Laboratory and clinical effects of the infusion of ACD solution during plateletpheresis

Plasma Exchange in Acute and Acute on Chronic Liver Failure

Liver failure in the context of acute (ALF) and acute on chronic liver failure (ACLF) is associated with high mortality in the absence of a liver transplant. For decades, therapeutic plasma exchange (TPE) is performed for the management of immune-mediated diseases. TPE has emerged as an attractive extracorporeal blood purification technique in patients with ALF and ACLF. The basic premise of using TPE is to remove the toxic substances which would allow recovery of native liver functions by facilitating liver regeneration. In recent years, encouraging data have emerged, suggesting the benefits of TPE in patients with liver failure. TPE has emerged as an attractive liver support device for the failing liver until liver transplantation or clinical recovery. The data in patients with ALF suggest routine use of high-volume TPE, while the data for such a strategy are less robust for patients with ACLF.

Predictive factors of poor blood collecting flow during leukocyte apheresis for cellular therapy

Leukocyte apheresis is necessary in various cellular therapies. However, maintenance of a stable flow rate during leukocyte apheresis is often difficult, even in patients or donors without major problems. Despite this, predictive methods and evidence regarding the reality of the situation are limited. We conducted a retrospective analysis involving adult patients who required leukocyte apheresis for the treatment of neoplasms using WT1-pulsed dendritic cell vaccine. Monocytes were separated from apheresis products to obtain dendritic cells. All the patients were pre-evaluated based on laboratory and chest X-ray findings and subjected to an identical apheresis procedure. The occurrence of poor blood collecting flow during leukocyte apheresis was monitored, and the frequency, clinical information, and associated risk factors were analyzed. Among 160 cases, poor blood collecting flow was observed in 53 cases (33.1%) in a median time of 54 min (range, 2-127 min) post-initiation of leukocyte apheresis. Owing to difficulty in obtaining higher collecting flow, a longer procedure time was required, and in some cases, the scheduled apheresis cycles could not be completed. Consequently, the number of harvested monocytes was low. Multivariable analysis indicated that female patients have an increased risk of poor inlet flow rate. Furthermore, prolonged QT dispersion (QTD) calculated using Bazett's formula was found to be a risk factor. Although the patients did not present any major problems during leukocyte apheresis, poor blood collecting flow was observed in some cases. Sex and pre-evaluated QTD might be useful predictors for these cases; however, further prospective evaluation is necessary.

Prophylactic administration of oral calcium carbonate during plateletpheresis: A bicentric prospective study

BACKGROUND:

Administration of anticoagulant citrate and dextrose (ACD-A) chelates ionized calcium in blood and causes hypocalcemia in plateletpheresis donors. The aim of the study was to observe the effects of oral calcium (Ca) supplementation during plateletpheresis on various parameters related to calcium metabolism.

MATERIALS AND METHODS:

This study was performed between January 2014 and December 2014 on 200 plateletpheresis donors. They were divided into two groups. In group A donors (n=100), no prophylactic oral calcium supplementation was given. In group B (n=100) donors, 2000 mg of calcium was given one hour before the start of the procedure, 500 mg was given at the start of the procedure and 500 mg calcium was given just before the end of procedure. Biochemical parameters like serum total calcium (T Ca), serum total magnesium (T Mg) and ionized calcium level (iCa) were measured before and after the procedure. Relative risk of citrate toxicity was measured between the two groups.

RESULTS:

There was a significant fall in total calcium (pre 9.02 mg/dl, post 8.23 mg/dl,), ionized calcium level (pre 1.14 mmol/L, post 0.91 mmol/L) and total magnesium (pre 1.92 mg/dl, post 1.79 mg/dl) amongst the donors who did not receive prophylactic calcium supplementation. Despite calcium intake, in prophylactic calcium intake group, we did observe a significant drop in total magnesium (pre 2.04 mg/dl, post 1.94 mg/dl) and ionized calcium level (pre 1.25 mmol/L, post 1.12 mmol/L, p<0.01). We did observe a drop in total calcium level, however, this observation was not statistically significant. The risk (RR=5.44) of citrate toxicity was higher among group A donors.

CONCLUSION:

Prophylactic oral calcium carbonate supplementation would help in to reduce the risk of citrate toxicity. Therefore, we suggest for prophylactic oral administration of 3000 mg elemental calcium carbonate in three divided doses to make PP procedures uneventful.

Comprehensive analysis of changes in clinically significant divalent serum cation levels during automated plateletpheresis in healthy donors in a tertiary care center in North India

BACKGROUND

Adverse effects due to apheresis are unusual. The most common apheresis-specific reaction is hypocalcemia due to citrate anticoagulation and induces ionized hypocalcemia and hypomagnesemia by chelating effect during the plateletpheresis; generally transient and self-limiting but has the potential of severely injuring donor. We have investigated total calcium (tCa(++)) and magnesium (tMg(++)) levels in sixty healthy plateletpheresis donors at different intervals during the procedure and 30 min post-procedure.

MATERIALS AND METHODS

A total of 60 procedures were performed on healthy donors. Blood samples were obtained from sterile diversion pouch placed on apheresis circuit. 5 ml sample in plain vials was obtained at different intervals during each procedure and 30 min after the end of the procedure. Samples were used for measurement of tCa(++) and tMg(++) levels.

RESULTS

There is continuous decrease in mean tCa(++) from baseline levels (9.83 ± 0.64 mg/dl) till end of procedure (8.33 ± 0.78 mg/dl), but after 30 min, levels again reached near their respective baseline values (9.42 ± 0.54 mg/dl). Similarly, mean tMg(++) fell from baseline levels (2.36 ± 0.3 mg/dl) till the end of procedure (1.39 ± 0.40 mg/dl). After 30 min, levels were again increased, their respective baseline values (2.25 ± 0.25 mg/dl).

CONCLUSION

There is continuous, gradual, and significant fall (P < 0.05) in mean tCa(++) and mean tMg(++) from baseline levels to till the end of procedure but after 30 min of completion of procedure, levels again reached near their respective baseline values.

Therapeutic plasma exchange: a technical and operational review

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique designed for the removal of large molecular weight substances. Examples of these substances include pathogenic autoantibodies, immune complexes, cryoglobulins, myeloma light chains, endotoxin and cholesterol containing lipoproteins. The basic premise of the treatment is that removal of these substances will allow for the reversal of the pathologic processes related to their presence. This review will cover the techniques for performing TPE, the kinetics of the removal of large molecules from the plasma and the benefits and risks of the different types of replacement fluids.

Anticoagulation techniques in apheresis: from heparin to citrate and beyond

Anticoagulation is essential for maintaining the fluidity of extravascular blood on the apheresis circuit. Although both citrate and heparin are used as an anticoagulant during apheresis, citrate is preferred for the majority of exchange procedures because of its safety and effectiveness. Complications of citrate are primarily due to physiologic effects of hypocalcemia. Symptoms of hypocalcemia and other citrate-induced metabolic abnormalities affect neuromuscular and cardiac function and range in severity from mild dysesthesias (most common) to tetany, seizures, and cardiac arrhythmias. Oral or intravenous calcium supplementation is advised for decreased ionized calcium levels and/or symptomatic management of hypocalcemia. Heparin-based anticoagulation is limited to certain apheresis procedures (membrane-based plasma exchange, LDL apheresis, or photopheresis) or is used in combination with citrate to reduce citrate load. While effective, heparin anticoagulation is associated with an increased frequency of bleeding complications and heparin-induced thrombocytopenia. J. Clin. Apheresis 2012. © 2012 Wiley Periodicals, Inc.

Adverse reactions in blood and apheresis donors: experience from two Italian transfusion centres

BACKGROUND

Blood and apheresis donations are widely considered to be safe with a low incidence of adverse reactions and injuries; however, data reported in the medical literature on the prevalence of adverse events in donors and studies on the predictive risk factors for donor reactions are limited and contradictory.

METHODS

From January 2002 to December 2006 we recorded every adverse reaction verified during 240,596 consecutive blood and apheresis donations (183,855 homologous whole blood donations, 6,669 autologous whole blood donations, 38,647 plasmapheresis, 2,641 plateletpheresis and 8,784 multicomponent donations) at the Italian Transfusion Centres of Verona and Ragusa,.

RESULTS

Using a special, pre-arranged form within the quality system, a total of 686 adverse reactions (related to 0.28% of all donations) were recorded. Vasovagal reactions, mostly of mild intensity, were the most commonly observed adverse reactions, with a frequency of 0.20% (487/ 240,596). The frequency of the vasovagal reactions varied according to the different types of donation, being 0.19% (346/183,855) for homologous whole blood donations, 0.24% (16/6,669) for autologous whole blood donations, 0.16% (63/38,647) for plasmapheresis, 0.68% (18/2,641) for plateletpheresis and 0.49 (43/8,784) for multicomponent donations. Citrate toxicity was reported in 0.38% (189/50,072) of apheresis donations. Severe adverse reactions were very rare, as they occurred in 0.004% of the donations (10/240,596).

CONCLUSIONS

In conclusion, the results of our 5-year survey document that apheresis and blood donation are safe procedures for the donor with a low incidence of adverse reactions; the adverse reactions that did occur were mostly mild and resolved rapidly.

Hypocalcemic symptoms during plateletpheresis using the COBE Spectra: a comparison of oral combination of 600mg calcium+300mg magnesium+100IU vitamin D3 vs. a 1000mg calcium in symptomatic donors

BACKGROUND

The aim of this study was to find an effective treatment for hypocalcemic symptoms during plateletpheresis and to evaluate if a combination of calcium, magnesium and vitamin D3 is more effective in comparison to routine calcium supplementation.

MATERIAL AND METHODS

A study group consisting of 10 donors, having a history of previous hypocalcemic symptoms during plateletpheresis, donated platelets twice in a one-month period. During the first donation combination tablets (600mg Ca+300mg Mg+100IU vitamin D3) were used to treat hypocalcemic symptoms while routine treatment calcium carbonate tablets (1000mg Ca) were used during the second donation. If symptoms persisted after 10min the same dose was repeated. A control group, with no supplementation, consisting of five donors, with no history of hypocalcemic symptoms, were included. Donor subjective symptoms were graded and recorded on four occasions: at the start of plateletpheresis, when symptoms appeared, 10min after the first tablet and at the end of donation. Samples for analysis of ionized calcium (iCa), magnesium and potassium were also taken at the same occasions.

RESULTS

All donors from the study group experienced minor or medium hypocalcemic symptoms and needed a second dose of supplementation. Calcium carbonate tablets completely relieved the hypocalcemic symptoms in six donors, it had no effect on three donors and one donor experienced aggravated symptoms. The combination tablets completely relieved the symptoms in three donors, one donor experienced a partial relief and six donors had no relief of symptoms. There were no significant differences in iCa, potassium and magnesium levels were noted in the study group irrespective of which tablets were used for treatment of hypocalcemic symptoms. After plateletpheresis the median iCa levels declined by 30% and potassium levels declined by 3-11% in all donors while the magnesium levels were not significantly affected. There was no correlation between the presence of symptoms and the changed levels of iCa or magnesium.

CONCLUSION

Addition of magnesium and vitamin D3 to calcium seems to have no beneficial effect in the treatment of hypocalcemic symptoms in plateletpheresis donors.

Tolerable infusion rate of citrate based on clinical signs and the electrocardiogram in conscious dogs

BACKGROUND & AIMS

The possible clinical significance of the toxic effects of citrate has not yet been fully clarified. This study was therefore conducted to confirm the toxicity and determine the tolerable infusion rate of citrate administered by rapid intravenous infusion to conscious dogs.

METHODS

Citrate solutions were infused via the cephalic vein of 4 conscious dogs at 0.33, 0.67, or 1.33mmol/kg/h up to 1.33mmol/kg. Clinical signs and the electrocardiogram were observed during and after infusion. Serum citrate and ionized calcium levels were also measured.

RESULTS

Although the mean citrate level increased in accordance with the infusion rate, the calcium level decreased. No significant changes in clinical signs or the electrocardiogram were observed during infusion at 0.33mmol/kg/h despite an increase in the serum citrate level to 1.22+/-0.11mmol/l (pre-infusion value: 0.38+/-0.01mmol/l) and a decrease in the serum calcium level to 1.28+/-0.03mmol/l (pre-infusion value: 1.50+/-0.05mmol/l). Vomiting and QTc prolongation were observed at 0.67mmol/kg/h or higher. Salivation and tachycardia were observed at 1.33mmol/kg/h.

CONCLUSIONS

Based on clinical signs and the electrocardiogram, the tolerable infusion rate of citrate in conscious dogs is concluded to be 0.33mmol/kg/h.

EFFECT OF WHOLE BLOOD CLOTTING TIME IN RATS WITH IONIZED HYPOCALCEMIA INDUCED BY RAPID INTRAVENOUS CITRATE INFUSION

Although the toxic effects of citrate including hemodynamic and cardiovascular changes result from a decrease in ionized calcium levels in serum due to chelating action, these effects of citrate on blood coagulation have not yet been fully clarified. The present study examines whether serum citrate and ionized calcium levels affect whole blood clotting time in rats using the test tube method in which citrate is administered by rapid intravenous infusion. Citrate was infused via the tail vein into 10 rats at 3, 4 or 5 mmol/kg/hr for 1 hr, and then whole blood clotting time, serum citrate and ionized calcium levels were determined. Whole blood clotting time did not significantly change at citrate infusion rates of 3 and 4 mmol/kg/hr. However, at 5 mmol/kg/hr, whole blood clotting time was significantly prolonged by a factor of 2.1 relative to the untreated group, when the serum citrate level was 10.03 +/- 1.39 mmol/l (59.0-fold higher than that in the untreated group) and the serum-ionized calcium level was 0.29 +/- 0.02 mmol/l (0.2-fold lower than that in the untreated group). These results suggest that whole blood clotting time is significantly prolonged in rats with severe ionized hypocalcemia.

Efficacy and Safety of a New Whole-blood Low-density Lipoprotein Apheresis System (Liposorber D) in Severe Hypercholesterolemia

Low-density lipoprotein (LDL) apheresis is an extracorporeal modality to lower LDL cholesterol. While most of the devices eliminate LDL particles from plasma, a recently introduced whole-blood perfusion column (DALI) adsorbs lipoproteins directly from whole blood. We investigated the efficacy and safety of a new whole-blood LDL apheresis system (Liposorber D) in 10 patients with severe hypercholesterolemia in a multicenter trial. In 93 LDL aphereses, the mean reduction in LDL cholesterol and lipoprotein(a) was 62.2 +/- 11.5% and 55.6 +/- 16.9%, respectively (P < 0.01). If hemodilution during apheresis was considered, the reductions were 58.0 +/- 10.9 and 55.3 +/- 10.9%, respectively (P < 0.01), while high-density lipoprotein (HDL) cholesterol did not change significantly. Three mild episodes of hypocalcemia and two mild episodes of arterial hypotension were observed; however, LDL apheresis could be continued in each case. In conclusion, the new whole-blood LDL apheresis with Liposorber D is a safe, simple, and useful modality to reduce LDL cholesterol and lipoprotein(a) in cardiovascular high-risk patients.

Randomized placebo-controlled study of oral calcium carbonate administration in plateletpheresis: I. Associations with donor symptoms

BACKGROUND

The effect of oral calcium (Ca) supplements in preventing citrate-induced symptoms during plateletpheresis was evaluated in a randomized, blinded, placebo-controlled trial.

STUDY DESIGN AND METHODS

Twenty-three donors (12 men, 11 women) underwent four plateletpheresis procedures each, ingesting either 1 or 2 g of oral Ca carbonate or an equivalent placebo 30 minutes before donation. Ten of these subjects subsequently ingested 4 g of open-label Ca before a fifth procedure. All procedures were conducted at the same citrate infusion rate (1.5 mg/kg/min) for 90 minutes.

RESULTS

Ingestion of 2 g of oral Ca resulted in a significant reduction in the severity of paresthesias and a significant, though modest, increase in serum ionized calcium (iCa), but no significant improvement in total symptom scores, compared to placebo. Minimal effects were seen with the 1-g dose. The two factors most highly correlated with development of severe symptoms were decreased levels of iCa and ionized magnesium (iMg) at 30 minutes into apheresis. Lower preapheresis serum albumin, creatinine, vitamin D, iMg, and total Mg concentrations were also significantly associated with symptoms. Women experienced more frequent and severe symptoms than men, however, gender was not associated with symptoms after adjustment for lower serum albumin, creatinine, and Mg levels. Ingestion of 4 g of Ca offered no improvement in symptoms or iCa levels compared with the 2-g dose.

CONCLUSION

Prophylactic oral Ca was associated with modest improvements in citrate-induced symptoms and laboratory parameters. Baseline albumin and Mg levels were strongly predictive of the development of symptoms. In donors with a prior history of uncomfortable citrate-related effects, a 2-g oral Ca dose before apheresis is recommended.

Randomized placebo-controlled study of oral calcium carbonate supplementation in plateletpheresis: II. Metabolic effects

BACKGROUND

The metabolic effects of oral calcium (Ca) supplementation during plateletpheresis were evaluated in a randomized, placebo-controlled trial.

STUDY DESIGN AND METHODS

Twenty-three donors underwent four plateletpheresis procedures each, receiving in random order, elemental Ca (Ca) 1 or 2 g orally, or a corresponding placebo, 30 minutes before donation. Ten of these donors underwent a fifth procedure using a 4-g Ca dose. All procedures were performed at a fixed citrate infusion rate of 1.5 mg per kg per minute.

RESULTS

Oral Ca induced dose-sensitive changes in parathyroid hormone (iPTH), total (tCa), and ionized (iCa) calcium levels. Compared to placebo, the greatest improvement in tCa and iCa levels occurred after the 2-g Ca dose (tCa of 73, 89, and 25% above placebo levels at 60 min, using 1, 2, and 4 g of oral Ca, respectively). Twenty-four hours after apheresis, serum tCa and iCa levels were higher, and iPTH levels lower, in donors who received oral Ca rather than placebo. Marked increases in urinary Ca and magnesium (Mg) excretion occurred at the completion of apheresis, were unaffected by Ca dose, and returned to baseline within 24 hours. Plateletpheresis also induced significant changes in serum alkaline phosphatase, 1,25-dihydroxyvitamin D, and osteocalcin levels immediately and at 24 hours after apheresis.

CONCLUSION

Plateletpheresis induces marked acute metabolic effects, with sustained changes evident up to 24 hours after the completion of apheresis. Oral Ca supplementation exerts a significant but clinically modest impact on selected laboratory variables associated with these effects. Further studies are indicated to examine the long-term impact of plateletpheresis, with or without Ca supplementation, on donor Ca balance and bone density.

Vasovagal reactions in apheresis donors

BACKGROUND

The incidence rate of vasovagal reactions (VVRs) in apheresis is known to be higher in women than in men donors. VVRs in women apheresis donors were therefore analyzed to find out possible factors for their high incidence.

STUDY DESIGN AND METHODS

VVR incidence was compared between whole blood (WB) and apheresis donation in relation mainly to age and circulatory blood volume (CBV). In addition, blood pressure and pulse rate were measured during apheresis.

RESULTS

In WB donors, the VVR incidence was 0.83 and 1.25 percent, while in apheresis donors it was 0.99 and 4.17 percent in men and women, respectively. The VVR incidence decreased with age in WB donors, but age dependence was very weak in apheresis donors. In elderly women, the incidence increased with repeating cycle of apheresis. There were three different patterns of pulse fluctuation during apheresis, that is, stable (type A), increased rate during blood withdrawal (type B), and irregular pattern (type C). Elderly women donors and donors who suffered from VVRs mostly showed type B fluctuation. There was no particular fluctuation in blood pressure in relation to apheresis cycles.

CONCLUSION

The VVR incidence rate was particularly high in women apheresis donors over 45 years old and increased with repeating cycles of apheresis. Smaller CBV, high sensitivity of low-pressure baroreceptors, and citrate effects on cardiovascular reflex might be major factors involved in the high incidence of VVRs.

Treatment for the decline of ionized calcium levels during peripheral blood progenitor cell harvesting

BACKGROUND

ACD-A solution containing sodium citrate and citric acid is used as an anticoagulant agent during peripheral blood progenitor cell (PBPC) harvesting, and in rare cases can cause fatal citrate intoxication. The aim of this study was to establish effective methods for stabilizing ionized calcium (ICa) levels during PBPC harvesting.

STUDY DESIGN AND METHODS

ICa was measured during 46 apheresis procedures conducted in 26 patients. Four patients in four procedures were infused with calcium gluconate solution before PBPC harvesting; three patients in six procedures were infused with calcium gluconate when symptoms of citrate intoxication appeared; and four patients in five procedures received a continuous infusion. Five patients in five procedures took an isotonic sports drink containing calcium when hypocalcemic symptoms appeared. The ICa level, blood pressure, and pulse rate were measured.

RESULTS

ICa declined rapidly from the preapheresis level of 1.081(+/-0.092) mM to 0.937(+/-0.081) mM (13.3%, p < 0.0001) 10 minutes after the start of apheresis and continued to decline until the completion of the procedure. When patients received a continuous infusion of calcium during apheresis, ICa was relatively stabilized. ICa significantly rose (6.1 +/- 3.6%, p < 0.02) within 2 to 5 minutes after oral intake of an isotonic sports drink containing calcium and was maintained within normal range for 31 to 55 minutes.

CONCLUSION

An isotonic sports drink containing calcium has a quick stabilizing and a longer maintenance effect on ICa. Thus, we recommend the intake of an isotonic sports drink containing calcium as the easiest and best method for preventing hypocalcemia during apheresis.

QTc prolongation in apheresis platelet donors

BACKGROUND

Citrate infusion during apheresis procedures can cause lowering of the plasma ionized calcium leading to prolongation of the QT interval and hypotension. At the myocardial level, QTc measurement is a sensitive marker of subphysiologic calcium values caused by citrate toxicity.

STUDY DESIGN AND METHODS

Seventy-six regular platelet donors were recruited into this study. QTc intervals were measured continuously for 3 minutes at four different points during the apheresis procedures. The blood pressure was recorded every 5 minutes throughout the procedure.

RESULTS

The baseline QTc value for men was 406.5 +/- 13.1 milliseconds(1/2) and for women was 417.6 +/- 13.3 milliseconds(1/2) (p = 0.0016). OTc prolongation occurred in all procedures in all donors. Maximum recorded values were significantly higher in women than in men (450.8 +/- 20.8 vs. 424.8 +/- 14.3 ms(1/2); p = 0.0025). All QTc values returned to baseline by 15 minutes after the procedure. Changes in blood pressure were minimal and no donor experienced severe symptoms.

CONCLUSIONS

QTc prolongation always occurs during plateletpheresis. This prolongation is greater in women than in men. This study indicates that it may be advisable to assess donors for family or personal history of syncope and family history of sudden death to exclude those at increased risk of arrhythmias because of asymptomatic carriage of a long-QT gene. In addition baseline QTc measurement is a simple noninvasive procedure that could be applied to further studies with a view to enhancing donor safety in apheresis.

National audit of citrate toxicity in plateletpheresis donors

Citrate toxicity complicating plateletpheresis is not uncommon. However, the scale and severity of the problem have never been formally addressed. In order to answer these questions we undertook a national audit of 13 070-platelet procedures throughout 17 apheresis centres in England over a 3-month period from 1 April to 30 June 2000. A standard form was distributed to each centre to record the symptoms/signs of citrate toxicity which were then graded (grades 1-5) according to their severity. The following variables were studied to determine whether they influenced the frequency and severity of citrate toxicity: 1. The type of manufacturer's cell separator used (Cobe Spectra, Haemonetics, Baxter Amicus and Trima). 2 The type of procedure: single needle, dual needle, single, double or triple dose. 3 The way in which donors were instructed to report symptoms of citrate toxicity.

OUTCOME

Plateletpheresis is a relatively safe procedure provided that donors who experience severe reactions receive appropriate treatment. The incidence of severe citrate toxicity (0.03% procedures) is comparable to that of severe faints following whole blood donation, indicating a comparable margin of safety. Donors should be warned of the symptoms of citrate toxicity at their first attendance only. More frequent reminders encourage donors to over-report symptoms of mild citrate toxicity.

Comprehensive analysis of citrate effects during plateletpheresis in normal donors

BACKGROUND

Although plateletpheresis procedures are generally well tolerated, the clinical and metabolic consequences associated with rapid infusion of up to 10 g of citrate are underappreciated, and a comprehensive description of these events is not available.

STUDY DESIGN AND METHODS

Clinical and laboratory changes were studied in seven healthy donors undergoing three 90-minute plateletpheresis procedures each, at continuous, fixed citrate infusion rates of 1.1, 1.4, and 1.6 mg per kg per minute.

RESULTS

Serum citrate levels increased markedly with increasing citrate infusion rates and did not achieve a stable plateau. As citrate infusion rates increased, the total volume processed and platelet yields also increased, but donor symptoms became more severe. Ionized calcium (iCa) and ionized magnesium (iMg) concentrations decreased markedly, by 33 and 39 percent below baseline, respectively, at a citrate rate of 1.6 mg per kg per minute. Intact parathyroid hormone levels were higher at 30 minutes than at later time points, despite progressive decreases in iCa and iMg. Urine citrate, calcium, magnesium, sodium, and potassium concentrations and urine pH values increased markedly during all procedures.

CONCLUSION

Marked, progressive increases in serum citrate levels occur during plateletpheresis, accompanied by symptomatic decreases in iCa and iMg, with significantly increased renal excretion of calcium, magnesium, and citrate.

Effect of low-dose citrate anticoagulation on the clinical safety and efficacy of direct adsorption of lipoproteins (DALI apheresis) in hypercholesterolemic patients: a prospective controlled clinical trial

Direct adsorption of lipoproteins (DALI) is the first lipid apheresis system compatible with whole blood with the advantage of a very simple procedure. A mixture of heparin plus citrate (ACD-A) is used for the anticoagulation regimen (AR). A clinical, prospective, controlled crossover study was performed to test the safety and efficacy of low-dose citrate (LDC) anticoagulation in DALI. Five chronic DALI patients suffering from coronary heart disease and hypercholesterolemia underwent 3 DALI sessions each using the LDC anticoagulation regimen (60 IU heparin/kg body weight as initial bolus; 1:40 ACD-A: blood as perfusion). This was compared to 3 sessions per patient with the standard AR (bolus of 20 IU heparin/kg, 1:20 ACD-A as perfusion). Patient blood volumes (1.6; average of 7,040 ml) were treated with 750 ml adsorber gel per session at a blood flow rate of 60 ml/min. Mean LDL and Lp(a) reductions exceeded 60% with both AR. No clinical side effects were observed. Both AR controlled the coagulation well as evidenced by a sufficient prolongation of the partial prothrombin time (PTT) and activated clotting time as well as low thrombin-antithrombin (TAT) formation. Biocompatibility parameters exhibited favorable results (low activation of complement and cells, and only slight formation of C3a, C5a, beta-thromboglobulin, elastase, and TNF-alpha). The asymptomatic bradykinin generation was comparable in both study arms. LDC optimized the ionized calcium levels and pH in the efferent blood postadsorber. LDC anticoagulation was safe and effective, and may further improve the tolerance of DALI apheresis in hypercholesterolemic patients.

Enhanced HPC recruitment in children using LVL and a new automated apheresis system

BACKGROUND

A new automated apheresis system has recently been reported as useful in improving peripheral blood HPC collection in adults. The aim of this study has been to verify the utility of this system (AutoPBSC, COBE BCT) for standard leukapheresis and for LVL in the pediatric setting.

STUDY DESIGN AND METHODS

A prospective study was set up in 29 leukapheresis procedures carried out in 26 children with malignant diseases and body weight under 40 kg who had undergone mobilization with G-CSF or with G-CSF and chemotherapy. Leukapheresis procedures were performed under two protocols, depending on the total blood volume processed: standard leukapheresis (< or=3) and LVL (>3). The need to prime the tubing set with blood was determined, and the inlet flow rate, collection time, recruitment of CD34+ cells, CD34+ cell collection efficiency, component volume, leukapheresis cell composition, and preapheresis and postapheresis peripheral blood counts were measured. Paired t test, Spearman's correlation coefficient, and the Mann-Whitney U test were employed for statistical analysis.

RESULTS

Because of the low extracorporeal volume (167 mL) of the tubing set of the automated blood processor, priming was necessary in only 2 of 26 patients, both weighing under 10 kg. LVL showed better CD34+ cell yield (7.5 vs. 2.3 x 10(6)/kg; p = 0.047), higher recruitment (2.1 vs. 0.9; p = 0.002), and greater collection efficiency (50% vs. 33%; p = 0.005) than standard leukapheresis. No significant differences were found between groups in collection time. In LVL procedures, CD34+ cell collection efficiency and recruitment were not significantly influenced by the inlet flow rate.

CONCLUSION

The AutoPBSC is a reliable system for peripheral blood HPC collection in children mainly when used in combination with LVL. The major advantage of this software is a reduced need for priming. LVL allows better CD34+ cell collection efficiency, enhanced recruitment, and improved CD34+ cell yield.

Low density lipoprotein hemoperfusion by direct adsorption of lipoproteins from whole blood (DALI apheresis): clinical experience from a single center

The elimination of low density lipoprotein (LDL) and lipoprotein (a) (Lp[a]) by conventional LDL apheresis techniques can only be achieved in a cell-free medium and thus requires the initial separation of plasma from the blood cells. The present paper describes the first LDL hemoperfusion system which is able to adsorb LDL and Lp(a) directly from whole blood. This simplifies the procedure substantially. The adsorber consists of polyacrylate ligands linked to a modified polyacrylamide matrix. These negatively charged polyacrylate ligands interact with the positively charged apoprotein B moiety of LDL and Lp(a), which results in selective adsorption of these lipoproteins onto the column. Three hypercholesterolemic patients suffering from overt atherosclerotic complications were treated weekly by direct adsorption of lipoproteins (DALI) (n = 20 sessions each). All patients were on the highest tolerated dose of cholesterol synthesis enzyme (CSE) inhibitors. About 1.3 patient blood volumes were treated per session. The anticoagulation was performed with acid citrate dextrose (ACD-A). The following acute reductions were achieved: LDL: 66%; Lp(a): 63%; and triglycerides: 29%. High density lipoprotein (HDL) (-13%) and fibrinogen (-16%) were not substantially reduced. The sessions were essentially uneventful. Due to a low ACD-A infusion rate, no hypocalcemic episodes were registered. One patient on enalapril was treated without complications when this angiotensin converting enzyme (ACE) inhibitor was withdrawn 2 days prior to apheresis. In summary, in our hands, DALI apheresis proved to be a simple, safe, and efficient method of lipid apheresis in hypercholesterolemic patients refractory to conservative lipid lowering therapy.

Mechanisms of adverse effects during hemapheresis

For over 20 years blood components have been collected from normal donors by automated hemapheresis. Cell separators have become increasingly sophisticated, and relatively pure component "concentrates" can be obtained quite safely. Cytapheresis donors are monitored carefully, and serious reactions are very rare. In contrast, therapeutic apheresis procedures may be technically demanding and frequently are performed on very sick patients. Large volumes of blood are rapidly removed from the patient, anticoagulated, and separated into components by the automated cell separator. The blood component containing the pathogenetic factor (e.g., plasma containing an antibody) is retained outside of the body, and the remaining components (e.g., red cells, white cells, and platelets) plus the replacement fluid are reinfused. Complications can occur in normal cytapheresis donors because of the technical challenges of the procedure (e.g., extracorporeal circuit to be filled, use of citrate anticoagulant, need for large bore intravascular access, and rapid blood flow rates). All of these factors apply also to therapeutic patients plus the additional requirement for replacement fluids, and the clinical features of the underlying illness for which each patient is being treated. Fortunately, even with therapeutic patients, most complications are of modest severity and are easily managed with only temporary slowing or interruption of the hemapheresis procedure.

Plasma separation for artificial liver support

A bioartificial liver (BAL) support system, using plasma separation, has been developed to support acute liver failure patients. This study examined 14 consecutive BAL treatments in nine patients with severe acute liver failure. We report methods to achieve and manage plasma separation for an extended period of time. The mean duration of a BAL treatment was 435 minutes, with 26-59 liters of blood processed. Ionized hypocalcemia resulting in muscle twitching was a side effect of the therapy. Ionized calcium levels decreased significantly (P < .02) after BAL treatment; however, total calcium levels increased (P < .05). No significant changes were noted in heart rate, electrocardiogram [Q-T (Q-Tc) interval], blood pressure, prothrombin time, partial thromboplastin time, hematocrit, platelet count and serum phosphorous, magnesium, glucose, and pH. Plasma fibrinogen levels decreased significantly (P < .002). Ionized hypocalcemia due to the chelating effect of sodium citrate was controlled by calcium chloride administration, adjustment of blood separation rates, and reduction of the blood-to-citrate ratio. This report demonstrates that intensive, large-volume plasma separation for long periods of time can be achieved safely in critically ill patients without serious adverse effects.

Therapeutic plasma exchange: complications and management

Therapeutic plasma exchange is a treatment modality used in a variety of disease states, some of which are characterized by renal involvement (ie, Goodpasture's syndrome, multiple myeloma, cryoglobulinemia, and thrombotic thrombocytopenic purpura). To investigate the safety of this procedure we evaluated all patients receiving plasma-pheresis at the University of Connecticut from January 1988 to June 1991. Sixty-eight adverse reactions occurred in 699 treatments, resulting in an incidence of 9.7%. The most frequent complications were symptoms of hypocalcemia, hypovolemia, and anaphylactoid reactions. The incidence of hypocalcemic symptoms was lowered with the prophylactic administration of calcium. Without calcium prophylaxis the incidence of symptoms was 9.1% (six in 66 treatments), whereas with calcium prophylaxis the incidence was reduced to 1% (six in 633 treatments) (P < 0.01). Treatments in which albumin was administered as volume replacement were associated with fewer adverse reactions when compared with those using fresh-frozen plasma (1.4% v 20%). Our experience, combined with the 15,658 procedures reported in the literature, reveals that serious complications do not commonly occur. These are characterized by cardiovascular events (0.2%), respiratory events (0.2%), and anaphylactoid reactions (0.25%). Hemorrhage and infection are rare, each occurring at a rate of 0.02%. Death was reported in eight of 15,658 procedures (0.05%). We conclude that therapeutic plasma exchange is relatively safe and alterations in plasma proteins generally are well tolerated. Prophylactic calcium administration lowers the incidence of hypocalcemic symptoms. Adverse reactions are associated more commonly with the administration of fresh-frozen plasma.

The collection of platelets by apheresis procedures

Collection of platelets by apheresis has been a major advance in transfusion medicine. It has allowed the supply of a therapeutically beneficial component to grow with medical needs. Donors find fulfillment in more frequent donations than are possible with whole blood and know that their donation fills a special need. New technology allows leukocyte reduction in the collection of the component with or without the use of filtration. Matching for refractory patients is possible. However, platelets collected by apheresis have not been shown to be hemostatically different from platelets separated from whole blood donations, and thus, do not represent an advance in therapeutic efficacy. The use of apheresis platelets does reduce donor exposure, but this has not been shown to be a safety advance, although it seems intuitively obvious that transfusion risk is statistically reduced in some patients requiring only a few platelet transfusions. Support of patients by apheresis platelets may or may not reduce the risk of alloimmunization. Apheresis platelets from some equipment have less white blood cell contamination even in the absence of filtration, which may be an advantage. Apheresis platelets could be a major step in the ultimate customization of blood collection, in which some donors would preferentially donate red blood cells, whereas others would donate platelets or plasma depending on their blood type and ability to donate frequently, and the current medical need of their donation. Perhaps this would be the most significant advance from the medical progress initiated by Cohn almost 50 years ago.

[Safety of donors, quality of products, how much to reduce the quantity of citrate]

We examined 1,053 blood samples from 48 donors, for the effect of gradual reduction of citrate. We observed that: 1--Platelet count does not show any significant variation between 1/8 to 1/18 ratio. 2--In 13.3% of the cases, platelet clumping starts at 1/18 ratio. 3--There was no significant variation of the thrombin plasma level between 1/8 to 1/16 ratio (by measuring thrombin/ATIII complex). Our results show clearly that we can reduce the citrate ratio to 1/14 without expecting any adverse effect. Therefore we designated 1/14 as the security ratio. Parallel to this we also found that the average level +/- SD of ionized calcium is 100 +/- 10 muMol at 1/14 ratio.

Filtration of fresh frozen plasma used as substitution fluid in plasma exchange in order to remove microaggregates

Freshly melted fresh frozen plasma (FFP) contains a large number of particles smaller than 20 microns in diameter. These particulate materials (microaggregates) consist of aggregated triglyceride-rich lipoproteins (LA) and precipitable aggregates closely resembling fibrin (FA). Both LA and FA injected into a rat's tail vein were trapped in the lung and formed emboli in the pulmonary arterioles. To prevent the passage of these microaggregates into the systemic circulation, a new circuit was devised for plasma exchange containing a filter with a pore size of 0.2 microns. In 17 patients with fulminant hepatitis who received plasma exchange transfusions and subsequently died and were autopsied, the incidence of pulmonary complications was significantly lower in the 12 patients who received filtered FFP. According to these results, the possibility of pulmonary complications due to micro-embolism developed by microaggregates in FFP should be taken into account when a large amount of FFP is repeatedly infused into critically ill patients.

Regional anticoagulation: hemodialysis with hypertonic trisodium citrate

We have developed a simplified method for performing regional citrate anticoagulation during hemodialysis. High ultrafiltration rates and specialized equipment were obviated by the use of a 1.6-mol/L trisodium citrate solution and a standard calcium-containing dialysate. Thirty-six dialyses were performed with this technique on 14 stable and 22 high bleeding risk patients. There was no significant decline in plasma-ionized calcium during citrate dialysis, ie, 3.85 +/- 0.34 mg/dL (mean +/- SE) predialysis, to 3.31 +/- 0.26 postdialysis; furthermore, no patient developed neuromuscular symptoms or evidence of cardiovascular instability from hypocalcemia. Serum sodium rose with this procedure, but not to hypernatremic levels. This method of citrate dialysis is safe and effective during continuous blood flow (double-needle) hemodialysis, and is no more difficult to perform than conventional heparin dialysis. Single-needle (reciprocating blood flow) hemodialysis was successfully performed by the additional use of a calcium-free dialysate and separate calcium chloride infusion (10% calcium chloride), but risks the production of unexpected hypercalcemia.