Novel Applications of Modified Ultrafiltration and Autologous Priming Techniques to Reduce Blood Product Exposure on ECMO

Patients needing the assistance of extracorporeal membrane oxygenation (ECMO) are at risk of hemodilution and, in some instances, may require exposure to large amounts of allogeneic blood products. Patient outcomes can be improved by taking steps to reduce transfusions and hemodilution. Currently, modified ultrafiltration (MUF) is used across the world to reduce hemodilution after cardiopulmonary bypass (CPB). Another common technique during bypass initiation is autologous priming. By applying modified versions of these techniques, ECMO patients may potentially benefit. Usually, patients requiring immediate transition from CPB to ECMO are not stable enough to tolerate MUF. Through alterations of the CPB and ECMO circuit tubing, MUF can be performed once on ECMO. Another technique to potentially lower the transfusion requirements for ECMO patients is a complete circuit blood transfer during an ECMO circuit exchange. While selective component changes are preferred if possible, occasionally a complete circuit change must be done. To minimize hemodilution or prevent priming with blood products, the original ECMO circuit's blood can be transferred to the new ECMO circuit before connecting to the patient. Both of these techniques, in our opinion, helped to reduce the number of transfusions that our ECMO patients have seen during these critical time periods.

Perfusion techniques toward bloodless pediatric open heart surgery

There continues to be evidence regarding the negative impact of blood transfusion on morbidity and mortality in the adult literature, including infection risk, increased hospital and intensive care length of stay, and costs. More effort has been put into reducing the use of blood components in adult surgical centers but blood transfusions continue to be used frequently in pediatric centers. From 2002 through 2005, we embarked on a mission of reduced prime volume in an effort toward bloodless cardiac surgery to meet the needs of the Jehovah's Witness patient. The same bloodless surgical and perfusion techniques were applied to all patients undergoing cardiopulmonary bypass beginning in 2006. Circuit size was minimized and acute normovolemic hemodilution (ANH) was considered and attempted more often, especially if a re-operation. Retrograde arterial prime (RAP) and venous antegrade prime (VAP), dilutional or balanced ultrafiltration during cardiopulmonary bypass, modified arteriovenous ultrafiltration post bypass, and cell salvage of remaining circuit contents after flushing with crystalloid were recorded. ANH, RAP, and VAP, separately or in combination, were used less than 1% of the time prior to 2006. From 2006-2008 ANH was performed on 42% of the patients and RAP/ VAP was performed on 70% of the patients. From 2006-2008, 43% (287 of 662) of the open heart surgeries were performed bloodless in the operating room versus 30% (193 of 633) from 2003-2005. Bloodless surgery more than doubled for the 0-6, 6-15, and 15-20 kg groups from 3.5%, 23%, and 23% respectively in 2003-2005 to 9%, 44%, and 58%, respectively in 2006-2008. With the cooperation of the entire cardiac surgical team, bloodless open heart surgery is achievable in a pediatric cardiac surgical center, including neonates.

Erythropoietic therapy: Cost efficiency and reimbursement

PURPOSE

The practice of blood conservation is aimed at improving patient outcomes by avoiding allogeneic transfusions via a coordinated multidisciplinary, multipronged approach. The numerous blood conservation techniques and transfusion alternatives now available are described.

SUMMARY

Ongoing concerns exist regarding the availability of the nation's and the world's blood supply. In addition, the number of measures required to ensure blood safety has led to increases in the price of blood and blood products over the past 10-15 years. Moreover, blood transfusion carries inherent risks even under the most favorable circumstances. Investigations have established that injudicious transfusion is associated with development of ventilator-associated pneumonia, nosocomial infection, and organ dysfunction. Because most single blood-conservation techniques reduce blood usage by a mere 1-2 units, a series of integrated conservation approaches are required. These include preoperative autologous donation, use of erythropoietic agents, blood conservation techniques such as acute normovolemic hemodilution, individualized assessment of anemia tolerance, implementation of conservative transfusion thresholds, meticulous surgical techniques, and judicious use of phlebotomy and pharmacologic agents for limiting blood loss. Erythropoietic agents such as epoetin alfa have been used successfully to increase hemoglobin and decrease transfusion requirements, and are appropriate when used in advance of elective surgical procedures. Acquisition costs of erythropoietic stimulating agents versus costs of blood justify economic evaluation by hospitals to make the most cost-effective choice under current economic constraints.

CONCLUSION

Initiating a blood management program requires planning and support from those who are concerned about blood usage reduction and outcomes improvement. Launching a vigorous and ongoing educational program to raise awareness about the risks and hazards associated with blood transfusion is an important step in helping to reshape the medical staffs' attitudes about transfusion and the most cost-effective way to achieve clinical goals.

Retinale Zentralvenen- und Venenastverschlüsse

BACKGROUND

The main object of this study was to find out what treatment methods are currently preferred for central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) in Germany, Austria and Switzerland.

METHODS

A questionnaire concerning the different medicamentous, surgical and laser treatments available for CRVO and BRVO was developed and sent out to the members of the German Retina Society.

RESULTS

This analysis is based on 124 returned questionnaires. We found that 64% of our colleagues recommend isovolemic hemodilution in patients with CRVO. Pentoxyfyllin infusions are endorsed by 32% and 27%, respectively, for CRVO and BRVO. Panretinal photocoagulation is applied only if neovascularization is present by 39% of those responding, whereas 61% perform prophylactic photocoagulation when there is no visible neovascularization, depending on the degree of ischemia. In the case of macular edema due to BRVO 52% recommend macular grid photocoagulation. Sheathotomy is recommended by 51% for BRVO suggest, and 43% advise radial optic neurotomy (RON) for CRVO. Intravitreal injection of triamcinolone is performed for CRVO or BRVO by 58% and 56%, respectively, and para-bulbar injection of triamcinolone by 2% and 3%. Intravitreal anti-VEGF treatment is applied by 72% of respondents, the majority (94%) using bevacizumab for this purpose.

CONCLUSION

Members of the German Retina Society apply widely differing treatments in patients with CRVO and BRVO. Further clinical studies to evaluate the different therapeutic options seem necessary in order to set up guidelines for the treatment of venous retinal occlusions.

Prediction of the effect of acute normovolemic hemodilution on the hematological constituents of sequestered autologous whole blood

During acute normovolemic hemodilution (ANH), autologous whole blood is collected in a series of collection bags containing anticoagulant. The effect of hemodilution on the actual hematological constituents of this sequestered whole blood product has never been examined. We developed a mathematical model that predicts how whole blood bag constituents change during ANH to elucidate the theoretical basis for ANH efficacy. Formulas were derived to calculate the effect of ANH on [X], the blood constituent of interest. An exponential envelope was defined so that the projected impact of ANH on each constituent could be computed while initial blood volume and whole blood bag volume (WB(ANH)) were manipulated. Equivalency of autologous whole blood hemoglobin, platelets, and fibrinogen were determined by comparison with standard allogeneic blood products. We determined that the concentration of blood constituent X in a particular unit of collected blood ([X](n)) is provided as a fraction of the initial concentration ([X](0)). As WB(ANH) increases relative to estimated blood volume, the decrement in [X](n) increases in successive blood collection bags. Irrespective of initial blood volume, the equivalence of a 450-mL autologous whole blood bag to 1 U of packed red cells and 1 U of whole blood-derived platelet concentrate is 13.3 g/dL and 123 x 10(3)/microL, respectively. The impact of ANH on autologous whole blood constituents may be accurately predicted using this model. Conversion of WB(ANH) into equivalent allogeneic blood products could provide a useful method of comparing outcome in various ANH studies. The exponential envelope may be used to assess the actual ANH technique performed by the anesthesiologist, which in turn may impact quality assurance standards.

Low-prime system minimizes transfusions and hemodilution in coronary bypass

Standard heart-lung machines lead to substantial hemodilution with associated impaired organ function and increased need for blood transfusions. The aim of this study was to evaluate the effect of the new PRECiSe low prime volume system on perioperative myocardial damage, hemodilution, and transfusions. In a case-matched prospective study, 40 patients undergoing coronary artery bypass surgery using PRECiSe were compared with 40 patients on a standard heart-lung machine. In the PRECiSe group, the prime volume was significantly reduced, resulting in less hemodilution and transfusion requirements during and after extracorporeal circulation: only 10% of patients needed transfusions vs. 35% in the control group, with an average transfusion need of 0.16 vs. 1.25 units. There were no significant differences in perioperative cardiac-specific enzymes. The PRECiSe system was considered safe and effective for coronary artery bypass surgery.

Hemostasis and hemodilution: a quantitative mathematical guide for clinical practice

Quantitative changes of hemostasis during hemodilution remain unclear. With the increasing popularity of artificial blood substitutes (ABS), which solely provide oxygen-transport capacity, this issue becomes even more complex. We developed a mathematical model to quantitatively analyze hemostasis during hemodilution and validated it by recalculating patient data. We calculated and compared maximal allowable blood losses (MABL) related to minimal acceptable hematocrit, platelet concentration, and plasma fibrinogen concentration. MABL is the maximal blood loss that can be tolerated without any additional blood products. The variable with the smallest MABL thus limits hemodilution foremost. Hemodilution included isovolemic replacement of blood loss with colloid or acute normovolemic hemodilution (ANH) followed by isovolemic replacement of blood loss with colloid and ABS. We also related our findings to preoperative patient data (n = 204). The decline in platelet concentrations rarely (<2% of all patients) limits hemodilution. By contrast, critical plasma fibrinogen (< or =100 mg/dL) concentrations can often (< or =20% of all patients) limit hemodilution if their initial concentrations are within the lower normal range (<300 mg/dL). These findings become more frequent if ANH is combined with ABS. Under those circumstances ANH blood products are solely required for stabilization of hemostasis, thereby defeating the original purpose of combining ANH with ABS.

IMPLICATIONS

The causes of quantitative changes of hemostasis during hemodilution, as well as their clinical effect and relevance, remain unclear. Using a validated, realistic mathematical model, we demonstrate that hemostasis, especially plasma fibrinogen, can limit the extent of hemodilution. This phenomenon is particularly prominent when acute normovolemic hemodilution is combined with artificial blood substitutes.

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.

[Factors associated with blood transfusion during anesthesia for scheduled hip or knee arthroplasty in France]

GOAL OF THE STUDY

To determine over a whole country what are the factors associated with an intraoperative homologous blood transfusion and with the use of autologous techniques (preoperative autologous blood donation: PABD; acute normovolemic hemodilution: ANVH; intraoperative red cell salvage: IRCS).

STUDY DESIGN

National enquiry using a large representative sample (3 days of anaesthesia in France).

METHODS

Univariate followed by multivariate analyses of data gathered in 1996 during the survey leaded by the French society of anaesthesia and intensive care (Sfar) and corresponding to 884 scheduled hip and knee prosthesis surgical procedures.

RESULTS

Factors associated with a decreased use of PABD programme were: 1--old age and high ASA physical status; 2--procedures of short duration. By contrast, an increased use of PABD was associated with anaesthetics in which a closed circuit had been used. Except for a significant association with increasing age and with absence of PABD used, no additional factor was found to be linked with ANVH. No factor among those studied was found related to the use of IRCS. Homologous blood transfusion was more frequently used in ASA > or = 3 patients, in long duration surgeries while its use was decreased in patients with PABD (odds ratio--for reduction by PABD: 4.4 [95% confidence interval: 2.2-8.8]). Homologous blood transfusion was not related to the use of ANVH or IRCS.

CONCLUSION

These data obtained from a large national survey confirm previously published studies and meta-analyses and are in agreement with current recommendations. An unexpected relation between PABD and closed circuit anaesthesia has been found.

Autotransfusion in cardiac surgery

There are a number of problems with allogeneic blood transfusion. Some of these problems are defined and can be quantified, such as the problem of rising cost or the risk of viral infection, but some of the problems are not well defined and it is only outcome data that point to allogeneic blood transfusion contributing to patient mortality and morbidity. Autotransfusion includes any technique in which the patient's own blood is collected, processed and stored, followed by reinfusion when circumstances dictate. In the perioperative period of cardiac surgery, a number of techniques are recognized as useful in this context. Preoperative autologous donation, with or without erythropoietin supplementation, intraoperative acute normovolaemic haemodilution, intraoperative cell salvage, postoperative cell salvage (reinfusion of shed mediastinal blood) and platelet rich plasmapheresis are all techniques which are used with more or less enthusiasm to reduce the need for an allogeneic blood transfusion. Modification of the priming technique of the cardiopulmonary bypass circuit using an autologous blood prime is included in this review even though it does not fall strictly within the definition of autotransfusion. Although autotransfusion is not the answer to every problem, there is no doubt that it should play a significant part in the strategy of blood conservation.

Utilization of technologies to reduce allogeneic blood transfusion in the United States

Concern over safety of the blood supply has led to the use of technologies to reduce allogeneic blood transfusion. The objective of this research was to determine the utilization of these technologies in the United States. We evaluated the following techniques: preoperative autologous donation (PAD), cell salvage (CS) and acute normovolemic haemodilution (ANH); and the following pharmaceuticals: aprotinin (APR), epsilon-aminocaproic acid (EACA), tranexamic acid (TXA), desmopressin (DDAVP) and recombinant human erythropoietin (EPO). In 1997, we conducted a cross-sectional mail survey of service chiefs at 1000 US hospitals randomly selected and stratified by status as a provider of open-heart surgery, geographical location and hospital bed size. Sixty-nine per cent (690) of hospitals responded to at least one of the four surveys sent to each hospital. Hospitals reported use of techniques more than pharmaceuticals (P < 0.001); PAD (83%, n = 206) and CS (82% n = 420) were used most frequently. Lack of familiarity was the most common reason cited for infrequent use of pharmaceuticals. Organizational characteristics (e.g. provision of open-heart surgery, size, geographical location, teaching status and type of hospital) were differentially associated with technology use. There is greater use of techniques than pharmaceuticals in US hospitals to reduce the need for allogeneic blood in the peri-operative setting. Providing open-heart surgery is strongly associated with the utilization of these technologies.

[Isovolemic hemodilution--a treatment method for central retinal vein obstruction]

OVCR--is a vascular disease of the posterior pole of the eye, witch leads usually, to a significant decrease of the visual acuity. The actual management of the disease is still inefficient of the functional recovery of those patients. Among the medical treatment methods, is also the isovolemic hemodilution, witch must be established only after a thorough cardio-vascular and renal examination. The present study shows an increase of the visual acuity in the patients treated with isovolemic hemodilution followed by LASER Argon photocoagulation.

[Analysis of a blood use list for orthopedic operations]

OBJECTIVE

Is the documentation of blood utilisation, as demanded in the guidelines of serology and transfusion medicine, a proper instrument of quality control for the use of homologous blood saving techniques?

PATIENTS AND METHODS

We analysed retrospectively a list of blood utilisation based on 12,482 surgical procedures in orthopaedic surgery. This list included the type of operation, the number of transfused packed red cell units and, if applicable, the type of homologous blood saving technique (preoperative blood donation, mechanical autotransfusion and isovolaemic haemodilution). Total hip and knee replacement patients were divided in two groups according to base line haemoglobin (A: Hb > 13 mg%, B: hB < or = 13 mg%).

RESULTS

The increase of the percentage of patients not receiving homologous blood achieved by blood saving techniques is more pronounced in group B. Preoperative blood donation seems to be the most effective technique with a percentage of patients not receiving homologous blood of 93% in group A and 80% in group B of total hip replacement. This high percentage cannot be improved when preoperative blood donation is combined with mechanical autotransfusion or isovolaemic haemodilution. The efficiency of mechanical autotransfusion and isovolaemic haemodilution can be improved by combination of the two techniques.

CONCLUSIONS

A list of blood utilisation as presented can serve as a basis for guidelines regarding the use of homologous blood saving techniques. Moreover such a simple statistic provides a means of quality control and provides information about the likelihood of transfusion.

Use of interventions to minimise perioperative allogeneic blood transfusion in Australia. A survey by the International Study of Perioperative Transfusion (ISPOT) Study Group

OBJECTIVE

To investigate use of interventions to minimise need for perioperative transfusion of allogeneic blood in surgical units in Australia.

DESIGN

Two questionnaire-based surveys of practice.

SETTING

All hospitals in Australia, 1996-1997.

PARTICIPANTS

Survey 1: all Australian hospitals that have at least 50 beds and undertake surgery; Survey 2: surgical units identified as using the interventions.

MAIN OUTCOME MEASURES

Reported rates of use of the various interventions (preoperative autologous donation, acute normovolaemic haemodilution [ANH], cell salvage, and drugs); use of guidelines; and perceptions about the appropriateness of current levels of use.

RESULTS

Survey 1 was returned by 349 of 400 hospitals (87%) and Survey 2 by 324 of 578 surgical units (56%). Preoperative autologous donation was most widely used (70% of hospitals), most commonly in units performing orthopaedic or vascular surgery (65% and 37%, respectively). Cell salvage and ANH were used by 27% and 24% of hospitals, respectively, most often in units performing cardiothoracic (40% and 44%, respectively) and vascular surgery (29% and 15%, respectively). These three interventions were used significantly more in private than in public hospitals (P < 0.05). Use of printed guidelines was uncommon. Respondents considered that autologous transfusion techniques should be used more widely because of their perceived efficacy and concerns about safety of allogeneic blood. Perceived barriers to greater use included lack of surgeon or physician interest, uncertain scheduling of surgery in public hospitals and cost (cell salvage). Drugs to minimise blood loss were used by fewer than 10% of hospitals.

CONCLUSIONS

Interventions to minimise the need for perioperative allogeneic blood transfusion (apart from drugs) are widely used in Australia. However, enthusiasm for intraoperative techniques of re-infusing autologous blood needs to be assessed against the evidence of their efficacy and cost-effectiveness.

Ultrafiltration method for measuring vascular access flow rates during hemodialysis

BACKGROUND

The vascular access blood flow rate (QA) has been shown to be an important predictor of vascular access failure; therefore, the routine measurement of QA may prove to be a useful clinical method of vascular access assessment.

METHODS

We have developed a new ultrafiltration (UF) method for determining QA during HD from changes in arterial hematocrit (H) after abrupt changes in the UF rate with the dialysis blood lines in the normal (DeltaHn) and reverse (DeltaHr) configurations. This method accounts for cardiopulmonary recirculation and requires neither intravenous saline injections nor accurate knowledge of the dialyzer blood flow rate. Clinical studies were conducted in 65 chronic HD patients from three different dialysis programs to compare QA determined by the UF method with that determined by saline dilution using an ultrasound flow sensor.

RESULTS

Arterial H increased (P<0.0001) after abrupt increases in the UF rate when the lines were in the normal and reverse configurations. An increase in the UF rate from the minimum setting to 1.8 liter/hr resulted in a DeltaHn of 0.3+/-0.2 (mean +/- SD) H units and a DeltaHr of 1.6+/-1.0 H units. Q(A) values determined by the UF method (1050+/-460 ml/min) were 16+/-25% higher (P<0.001) than those determined by saline dilution (950+/-440 ml/min); the calculated QA values by the UF and saline dilution methods correlated highly with each other (R = 0.92, P<0.0001). The average coefficient of variation for duplicate measurements of QA determined by the UF method in a subset of these patients (N = 21) was approximately 10% when assessed in either the same dialysis session or consecutive sessions.

CONCLUSIONS

The results from this study show that changes in arterial H after abrupt changes in the UF rate can be used to assess Q(A).

Blood conservation techniques for cardiac surgery: a survey of French centres

A survey resulting from a partnership between CECEC (Centre d'Etudes en Circulation Extra-Corporelle) and Laboratoires Hoechst, France was carried out amongst all French adult cardiac surgery centres. The aim of this study was to investigate the various strategies used to decrease blood loss during open-heart surgery. Due to an exceptionally high response rate, we are able to report the current practice of French cardiac centres which account for 75% of open-heart adult surgery. The three most interesting strategies for blood conservation appear to be haemodilution, blood salvage from the extracorporeal circuit and previously deposited autologous blood transfusion, yet the three methods which are predominantly used are haemodilution (92.7%), aprotinin therapy (87.8%) and blood salvage from the extracorporeal circuit (82.9%).

Mathematical considerations in the practice of acute normovolemic hemodilution

BACKGROUND

Acute normovolemic hemodilution (ANH) is recommended as a simple and cost-effective method of autologous transfusion. The present mathematical model, based on the current clinical practice of removing 2 to 3 units of fresh whole blood, defines the indications for ANH.

STUDY DESIGN AND METHODS

A mathematical model and subsequent nomograms were developed to define patients for whom removal of 2 to 3 units (450 mL each) would allow a theoretical red cell savings equivalent to 1 unit of packed red cells (volume, 250 mL; hematocrit, 60%), that is, a successful application of the technique. Minimal safe target hematocrits were defined as 30, 26, and 22 percent.

RESULTS

The minimal initial hematocrits required for given patient weights are displayed on nomograms derived from the mathematical model. The nomograms also indicate the surgical blood loss allowed without ANH: for example, a 75-kg man, (2-unit ANH, minimal safe hematocrit 22%) requires a minimal initial hematocrit of 42 percent (surgical blood loss of 0.64 x estimated blood volume = 3100 mL).

CONCLUSION

ANH involving the removal of 2 to 3 units (450 mL each) may be useful in patients with anticipated blood loss exceeding 50 percent of estimated blood volume, high initial hematocrit, and a capacity to tolerate dilution-induced anemia.

The effects of hemodilution with polyethylene glycol bovine hemoglobin (PEG-Hb) in a conscious porcine model

BACKGROUND

Severe hemodilution in large mammals has been used rigorously for the safety and efficacy testing of hemoglobin-based red blood cell substitutes. The effects of hemodilution with polyethylene glycol-modified bovine hemoglobin (PEG-Hb) were investigated in an unanesthetized porcine model.

METHODS

Immature Yorkshire cross barrow pigs were subjected to exchange transfusion with PEG-Hb (n = 6) or dextran 70 (n = 4) until an 80% reduction in hematocrit was achieved.

RESULTS

All six (100%) PEG-Hb-infused pigs and only one (25%) dextran 70 control pig survived the resultant reduction in erythrocytes. Heart rates and mean arterial pressure were not significantly affected by PEG-Hb infusion. Pigs infused with PEG-Hb maintained normal levels of blood pH, PO2, and PCO2 while dextran 70 controls showed low PvO2, PaCO2, and the development of acidosis. Histological evaluation revealed that the surviving dextran 70 control animal exhibited possible anoxia-induced hepatic centrilobular necrosis. PEG-Hb-treated pigs demonstrated the presence of renal tubular cell cytoplasmic vacuoles and vacuolated macrophages in spleens.

CONCLUSIONS

The results indicate that PEG-Hb effectively supports life close to lethal levels of anemia.

Observations on isovolemic hemodilution in acute ischemic stroke

The reduction of blood viscosity is an alternative of the improvement of the cerebral flow during an acute ischemic stroke (AIS). We studied 18 patients with AIS, ranging in age from 44 to 72 years (mean age 57 years), 11 females and 7 males. We applied an isovolemic hemodilution for 2 days starting with an emission of 250 or 500 ml blood, followed by the infusion of an equal amount of 6% HAES-steryl solution. We made determination of hematocrit, plasma density, plasma viscosity 1, 3 and 6 hours before and after the infusion; a decrease was noted in all the studied hemorheologic parameters, and the short term clinical course was an improvement. In conclusion, the isovolemic hemodilution using 6% HAES solution reduced hematocrit, plasma density, plasma viscosity but no changes were noted in the hemodynamic parameters; isovolemic hemodilution as the single therapeutic method in AIS does not solve the therapy, involving only one pathogenetic link, i.e., the microcirculation.

Impact of autologous blood transfusion on blood support in general thoracic surgery: analysis of 969 patients over a 5-year period

Autologous blood transfusion (ABT) is increasingly used in order to avoid transfusion-related risks. The effectiveness of this simple and feasible procedure depends on several factors, such as the timing of surgery, the patient's overall condition and, last but not least, the pre-disposition of the medical team towards the routine use of ABT. We report our experience in blood support with ABT for general thoracic surgical patients, indicating an overall partially satisfactory outcome due to a limited use of the procedure. In 1992, 61 patients (38%) received autologous blood only, as compared to 9 patients (6%) who had received ABT in 1989. The average pre-deposit per patient ratio in 1992 was 1.2 units, which provided insufficient autologous blood support. In the same period, only 23 patients were subjected to acute normovolemic hemodilution (ANH). However, we noted a reduction of homologous transfusions from 2.9 +/- < 2.1 in 1989 to 2.0 +/- < 1.5 in 1992 (P < 0.01). In addition, we observed that a single pre-deposit was not enough to enhance erythropoiesis and to improve post-operative red blood cell rescue when performed in patients with Hb > 11 g%. Based on our data, we emphasize a more extensive move to ANH, along with pre-deposit, in order to avoid unnecessary homologous blood transfusions.

[Transfusion incidence and indications for homologous blood sparing measures in single stage breast carcinoma operations]

Under a ruling by the Bundesgerichtshof from December 17, 1991 (AZ VI ZR 40/91), the surgeon is obliged to inform a patient about the risks of a possible blood transfusion if the transfusion frequency is 5% or more. Between January 1989 and December 1994, 273 patients with primary breast cancer at the stages pT1-3, N1-2, M0 underwent one-time modified radical mastectomy (n = 164) or a breast conserving operation (n = 109) in our hospital. The number of blood transfusions, pre- and postoperative haemoglobin, age, tumour size, lymph node involvement, kind and duration of the operation and the postoperative course were analysed. In all, 44 of the 273 patients (16.1%) received an homologous blood transfusion perioperatively. The annual transfusion rates were 39.4% (1989), 44.8% (1990), 12.2% (1991), 16.6% (1992) and 3.1% (1993), falling to 2.2% in 1994. The mean pre- and postoperative haemoglobin concentrations did not differ significantly (p > 0.05) over the years: 13.4 +/- 1.0 g/dl and 12.0 +/- 1.1 g/dl in 1989 and 13.7 +/- 1.2 g/dl and 11.8 +/- 1.2 g/dl in 1994. Patients who received transfusions had preoperative anaemia (p < 0.021), bigger tumours (p < 0.0005) and mastectomy operations significantly more frequently than patients not given transfusions. There were no correlations between transfusions and age, lymph node involvement and kind and duration of operation. We conclude that, cognizant of a transfusion frequency of 2.2% in our hospital in one-time breast cancer operations, only patients with anaemia or large tumours require blood transfusions, for which autologous blood donations or normovolaemic haemodilution are the choices. The patients' attention is to be drawn to these. In cases of normal preoperative haemoglobin and small tumours, the physician should inform the patient that experience has shown that in all probability a blood transfusion will not be necessary and so a preoperative autologous blood donation or normovolaemic haemodilution can be dispensed with.

Intraoperative autologous blood salvage with cardiac surgery: an analysis of five years' experience in more than 3,000 patients

STUDY OBJECTIVE

To analyze intraoperative autologous salvage of shed mediastinal blood and subsequent transfusion in cardiac surgery.

DESIGN

Retrospective statistical analysis.

SETTING

University hospital.

PATIENTS

Three thousand twenty two patients undergoing cardiac surgery from 1984 to 1988.

INTERVENTIONS

A review of anesthesia and transfusion records of all patients who underwent intraoperative salvage of shed blood and autologous transfusion using the Sorenson Receptal Auto Transfusion System (ATS) with saline wash prior to reinfusion in cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

The salvaged blood volume ranged from 36 to 2,795 ml, with a mean of 321 +/- 222 ml (SD). Eighteen percent of patients did not receive any homologous blood products during their hospitalization. Patients who received only salvaged autologous transfusion were younger, had higher preoperative hemoglobin and hematocrit values, had a larger body surface area, and had shorter surgeries compared with patients who received only homologous blood or both autologous and homologous blood. More blood products were given to patients who received salvaged autologous blood compared with those who did not. Patients who underwent normovolemic hemodilution prior to extracorporeal circulation with subsequent reinfusion received significantly fewer blood products. Ten preoperative and four intraoperative variables significantly influenced the salvaged volume. Previous cardiac surgery was the most significant preoperative variable, and repair of ventricular septal defect produced by myocardial ischemia was the most significant intraoperative variable.

CONCLUSION

Considering the average salvaged volume and its current autologous transfusion-related expense, autologous blood salvage is potentially an economic benefit. Perioperative blood conservation requires a considerable commitment from surgeons, anesthesiologists, perfusionists, and intensive care physicians to be effective.

[A therapeutic comparison between hemodilution and pentoxifylline in arterial obstructive disease. An objective assessment by quantitative Doppler sonography]

The effects of a five-week course of haemodilution or pentoxifylline were compared in two matched groups of 10 patients each (18 men, 2 women; mean age 63 [47-77] years) with peripheral vascular disease of the legs, using clinical findings and Doppler ultrasound measurements as the criteria. Ten patients (group I) had six venesections of 400 ml each followed by the injection of 500 ml low-molecular dextran (10%), while the other ten (group II) received 400 mg pentoxifylline four times daily by mouth after initial intravenous loading. Pain-free and maximal walking distance increased in group I by 139 and 598 m, respectively (P less than 0.01), and by 155 (P less than 0.01) and 191 m in group II. The greater increase in maximal walking distance in group I was significant as calculated by regression analysis (P less than 0.05). Only in group I was there a significant prestenotic maximal and effective increase in blood flow velocity (by 66%: P less than 0.001 and 68%: P less than 0.05, respectively), while the poststenotic effective velocity also increased significantly by 66% (P less than 0.01). There was no significant change in group II patients.

Role of perfusion pressure and flow in major organ dysfunction after cardiopulmonary bypass

The role of perfusion pressure and flow during cardiopulmonary bypass with moderate hypothermia and hemodilution in the development of new postoperative renal or clinically apparent cerebral dysfunction was examined in 504 adults. Cardiopulmonary bypass flow was targeted at greater than 40 mL.kg-1.min-1 and pressure at greater than 50 mm Hg. Flows and pressures less than target occurred in 21.6% and 97.1% of patients, respectively. Fifteen patients (3.0%) suffered new renal and 13 (2.6%) new central nervous system dysfunction. Low pressure or flow during cardiopulmonary bypass, expressed in absolute values or in intensity-duration units, were not predictors of either adverse outcome. Multivariate analysis identified use of postoperative intraaortic balloon counterpulsation (p less than 10(-6], excessive blood loss in the ICU (p less than 10(-4], need for vasopressors before cardiopulmonary bypass (p less than 10(-4], postoperative myocardial infarction (p less than 10(-3], emergency reoperation (p less than 0.002), excessive postoperative transfusion (p less than 0.02), and chronic renal disease (p less than 0.03) as independent predictors of postoperative renal dysfunction. Independent predictors of postoperative central nervous system dysfunction were cardiopulmonary resuscitation in the intensive care unit (p less than 10(-6], intracardiac thrombus or valve calcification (p less than 0.02), and chronic renal disease (p less than 0.03). Age greater than 65 years (40.7% of patients) did not predict either outcome. We conclude that failure of the native circulation during periods other than cardiopulmonary bypass rather than the flows and pressures considered here is the major cause of renal and clinically apparent central nervous system dysfunction after cardiac operations.