Plateletpheresis in the Era of Automation: Optimizing Donor Safety and Product Quality Using Modern Apheresis Instruments

Abstract

The increases in major surgeries, transplantations and speciality clinics have significantly increased the utilization of platelet concentrates including single donor platelets (SDP). The advantages of SDP or apheresis platelet have been discussed elaborately by previous authors as compared to random donor platelets. Here we share our experiences of plateletpheresis procedures using the modern apheresis machines with regards to product quality and donor safety. This study included 3016 procedures of plateletpheresis (1397 on Amicus and 1619 on Trima accel cell separators) on eligible donors using recommended apheresis kits. A target yield of 3 × 10¹¹ was set as the end point of each procedure. Donor details, procedure details and donor adverse reactions if any were documented. Statistical analysis was done using the SPSS statistical package (version 13, USA). Of the total 6276 donors screened 2049 (32.6%) were deferred due to various reasons. Out of remaining 4227 eligible donors; 3016 (71.4%) underwent plateletphereis procedures based on the requirement of SDP by the patients. Mean pre-procedure platelet count and hematocrit in donors were 188.3 × 10⁶/mL and 41.7% respectively. Mean procedure time in Amicus (76.6 min) was significantly more than the Trima accel (64.3 min) (p = 0.02). Platelet yield by Trima accel and Amicus was 2.96 × 10¹¹ and 3.08 × 10¹¹ respectively (p = 0.061). A total of 40 donors (1.33%) suffered adverse effect during or after apheresis procedures. While the modern plateletpheresis devices are both donor and user friendly at the same time they provide quality product consistently in lesser time.

Introduction

The advantages of apheresis platelet or single donor platelet (SDP) have been discussed by previous authors extensively. With the increase of specialty clinics like oncology, clinical hematology, critical care medicine, hepatology and transplants the use of platelet concentrates have increased in the recent past [1, 2]. Unlike platelet concentrates prepared from whole blood also known as random donor platelets (RDP), SDPs are associated with lower transfusion transmitted infections, alloimmunization, platelet refractoriness and other transfusion related adverse events [3, 4]. There has been an increasing trend towards the use of SDP to support thrombocytopenic patients. Collection of SDP by apheresis procedure also known as plateletpheresis is usually safe without serious complications to the donors [5, 6].

Various types of apheresis machines are now available commercially working on the principle of centrifugation. All these machines were studied elaborately and found to be user friendly, donor friendly thereby providing optimized platelet quality [7, 8].

Ours being a tertiary care hospital with active specialty clinics we have facility of plateletpheresis program. Here we share our experience of plateletpheresis or collections of SDP using latest apheresis machines and discuss our observation on donor safety and platelet quality with regards to platelet yield and leukodepletion.

Materials and Methods

This retrospective study included 3016 procedures of plateletpheresis from January 2013 to June 2019. All procedures were performed on eligible donors taking informed consent as per laws enacted in the Drugs and Cosmetic Acts (DCA), India [9]. All procedures were performed by the same apheresis team.

Donor Selection

Following registration all donors were screened for age, weight, blood group, medical history, drug history, vein status and other selection criteria mandated by the DCA. For donors who qualified in the initial screening test, whole blood samples were collected for mandatory laboratory screening as per national guidelines for plateletpheresis.

Donor Sampling

Whole blood (WB) samples in EDTA and clotted vials were collected before plateletpheresis procedure. Hematological parameters such as platelets (PLT), hemoglobin (Hb), hematocrit (Hct), WBC count were measured using a calibrated automated cell counter (iCount 3CP, IRIS Healthcare Technologies Private Limited, India). Blood group and antibody screening were confirmed followed by testing for infectious markers like anti-HIV 1 & 2, anti-HCV, HBsAg, syphilis and malaria. Anti-HIV 1 & 2, anti-HCV and HBsAg test were performed by the automated VITROS ECiQ immunodiagnostic system based on enhanced chemiluminescence technology (Ortho Clinical Diagnostics, UK). Treponema pallidum antibodies for syphilis were done by rapid qualitative, immunochromatography method (Medsource Ozone Biomedicals Pvt. Ltd. Haryana, India). Malaria antigens for Plasmodium falciparum and Plasmodium vivax were tested by rapid qualitative, chromatographic immunoassay (MicroGene Diagnostic Systems (P) Ltd, Thane, India).

Procedure and Donor Safety

Only those donors who were qualified in the screening test were selected for plateletpheresis procedure. All plateletpheresis procedures were performed following manufacturer’s instructions and departmental standard operating procedure (SOP) using recommended apheresis kits. The end point of each procedure was based on the target yield of 3 × 10¹¹ platelets per unit. Donor details like name, registration number, blood group, age, gender, weight, hematological values and plateletpheresis procedure details, such as kit details, total blood volume processed, anticoagulant (acid-citrate-dexrose -A, ACD-A) volume used, procedure time, blood flow rate and collection efficiency of machines (PLT yield/Total PLT processed × 100) were recorded for each procedure in the procedure register [2, 8]. All donors were administered prophylactic oral calcium (1000 mg) and they were explained the details of procedure before starting it [10]. They were advised to report discomfort if any to the apheresis team during or after the procedure. They were asked to take adequate rest after the procedure and leave the aphresis centre after obtaining permission from the apheresis team. Donor adverse reactions if any were managed appropriately and documented following departmental SOP. Vasovagal adverse reactions were classified into three categories of severity: Mild grade (grade I) for presyncopal vasovagal reactions such as pallor, sweating, anxiety; moderate grade (grade II) for hypotension, vomiting, and transient loss of consciousness; and severe grade (grade III) for loss of consciousness associated with other signs and symptoms such as recurrent vomiting, prolonged pulse and/or blood pressure recovery times, incontinence and convulsions [11, 12].

The numbers of plateletpheresis procedures performed on each machine are as follows:

1. Amicus cell separator, (version 3.21, Fresenius Kabi AG, Bad Homburg, Germany): 1397.

2. Trima accel cell separator (version 5.1, Terumo BCT, Lakewood, USA): n = 1619.

Quality Control of SDP

Approximately 1 mL sample from each bag was collected in EDTA vial after thoroughly stripping the segment to ensure a representative product of the bag. All samples were mixed thoroughly and subjected to measurements of quality parameters such as volume, pH, Hct, PLT, RBC and WBC counts [13–16]. The pH of all platelet units were measured by a calibrated portable pH meter (EUTECH instruments, Thermo Fisher Scientific, Singapore) following manufacturer’s instruction. Residual WBC content of the bag was measured by Nageotte chamber hemocytometer counts [17]. Swirling in platelet units was assessed visually and documented as ‘present’ or ‘absent’.

Statistical Analysis

Statistical analysis was done using the SPSS statistical package (version 13, USA). All results were calculated as mean ± SD and a ‘p’ value of < 0.05 was considered statistically significant. Mean values were compared using the unpaired or paired Student’s t test as appropriate.

Results

Of the total 6276 donors screened during the study period 2049 (32.6%) were deferred due to various reasons. The primary causes of overall deferral were poor venous access (32.2%), low hemoglobin (29.6%) and low platelet count (26.9%). Where out of 606 donors with low hemoglobin 521 (85.9%) were females; 368 (55.8%) donors among 659 deferred due to poor venous access were females. Table 1 describes the overall demographic and hematological parameters of the donors who underwent plateletpheresis irrespective of the cell separators. The median age of donors was 34 years with a male to female ratio of 17: 1. Mean pre-procedure platelet count and hematocrit were 188.3 × 10⁶/mL and 41.7% respectively. Mean anticoagulant use in Trima accel and Amicus was 309.3 mL and 319.4 mL respectively with no statistical significance (p = 0.08) (Table 2). Mean procedure time in Amicus (79.6 min) was significantly more than the Trima accel (64.3 min) (p = 0.02). Mean collection efficiency of both cell separators was comparable.

Table 1.

Donor demographic and hematological parameters (n = 3016)

Donor parameters	Values
Age in years (range)	34 (19–54)
Gender (M: F)	17: 1
Weight (kg)	63.7 ± 9.23
Height (m)	1.61 ± 3.1
Body surface ares (BSA) (m2)	1.66 ± 1.9
Total blood volume (TBV) (mL)	M:4497 ± 451, F:3773 ± 399
Platelet count (× 106/mL)	188.3 ± 36.2
Leukocyte count (× 106/mL)	7.5 ± 0.7
Hemoglobin (Hb) (gm/dL)	14.7 ± 1.1
Hematocrit (Hct) (%)	41.7 ± 2.9

All demographic parameters expressed as median ± SD

All hematological values expressed as mean ± SD

Table 2.

Details of plateletpheresis procedures (n = 3016)

Parameters	Trima accel (n = 1619)	Amicus (n = 1397)
Vein access	Single	Single
Anticoagulant (ACD) (mL)	309.3 ± 57.7	319.4 ± 65.8
Draw rate (mean) (mL/min)	Moderate (≤ 120)a	80(mean)
Return rate (mean) (mL/min)	≤ 302a	80 (mean)
Mean Procedure time (min)	64.3 ± 13.3	79.6 ± 12.9*
Whole blood processed (mL)	2662.3 ± 671.6	2771.2 ± 634.9
Mean collection efficiency (%)	67.3 ± 5.5	66.1 ± 4.6

All values expressed as mean ± SD

*Significant compared with Trima accel

^aAutomatic machine program. Draw and return flow based on donor total blood volume (TBV) and needle blood flow

Quality of platelet product obtained from both machines was comparable with parameter values within recommended range (Table 3). The mean volume of product processed by Trima accel was 217.4 mL and Amicus was 223.8 mL. Platelet yield by Trima accel and Amicus was 2.96 × 10¹¹ (range: 2.72 – 3.15) and 3.08 × 10¹¹ (range: 2.87–3.31) respectively (p = 0.061). A total of 31(2.2%) and 42 (2.6%) SDP collected by Amicus and Trima accel respectively could not met the target yield of ≥ 3 × 10¹¹ platelets per unit as described in the Indian national standards [13]. However 97.6% of the product could achieve the target platelet yield against the recommended ≥ 75% published by the national authority [13]. Quality parameters of SDP obtained in the present study were compared with the national and international standards (Table 3). Plateletpheresis associated citrate toxicity was higher with the Amicus (11 vs. 9) and vasovagal side effects was observed more with Trima accel (7 vs. 4). A total of 40 donors (1.33%) suffered adverse effect during or after apheresis procedures (Table 4).

Table 3.

Quality control of products obtained from the apheresis systems (n = 3016)

Parameters	Trima accel (n = 1619)	Amicus (n = 1397)	DCA [13]	NABH [16]	AABB [14]	Council of Europe [15]
Volume (mL)	217.4 ± 17.1	223.8 ± 11.7	NA	>200	~200	>40 mL per 60 × 109
pH	7.08 ± 0. 37	7.01 ± 0.21	≥6	>6	≥6.2	≥6.4
Yield(× 1011)	2.96 ± 0.8	3.08 ± 1.4	≥3	≥3	≥3	≥2
WBC (× 106)	1.3 ± 0.51	1.6 ± 0.43	NA	NA	< 5	< 1
RBC (mL/unit)	0.69 ± 0.39	0.73 ± 0.47	NA	Traces to 5 ml	Traces to 0.5 ml	NA
Hct (%)	0.4 ± 0.43	0.3 ± 0.51	NA	NA	1	0.8
Recommended target met requirement of tested units (%)	≥97.4	≥97.8	≥75	≥75	≥90	≥90

All values expressed as mean ± SD

Table 4.

Donor adverse events in plateletpheresis (n = 3016)

Adverse events	Trima accel (n = 1619)	Amicus (n = 1397)	Total n (%)
Citrate toxicity	9	11	20
Hematoma	5	4	9
Vasovagal	7	4	11
Mild (Grade I)	6	4	10
Moderate (Grade II)	1	0	1
Severe (Grade III)	0	0	0
Total n (%)	21 (1.29)	19 (1.36)	40 (1.33%)

Discussion

The last few decades have observed increased demand and utilization of SDP in view of its quality and efficacy in clinical practice [8, 18, 19]. Today plateletpheresis is a common procedure performed in many blood centers including the developing nations. Donor deferral was a concern in the present study. Male donors were predominant as females were mostly deferred due to low hemoglobin and poor venous access. Low hemoglobin and poor venous access were observed in 47.7% and 33.7% of the total 1092 female donors deferred. Out of 3016 plateletpheresis procedures only 167 (5.5%) were females. Where the present study observed a donor deferral of 32.6%, the values were 28.03% and 25.4% respectively in studies performed by Arora et al. and Tondon et al. [18, 20]. Low platelet count (50.75%) was the major cause of deferral observed by Arora et al. [18]. The current study found low platelets (< 150 × 10⁶/mL) in 551 donors (26.9%). Low platelet count in normal donor population is a concern and affects the SDP donor registry. Das et al. observed low platelet count among the blood donor population in Eastern India and commented on poor platelet yield in random donor platelets [21]. A low normal pre-apheresis platelet count was observed in the SDP donor population. Of the total 3016 plateletpheresis procedures performed using both the machines 1710 donors (56.7%) had platelet count of ≤ 200 × 10⁶/mL. Such observations were also reported by previous authors [22–24]. Where deferral due to low hemoglobin was observed in 20.89% by Arora et al. with concurrent results by others authors, the present study found 29.6% of donor deferral due to low hemoglobin [8, 18, 20]. This high deferral due to low hemoglobin may be due to more female donors registering for SDP screening. A total of 1469 females were screened in the current study.

Both machines used in the present study consistently provided optimized platelet products irrespective of their variations in inherent working programs. Mean procedure time was significantly higher in Amicus (79.6 min) than Trima (64.3 min) (p = 0.02). As procedure time directly concerns the apheresis donors therefore it is an important parameter to evaluate the safety and comfort of healthy donors. While Bueno et al. observed a mean procedure time of 55.8 min by Trima, this was 78 min by Amicus as shown by Burgstaler et al. [25, 26]. Both machines exhibited comparable collection efficiency and ACD utilization. Though significant CE variation was not observed in the present study (67.3% vs. 66.1%) but CE is said to be greatly affected by platelet yield and post-procedure platelet which in turn depend on the donor population [27, 28].

The mean volume of final product was higher in the Amicus compared Trima accel but the difference was not significant. (p = 0.11). Mean yield of platelets in the final product, which is the most important quality parameter, was found to be comparable in both the machines (p = 0.061) (Table 3) with red cell contamination much below the allowable limits [8, 16, 29, 30]. According to the American Association of Blood Banks (AABB), 90% of SDP must contain ≥ 3 × 10¹¹ platelets per unit while the Council of Europe, recommends platelet count ≥ 2 × 10¹¹ per unit [14, 15]. These levels have been determined to provide desired haemostatic platelet doses to the recipient. In the present study 97.6% of the platelet product could achieve the target platelet yield of ≥ 3 × 10¹¹ against the recommended ≥ 75% or ≥ 90% published by national and international authorities respectively [13–16]. Adequate dose of platelets reduces the transfusion frequency and consequently less number of donor exposures and cost of treatment. The new generation apheresis machines have been found to provide leukodepleted products consistently [31, 32]. In the present study the mean residual leukocyte content was observed to be 1.3 × 10⁶ and 1.6 × 10⁶ per SDP unit by Trima accel and Amicus respectively and all products complied with the AABB criteria of < 5 × 10⁶ leukocytes per unit [14].

Authors in the past investigated that older version cell separators like CS 3000 and Hemonetics MCS 3p could met the target yield of 3 × 10¹¹ PLT per unit in 40% products only [33]. Others have concluded that the older machines failed providing leukodepleted SDP and new generation cell separators are capable of giving an optimized SDP unit in terms of platelet yield, red cell contamination and leukodepletion. They also commented that technological developments in cell separators have resulted in cleaner separation between platelets and white cells, thus reducing cross contamination [8, 34, 35].

Plateletpheresis is a safe procedure without significant complications but at times symptoms due to citrate toxicity and other adverse events may cause discomfort to the donors. Early recognition of adverse events related to plateletpheresis and thereby preventing their occurrences is important to encourage donor retention [36]. Donor adverse events like citrate toxicity, hematoma and vasovagal reactions were observed in 40 donors (1.33%) and were comparable in both the machines. Despite administering prophylactic oral calcium (1000 mg) as suggested by previous authors citrate toxicity was found in 20 out of the 40 affected donors in the present study [10, 37]. It was observed that 20% of procedures performed with prophylactic calcium were associated with symptoms, most of which were mild [38]. The various reasons for these symptoms may include (a) donors who undergo the procedure repeatedly or for prolonged periods are susceptible to an accumulation of excess citrate leading to inappropriate metabolism by the body [39]. (b) Hypocalcaemia like symptoms may be caused by hypomagnesaemia and calcium supplementation becomes unfruitful [40, 41], (c) apheresis procedures in donors with low normal platelet count take more time to achieve the target yield and result in higher infusion of ACD [42], (d) symptoms may be due to suboptimal dose of prophylactic oral calcium because it has been observed that administration of 2000 mg of calcium carbonate was associated with a statistically significant reduction in the severity of paresthesia [38, 43], (e) we also predict that calcium dose and its time of administration play role in counter acting the effect of citrate metabolism. Philip et al. observed 61% of the affected donors complaining of vascular injury followed by citrate related reactions in 35.3% [10]. In contrast the current study witnessed more citrate related reactions than vasovagal reactions or vascular injury. Majority of vascular injury can be prevented by good vein selection and skilled phlebotomist. Seldom donor inattentiveness, excessive arm movement or high return rate in a case of thin vein may cause vascular injury. In a multi-centric study by McLeod et al. 2.18% of plateletpheresis donors suffered acute adverse reaction where most of the reactions were associated with the Haemonetics machine [44].

Conclusion

We conclude that plateletpheresis using new generation automated cell separators have significantly optimized quality of SDP in terms of platelet yield, leukodepletion and red cell contamination in comparison to their older versions. Moreover an increase in collection efficiency, lesser whole blood processing, reduced procedure time and low utilization of anticoagulants greatly enhanced donor safety thereby ensuring donor retention, bigger voluntary donor pool and repeat donations. Further to prevent citrate related toxicity and recommendation by previous workers; apheresis centres may administer prophylactic oral calcium to donors in a dose of 1000–2000 mg at least 30 min prior to the procedure.