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Tests were performed on a "shell" type heat exchanger used in a simulated extracorporeal circulation. The counter flow mode was the most efficient pattern and recommendations are made on which flow pattern should be employed with low water flow rates.
An extracorporal system of freely mobile, unanaesthetized rats is presented. This model was used in experiments on the biocompatibility of silicone rubber and new types of hollow membranes. The results confirm a sensitive reaction of haematological parameters to various test substances, thus indicating that the model is very suitable. Carrying out a membrane plasma separation in rats makes it possible also to use rats for studies on detoxification and thus to use the advantages offered by this experimental animal to the full.
We describe here successful open heart surgery with extracorporeal circulation and haemodilution in a child with severe congenital factor VII deficiency. Substitution therapy was realized with factor VII concentrate (SD proconvertin concentrate, Bio-Transfusion). This is the first report case of successful cardiac surgery in severe congenital factor VII deficiency.
A zero-heat-flow transducer was designed to monitor blood temperature during extracorporeal circulation. The probe was covered with a thick metal shell that was heated or cooled to match the surface temperature of the circulation tube, causing the net heat flow across theprobe to be reduced to zero. Experiments showed that fluid temperatures between 20 degrees C and 40 degrees C measured from the surface of a Tygon tube would be accurate within +/- 0.2 degrees C. Response time of ramp-like change in the fluid temperature from 20 degrees C to 30 degrees C was about 3 min. Animal and clinical tests showed this device to be highly accurate.
Between 1983 und 1991, emergency pulmonary embolectomy with the aid of extracorporeal circulation was performed in 13 patients. Ten patients were in class IV according to Greenfield, seven came into the operating theater with external cardiac massage. The 30-day mortality was 46%. In the same period, 15 venous interruption procedures were performed (three Adams de Weese Clip, ten Greenfield-Filter, and two femoral vein ligations). Eight times the venous interruption procedure was done prophylactically. The acute pulmonary embolism of class III and IV according to Greenfield is an indication for lytic therapy. We operate only if there is a contraindication to lytic therapy or if there is deterioration of the clinical state.
Different systems for beating heart procedures and low priming systems limited to coronary artery bypass grafting (CABG) have been introduced. We describe Priming Reduced Extracorporeal Circulation Setup (PRECiSe), a new low priming system which sup-plies all the features of cardiopulmonary bypass (CPB). PRECiSe incorporates the DeltaStream diagonal pump, which pumps blood from the right atrium to the aorta via a membrane oxygenator and a filter; the system is placed beneath the patient's head resulting in extremely short tubing. A reservoir allows the use of suckers and vents. Autologous blood priming furthers reduces hemodilution. In a safety study the system was used for extracorporeal circulation in 11 patients undergoing CABG without adverse effects. By use of PRECiSe mean priming was reduced to 268.5 ml resulting in minimal hemo-dilution and transfusion requirements.
INTRODUCTION: We report two drowning victims with hypothermic circulatory arrest who were resuscitated with the use of extracorporeal circulation (ECC). The first patient developed severe post-bypass pulmonary oedema and inspired us to use a leucocyte-depletion filter in the second patient to attenuate leucocyte-mediated pulmonary reperfusion injury. METHODS: In the first patient, a standard extracorporeal circuit was used. In the second patient, systemic leucocyte depletion was applied using leucocyte-depletion filters (Pall RS 1, Pall, Portsmouth, UK), in the venous side of the extracorporeal circuit. Circulating leucocyte counts were measured and arterial blood gas analysis and chest X-rays were performed. RESULTS: Both patients showed a decrease of the circulating leucocyte counts during rewarming and had nearly similar leucocyte counts on arrival at the intensive care unit (ICU). The first patient developed severe pulmonary oedema, with poor arterial blood gases, whereas the second patient, who had leucocyte-depletion by filtration, did not develop severe pulmonary oedema, and had good arterial blood gases. CONCLUSION: Profound leucocyte-depletion by means of filtration may have contributed to limit leucocyte-mediated pulmonary reperfusion injury.
To compare the safety and efficacy of coronary artery bypass grafting without using extracorporeal circulation with standard cardiopulmonary bypass technique, based on certain early postoperative criteria, we designed a fully randomized and prospective study on two similar groups of 25 patients (off-pump and on-pump groups). The groups were compared for hemodynamic data (cardiac index, systemic vascular resistance, left- and right-ventricular stroke-work indices, inotropic and mechanical support needs) and enzyme levels (CK-MB and SGOT), as well as mortality, perioperative infarction rate, homologous transfusion requirements, and the symptomatology in the first follow-ups. There was no mortality or perioperative myocardial infarction in either group. Inotropic (25% vs. 4%) and mechanical (4% vs. 0) support requirements and homologous blood consumption (percentages of patients that needed no transfusion: 20% vs. 72%) were greater in the on-pump group. Results were otherwise similar. It is concluded that, in technically suitable cases, off-pump coronary artery bypass surgery is as safe and efficient as the standard on-pump technique and can be used in particular when cannulation, hypothermia, or cardiopulmonary bypass must be avoided. With these properties, this technique could take an important place in the cardiac surgeon's armamentarium.
OBJECTIVE: Blood activation during extracorporeal circulation is associated with morbidity and mortality in cardiac surgery. This activation can be diminished by usage of heparin-coated circuits. Nitric oxide has also been reported to influence humoral and cellular components of blood. This study was performed to determine biomaterial-dependent part of blood activation. DESIGN: Fresh, whole human blood mixed with Ringer's solution was circulated through a heart-lung machine for two and half hours. Five circuits were heparin-coated (group HC), whilst five other circuits were uncoated (group NC). During the last half hour NO was added to the oxygen/air mixture. METHODS: Blood activation was estimated by measuring following parameters: interluekin 6, complement activation products C3a and terminal complement complex, and oxygen free radicals (OFR) production capacity, which was determined using chemiluminescence enhanced by serum opsonized zymosan (SOZ) and phorbol myristate acetate (PMA). Granulocyte activation was measured as release of myeloperoxidase (MPO) and human neutrophil lipocalin (HNL). RESULTS: OFR in granulocyte suspension stimulated by SOZ and PMA were significantly lower in the NC group, mostly later during ECC. Similarly, lower neutrophil and monocyte counts were observed in this group. NO increased superoxide production in the whole blood in heparin-coated circuits, but did not change OFR in isolated granulocytes. MPO was also affected by heparin-coating. NO supply seemed to increase release of MPO and HNL. It is concluded that heparin-coating contributed to reduction of biomaterial-dependent blood activation. An addition of NO at late stage of ECC tended to influence this activation.
OBJECTIVE: Cardiopulmonary bypass (CPB) is known to cause part of the systemic inflammatory reaction after cardiac surgery that can be responsible for organ failure. A novel technique based on a minimal extracorporeal circulation (MECC(R)) system has been evaluated with regard to the inflammatory response in a prospective study involving patients undergoing coronary artery bypass grafting. METHODS: Sixty consecutive patients were randomly assigned to either standard normothermic CPB (n=30) or the MECC system, with a reduced priming volume, no aortic venting and no venous reservoir, excluding the blood-air interface (n=30). Specific evaluation of cytokine release (IL-1beta, IL-6, TNF-alpha), as well as neutrophil elastase secretion and beta-thromboglobulin release from platelets and S100 protein assay were performed. Serial blood samples were taken prior to the onset, after initiation, at the end and after weaning of the CPB; further samples were collected 6 and 24h after the end of the CPB. RESULTS: All patients were similar with regards to pre- and intra-operative characteristics and clinical outcomes were comparable for both groups. MECC system allowed a reduced hemodilution with a mean drop of the hematocrit of 8.5 vs. 15.3% (P<0.05). Mononuclear phagocytes dropped in a more important manner under standard CPB conditions (247+/-151 vs. 419+/-168, P=0.002), but both groups demonstrated a rise in monocyte count at the end of the CBP. No significant release of IL-1beta was observed in either group. By the end of CPB, IL-6 levels were significantly lower in the MECC group (38.8+/-19.6 vs. 87.9+/-78.9, P=0.04), despite a higher monocyte count. Plasma levels of TNF-alpha rised significantly more during standard CPB than with the MECC system (17.8+/-15.4 vs. 10.1+/-5.6, P=0.002). With MECC, the neutrophil elastase release was reduced (72.7+/-47.9 vs. 219.6+/-103.4, P=0.001). Platelet count remained at higher values with the minimal compared to standard CPB. It is noteworthy to consider that beta-thromboglobulin levels showed slightly lower platelet activation in the MECC group at all times of CPB (110.5+/-55.6 vs. 134.7+/-46.8, P=0.10). The pattern of release of S100 protein showed higher values in patients undergoing standard CPB than after MECC. CONCLUSIONS: The MECC system is suitable to maintain total extracorporeal circulation and demonstrates a lower inflammatory reaction when compared to standard CPB.
Severe tracheal stenosis represents a life threatening malformation which necessitates early surgery. Two patients aged one and two years, respectively, were followed-up for signs of congenital stridor. Following respiratory infection both children became critically ill with severe dyspnoea necessitating intubation and artificial ventilation. In the first patient, echocardiography, tracheobronchoscopy and other investigations revealed a pulmonary artery sling with tracheal compression and hypoplasia of the whole trachea. In the second child, presence of a short local tracheal stenosis was found, the cause of which could not be clarified. In the patient with the pulmonary sling, resection and reimplantation of the anomalous left pulmonary artery was performed first. In both children, however, surgical reconstruction of the lower airways was necessary. Surgery was performed from a midline sternotomy approach in extracorporeal circulation. The hypoplastic trachea with circular rings in the first child was enlarged with a pericardial patch. In the second child, the local tracheal stenosis was resected and a direct anastomosis of the trachea was performed. In both patients, transient formation of granulations was observed. Both children, however, survived and their clinical condition remains good 18 and 9 months, respectively, after surgery. Tracheobronchoscopic controls show very good result. Our experience confirms the possibility of successful surgical reconstruction of lower airways in young children using extracorporeal circulation. Good interdisciplinary cooperation between the surgeon and other specialists is an important prerequisite of good surgical results.
Long-term extracorporeal support for acute lung failure was introduced in 1972. In the 1970s, much effort was concentrated on technical improvements. However, a multicenter study comparing continuous positive-pressure ventilation and continuous positive-pressure ventilation plus extracorporeal circulation failed to show improvement in survival rates. In the 1980s, new physiopathologic concepts were developed, such as extracorporeal CO2 removal coupled with lung rest. The main complication of the technique was bleeding due to systemic heparinization. However, the technology used in that period was the same as in the 1970s. Recently, technological improvement--such as percutaneous cannulation and surface-heparinized artificial lungs--has allowed clinical performances to improve substantially. "Lung rest" philosophy, coupled with safe technology, may provide a rational basis to test this technique in a randomized fashion for widespread use.
Clinical characteristics of protease inhibitor, nafamostat mesilate (FUT-175:FUT), as an anticoagulant for extracorporeal circulation (ECC) were evaluated in hemodialysis and membrane plasmapheresis. FUT inhibited broad enzymatic systems including coagulation, platelet, complement, fibrinolysis and kinin cascades, which were commonly activated in the course of ECC. FUT showed regional anticoagulability, in which anticoagulating effects were firmly limited in extracorporeal circuit, and hemostatic time after ECC was significantly shortened by the use of FUT. FUT had no effects on lipid and bone metabolisms and FUT could not be adsorbed to anion exchange resin. These results indicate that FUT possesses superior characteristics as an anticoagulant for ECC to heparin, and FUT is very useful especially for ECC of patients with high bleeding risk.
Microemboli during extracorporeal circulation (ECC) might be a reason for postoperative neuropsychological dysfunction. This case report shows that reduction of microbubbles in the arterial line, as well as high intensity transient signals (HITS) in the middle cerebral artery (MCA), could be accomplished by use of a dynamic bubble trap (DBT) during routine coronary artery bypass graft (CABG) surgery in a 63-year-old male. The DBT was placed after the arterial filter, an ultrasound Doppler device was used for detection of microemboli before and after the DBT. HITS were measured by a transcranial ultrasound Doppler in both MCAs. For first 32 min of ECC, the DBTwas excluded; 54 916 microbubbles and 507 HITS were counted. In the next 30 min, blood flow was directed through the DBT. This led to a significant reduction of microbubbles from 55 888 to 18 237; accordingly, only 120 HITS were registered. A DBT, integrated in ECC for routine CABG, effectively reduces air bubbles, thus protecting the cerebrovascular system from microembolization, as demonstrated by lower HITS counts.
A total of 94 cases were analyzed. Transient cerebral circulatory disorders in a majority of the patients with cardiac defects were caused by intraoperative factors. Clarification of these factors and the study of clinical course of the disorders made it possible to diagnose them timely and begin the differentiated treatment.
In 30 patients with acquired and 14 with congenital heart diseases operated on under extracorporeal circulation a significant decrease in the blood Mg level was noted, its amount never returning to the preoperative one within the first week. Therapy with Mg salts helped to prevent these disorders and to maintain the plasma and erythrocytes Mg levels within the normal limits throughout the whole period of therapy.
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