Blood Warming Devices Research Articles

Cold platelet transfusion: The effects of a fluid warmer on platelet function.

Recently the US Food and Drug Administration has granted variances to select blood centers to supply cold-stored platelet components (CSP). In hemorrhage resuscitation warming of blood components with approved fluid warming devices is common. Pathogen-reduced apheresis platelet units were collected and stored in one of two ways: (1) CSP-I, (2) CSP-D. CSP-I were collected and immediately stored at 1-6°C until used. CSP-D were collected and stored at 20-24°C for 5 days and transferred to storage at 1-6°C until use. Aggregometry using arachidonic acid (AA), adenosine diphosphate (ADP) and collagen as agonists was performed on the unit samples before and after the units were infused through a Ranger blood-warming device. CSP-I, 23 units, had very high aggregation responses to all agonists (all ≥47.6 ± 20.7). There was a statistically significant reduction in ADP-induced aggregometry results from 55.1 ± 23.2 before compared to 33.5 ± 14.6 following infusion of the PLT through the blood warmer (p < .001). There were no differences in AA and collagen aggregometry results before and after the infusion of the platelets through the blood warmer. CSP-D had 5 of the 15 units with visible clotting in the bag. The 10 CSP-Ds studied had lower aggregation than all agonists before and after infusion through the blood-warming device (all ≤49.9 ± 35.9). We detected a statistically significant reduction in ADP-induced aggregometry in CSP-I run through a Ranger blood-warming device with no change with AA or collagen agonist aggregometry.

Cost-effectiveness of the TherMax blood warmer during continuous renal replacement therapy.

Hypothermia is a common adverse event during continuous renal replacement therapy (CRRT), affecting multiple organ systems and increasing risk of poor health outcomes among patients with acute kidney injury (AKI) undergoing CRRT. TheraMax blood warmers are the next generation of extracorporeal blood warmers which reduce risk of hypothermia during CRRT. The purpose of this study is to elucidate the potential health economic impacts of avoiding CRRT-induced hypothermia by using the novel TherMax blood warming device. This study compares health care costs associated with use of the new TherMax blood warmer unit integrated with the PrisMax system compared to CRRT with a standalone blood warming device to avoid hypothermia in continuous renal replacement therapy (CRRT). An economic model was developed in which relevant health states for each intervention were normothermia, hypothermia, discharge, and death. Clinical inputs and costs were obtained from a combination of retrospective chart review and publicly available summary estimates. The proportion of AKI patients treated with CRRT who became hypothermic (<36°C) during CRRT treatment was 34.5% in the TherMax group compared to 71.9% in the 'standalone warmer' group. Given the 78.7-year average life expectancy in the US and the assumed average patient age at discharge/death of 65.4 years, the total life-years gained by avoiding mortality related to hypothermia was 9.0 in the TherMax group compared to 8.0 in the 'standalone warmer' group. Cost per life-year gained was $8,615 in the TherMax group versus $10,115 in the 'standalone warmer' group for a difference of -$1,501 favoring TherMax. The incremental cost-effectiveness ratio was negative, indicating superior cost-effectiveness for TherMax versus 'standalone warmer'. The TherMax blood warming device used with the PrisMax system is associated with lower risk of hypothermia, which our model indicates leads to lower costs, lower risk of mortality due to hypothermia, and superior cost-effectiveness.

Platelet transfusion: The effects of a fluid warmer on platelet function.

Thirty-one units of hospital blood bank apheresis PLTs were obtained. PLT-rich plasma (PRP) aggregometry and thromboelastography (TEG) were performed on the unit samples before and after the units were infused through a Ranger blood/fluid warming device. There were no differences in any of the aggregometry results before and after infusion of the PLTs through the blood warmer (all P > .32). There was a significant reduction in the TEG maximum amplitude (MA) of 69.8 ± 7.9 mm before and 66.0 ± 8.8 mm after (P < .001) infusion of the PLTs through the blood warmer and α angle 61.8 ± 9.4° before and 59.3 ± 8.2° after (P = .044) infusion of the PLTs through the blood warmer, although both mean values were within normal range for the TEG and not clinically significant. There were very good correlations of aggregometry and TEG results before and after infusion of the PLTs through the blood warmer device. This study did not demonstrate significant deleterious effect on PLT function from infusing apheresis PLT units through a blood warming device by PRP aggregometry. We did detect a statistically significant-but not clinically significant-reduction in TEG MA and α angle. The prohibition of transfusing PLT units though the Ranger blood warming device is not indicated.

Hemolysis of irradiated leukoreduced red blood cells during rapid warming: An in vitro experimental study.

BackgroundAlthough water chambers are often used as surrogate blood-warming devices to facilitate rapid warming of red blood cells (RBCs), these cells may be damaged if overheated. Moreover, filtered and irradiated RBCs may be damaged during the warming process, resulting in excessive hemolysis and extracellular potassium release.MethodsUsing hand-held syringes, each unit of irradiated and leukocyte-filtered RBCs was rapidly passed through a water chamber set to different temperatures (baseline before blood warming, 50℃, 60℃, and 70℃). The resulting plasma potassium and free hemoglobin levels were then measured.ResultsWarming RBCs to 60℃ and 70℃ induced significant increases in free hemoglobin (median [interquartile ranges] = 60.5 mg/dl [34.9–101.4] and 570.2 mg/dl [115.6–2289.7], respectively). Potassium levels after warming to 70℃ (31.4 ± 7.6 mEq/L) were significantly higher compared with baseline (29.7 ± 7.1 mEq/L; P = 0.029). Potassium levels were significantly correlated with storage duration after warming to 50℃ and 60℃ (r = 0.450 and P = 0.001; r = 0.351 and P = 0.015, respectively).ConclusionsRapid warming of irradiated leukoreduced RBCs to 50℃ may not further increase the extracellular release of hemoglobin or potassium. However, irradiated leukoreduced RBCs that have been in storage for long periods of time and contain higher levels of potassium should be infused with caution.

Stored Platelet Functionality Is Not Decreased After Warming with a Fluid Warmer

Warming of IV-administered fluids and blood products is routinely performed in the operating room to help maintain normothermia. Current guidelines recommend against the warming of platelets (PLTs), although there is no evidence for this prohibition in the literature. Our goal in this pilot study was to determine whether the warming of stored PLTs had any effect on their function. Ten units of 3-day-old, PLT-rich plasma-derived whole blood PLTs were acquired from the transfusion service. A 5-mL aliquot was taken from each unit before warming (control samples). The remainder of the unit was then passed into a blood-warming device and held there for 2 minutes. Postwarming (warmed) PLT samples were then collected from the effluent end of the warming device. PLT aggregometry assays with adenosine diphosphate, collagen, and arachidonic acid as agonists were performed on the control and warmed samples. Thromboelastography tests were also performed on the control and warmed samples from 6 of the 10 PLT units. The mean temperature of the control and warmed samples was 22.4°C ± 0.5°C and 37.8°C ± 2.3°C, respectively. There was no significant difference (all P ≥ 0.13) in any of the PLT aggregometry assays or in the maximum amplitude of the thromboelastography test between the control and the warmed samples. The observed mean of only 1 parameter decreased (PLT aggregometry with 5 μM adenosine diphosphate) by 5% (95% confidence interval, -115% to 105%). The maximum change observed was PLT aggregometry with arachidonic acid as agonist, which increased by 116% (95% confidence interval, -91% to 323%). Although small in size, the results of this study do not support the prohibition against mechanical PLT warming. Studies of PLT activation after warming are also warranted.

Indicators of erythrocyte damage after microwave warming of packed red blood cells.

Localized overheating of packed red blood cells (PRBCs) after microwave warming with consequent damage to erythrocytes has been reported. We therefore compared possible cellular markers of erythrocyte damage, as measured by flow cytometry, with laboratory indicators of hemolysis to evaluate the effects of microwave warming on PRBCs. PRBC samples were warmed to room temperature or to 37, 42, 47, 52, or 57 degrees C in a water bath. Flow cytometry was performed after fluorescein labeling using antibodies to spectrin, Ca(2+)-ATPase, and Na(+)-K(+)-ATPase. The forward-to-sideward scatter (FSC/SSC) ratio and antibody binding were evaluated. Plasma free hemoglobin (FHb) and alpha-hydroxybutyrate dehydrogenase (HBDH) were measured immediately after heating and after 48 h. In addition, all measurements were made before and after the heating of PRBCs to 35 degrees C by a microwave blood warmer. Analysis of 15000 erythrocytes showed a decrease in the FSC/SSC ratio and antibody binding above 47 degrees C [at 37 degrees C, median (SD) of 94.2 (7.4) with 0.07 (0.05)% fluorescein-positive; at 52 degrees C, median (SD) of 177.0 (19.0) with 18.5 (6.4)% positively gated; P <0.001]. FHb [room temperature, 0.3 (0.2) g/L] was increased 2-fold at 37 and 42 degrees C, 4-fold at 47 degrees C, and 25-fold at 52 degrees C. HBDH increased in parallel. Hemolysis markers showed an additional twofold increase 48 h after heating to 42 and 47 degrees C. Microwave heating to 35 degrees C did not produce significant changes of any marker. All markers of cellular damage were altered after heating to >47 degrees C, and a substantial part of hemolysis was delayed. The methodology can be used for future testing of other blood warming devices.

Effect of Heat on Stored Red Cells during Non–Flow Conditions in a Blood–Warming Device

Background and Objectives: While blood is flowing within a transfusion–warming device, the blood temperature is usually less than that applied externally. If the flow is temporarily stopped, the temperature can rise above 37°C in some warming devices. We sought to determine whether temperatures near 45°C achieved during prolonged non–flow conditions in a blood warmer are harmful to red cell integrity. Materials and Methods: After 42 days of storage at 4°C, red cells were exposed to 44.7°C for 30 min while stationary in a blood warming device (Augustine Medical, Inc., 241 Fluid Warming Set) and examined for cell counts, hemolysis and osmotic fragility. Results: Red cell, white cell and platelet counts, hemoglobin, PCV and potassium were unchanged following heat treatment. Plasma hemoglobin was 508±132 mg/dl following heat treatment compared to 396±188 for the control (p>0.05). In the osmotic fragility test, hemolysis remained within normal limits when tested at 0.60 and 0.65% sodium chloride (NaCl) and was unchanged at the 0.5% NaCl level. At the 0.75% NaCl level, there was 16±5.1% hemolysis of heated 42–day–old red cells compared to 11±3.4% for the control (both of which being above the 9% upper limit for fresh control red cells). Conclusions: We conclude that elevated temperatures achieved during temporary cessation of flow in the Augustine Medical, Inc., 241 Fluid Warming Set for as long as 30 min do not cause notable hemolysis or other damage to red cells.

Effect of Heat on Stored Red Cells during Non‐Flow Conditions in a Blood‐Warming Device

Abstract Background and Objectives: While blood is flowing within a transfusion‐warming device, the blood temperature is usually less than that applied externally. If the flow is temporarily stopped, the temperature can rise above 37°C in some warming devices. We sought to determine whether temperatures near 45°C achieved during prolonged non‐flow conditions in a blood warmer are harmful to red cell integrity. Materials and Methods: After 42 days of storage at 4°C, red cells were exposed to 44.7°C for 30 min while stationary in a blood warming device (Augustine Medical, Inc., 241 Fluid Warming Set) and examined for cell counts, hemolysis and osmotic fragility. Results: Red cell, white cell and platelet counts, hemoglobin, PCV and potassium were unchanged following heat treatment. Plasma hemoglobin was 508±132 mg/dl following heat treatment compared to 396±188 for the control (p&gt;0.05). In the osmotic fragility test, hemolysis remained within normal limits when tested at 0.60 and 0.65% sodium chloride (NaCl) and was unchanged at the 0.5% NaCl level. At the 0.75% NaCl level, there was 16±5.1% hemolysis of heated 42‐day‐old red cells compared to 11±3.4% for the control (both of which being above the 9% upper limit for fresh control red cells). Conclusions: We conclude that elevated temperatures achieved during temporary cessation of flow in the Augustine Medical, Inc., 241 Fluid Warming Set for as long as 30 min do not cause notable hemolysis or other damage to red cells.

Rapid In-line Blood Warming Using Microwave Energy: Preliminary Studies

The management of massive blood loss resulting from trauma or surgery necessitates rapid transfusion capability. Hypothermia secondary to shock, transfusion, and prolonged surgical procedures significantly increases morbidity and mortality in these patients. Transfusion at high flow rates frequently exceeds the warming capacity of conventional blood-warming devices, whose inherent resistance also limits the maximal flow rates. Microwave ovens are capable of blood warming, but have been associated with unacceptable hemolysis. We have investigated the possibility of using microwave energy to provide rapid in-line blood warming. Fresh blood from 10 human subjects was warmed from an average of 18 degrees C to temperatures ranging from 37 to 39 degrees C at flow rates from 250 to 500 mL/min. Laboratory analysis of free plasma hemoglobin, haptoglobin, hematocrit, hemoglobin, and electrolytes showed no difference between heated and control samples. LDH was elevated in those samples warmed repeatedly, but remained within the normal range. These data indicate the potential for further investigation utilizing properly controlled microwave energy for in-line blood and fluid warming.

Evaluation of blood-warming devices with the apparent thermal clearance

Hypothermia (less than 35 C) associated with massive transfusions is a serious clinical problem. Maintenance of normal temperatures in this setting is essential and requires the use of rapid and efficient blood-warming devices. The optimal design of such units should include a low priming volume, large heat transfer area, low pressure drop, the ability to operate at high flow rates, and the capability of warming blood from 4 to 32 C, or higher, without untoward effects. We have previously formulated a theoretic model for blood warmers and described a measure of the intrinsic efficiency of these devices, the apparent thermal clearance (VT,cl). In this study, we tested four different types of commercially available blood warmers (the single-coil immersion heater; the single-channel dry wall electric heater; the multichannel countercurrent heat exchanger; and the single-channel, countercurrent heat exchanger) and determined the apparent thermal clearance values using saline and packed red blood cells. The results indicate that only the single-channel countercurrent unit is efficient enough to meet the established requirements. The apparent thermal clearance provides a useful and rigorous means for comparing and evaluating blood-warming devices.

In‐line Blood Warming and Microfiltration Devices

Homogeneous microaggregate-free whole blood at +5 degrees C was transfused at constant pressures of 20 and 40 kPa through two micro-filtration and blood warming devices, and the temperature of the blood was recorded before it reached the venous cannula. The flow rates with the Fenwal system were 58 and 139 g/min, whereas the micro-filter MF10B combined with the Portex Coil allowed flow rates of 143 and 224 g/min. The warming capacities of the two warmers were almost equal and this did not prove to be their weak point. The infusion temperature varied considerably during the transfusion. Increasing the priming volume of the coil would raise the mean infusion temperature. A pressure infusor (Fenwal) was tested, and the internal pressures of the blood bag and the infusor were determined separately. The bag pressure differed significantly from the infusor pressure as the blood bag emptied, making the usefulness of the infusor manometer questionable.

In‐line Blood Warming and Microfiltration Devices: II. Influence of Blood Temperature on Flow Rate and Hemolysis During Pressure Transfusion Through Microfilters and Transfusion Sets

The influence of blood temperature on flow rate and hemolysis was studied. Homogeneous aggregate-free blood was transfused through six different microfilters and transfusion sets, combined with a large-bore venous cannula (Venflon No. 2) at a constant pressure of 20 kPa. Flow rates and plasma hemoglobin for cold (+5 degrees C) and prewarmed (+37 degrees C) blood were determined separately. Warming the blood from +5 degrees C to +37 degrees C improved the flow from 49 to 86%. The best flow rates with +37 degrees C blood were obtained with surface filters (MF10B, 275 g/l), and the poorest with depth filters (Swank, 179 g/l). However, the transfusion set and venous cannula seemed to have more influence on the total flow resistance. The Fenwal "dry-heat" warmer was found to have a great flow resistance. The pressure transfusion caused only a slight increase in free plasma hemoglobin of cold blood and no increase in prewarmed blood. It seems more practical to warm the entire blood unit before transfusion than to use so-called in-line blood warmers, because prewarming results in a flow rate approximately twice as high as that obtained with coils.