Clinical use of blood transfusion devices

Laboratory and clinical comparison of the efficacy of prestorage leukoreduction of red cells at cold versus room temperature

BACKGROUND

The temperature at which filtration takes place has been reported to influence the efficacy of leukoreduction. We aimed to compare the residual leukocyte count (RLC) in red cell units (RCUs) filtered at cold (CT) versus room temperature (RT) and to assess whether this correlates clinically with a difference in the incidence of acute transfusion reactions (ATRs).

METHODS AND MATERIALS

In the first part of the study, whole blood units collected were randomly allocated for subsequent filtration at CT and RT, respectively. RLC postfiltration was assessed using flow cytometry. The second part of the study was a nonrandomized clinical trial in which incidence of ATR was compared between RCUs filtered at RT and CT for 6 months each.

RESULTS

Thirty-five RCUs each underwent leukofiltration at CT and RT, respectively. The median RLCs in the filtered units at CT and RT were 0.02 × 10⁶ and 0.1 × 10⁶ leukocytes/unit, respectively (p = .0001), with no difference in red blood cell (RBC) recovery (p = .41). During the second part, 3455 RCUs filtered at RT and 3539 RCUs filtered at CT were transfused to patients. The rate of febrile non-hemolytic transfusion reaction (FNHTR) among transfused patients was less with units filtered at CT (1 per 2000 transfusions) in comparison to RT (1 per 588 transfusions). The difference was, however, not significant (p = .14).

CONCLUSION

If change in temperature alone can cause significant reduction in leukocytes, then it is a simple way to curtail the rate of this common yet unpleasant reaction and reduce the reaction rate at minimal cost.

Pressure Infusion Cuff and Blood Warmer during Massive Transfusion: An Experimental Study About Hemolysis and Hypothermia

Background

Blood warmers were developed to reduce the risk of hypothermia associated with the infusion of cold blood products. During massive transfusion, these devices are used with compression sleeve, which induce a major stress to red blood cells. In this setting, the combination of blood warmer and compression sleeve could generate hemolysis and harm the patient. We conducted this study to compare the impact of different pressure rates on the hemolysis of packed red blood cells and on the outlet temperature when a blood warmer set at 41.5°C is used.

Methods

Pressure rates tested were 150 and 300 mmHg. Ten packed red blood cells units were provided by Héma-Québec and each unit was sequentially tested.

Results

We found no increase in hemolysis either at 150 or 300 mmHg. By cons, we found that the blood warmer was not effective at warming the red blood cells at the specified temperature. At 150 mmHg, the outlet temperature reached 37.1°C and at 300 mmHg, the temperature was 33.7°C.

Conclusion

To use a blood warmer set at 41.5°C in conjunction with a compression sleeve at 150 or 300 mmHg does not generate hemolysis. At 300 mmHg a blood warmer set at 41.5°C does not totally avoid a risk of hypothermia.

Feasibility of red blood cell transfusion through small bore central venous catheters used in neonates

OBJECTIVE

To determine whether packed red blood cell transfusions through small-bore central venous catheters used in critically ill neonates results in significant hemolysis.

DESIGN

In vitro experimental study using a mock transfusion setup incorporating a syringe pump, prestorage leukoreduced fresher, and older CPDA-1 red blood cell units and pressure transducer simulating neonatal transfusion through 1.9-Fr NeoPICC central venous catheter.

SETTING

Laboratory setting.

SUBJECTS

None.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Spun hematocrit, plasma free hemoglobin (hemoglobin), lactate dehydrogenase, and potassium were analyzed pretransfusion, at various times during transfusion, and posttransfusion. Intraluminal pressures were measured using a TruWave Disposable Pressure Transducer. Using fresher (5-8 days old) and older (29-30 days old) CPDA-1 red blood cells, we compared 2 and 20 mL/hr flow rates. Statistical analysis was performed using repeated measures of analysis of variance to compare the differences in means between flow rates. Mean intraluminal pressures at the end of each experiment were significantly higher at 20 mL/hr flow rates (>360 mm Hg) in both fresher and older red blood cells than at 2 mL/hr (range, 61-70 mm Hg). Overall, potassium, lactate dehydrogenase, and plasma free hemoglobin concentrations were significantly higher for older red blood cells at either 2 or 20 mL/hr (p<.001). Both fresher and older red blood cells demonstrated higher potassium concentrations at 20 mL/hr (22.4%, p<.001;0.7%, p>.05, respectively); however, these increases were not clinically significant. Furthermore, lactate dehydrogenase, hematocrit, and plasma free hemoglobin differences seen at 2 and 20 mL/hr did not coincide with changes in potassium.

CONCLUSIONS

No clinically significant hemolysis was evidenced with red blood cell transfusion through small-bore central venous catheters when using fresher or older CPDA-1 red blood cells at 2 or 20 mL/hr.

[Technical constraints in rapid vascular fluid replacement]

Rapid fluid infusion remains the cornerstone for therapy of hypovolaemic shock. The principal limitations of flow rate are governed by the four variables of Poiseuille's law: tube internal diameter and length, viscosity of the fluid passing through the tube, and the pressure gradient between the two ends of the tube. Conventional transfusion systems, with wide bore tubing (up to 5.0 mm internal diameter), large bore cannulas (8.5 French introducer catheters), high pressure (up to 300 mmHg) and diluted blood, can result in a maximum flow rate of about 1,000 ml.min-1 (for crystalloid solutions). Specific apparatus for rapid infusion can increase this to 1,500 ml.min-1 (Rapid Infusion System, Haemonetics). Dry-heat warming devices and microfiltration, to remove microaggregates and prevent non haemolytic febrile transfusion reactions, seem necessary when carrying out rapid transfusions. However, the use of microaggregate filters could be avoided by the routine production of leukocyte-poor red blood cell concentrates.

[Leukocyte removal in a closed system of human red-cell concentrates: a technic coupled with the automated extraction of the buffy coat using a sterile connector from a filtration kit]

A technique, integrally run in a closed system, for leucocyte depletion of human red cell concentrates is described. It associates two complementary processes: buffy-coat removal and filtration. The first step is carried out with an automated system for blood component preparation (Compomat, NPBI); its efficiency is improved by a custom made blood collection set with ACD anticoagulant solution in the primary bag. The second step is simplified by a filtration kit requiring only one sterile connection for operation (SCD 312, Dupont de Nemours) and allowing a standardised rinsing of the filter. Quality control of 33 units so prepared shows principally: --an intensive leuko-depletion (4 logs) enabling leukocyte contamination to be kept below 10(6) per unit; --a moderate red cells loss (15 ml for the first step and 20 ml for the second one). This technique provides a permanently available and very pure blood component. Moreover it offers new potential for standardisation and mastery of quality control.

[Viability of human red blood cells preserved for 35 days after leukocyte depletion (in vitro study)]

24 leukocyte poor red cells concentrates (L.P.R.C.) were prepared by sterile connection of a leucocyte filter between the primary bag and the SAGM bag of a blood unit after centrifugation. Their quality was followed up to 42 days by means of a panel of tests including, ATP and 2,3-DPG levels, hemolysis, plasma potassium, lactate and glucose, and counts of the microaggregates. 24 standard units acted as a control group. Results showed better preservation of LPRC and especially less hemolysis, higher ATP levels and at least equal oxyphoric capacity (explored by 2,3-DPG). Microaggregate formation was dramatically reduced and bacteriologic checks (48 at day 25 and 48 at day 42) were all negative. Leucocyte depletion appears as a new way to improve functionality of erythrocytes during storage in the SAGM medium. 35 days shelf life will allow this blood product to be more available and its preparation more standardised.