Efficacy of a new oxygenator-integrated fat and leukocyte removal device.

We evaluated the effectiveness of a new oxygenator-integrated device for removing lipid particles and leukocytes from shed mediastinal blood in 20 patients undergoing elective cardiac surgery under cardiopulmonary bypass. Another 20 patients undergoing cardiac surgery without the device served as controls. After filtration with the RemoveLL device, lipid particles, leukocytes, and fats were significantly reduced compared to preoperative levels. In the control group, blood fats and lipid particles at the end of cardiopulmonary bypass were significantly increased compared to preoperative levels. Leukocyte counts at the end of bypass were significantly lower in patients who had the filtration device compared to the control group. Platelets counts and hematocrit changes were not significantly different between the 2 groups.

Noncardiac surgery brain injury: etiologic factors and prevention.

EXCERPT: During total joint arthroplasty, showers of bony spicules, marrow fat, and clot are carried by venous blood to the lungs, creating conditions not unlike those present in patients who have suffered traumatic long bone fractures. There is recent evidence that, like the fat embolism syndrome (FES), which often has a component of neurologic dysfunction, total joint arthroplasty and femoral nailing are associated with intraoperative brain embolization as determined by transcranial Doppler ultrasonography, and magnetic resonance brain imaging. Although there are good data demonstrating that intraoperative brain embolization occurs during total joint arthroplasties, the makeup and, even more importantly, the clinical significance of these emboli remain speculative. Brain microemboli resulting from cardiac surgery occur by the millions and may cause focal ischemia resulting in significant neurologic dysfunction. Our studies suggest that the major source of these microemboli is lipid droplets of the patient's fat that drip into the blood in the surgical field. This lipid-laden blood is aspirated and then returned to the patient via the cardiopulmonary bypass (CPB) apparatus. Our investigations have focused on the causes (microemboli), consequences (brain damage), and strategies for elimination of brain lipid microemboli resulting from salvaged blood collected during surgery.

Fat reduction in pericardial suction blood by spontaneous density separation: an experimental model on human liquid fat versus soya oil.

Pericardial suction blood (PSB) contains mediastinal liquid wound fat with an embolic potential to cause brain damage after cardiopulmonary bypass (CPB). The aims were to measure how fat separates spontaneously from blood by density and how temperature and fat surface adhesion affect the results under experimental conditions. Human liquid fat was heat-extracted from retrieved pericardial fat tissue of coronary artery bypass graft (CABG) patients (n = 10). Human fat or soya oil, 5% and 10%, respectively, were mixed with postoperatively shed mediastinal blood (n = 20). The mixture was loaded into a temperature-controlled (37 degrees C, 20 degrees C, 10 degrees C) vertical separation column. At 1, 2.5, 5 and 10 minutes, the blood was collected in five fractions, representing layers of density separation, followed by centrifugation. Human fat solidified at 8 degrees C. Soya oil remained liquid below 0 degrees C. Soya oil separated fast in water, but was slower in blood. At 10 minutes and 37 degrees C 73 +/- 6% of added soya oil was found in the top 20% fraction. Human fat at 37 degrees C behaved similarly to soya oil, with 58 +/- 2% separation at 10 minutes. However, at lower temperatures the density separation became less efficient (p < 0.001), whereas human fat more effectively adhered to the walls of the column, which added to the removal. In total, 66%-78% of the human fat was removed, depending on temperature. In conclusion, fat in PSB can be reduced by simple density separation and surface adhesion while it is temporarily retained from the CPB circuit.

A prospective randomised comparison of cardiotomy suction and cell saver for recycling shed blood during cardiac surgery.

OBJECTIVE: Post-operative neuropsychological complications correlate with intra-operative microemboli in the middle cerebral artery. When severe neurological complications follow cardiac surgery, diffuse cerebral fat emboli are present at autopsy. Recycling shed blood with cardiotomy suction is an important source of cerebral fat microemboli. A cell saver may reduce this. METHODS: Twenty patients were prospectively randomised to assess the amount of fat in blood salvaged from the pericardium and returned to the patient with either cell saver or cardiotomy suction. Blood samples were taken before and after filtration in the cardiotomy suction group or cell saver processing in the cell saver group. After centrifuging samples, fat content was graded on a scale of 0-3 by a blinded independent observer. Fat content was also quantified by weight. RESULTS: Compared with cardiotomy suction, cell saver removed significantly more fat from shed blood. Median fat grading after cell saver was 0 (0-1) compared with 1 (1-2) for cardiotomy suction (P=0.0001). Percentage reduction in fat weight achieved by cell saver or cardiotomy suction was 87% compared to 45% (P=0.007). There was no difference in the post-operative use of blood or blood products, haemoglobin, or bleeding between the two groups. CONCLUSION: Use of cell saver results in less fat being recycled during cardiopulmonary bypass.

Detection and removal of fat particles from postoperative salvaged blood in orthopedic surgery.

BACKGROUND: Although transfusion or return of salvaged shed blood has become popular in major orthopedic procedures, this blood-saving method is still controversial because shed blood may be contaminated with chemical and tissular debris, such as fat particles, which may increase the risk of fat embolism after bone surgery. STUDY DESIGN AND METHODS: In an effort to find an easy, reliable method for determination of both fat particle content and removal from shed blood, analyses of perioperative blood samples were performed with a cell counter (Technicon H3 [H3]) in orthopedic patients undergoing spinal fusion in which postoperative shed blood was collected and returned with a blood collection canister. A screen or surface filter was intercalated in the return line to eliminate microaggregates, fat particles, and/or WBCs. RESULTS: Fat particles in shed blood are clearly detected as a condensed, sigmoidal-shaped area at the right-hand side of the PMN zone in the channel in which the H3 measures particles according to their degree of lobularity. This signal can be reproduced by the addition of animal or vegetable fat to venous blood, but not by the addition of activated platelets or RBC membranes. Fat particles, together with WBCs and microaggregates, in shed blood were effectively removed by surface filters, whereas screen filters were not effective. CONCLUSION: The use of the TH3 seems to be an easy, reliable, and low-cost approach for monitoring fat particle content and removal from postoperative salvaged shed blood in orthopedic procedures.

Pharmacological strategies for blood conservation in cardiac surgery: erythropoietin and antifibrinolytics.

PURPOSE: We review the clinically important benefits of the two principal pharmacological strategies, erythropoietin (EPO) and antifibrinolytics (aprotinin and lysine analogues), to decrease transfusion of allogeneic blood products (ABP) during and after cardiac surgery. SOURCE: Articles were selected from an ongoing review of the literature, with special attention to meta-analyses dealing with EPO and/or antifibrinolytics and cardiac surgery. PRINCIPAL FINDINGS: The few studies available include a number of patients insufficient to allow definitive conclusions on the benefits of EPO in cardiac surgery. Further studies are required to determine the optimal dose of EPO and to compare its cost-effectiveness with other blood sparing strategies in this context. Both aprotinin and lysine analogues effectively decrease ABP transfusions and the incidence of re-thoracotomy. In addition, high-dose aprotinin reduces cerebrovascular morbidity and mortality after cardiopulmonary bypass. Several mechanisms have been put forward to explain these beneficial effects, some of which could well be common to all antifibrinolytics. The clinical benefits of aprotinin's unique anti-inflammatory effect are not entirely clear but the finding that it reduces the incidence of stroke and death is certainly a major argument in favor of its utilization. Yet, we have to ensure that aprotinin's benefits are not offset by side-effects such as allergy. CONCLUSIONS: We still need large scale studies to definitely confirm the benefits and exclude the deleterious effects of these drugs on outcomes other than ABP requirements. At present, aprotinin is the only agent that has been shown to reduce the risk of cerebrovascular accident and mortality after cardiac surgery in adults.

Fat elimination from autologous blood.

Bowl-based autotransfusion devices reduce the amount of fat found in shed blood, but cannot completely eliminate fat particles. When fat is seen on the surface of the processed blood, this blood should be filtered with a leukocyte removal filter before retransfusion.

Processing scavenged blood with a cell saver reduces cerebral lipid microembolization.

BACKGROUND: Microembolization during cardiopulmonary bypass (CPB) can be detected in the brain as lipid deposits that create small capillary and arteriolar dilations (SCADs) with ischemic injury and neuronal dysfunction. SCAD density is increased with the use of cardiotomy suction to scavenge shed blood. Our purpose was to determine whether various methods of processing shed blood during CPB decrease cerebral lipid microembolic burden. METHODS: After hypothermic CPB (70 minutes), brain tissue from two groups of mongrel dogs (28 to 35 kg) was examined for the presence of SCADs. In the arterial filter (AF) group (n = 12), shed blood was collected in a cardiotomy suction reservoir and reinfused through the arterial circuit. Three different arterial line filters (Pall LeukoGuard, Pall StatPrime, Bentley Duraflo) were used alone and in various combinations. In the cell saver (CS) group (n = 12), shed blood was collected in a cell saver with intermittent preocessing (Medtronic autoLog model) or a continuous-action cell saver (Fresenius Continuous Auto Transfusion System) and reinfused with and without leukocyte filtration through the CPB circuit. RESULTS: Mean SCAD density (SCAD/cm2) in the CS group was less than the AF group (11 +/- 3 vs 24 +/- 5, p = 0.02). There were no significant differences in SCAD density with leukocyte filtration or with the various arterial line filters. Mean SCAD density for the continuous-action cell saver was 8 +/- 2 versus 13 +/- 5 for the intermittent-action device. CONCLUSIONS: Use of a cell saver to scavenge shed blood during CPB decreases cerebral lipid microembolization.

[The effects of injection salviae miltiorrhizae in preventing and treating fat embolism syndrome].

This study was to examine the effects and mechanisms of injectio salviae miltiorrhizae (ISM) in preventing and treating fat embolism syndrome (FES), which was simulated by intravenous injection of homologous bone marrow fat in 16 dogs. PaO2, free fatty acids (FFAs), TXA2/PGI2, SOD/MDA were measured in different times combined with X-ray, conjunctiva microcirculation observation, radioisotope scanning and histologic examination. It was found that in the control group there were a significant fall in PaO alpha and rise in FFAs and MDA; blood clot stained with oil red O showed many fat droplets; radioisotope scanning revealed mild hypoperfusion or perfusion defects. In the treatment group, arterial oxygen levels were maintained, serum level of FFAS and MDA was reduced significantly. It is concluded that there is damage induced by oxygen-derived radicals in FES, LSM is an effective therapy for the FES, and 99mTc radioisotope scanning is a promising technique for noninvasive identification of FES in the early stage.

[Preventive use of tiadenol in pulmonary fat embolism in rabbits with multiple experimental fractures]. / Sull'impiego preventivo del tiadenolo nell'embolia adiposa polmonare di conigli con fratture multiple sperimentali.

Preventive treatment with tiadenol administered to rabbits given experimental multiple fractures succeeded to a certain extent in modifying the adipose pulmonary embolism process. Since the drug is able to reduce tissue lipolysis, it was deduced that this enzyme is of limited importance in the genesis of adipose embolisms.