extracorporeal circulation with addition of nitric oxide.

BACKGROUND: Heart operations performed with extracorporeal circulation (ECC) are associated with an inflammatory response. This response is partially due to granulocyte activation. Leukocyte derived free radicals are involved in tissue injury. The purpose of this study was to observe whether nitric oxide influence the inflammatory response during simulated ECC. METHODS: In a model of simulated extracorporeal circulation, fresh whole human blood mixed with Ringer's solution was circulated through a heart-lung machine for three hours. In five circuits NO was added to oxygen/air mixture (group N), while five other circuits were ventilated with oxygen/air mixture (group C). The methods for estimating the inflammatory response were determination of oxygen free radicals production capacity, using chemiluminescence, and measurements of concentration of granulocyte derived proteins (myeloperoxidase and human neutrophil lipocalin). RESULTS: All measured parameters were similarly independent of additional supply of nitric oxide almost throughout extracorporeal circulation time. The sole significant difference between the two groups was found at an early stage of extracorporeal circulation, when luminol-enhanced chemiluminescence in whole blood was higher in the N group (1,500, 1,470-1,950 vs 1,038, 750-1,050 in the control group; medians with quartiles). A similar tendency was observed in lucigenin-enhanced chemiluminescence at 60 min of extracorporeal circulation (625, 560-875 in the N group vs 400, 360-525 in the control group; medians with quartiles). CONCLUSIONS: Nitric oxide supply does not influence inflammatory response during three hours long extracorporeal circulation, although some protective effect on hydrogen peroxide production in whole blood was detected in the initial phase of extracorporeal circulation.

Acridines↗

[Perioperative oxygenation and pulmonary shunt during myocardial revascularization in function of duration of extracorporeal circulation].

Perioperative oxygenation is of great importance for the result of operative treatment, especially in patients undergoing open-heart surgery. We studied effect of the duration of extracorporeal circulation on value of pulmonary shunt in 27 patients undergoing coronary artery bypass grafting surgery. The patients were divided into one of two groups according to the duration of extracorporeal circulation: A1 group--extracorporeal circulation less than 90 minutes (9), and A2 group extracorporeal circulation over 90 minutes (18). Measurements of pulmonary shunt were performed at the following times: before (I) and after induction of anaesthesia (II), 5 minutes (III), 2 hours (IV) and 6 hours (V) after extracorporeal circulation, 30 minutes after extubation (VI), 24 hours after extracorporeal circulation (VII), on the second (VIII), third (IX), fifth (X), eighth (XI) and thirteenth (XII) postoperative day. Pulmonary shunt was calculated according to the standard shunt equation (Berggren 1942) in control times I-VII, and formula of estimated shunt in control times VIII-XII. The length of extracorporeal circulation had influence on pulmonary shunt and oxygenation in patients undergoing myocardial revascularization. Extracorporeal circulation lasting over 90 minutes significantly increased pulmonary shunt in the first 24 hours after extracorporeal circulation, excluding the period of artificial ventilation following operation. The recovery of pulmonary function occurred between the eighth and the thirteenth postoperative day, regardless of the duration of extracorporeal circulation.

Coronary Artery Bypass↗

Coronary circulation and myocardial oxygen consumption after extracorporeal circulation and after cardioplegic arrest.

The influence of haemodilution or of blood perfusion on the coronary circulation, myocardial oxygen consumption and on haemodynamic parameters was examined in two comparable groups of patients with slight congenital acyanotic cardiac malformation without indications of myocardial damage. In a third group of patients similar data were collected before and after artificial cardiac arrest by cardioplegic solutions. No findings concerning this question could be found in the literature. Coronary circulation was measured by the argon-gas-technique of Bretschneider et al. A fall in haemoglobin of 4.8% caused by haemodilution resulted in the first group in an increase in the cardiac index of about 8% and an increase in the coronary circulation of about 100% over the initial value with a simultaneous decrease in the coronary resistance due to coronary dilatation and reduction in blood viscosity. The myocardial O2 consumption was raised in spite of an increase in the coronary-venous O2 saturation and a clear reduction in the AVD O2. In contrast, the patients in the blood perfusion group showed no change in the coronary circulation and coronary resistance although a decrease of the myocardial O2 consumption was observed. The cardiac index fell to about 16% in these patients. After cardioplegic cardiac arrest there was no significant reduction in myocardial blood flow except for a decrease of myocardial oxygen consumption of about 20% The results are discussed and cantra-indications of haemodilution perfusion and cardioplegic cardiac arrest mentioned.

Cardiac Output↗

Estimation of total body fluid shifts between plasma and interstitium in man during extracorporeal circulation.

Fluid transport between plasma and interstitium during extracorporeal circulation was studied in seven patients undergoing aortocoronary bypass grafting. The absolute shifts in plasma volume during hypothermia were determined as the difference between input and loss of fluid and the changes in blood volume. The change in haemoglobin concentration due to acute haemodilution when starting extracorporeal circulation was used to calculate the absolute blood and plasma volume. The Starling equation for exchange across the capillary wall was used to describe fluid shifts. The total fluid filtered during the 60- to 90-min period of extracorporeal circulation averaged 34.1 +/- 11.1 (s.d.) ml/min. The total body filtration coefficient from the Starling relationship averaged 0.046 +/- 0.012 ml/kg.mmHg.min (0.354 +/- 0.092 ml/kg.kPa.min). Haemodilution, reducing colloid osmotic pressure in plasma (COPP) by approximately 10 mmHg (1.3 kPa) will result in a loss of plasma fluid of around 2 1 per hour. When corrected for lower fluid viscosity due to hypothermia during extracorporeal circulation, CFC would be about 40% higher, and a filtered volume of nearly 3 1 in a normothermic 70-kg person would be expected. Crystalloid haemodilution for shorter periods of time does not produce excessive oedema and thus may be well tolerated.

Aged↗

Prophylactic administration of tranexamic acid preserves platelet numbers during extracorporeal circulation in rabbits.

Neonatal extracorporeal life support is associated with platelet consumption and hemostatic disorders. This study in rabbits was undertaken to evaluate the effect of heparin coating and of the plasminogen and plasmin inhibitor, tranexamic acid on platelet consumption during extracorporeal circulation. Fibrinogen consumption was prevented by heparin coating, but platelet consumption was only prevented after the prophylactic administration of tranexamic acid. The authors concluded that inhibition of the fibrinolytic system had a specific effect on preserving platelet numbers, rather than improving the thromboresistance of the artificial surface. The main advantage of a heparin coating is the anticoagulant activity of the surface. Thus systemic heparinization can be reduced or omitted.

Animals↗

Predictive criteria for the need of extracorporeal circulation in single-lung transplantation.

Use of extracorporeal circulation is mandatory in heart-lung and en bloc double-lung transplantation. However, no criteria exist to predict the necessity of its application during single-lung transplantation for parenchymal lung diseases. We therefore reviewed our experience in 23 patients undergoing single-lung transplantation for idiopathic pulmonary fibrosis. All patients were evaluated by preoperative right heart catheterization. For intraoperative monitoring, a pulmonary artery thermodilution catheter was placed in the contralateral lung to repeatedly assess pulmonary artery pressure, cardiac output, and pulmonary vascular resistance. Extracorporeal circulation was necessary during graft implantation in 4 patients, whereas 19 patients underwent operation without it. Preoperative demographic patient data, time of ischemia, and hemodynamic values obtained preoperatively and before the clamping of the pulmonary artery showed no significant differences between groups. In contrast, after the clamping of the pulmonary artery, a significant drop in cardiac index of about 1.5 L.min-1.m-2 (p less than 0.01) and a concomitant rise in pulmonary vascular resistance (p less than 0.01) was observed in the group requiring extracorporeal circulation, whereas these variables showed no significant changes in the other 19 patients. Pulmonary artery pressure rose significantly in both groups (p less than 0.05), without significant differences between them. It is concluded that intraoperative assessment of cardiac index and pulmonary vascular resistance is essential for estimation of cardiac performance during single-lung transplantation. A decrease in cardiac index of more than 1.5 L.min-1.m-2 after the clamping of the pulmonary artery rather than the degree of pulmonary hypertension is indicative of the need of extracorporeal circulation.

Adult↗