Fat removal during cell salvage: a comparison of four different cell salvage devices

PRISM: A Novel Human Islet Isolation Technique

BACKGROUND

Successful pancreatic islet isolations are a key requirement for islet transplantation in selected patients with type 1 diabetes. However, islet isolation is a technically complex, time-consuming, and manual process. Optimization and simplification of the islet isolation procedure could increase islet yield and quality, require fewer operators, and thus reduce cost.

METHODS

We developed a new, closed system of tissue collection, washing, buffer change, and islet purification termed PancReatic Islet Separation Method (PRISM). In the developmental phase, pump and centrifuge speed was tested using microspheres with a similar size, shape, and density as digested pancreatic tissue. After optimization, PRISM was used to isolate islets from 10 human pancreases.

RESULTS

Islet equivalents viability (fluorescein diacetate/propidium iodide), morphology, and dynamic glucose-stimulated insulin secretion were evaluated. PRISM could be performed by 1 operator in 1 flow cabinet. A similar islet yield was obtained using PRISM compared to the traditional islet isolation method (431 234 ± 292 833 versus 285 276 ± 197 392 islet equivalents, P = 0.105). PRISM islets had similar morphology and functionality.

CONCLUSIONS

PRISM is a novel islet isolation technique that can significantly improve islet isolation efficiency using fewer operators.

Cell Salvage in Oncological Surgery, Peripartum Haemorrhage and Trauma

Oncological surgery, obstetric haemorrhage and severe trauma are the most challenging conditions for establishing clinical recommendations for the use of cell salvage. When the likelihood of allogeneic transfusion is high, the intraoperative use of this blood-saving technique would be justified, but specific patient selection criteria are needed. The main concerns in the case of oncological surgery are the reinfusion of tumour cells, thereby increasing the risk of metastasis. This threat could be minimized, which may help to rationalize its indication. In severe peripartum haemorrhage, cell salvage has not proven cost-effective, damage control techniques have been developed, and, given the risk of fetomaternal alloimmunization and amniotic fluid embolism, it is increasingly out of use. In trauma, bleeding may originate from multiple sites, coagulopathy may develop, and it should be evaluated whether re-transfusion of autologous blood collected from uncontaminated organ cavities would be feasible. General safety measures include washing recovered blood and its passage through leukocyte depletion filters. To date, no well-defined indications for cell salvage have been established for these pathologies, but with accurate case selection and selective implementation, it could become safe and effective. Randomized clinical trials are urgently needed.

Comparison of cell salvage with one and two suction devices during cesarean section in patients with placenta previa and/or accrete: a randomized controlled trial

Background

Cell salvage has recently been recommended for obstetric use in cases with a high risk of massive hemorrhage during cesarean section (CS). However, limited data are available to support the use of one suction device to collect lost blood. This study aimed to investigate the volume of red blood cells (RBCs) salvaged and the components of amniotic fluid (AF) in blood salvaged by one suction device or two devices during CS in patients with placenta previa and/or accrete.

Methods

Thirty patients with placenta previa and/or accrete undergoing elective CS in the Women's Hospital of Zhejiang University School of Medicine were recruited for the present study from November 1, 2017 to December 1, 2018. The patients were randomly assigned to one of the two groups according to an Excel-generated random number sheet: Group 1 (n = 15), in which only one suction device was used to aspirate all blood and AF, and Group 2 (n = 15), in which a second suction device was mainly used to aspirate AF before the delivery of the placenta. Three samples of blood per patient (pre-wash, post-wash, and post-filtration) were collected to measure AF components. The salvaged RBC volumes were recorded. Continuous data of pre-wash, post-wash, and post-filtration samples were analyzed by using one-way analysis of variance with Tukey's test for multiple comparisons, or Kruskal-Wallis test with Dunn test for multiple comparisons. Comparisons of continuous data between Group 1 and Group 2 were conducted using Student's t test or Mann-Whitney U test.

Results

The salvaged RBC volume was significantly higher in Group 1 than that in Group 2 (401.6 ± 77.2 mL vs. 330.1 ± 53.3 mL, t = 4.175, P < 0.001). In both groups, squamous cells, lamellar bodies, and fat were significantly reduced by washing (all P<0.001) and squamous cells were further reduced by filtering (P < 0.001). Squamous cells were found in six post-filtration samples (three from each group). Lamellar bodies and fat were completely removed by filtering. Insulin-like growth factor binding protein 1, alpha-fetoprotein, albumin, lactate dehydrogenase, and potassium were significantly reduced post-wash (all P < 0.05), with no further significant reduction after filtration in either group (all P > 0.05). The mean percentage of fetal RBCs post-filtration was (1.8 ± 0.8)% with a range of 1.0% to 3.5% and (1.9 ± 0.9)% with a range of 0.7% to 4.0% in Groups 1 and 2, respectively, showing no significant difference between the two groups (U = 188.5, P = 0.651).

Conclusion

Cell salvage performed by one suction device could result in higher volume of salvaged RBCs and can be used safely for CS in patients with placenta previa and/or accrete when massive hemorrhage occurs.

Trial registration number

ChiCTR-INR-17012926, http://www.chictr.org.cn/ Chinese Clinical Trial Registry.

Neurologic Complications of Fat Embolism Syndrome

PURPOSE OF REVIEW

Fat embolism syndrome (FES) is a rare disorder with potentially devastating neurologic complications. This article reviews the history, pathophysiology, clinical features, diagnosis, and treatment of FES with a focus on its neurologic aspects.

RECENT FINDINGS

The neurologic complications of FES are more commonly recognized with current diagnostic testing and increase awareness of the disorder. FES may present initially with neurologic manifestations. Prompt diagnosis of FES and of its neurologic manifestations could be lifesaving. This includes respiratory support and management of neurological complications. The classic clinical triad of pulmonary insufficiency, neurologic disturbances, and petechial skin rash typically presents 24 to 72 h following an initial insult, most commonly a traumatic long bone fracture. Early onset (< 24 h) and delayed onset (> 72 h) have been described. Neurologic manifestations may include ischemic/hemorrhagic strokes, retinal ischemia, seizures, autonomic dysfunction, and diffuse brain injury. Diagnosis remains clinical. Management consists mainly of supportive care.

Additional filtering of blood from a cell salvage device is not likely to show important additional benefits in outcome in cardiac surgery

BACKGROUND

Several authors and manufacturers of cell salvage devices recommend additional filtering of processed blood before transfusion. There is no evidence to support this practice. Therefore, we compared the clinical outcome and biochemical effects of cell salvage with or without additional filtering.

STUDY DESIGN AND METHODS

The patients, scheduled for coronary artery bypass grafting, valve replacement, or combined procedures were part of our randomized multicenter factorial study of cell salvage and filter use on transfusion requirements (ISRCTN 58333401). They were randomized to intraoperative cell salvage or cell salvage plus additional WBC depletion filter. We compared the occurrence of major adverse events (combined death/stroke/myocardial infarction) as primary outcome and minor adverse events (renal function disturbances, infections, delirium), ventilation time, and length of stay in the intensive care unit and hospital. We also measured biochemical markers of organ injury and inflammation.

RESULTS

One hundred eighty-nine patients had cell salvage, and 175 patients had cell salvage plus filter and completed the study. Demographic data, surgical procedures, and amount of salvaged blood were not different between the groups. There was no difference in the primary outcome with a risk of 6.3% (95% confidence interval [CI], 3.34-11.25) in the cell salvage plus filter group versus 5.8% (95% CI, 3.09-10.45) in the cell salvage group, a relative risk of 1.08 (95% CI, 0.48- 2.43]. There were no differences in minor adverse events and biochemical markers between the groups.

CONCLUSION

The routine use of an additional filter for transfusion of salvaged blood is unlikely to show important additional benefits.

Traditional and emerging technologies for washing and volume reducing blood products

Millions of blood components including red blood cells, platelets, and granulocytes are transfused each year in the United States. The transfusion of these blood products may be associated with adverse clinical outcomes in some patients due to residual proteins and other contaminants that accumulate in blood units during processing and storage. Blood products are, therefore, often washed in normal saline or other media to remove the contaminants and improve the quality of blood cells before transfusion. While there are numerous methods for washing and volume reducing blood components, a vast majority utilize centrifugation-based processing, such as manual centrifugation, open and closed cell processing systems, and cell salvage/autotransfusion devices. Although these technologies are widely employed with a relatively low risk to the average patient, there is evidence that centrifugation-based processing may be inadequate when transfusing to immunocompromised patients, neonatal and infant patients, or patients susceptible to transfusion-related allergic reactions. Cell separation and volume reduction techniques that employ centrifugation have been shown to damage blood cells, contributing to these adverse outcomes. The limitations and disadvantages of centrifugation-based processing have spurred the development of novel centrifugation-free methods for washing and volume reducing blood components, thereby causing significantly less damage to the cells. Some of these emerging technologies are already transforming niche applications, poised to enter mainstream blood cell processing in the not too distant future.

A new approach for fat removal in a discontinuous autotransfusion device-concept and evaluation

BACKGROUND

Fat present during blood salvage in orthopaedic or cardiac surgery can pose a risk of fat embolism and should be eliminated before transfusion. Based on observations of central fat accumulation at the bottom of Latham bowls, a fat reduction program was developed using two volume displacements, where blood temporarily is removed and respun in the bowl to force the fat through the RBC sediment.

MATERIALS AND METHODS

Pooled ABO-matched RBC and FFP were adjusted to a haematocrit of 10%, and human fat tissue added to a concentration of 1·25 vol%. In six experiments, blood was processed with the new-generation cell salvage device CS Elite in a newly developed fat reduction program in bowls of three sizes. Volumetric quantification of fat was performed after centrifugation of blood samples in Pasteur pipettes. From volumes, haematocrits and the concentrations of fat, RBC recovery and fat elimination rates were calculated.

RESULTS

Fat removal rates of 93·2 ± 2·8, 97·0 ± 2·1 and 99·6 ± 0·3% were observed with a 70-ml, 125-ml and 225-ml bowl, respectively, and even higher rates when removal rates were calculated one cycle. At the same time, high RBC recovery and plasma elimination rates were maintained, not significantly different to the default program mode.

CONCLUSION

Modifications in process parameters and sequence led to a fat reduction program that significantly improves fat removal with the Cell Saver Elite from 77·4 ± 5·1% in the default mode to an average of 98·6 ± 1·1%, yielding results equivalent to the continuous cell salvage system (C.A.T.S).

Performance of a new-generation continuous autotransfusion device including fat removal and consequences for quality controls

BACKGROUND AND OBJECTIVES

Cell salvage plays a key role in blood conservation. To maintain high performance, quality management is recommended. Accordingly, a new-generation autotransfusion device was tested for its performance and compared with its predecessor. Two different calculations of quality parameters were applied.

MATERIALS AND METHODS

In an experimental study, the continuous autotransfusion devices CATSmart and Continuous Autotransfusion System (C.A.T.S) plus were tested using banked blood adjusted to a haematocrit of 20% and anticoagulated with heparin 5 U/L. Test blood was processed using an emergency programme, a high-quality programme/smart wash programme and a low-volume wash programme. Samples were taken after the production of 200 mL of red blood cells (RBC) and after the final emptying of the separation chamber. In an additional set of tests, blood containing 1·25% fat was processed with both devices to examine fat removal.

RESULTS

Both devices demonstrated an equally high performance with regards to product hematocrit (Hct); RBC recovery; and elimination rates of protein, heparin and fat. The high fat elimination rate (>99·8%) reported for C.A.T.S plus was confirmed for CATSmart, regardless of the used programme. Samples taken during the ongoing process show a higher haematocrit and RBC recovery rate than samples taken after the final emptying of the separation chamber. Interface sensors were not affected by fat in the blood.

CONCLUSIONS

The new-generation autotransfusion device CATSmart is not inferior to its predecessor and shows high performance with regards to RBC recovery, plasma and fat elimination in all programme modes. Samples for quality controls should be taken during blood processing.

Fat removal during cell salvage: an optimized program for a discontinuous autotransfusion device

BACKGROUND

Fat in wound blood observed in orthopedic or cardiac surgery might pose a risk for fat embolism during blood salvage. Fat removal was optimized in the washing process.

STUDY DESIGN AND METHODS

In an experimental study blood from fresh donations was adjusted to a hematocrit (Hct) of 25% and an admixture of 1.25% human tissue fat. This blood was processed with the cell salvage device XTRA in a modified program mode. Volumetric quantification of fat was performed after centrifugation of blood samples in Pasteur pipettes. From the volumes, the Hct levels and the concentrations of fat and other variables elimination rates and RBC recovery were calculated.

RESULTS

Pretests showed wash volume, wash flow, and process interruptions affecting fat elimination. With the new optimized fat elimination program Pfat removal rate of fat increased to 98.5 ± 0.9% for the 225-mL bowl. The product had a mean Hct of 48.7 ± 1.2% and a RBC recovery rate of 93.5 ± 2.3%. The program conserved the high elimination rates for albumin, heparin, potassium, and free plasma hemoglobin (98.8, 99.3, 95.3, and 94.9%, respectively). Similar high fat removal was also observed with bowls of smaller size, namely, 98.1% for the 175-mL bowl and 98.2% for the 125- and the 55-mL bowls. With test blood of Hct 10% a mean fat elimination of 99.6 ± 01% was observed.

CONCLUSIONS

A special program modification Pfat involving extra washing and RBC concentration steps significantly improves fat removal by the Latham bowl-based autotransfusion device XTRA, thus yielding results equivalent to the continuous cell salvage system.