New developments in autologous transfusion systems

Impact of intraoperatively salvaged and washed blood on stimulated cytokine release in vitro

BACKGROUND

Intraoperative blood salvage and processing it with commercially available devices is a widespread standard procedure to reduce allogeneic blood transfusion in patients undergoing major orthopedic surgery. The aim of this study was to investigate the impact of such processed blood on the immune system by measuring pro- and anti-inflammatory cytokines.

STUDY DESIGN AND METHODS

Salvaged blood from 20 patients undergoing hip arthroplasty was processed with a continuous autotransfusion system. One part of the processed blood was left without further treatment, one part was additionally leukoreduced, one part was irradiated, and one part was separated into its cellular and soluble fraction by centrifugation. Specimens from each part were mixed in vitro with venous blood from the patient in ratios of 3:1, 1:1, and 1:3 and incubated with endotoxin for 24 hours. Tumor necrosis factor (TNF)-α and interleukin (IL)-10 were measured in cell culture supernatants by enzyme-linked immunosorbent assay.

RESULTS

All parts of the salvaged blood were without a significant influence on TNF-α release. In contrast, IL-10 was significantly increased, independently of the admixtured salvaged blood being plain, additionally irradiated, or additionally leukoreduced. This IL-10 increase was also found with the cellular fraction of the plain salvaged blood, whereas the soluble fraction had no influence on IL-10 release.

CONCLUSION

Intraoperative salvaged blood is not immunologically inert. We observed a significant increase in the anti-inflammatory IL-10 response without affecting the proinflammatory TNF-α release. Neither leukofiltration nor gamma irradiation eliminated this effect that was limited only to the cellular fraction of the salvaged blood, suggesting red blood cells to be responsible for the observed immunomodulation.

Intraoperatively salvaged red blood cells contain nearly no functionally active platelets, but exhibit formation of microparticles: results of a pilot study in orthopedic patients

BACKGROUND

Previous data show improved clot formation after retransfusion of salvaged red blood cells (RBCs). This study was conducted to explore whether such RBCs contain clinically relevant numbers of active residual platelets (PLTs) or exhibit formation of microparticles (MPs).

STUDY DESIGN AND METHODS

Thirteen patients undergoing major orthopedic surgery were included in the study, and arterial blood samples from patients and samples from the retransfusion bag were analyzed with various PLT function tests and flow cytometry.

RESULTS

With commercial blood cell counters, the numbers of PLTs in the RBC unit were reduced to approximately 25% compared to patients' blood. In contrast, results from flow cytometry showed an 11- to 945-fold reduction in median counts referring to total PLTs and free PLTs. Interestingly, smaller quantities of PLT-derived MPs were found in samples from the retransfusion bag than in patients' arterial blood. Conversely, RBC- and white blood cell-derived MP counts were increased in the retransfusion bag compared to the patient. Rotational thrombelastometry and the Impact-R system (DiaMed) showed a pronounced impairment of PLT ability with regard to adhesion, aggregation, and clot formation. With the use of confocal microscopy, only a few free thrombocytes were detectable among the huge numbers of RBCs.

CONCLUSION

Only few free and thus active PLTs are detectable in processed RBCs. It seems very unlikely that these few PLTs can improve clot strength. Nevertheless, the impact of the detected MPs on thrombin generation needs to be clarified in further studies.

Cell salvage in obstetrics

The safety of cell salvage in obstetrics has been questioned because of the presumed risk of precipitating amniotic fluid embolism and, to a lesser extent, maternal alloimmunisation. For these reasons, experience in this field is limited and has lagged far behind that in other surgical specialties. There has, however, been renewed interest in its use over recent years, mainly as a result of problems associated with allogeneic blood transfusion. Our aim was to review the medical literature to ascertain the principles of cell salvage, the ability of the process to remove contaminants, and its safety profile in the obstetric setting. The search engines PubMed and Google Scholar were used and relevant articles and websites hand searched for further references. Existing cell salvage systems differ in their ability to clear contaminants and all require the addition of a leucocyte depletion filter. Although large prospective trials of cell salvage with autotransfusion in obstetrics are lacking, to date, no single serious complication leading to poor maternal outcome has been directly attributed to its use. Cell salvage in obstetrics has been endorsed by several bodies based on current evidence. Current evidence supports the use of cell salvage in obstetrics, which is likely to become increasingly commonplace, but more data are required concerning its clinical use.

[Foreign blood saving measures in orthopedic surgery]

Major transfusion-free orthopaedic surgery can be performed successfully. This requires advanced planning, good routines and close collaborative team efforts. Since most blood saving techniques reduce blood usage by just 1-2 units, a series of integrated preoperative, intraoperative and postoperative blood saving approaches is required. These include preoperative autologous donation, erythropoietic support, acute normovolemic hemodilution, intraoperative autotransfusion, individualized assessment of anemia tolerance, meticulous surgical techniques and the use of pharmacologic agents for limiting blood loss. For various reasons, we do not recommend the transfusion of wound drainage. This article describes the various methods for bloodless medical care.

Aprotinin reduces cardiac troponin I release and inhibits apoptosis of polymorphonuclear cells during off-pump coronary artery bypass surgery

OBJECTIVES

In addition to blood-sparing effects, aprotinin may have cardioprotective and anti-inflammatory effects during cardiopulmonary bypass-assisted cardiac surgery. In this study, the authors examined whether aprotinin had cardioprotective and/or anti-inflammatory effects in patients undergoing off-pump coronary artery bypass grafting.

DESIGN

A prospective randomized clinical trial.

SETTING

University hospital.

PARTICIPANTS

Fifty patients were randomized to control (n = 25) or aprotinin treatment (n = 25) groups.

INTERVENTIONS

Aprotinin was given as a loading dose (2 x 10(6) KIU) followed by a continuous infusion at 5 x 10(5) KIU/h until skin closure.

MEASUREMENTS AND MAIN RESULTS

Blood samples for cardiac troponin I; interleukin-6, interleukin-8, and interleukin-10; tumor necrosis factor alpha; and elastase were taken after anesthesia induction, completion of revascularization, and 6 hours, 12 hours, and 24 hours after revascularization. Blood samples were taken to assess for apoptosis in polymorphonuclear cells. Baseline plasma levels for cardiac troponin I did not differ between groups but were significantly lower in aprotinin-treated patients at the time of revascularization (p = 0.03) and 6 hours (p = 0.004) and 24 hours (p = 0.03) later. Aprotinin significantly reduced apoptosis in polymorphonuclear cells compared with control-treated patients (p = 0.04). There were no differences in plasma cytokine or elastase levels between groups.

CONCLUSIONS

The authors conclude that aprotinin reduces perioperative cardiac troponin I release and attenuates apoptosis in polymorphonuclear cells but has no significant effects on plasma cytokine levels in patients undergoing off-pump coronary artery bypass graft surgery.

Blood sparing in craniosynostosis surgery

One of the main risks of craniosynostosis surgery is the possible need for an allogenic blood transfusion (ABT). Most patients are operated on in the first months of life, when physiological conditions are particularly sensitive to even limited blood losses. Furthermore, most surgical techniques proposed in the past were based on extensive craniectomies and cranial remodeling. Because of the known infective and immunologic risks of ABT, in recent years more attention has been dedicated to factors that might help reduce the risk of ABT. We review recent preoperative (ie, erythropoietin administration), intraoperative (ie, acute normovolemic hemodilution, intraoperative blood salvage), and postoperative (ie, clinical monitoring, postoperative blood salvage) anesthesiologic procedures developed with this aim in mind. We also consider operative techniques and technical apparatus that reduce surgical invasiveness, particularly preoperative planning, age selection, and the role of endoscopic assistance and gradual distraction devices.

Comparison of perioperative blood salvage and postoperative reinfusion of drained blood during surgical correction of craniosynostosis in infants

BACKGROUND

The surgical correction of craniosynostosis may be associated with extensive blood loss and transfusion. The aim of this study was to compare the efficacy of the perioperative use of the continuous autotransfusion system (CATS group) and of the postoperative use of the CBCII ConstaVac(R) system (CV group) to reduce homologous transfusion in infants during repair of craniosynostosis.

METHODS

Two groups of consecutive infants, weighing <10 kg, and scheduled for the surgical correction of craniosynostosis, were compared retrospectively according to the blood salvaging system used: CATS group and CV group. The primary endpoint was the comparison of the total volume of homologous blood transfused.

RESULTS

There was no significant difference between the CV (n = 69) and the CATS (n = 135) groups with regard to physical, preoperative and postoperative data, except for the type of craniosysnostosis with more scaphocephaly in the CV group (P = 0.03). No significant difference in blood loss and homologous transfusion was observed between the two groups during the perioperative period. Two subgroups of patients were also compared: a subgroup including patients operated on with a linear craniectomy for scaphocephaly, and a subgroup including all other patients. There was also no significant difference in blood loss and homologous transfusion between the CV and the CATS groups for these two subgroups of patients.

CONCLUSION

Our results suggest that the postoperative use of the CBCII ConstaVac(R) system is as efficient as the perioperative use of the CATS(R) system for reducing homologous blood transfusion during repair of craniosynostosis in infants weighing <10 kg.

Blood support for pediatric surgery

Increasingly complicated surgeries are being performed on neonatal and pediatric patients. Provision of a safe and adequate blood supply is essential for the success of many of these surgeries. Depending on the clinical situation, autologous and/or allogeneic blood may be used. However, in all cases, every attempt should be made to minimize the number of donor exposures to reduce the risk of transfusion transmitted infections. Transfusion of neonatal and pediatric patients requires additional considerations too, such as the risk of graft vs host disease, cytomegalovirus infection, the effects of various preservative anticoagulant solutions, electrolyte levels during blood storage, and wheather or not leukoreduced components are indicated.

Perioperative autologous blood donation in children

Autologous blood donation in children has become a standard of care. Children have to live with the life-time complications associated with allogeneic blood including the transmission of known and unknown pathogens, and the impact of alloimmunization on future blood transfusions, organ transplants and pregnancies. Donor reaction, allogeneic exposure and utilization rates in pediatric preoperative autologous donation (PAD) programs are as good if not better than reported in adult literature. Children are very resilient when undergoing extreme isovolemic hemodilution (IHD). PAD, IHD and intraoperative blood recovery appear to be useful components of a pediatric blood conservation program. Prospective, randomized studies addressing the specific needs of children are required to properly define their perioperative role.