A mathematical model of cell salvage compared and combined with normovolemic hemodilution

BACKGROUND: Mathematical models have been used to describe the factors that affect cell salvage (CS) and normovolemic hemodilution (ANH). Here, the CS and ANH models were used to compare these two techniques alone or in combination with each other. STUDY DESIGN AND METHODS: Variables used for a hypothetical patient included an estimated blood volume of 5000 mL, a presurgery hematocrit (Hct) of 45 percent, and a transfusion trigger of 21 percent. The model accounts for both the effect of decreasing the Hct due to blood loss and the effect of increasing Hct due to the readministration of blood in an isovolemic patient. The efficacy of CS and ANH is defined to be the maximum allowable blood loss for a fixed blood volume and a fixed transfusion trigger. RESULTS: Comparison of CS with ANH showed that 3 units of ANH was comparable to CS when CS recovery rates ranged from 19 to 24 percent. For a patient with a blood volume of 5000 mL and a starting Hct of 40 percent, 3 units of ANH would allow for 3972 mL of blood to be lost before crossing a 21-percent transfusion trigger, whereas CS with a 125-mL bowl would allow for 7611 mL. CONCLUSION: When comparing ANH to CS, this mathematical model would suggest that CS has the potential to offer significantly greater red blood cell avoidance than does ANH; however, the combination of ANH with CS may offer allogeneic avoidance superior to either technique alone.     

Intraoperative blood salvage: a mathematical perspective

BACKGROUND: Intraoperative blood salvage (IBS) is one of several blood-conservation strategies employed to limit the use of allogeneic blood. IBS with mathematical modeling was studied to gain a better understanding of its benefits and limitations. STUDY DESIGN AND METHODS: Equations, based on a convergent geometric series, allowed the assessment of maximum allowable blood losses to avoid allogeneic RBC exposure in relationship to the fractional recovery of IBS. Such equations allowed us to calculate the potential "savings" in allogeneic RBC volume and to define better the efficiency of IBS. RESULTS: This model predicts that substantial amounts of RBCs (>2 units) can be recovered if there is large blood loss (e.g., >3000 mL) and if the minimal allowable Hct is low (e.g., 21%). As with other blood- conservation methods, this article shows that there are limits to the potential benefit of IBS for the avoidance of allogeneic RBC transfusion. CONCLUSION: IBS can be modeled with a convergent geometric series, and the amount of blood loss is dependent on the difference between the patient's starting Hct, the minimum allowable Hct, and the fractional recovery of RBCs. Such modeling illustrates the limited utility of IBS as a sole blood-conservation strategy.     

Preoperative red cell production in patients undergoing weekly autologous blood donation

BACKGROUND: Modest autologous blood donation programs involving weekly phlebotomy and threshold hematocrits for blood donation higher than 33 percent are frequently used in patients scheduled for elective cardiac surgery. This study was performed to determine the gain in red cells (RBCs) obtained with such a program. STUDY DESIGN AND METHODS: The blood bank and medical records of 225 adult patients (194 men, 31 women; mean age, 57 years [range, 18–77]) who donated blood for autologous use in elective cardiac surgery during a 3-year period were reviewed. Preoperative RBC production was estimated by the total volume of RBCs donated minus the change in circulating RBC volume between the first donation and the day before surgery. RESULTS: A total of 604 blood units were donated (2.7 units/patient; range, 1–3). The mean volume of RBCs donated was 522 mL (range, 171–732). Mean RBC production (over baseline RBC production) was 351 mL (range, 9–719), or 19 percent (range, 0.5-40) of the circulating RBC volume at baseline. CONCLUSION: A modest autologous blood donation program using three phlebotomies at weekly intervals and a threshold hematocrit for blood donation of 36 percent yields an average of 351 mL (range, 9–719) of RBCs. This is equivalent to 2 units (range, 0.5-4) of allogeneic packed RBCs at 180 mL per unit.     

Circulating RBC volume,measured with biotinylated RBCs,is superior to the Hct to document the hematologic effects of delayed versus immediate umbilical cord clamping in preterm neonates

BACKGROUND: One problem assessing the hematologic physiology of preterm infants after delivery and/or the efficacy and toxicity of therapeutic interventions affecting RBC measurements is the inability of blood Hct values to accurately reflect circulating RBC volume-owing to changes in plasma volume that influence Hct (i.e., a fall in plasma volume concentrates RBCs to increase Hct; a rise in plasma volume dilutes RBCs to decrease Hct). STUDY DESIGN AND METHODS: As part of a randomized, clinical trial testing the hypothesis that delayed clamping of the umbilical cord at delivery expands neonatal circulating RBC volume, blood Hct was compared to circulating RBC volume results measured directly with autologous, biotinylated RBCs or estimated mathematically with neonatal body weight and Hct values in neonates after immediate or delayed (60 sec) cord clamping. RESULTS: Circulating RBC volume measured directly with biotinylated RBCs significantly increased (p=0.04) in neonates after delayed (42.1 +/- 7.8 mL/kg) versus immediate (36.8 +/- 6.3 mL/kg) cord clamping-a difference not detected indirectly by measuring Hct or estimating circulating RBC volume mathematically. CONCLUSIONS: Because true hematologic effects of delayed versus immediate cord clamping may not be apparent or may be misinterpreted, when based on indirect measurements of Hct or calculations of circulating RBC volume, it is important to measure circulating RBC volume directly-as done with autologous, biotinylated RBCs-to document whether delayed cord clamping truly results in a transfer of significant quantities of RBCs from placenta to neonate. The clinical benefits and potential toxicities of increased RBC transfer to neonates require further studies.     

A randomized trial comparing acute normovolemic hemodilution and preoperative autologous blood donation in total hip arthroplasty

BACKGROUND: The value of acute normovolemic hemodilution (ANH) as compared to preoperative autologous blood donation (PABD) in orthopedic surgery is unknown. Therefore, a prospective, randomized study was conducted to compare these techniques in patients undergoing primary total hip arthroplasty. STUDY DESIGN AND METHODS: ANH patients underwent phlebotomy for up to 3 units, or to a target Hct level of 28 percent after induction of anesthesia. PABD patients were asked to donate up to 3 units before admission. RESULTS: Mean baseline Hct levels were not different in ANH and PABD patients (39. 7 +/- 4.5 vs. 41.8 +/- 3.8%, p = 0.09). No difference was found in allogeneic blood exposure among ANH and PABD cohorts: 4 (17%) of 23 ANH patients received a total of 9 allogeneic blood units, compared to no allogeneic transfusions in the PABD cohort (p = 0.30). Total blood costs associated with ANH were significantly (p<0.05) lower than blood costs associated with PABD ($151 +/- 154 vs. $680 +/- 253, respectively). CONCLUSION: In patients undergoing total hip arthroplasty, ANH is safe, can be considered equivalent to PABD in effectively reducing exposure to allogeneic RBCs, and is less costly than PABD.     

Cord blood as a source of autologous RBCs for transfusion to preterm infants

BACKGROUND: This prospective study was conducted to gain experience as to whether it is technically possible to produce autologous RBCs in additive solution from cord blood (CB), to optimize the blood supply for preterm infants. STUDY DESIGN AND METHODS: CB was collected from 47 infants with a mean (+/- SD) birth weight of 1717 (+/- 699) g. Whenever possible, RBC components were prepared by standard centrifugation using a six-bag system. All samples were put in sterility testing quarantine for 5 days, and a maximum storage of 14 days from collection to transfusion was specified. The babies were given either the autologous RBCs or standard allogeneic RBC concentrates, if autologous blood was not available. RESULTS: In 81 percent of the samples, autologous RBC components could be processed (vol, 7-87 mL; Hct, 31-82%). But within the group of extremely low birth weight infants (body weight <1000 g), a mean CB net volume of only 37 mL was collected, and the RBC preparation was successful only in exceptional cases. Three CB samples (8.6%) tested positive in sterility testing. Of the 47 infants, 21 were treated with a total of 62 allogeneic and 4 autologous RBC transfusions. Most infants with a body weight over 1400 g did not need any RBC transfusion. CONCLUSION: The preparation of autologous RBCs from the CB of preterm infants is technically possible in principle. However, major concerns must be raised as to whether such preparations are of benefit in ensuring safe care of neonates with blood components, with respect to the high rate of bacterial contamination and the limited availability in babies with low birth weight.     

Evaluation of a concurrent multicomponent collection system for the collection and storage of WBC-reduced RBC apheresis concentrates

BACKGROUND: Multicomponent apheresis procedures offer the possibility of collecting blood components that are standardized, as compared to those available with whole-blood donations. A new separator program for the concurrent collection of RBCs, platelets, and plasma (Amicus, Baxter Healthcare) was evaluated. STUDY DESIGN AND METHODS: Apheresis donors (n = 47) underwent concurrent collection of RBCs, platelets, and plasma by use of the single-needle procedure of the Amicus blood cell separator. A standardized RBC volume (100% Hct) of 200 mL was targeted with either 1 or 2 platelet concentrate units, depending on the donor's predonation characteristics. After collection, the RBC component was sterilely connected to an RBC collection set (Amicus) to allow for the addition of 100 mL of saline-adenine-glucose-mannitol preservative solution and WBC reduction at either ambient temperature or 4 degrees C. The RBC units were subsequently stored at 2 to 6 degrees C for 42 days, and the following in vitro measures were evaluated over the storage period: blood cell counts including Hct and total Hb, plasma Hb, potassium, pH, ATP, and 2,3 DPG. RESULTS: Procedure time averaged 74 +/- 9 minutes, and no adverse events were reported. The absolute RBC volume collected averaged 198 +/- 11 mL with an average Hct value of 83 +/- 2 percent. After filtration, the Hb content averaged 58.2 +/- 2.4 g per unit and residual WBCs averaged 0.038 +/- 0.015 x 10(6) per unit. Day 42 results showed that all units had on average more than 70-percent ATP maintenance, and all of the units had less than 0.8 percent he-molysis. All units had pH values higher than 6.5 on Day 42. CONCLUSION: The concurrent multicomponent collection system (Amicus) can reliably collect a standardized RBC unit of good quality. In vitro testing of the RBCs collected and stored for 42 days met the Council of Europe criteria for transfusion.     

Where does preoperative erythropoietin therapy count? A mathematical perspective

BACKGROUND: The administration of erythropoietin (EPO) can be used to increase a patient's hematocrit (Hct) in the preoperative period and thus possibly preclude the need for allogeneic red cells. However, the exact effect on the postoperative Hct of a given rise in Hct in the preoperative period (and on the avoidance of allogeneic blood) has not been thoroughly evaluated. STUDY DESIGN AND METHODS: Equations were developed on the basis of previously described relationships that allowed the assessment of the impact of a given preoperative Hct increase on the postoperative Hct under a variety of clinical situations. RESULTS: Equations were derived that related the change in preoperative Hct after the administration of EPO to the final Hct after a given blood loss. In a typical example (blood volume = 5000 mL, pre-EPO Hct of 40%, post-EPO Hct of 45% after blood losses of 1000, 2000, 3000, 4000, 5000, and 6000 mL), an additional 205, 168, 137, 112, 92, and 75 mL of red cells, respectively, would be present postoperatively over the volume in the same patient who did not receive EPO. For a smaller patient, such as a child (blood volume, 2500 mL), an additional 17 mL (5000-mL blood loss) to 83 mL (1000-mL blood loss) of red cells would be present postoperatively. Hemodilution and EPO act synergistically to yield additional postoperative red cell volume. CONCLUSION: The use of preoperative EPO with a preoperative increase in Hct results in an increased postoperative Hct after a surgical blood loss. Such a postoperative increase is a function of the volume of blood lost and the patient's blood volume but is independent of the patient's initial Hct. The final postoperative red cell volume increase associated with a preoperative increase in Hct of 1 to 5 percent is limited, however (generally equivalent to a fraction of 1 unit of allogeneic blood). Much of the increase in the patient's Hct vanishes at higher blood losses, and this therapy is most effective with blood loss of <4000 mL. EPO therapy alone may be most effectively used in patients with mild anemia who are undergoing routine surgical procedures that commonly require blood transfusion.     

Limitations of the hematocrit level to assess the need for red blood cell transfusion in hypovolemic anemic patients

BACKGROUND: The transfusion trigger that physicians use to determine whether a patient requires a red blood cell (RBC) transfusion is the peripheral venous hematocrit (Hct) value. Although this measurement is an indicator of the concentration of RBCs in the blood, it does not reveal the RBC volume, plasma volume, or total blood volume, nor does it give any indication of whether the patient is hypovolemic, normovolemic, or hypervolemic. STUDY DESIGN AND METHODS: Two patient populations were studied: 41 consecutive patients subjected to elective vascular surgery and 20 consecutive patients subjected to cardiopulmonary bypass surgery. The RBC volume was measured with (51)Cr- or (99m)Tc-labeled autologous fresh RBCs, and the plasma volume and total blood volume were estimated from the measured RBC volume and the total body Hct level. Measurements made 1 to 2 and 24 hours after surgery were compared to the preoperative values for these two groups of patients. RESULTS: During the 24-hour postoperative period, the RBC, plasma, and total blood volumes were reduced compared to the preoperative volumes. These patients were hypovolemic and anemic, and their Hct values during the 24-hour postoperative period were increased by a mean of 4 to 5 volume-percent compared to values that would be expected if they were normvolemic and anemic. CONCLUSIONS: The Hct values in hypovolemic anemic patients are elevated because the plasma volume does not increase to achieve the normovolemic anemic state.     

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 × 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.     

Use of a flow-cell system to investigate virucidal dimethylmethylene blue phototreatment in two RBC additive solutions

BACKGROUND: Limited photoinactivation kinetics, use of low-volume 30 percent Hct RBCs, and hemolysis have restricted the practicality of the use of dimethylmethylene blue (DMMB) and light for RBC decontamination. A flow-cell system was developed to rapidly treat larger volumes of oxygenated 45 percent Hct RBCs with high-intensity red light. MATERIALS AND METHODS: CPD-whole blood was WBC reduced, RBCs were diluted in additive solutions (either Adsol or Erythrosol), and suspensions were subsequently oxygenated by gas overlay. Intracellular or extracellular VSV and DMMB were sequentially added. VSV-infected RBC suspensions (45% Hct) were passed through 1-mm-thick flow cells and illuminated. Samples were titered for VSV, stored for up to 42 days, and assayed for Hb, supernatant potassium, ATP, and MCV. RESULTS: The use of oxygenated RBCs resulted in rapid and reproducible photoinactivaton of > or = 6.6 log extracellular and approximately 4.0 log intracellular VSV independent of additive solution. Phototreated Adsol RBCs exhibited more than 10 times greater hemolysis and 30 percent greater MCV during storage than identically treated Erythrosol RBCs. Phototreatment caused RBC potassium leakage from RBCs in both additive solutions. ATP levels were better preserved in Erythrosol than Adsol RBCs. CONCLUSION: A rapid, reproducible, and robust method for photoinactivating model virus in RBC suspensions was developed. Despite improved hemolysis and ATP levels in Erythrosol-phototreated RBCs, storage properties were not maintained for 42 days.     

A clinical study on the feasibility of autologous cord blood transfusion for anemia of prematurity

BACKGROUND: The objective was to investigate the use of autologous red blood cells (RBCs) derived from umbilical cord blood (UCB), as an alternative for allogeneic transfusions in premature infants admitted to a tertiary neonatal center. STUDY DESIGN AND METHODS: UCB collection was performed at deliveries of less than 32 weeks of gestation and processed into autologous RBC products. Premature infants requiring a RBC transfusion were randomly assigned to an autologous or allogeneic product. The primary endpoint was an at least 50 percent reduction in allogeneic transfusion needs. RESULTS: Fifty-seven percent of the collections harvested enough volume (> or =15 mL) for processing. After being processed, autologous products (> or =10 mL/kg) were available for 36 percent of the total study population and for 27 percent of the transfused infants and could cover 58 percent (range, 25%-100%) of the transfusion needs within the 21-day product shelf life. Availability of autologous products depended most on the gestational age. Infants born between 24 and 28 weeks had the lowest availability (17%). All products, however, would be useful in view of their high (87%) transfusion needs. Availability was highest (48%) for the infants born between 28 and 30 weeks. For 42 percent of the infants with transfusion needs in this group, autologous products were available. For the infants born between 30 and 32 weeks, autologous products were available for 36 percent of the infants. Transfusion needs in this group were, however, much lower (19%) compared to the other gestational groups. CONCLUSION: Autologous RBCs derived from UCB could not replace 50 percent of allogeneic transfusions due to the low UCB volumes collected and subsequent low product availability.     

Survival and function of baboon RBCs released from clotted blood and washed before autologous transfusion

BACKGROUND: One alternative to an allogeneic transfusion is the salvaging of the patient's own shed blood. In this study, baboon blood was allowed to clot and the RBCs that were released from the clotted blood lysed with and without urokinase were washed before autologous transfusion. STUDY DESIGN AND METHODS: Forty-four studies were done in 13 baboons (Papio cynocephalus or Papio anubis) over a 3-year period. In 24 studies, a 50-mL volume of blood was collected without an anticoagulant and stored at 22 degrees C for as long as 72 hours before washing and autologous transfusion. In 20 other studies, a 50-mL volume of blood was collected without an anticoagulant and allowed to clot for 30 to 60 minutes. Urokinase, ranging from 2,500 to 10,000 units per mL, was added, and the blood was stored at 22 degrees C for 24 hours before washing and autologous transfusion. RESULTS: RBCs that were stored at 22 degrees C without urokinase for 24 hours exhibited an in vitro recovery value of 45 percent, a (51)Cr 24-hour posttransfusion survival of 86 percent, and an index of therapeutic effectiveness of 39 percent. The (51)Cr T(50) value was normal at 14 days, and RBC oxygen-transport function was slightly reduced. RBCs that were stored at 22 degrees C for 24 hours with 10,000 units per mL of urokinase exhibited an in vitro recovery value of 89 percent, a (51)Cr 24-hour posttransfusion survival value of 86 percent, and an index of therapeutic effectiveness of 76 percent. The (51)Cr T(50) value was normal at 14 days, and the RBC oxygen-transport function was only slightly reduced. CONCLUSION: Autologous baboon RBCs isolated from clotted blood treated or not treated with urokinase and washed before transfusion have excellent survival and normal or only slightly reduced oxygen-transport function.     

The volume of returned red blood cells in a large blood salvage program: where does it all go? (CME)

BACKGROUND: Intraoperative blood salvage is the process whereby shed red blood cells (RBCs) are collected and returned to the patient. We analyzed the trends in the volume of returned RBCs by our blood salvage program across a 12‐hospital regional health care system over a 5‐year period. STUDY DESIGN AND METHODS: All quality control, RBC recovery, and patient demographic data relating to blood salvage are stored in a large database covering these 12 hospitals. Cases in which blood salvage was performed over a 5‐year period were stratified based on patient demographics, hospital, type of surgery, and volume of RBCs recovered. RESULTS: There were 19,867 surgeries performed during the study period in which blood salvage was used. The median volume of blood returned to each patient was 405 mL (25th‐75th percentile, 135‐750 mL). Defining the volume of an RBC unit as 200 mL, this represented a median of 1.1 RBC unit equivalents (25th‐75th percentile, 0.37‐2.1 units) returned to each patient. For the majority of patients, not more than 1 RBC unit equivalent was recovered. Overall, the ratio of cases where at least 1 RBC unit equivalent was recovered to cases where less than 1 RBC equivalent was recovered was 2.5:1; this ratio varied considerably between surgical procedures. CONCLUSIONS: Although overall the mean volumes of RBCs returned to the patients by intraoperative blood salvage were high, the actual volumes returned depended on the case mix. There appears to be an opportunity to use blood salvage more selectively to improve efficiency.     

ANH联合氨甲环酸对全膝关节置换术失血量和输血量的影响

目的观察急性等容血液稀释(ANH)联合氨甲环酸对全膝关节置换术失血量和输血量的影响。方法将98例全膝关节置换术患者通过电脑随机法分为ANH组和联合组,每组49例。ANH组行术中ANH,联合组采用ANH和氨甲环酸联合应用。观察两组患者自体输血前后血红蛋白(Hb)、红细胞压积(Hct)、血小板计数(PLT)变化及术前、术后凝血酶原时间(PT)、部分凝血活酶时间(APTT)、凝血酶时间(TT)、纤维蛋白原(FIB)、D-二聚体变化,记录患者失血量、异体血输注量、尿量和术后引流量。结果联合组自体输血后Hb、Hct平均水平明显高于ANH组,差异有统计学意义(P0.05);联合组术后D-二聚体水平明显高于ANH组,差异有统计学意义(P0.05);联合组失血量、异体血输注量及术后1d引流量明显少于ANH组,差异有统计学意义(P0.05)。结论自体输血与氨甲环酸联合应用可明显减少全膝关节置换术中失血量和异体血输注量,有一定的临床推广价值。     

A randomized clinical trial comparing immediate versus delayed clamping of the umbilical cord in preterm infants: short-term clinical and laboratory endpoints

BACKGROUND: Most neonates less than 1.0 kg birth weight need red blood cell (RBC) transfusions. Delayed clamping of the umbilical cord 1 minute after delivery transfuses the neonate with autologous placental blood to expand blood volume and provide 60 percent more RBCs than after immediate clamping. This study compared hematologic and clinical effects of delayed versus immediate cord clamping. STUDY DESIGN AND METHODS: After parental consent, neonates not more than 36 weeks' gestation were randomly assigned to cord clamping immediately or at 1 minute after delivery. The primary endpoint was an increase in RBC volume/mass, per biotin labeling, after delayed clamping. Secondary endpoints were multiple clinical and laboratory comparisons over the first 28 days including Score for Neonatal Acute Physiology (SNAP). RESULTS: Problems with delayed clamping techniques prevented study of neonates of less than 30 weeks' gestation, and 105 neonates 30 to 36 weeks are reported. Circulating RBC volume/mass increased (p = 0.04) and weekly hematocrit (Hct) values were higher (p < 0.005) after delayed clamping. Higher Hct values did not lead to fewer RBC transfusions (p > or = 0.70). Apgar scores after birth and daily SNAP scores were not significantly different (p > or = 0.22). Requirements for mechanical ventilation with oxygen were similar. More (p = 0.03) neonates needed phototherapy after delayed clamping, but initial bilirubin levels and extent of phototherapy did not differ. CONCLUSIONS: Although a 1-minute delay in cord clamping significantly increased RBC volume/mass and Hct, clinical benefits were modest. Clinically significant adverse effects were not detected. Consider a 1-minute delay in cord clamping to increase RBC volume/mass and RBC iron, for neonates 30 to 36 weeks' gestation, who do not need immediate resuscitation.     

Automated collection of double red blood cell units with a variable-volume separation chamber

BACKGROUND: Automated collection of blood components offers multiple advantages and has prompted development of portable devices. This study sought to document the biochemical and hematologic properties and in vivo recovery of red cells (RBCs) collected via a new device that employed a variable-volume centrifugal separation chamber. STUDY DESIGN AND METHODS: Normal subjects (n = 153) donated 2 units of RBCs via an automated blood collection system (Cymbal, Haemonetics). Procedures were conducted with wall outlet power (n = 49) or the device's battery source (n = 104). Units were collected with or without leukoreduction filtration and were stored in AS-3 for 42 days. The units were assessed via standard biochemical and hematologic tests before and after storage, and 24 leukoreduced (LR) and 24 non-LR RBCs were radiolabeled on Day 42 with Na(2)(51)CrO(4) for autologous return to determine recovery at 24 hours with concomitant determination of RBC volume via infusion of (99m)Tc-labeled fresh RBCs. RESULTS: Two standard RBC units (targeted to contain 180 mL of RBCs plus 100 mL of AS-3) could be collected in 35.7 +/- 2.0 minutes (n = 30) or 40.3 +/- 2.7 minutes for LR RBCs (n = 92). An additional 31 collections were conducted successfully with intentional filter bypassing. RBC units contained 104 +/- 4.1 percent of their targeted volumes (170-204 mL of RBCs), and LR RBCs contained 92 percent of non-LR RBCs' hemoglobin. All LR RBCs contained less than 1 x 10(6) white blood cells. Mean hemolysis was below 0.8 percent (Day 42) for all configurations. Adenosine triphosphate was well preserved. Mean recovery was 82 +/- 4.9 percent for RBCs and 84 +/- 7.0 percent for LR RBCs. CONCLUSIONS: The Cymbal device provided quick and efficient collection of 2 RBC units with properties meeting regulatory requirements and consistent with good clinical utility.     

Posttransfusion 24-hour recovery and subsequent survival of allogeneic red blood cells in the bloodstream of newborn infants

BACKGROUND: The feasibility, efficacy, and safety of transfusing stored allogeneic RBCs has been demonstrated for small-volume transfusions given to infants. We measured the posttransfusion recovery and intravascular survival of allogeneic RBCs stored up to 42 days to further elucidate their efficacy. STUDY DESIGN AND METHODS: Preterm infants were transfused with 1.0 mL of biotinylated RBCs plus 15 mL per kg of unlabeled allogeneic RBCs. Posttransfusion infant blood samples obtained at 10 minutes, and at 1, 2, 4, 7, 10, 14, and 21 days were used to determine the 24-hour posttransfusion recovery (PTR(24)), mean potential life span (MPL), and time to disappearance of 50 percent of biotinylated RBCs (T(50)). RESULTS: No significant differences were found between allogeneic RBCs stored 1 to 21 days versus 22 to 42 days for PTR(24), MPL, or T(50), indicating comparable posttransfusion circulation, regardless of storage age. Although MPL and T(50) values in infants using biotinylated RBCs were short, compared to those expected using chromium-labeled RBCs in adults, they agreed with results reported by others using biotinylated RBCs. CONCLUSIONS: Satisfactory posttransfusion RBC recovery and survival, measured with biotinylated RBCs, support earlier clinical trials that established the efficacy and safety of stored allogeneic RBCs for small-volume transfusions given to infants. The relatively short MPL and T(50) values in some infants may underestimate true survival due to ongoing erythropoiesis and infant growth with commensurate increase in blood volume during the time of RBC survival studies. Because values in infants differ from those expected using chromium-labeled RBCs in adults, and the number of posttransfusion determinations was few, additional studies are needed to define the mechanisms involved.     

Storage of red blood cells with improved maintenance of 2,3-bisphosphoglycerate

BACKGROUND: During storage, red blood cells (RBCs) rapidly lose 2,3-bisphosphoglycerate (2,3-DPG) leading to an increase in the affinity for O(2) and a temporary impairment of O(2) transport. Recent clinical evaluations indicate that the quality of transfused RBCs may be more important for patient survival than previously recognized. STUDY DESIGN AND METHODS: Glucose-free additive solutions (ASs) were prepared with sodium citrate, sodium gluconate, adenine, mannitol, and phosphates at high pH, a solution that can be heat-sterilized. CP2D was used as an anticoagulant. Additional CP2D was added to the AS to supply glucose. RBCs were stored at 4 degrees C and assayed periodically for intracellular pH (pHi), extracellular pH, glucose, lactate, phosphate, ATP, 2,3-DPG, hemolysis, and morphology. RESULTS: Storage in 175 mL of the chloride-free, hypotonic medium at a hematocrit (Hct) level of 59 to 60 percent resulted in an elevated pHi and the maintenance of 2,3-DPG at or above the initial value for 2 weeks without loss of ATP. The addition of 400 mL of storage solution followed by centrifugation and removal of 300 mL of excess solution to a Hct level of 60 to 66 percent further reduced the chloride concentration, resulting in the maintenance of 2,3-DPG for 4 weeks. Hemolysis was at 0.1 percent at 6 weeks. CONCLUSION: Improvements in the maintenance of 2,3-DPG were achieved with 175 mL of a chloride-free storage solution with familiar additives at nontoxic concentrations to increase pHi. Adding, instead, 400 mL of storage solution followed by the removal of 300 mL reduced the chloride concentration, increasing the pHi and extending the maintenance of 2,3-DPG to 4 weeks.     

Calculating the required transfusion volume in children

BACKGROUND: The traditional method of calculating blood volume for pediatric transfusion in the UK is weight (kg) x aimed increment in hemoglobin concentration (Hb; g/dL) x the transfusion factor, usually quoted at 3 or 4. This equation is without evidence base. The aim was to assess how the volume of red cells (RBCs) affects the increase in serum Hb in children and to devise a formula that allows accurate volume calculation. STUDY DESIGN AND METHODS: All pediatric intensive care charts for 2 years were examined retrospectively. The immediate pre- and posttransfusion Hb estimations and the precise volumes of RBC transfused were recorded. Fluid boluses and hemorrhagic loss during the transfusion were documented. RESULTS: A total of 7679 patient charts were examined with a total of 564 transfusions. All patients who were bleeding, had drain losses, or had concurrent colloid infusions were excluded, giving 379 data points. The correlation gradient between mL per kg blood transfused and increase in Hb was 5.02. There was no significant association between effect and patient weight, age, starting Hb, transfusion time, or sex. No significant difference was found in Hb at 1 and 7 hours posttransfusion. CONCLUSIONS: The following equation should be used to calculate transfusion volumes: weight (kg) x increment in Hb (g/dL) x 3/(hematocrit [Hct] level of RBCs). This predicts that with a UK standard Hct of 0.6, 10 mL/kg gives an increment of 2 g/dL. Care must be taken not to risk hypervolemia, while minimizing donor exposure. Hb estimation 1 hour after transfusion is the same as 7 hours after transfusion.