|Year : 2022 | Volume
| Issue : 1 | Page : 36-41
Assessment of hemoglobin content of packed red cells: A prospective study on hemoglobin content variation due to donor, collection, and processing-related factors. Is it time to label each unit with hemoglobin content?
Romesh Jain, Suchet Sachdev, Neelam Marwaha, Anubhav Gupta
Department of Transfusion Medicine, Postgraduate Institute of Medical Education & Research, Chandigarh, India
|Date of Submission||01-Jun-2021|
|Date of Decision||27-Oct-2021|
|Date of Acceptance||07-Feb-2022|
|Date of Web Publication||29-Apr-2022|
Dr. Suchet Sachdev
Department of Transfusion Medicine, Postgraduate Institute of Medical Education & Research, Chandigarh
Source of Support: None, Conflict of Interest: None
Background and Objectives: Red blood cell (RBC) transfusion continues to be administered on the basis of conventional wisdom and the notion of an average benefit per unit. The present study was aimed at estimating the hemoglobin (Hb) content in packed red blood cell (PRBC) units in three types of blood donors: Replacement blood donor (RD), First time voluntary blood donors (FTVD), and Regular/Repeat voluntary blood donors (RTVD). Methods: A total of 900 blood donors were divided equally into three groups of blood donors. Within each group, 100 collections were done in Double 350 ml, Triple 450 ml and quadruple 450 ml blood bags, respectively. The Hb concentration of the PRBC unit was done after the collection of representative samples from the PRBC unit. The volume of the PRBC unit was estimated by the formula: Weight of PRBC divided by its specific gravity. The net Hb content in the PRBC unit was calculated by the formula: Hb of PRBC multiply by its volume. Results: Net Hb content of 900 PRBC units were in the range of 30.77–87.36 g; mean was 52.91 ± 9.99 g. Net Hb content of PRBC bag was lower in PRBC prepared from RD as compared to FTVD and RTVD. We observed a range of net Hb content in the PRBC units and Hb content strongly correlated with the volume of PRBC. Conclusion: The present study shows that there is a range of Hb content of PRBC units. Adopting a policy of optimizing the dosage of RBC transfusion could have the potential to significantly improve RBC use and decrease patient exposure to allogeneic blood.
Keywords: Blood components, blood donor's hemoglobin, blood transfusion policy, hemoglobin estimation, standardized units of red blood cell, target hemoglobin
|How to cite this article:|
Jain R, Sachdev S, Marwaha N, Gupta A. Assessment of hemoglobin content of packed red cells: A prospective study on hemoglobin content variation due to donor, collection, and processing-related factors. Is it time to label each unit with hemoglobin content?. Glob J Transfus Med 2022;7:36-41
|How to cite this URL:|
Jain R, Sachdev S, Marwaha N, Gupta A. Assessment of hemoglobin content of packed red cells: A prospective study on hemoglobin content variation due to donor, collection, and processing-related factors. Is it time to label each unit with hemoglobin content?. Glob J Transfus Med [serial online] 2022 [cited 2022 May 20];7:36-41. Available from: https://www.gjtmonline.com/text.asp?2022/7/1/36/344335
| Introduction|| |
In India blood and blood components are categorized as “drug,” as per the Drugs and Cosmetics Act, 1940 and the Drugs and Cosmetics Rules, 1945. As per the act blood and blood components have to be labeled with the following specifications (a) date of collection and expiry (b) ABO and Rh grouping (c) free from the infectious marker (d) License number of blood bank (f) volume of the product. However, the actual content of the hemoglobin (Hb) is not required to be noted on the whole blood/packed red blood cell (PRBC) unit, nor the platelet count in the platelet concentrate. This is in contrast to other drugs where composition and “salt content” administered is known to the last milligram. However, red blood cell (RBC) units are still routinely prepared and transfused with no more than a guess as to their Hb content.
RBC transfusions are given as “number of units” without knowing the Hb content of these units. It is commonly said that transfusion of 1 unit to a nonbleeding euvolemic adult will increase Hb concentration by approximately 1 g per dl and the hematocrit (Hct) by 3%. Great variations exist with respect to Hb in individual units. These variations are due to differences in donor's predonation Hb, type of blood bag used (350/450 ml, presence/absence of additive solutions), and blood volume collected. Most blood centers consider 12.5 g/dL as the lower limit and up to 18 g/dL as the upper limit for the predonation Hb in blood donors.,, Theoretically, predonation Hb may vary up to 44% (12.5–18 g/dL) among blood donors. This difference will be reflected in the final Hb content of each unit. In India350 ml and 450 ml of whole blood is collected according to the weight of the blood donor. Considering 12.5 g/dL as the lower limit and 18 g/dL as the upper limit of donor's Hb, the net Hb content of the blood unit will range 43.75–81.00 g per unit. In India PRBC quality control criteria are based on volume and Hct and only 1% are needed to be tested and out of this 75% are needed to satisfy the quality control criteria.
There is limited literature on this subject and only one published study from India, which had shown a variation of nearly 100% in total Hb content among PRBC units. Recently, Shih et al. compared whole blood collection, processing, and storage-related parameters but the effect of first time or repeat donation and type of donation whether replacement or voluntary on the Hb content of the blood unit is still not known.
Aims and objectives
We planned this study with an aim to compare the Hb content of PRBC units in different types of blood donors and factors affecting the Hb content of PRBC.
| Materials and Methods|| |
This study was conducted in the Transfusion Medicine Department of a tertiary care hospital in North India after getting ethical approval from the institute ethics committee and written informed consent by blood donors.
This was a cross-sectional pilot study, conducted on blood donors to compare the Hb content of PRBC prepared by three different protocols in replacement blood donors (RD), first-time voluntary blood donors (FTVDs), and regular/repeat voluntary blood donors (RTVD). In the present study, we enrolled 900 prospective blood donors which were divided equally into three groups, i.e., 300 donors in each group. One hundred units each were collected in double bags (D350, 350 ml), triple bags (T450, 450 ml), quadruple bags (Q450, 450 ml) in each of the three groups, respectively. Voluntary blood donor, first-time voluntary blood donor, regular voluntary blood donor/repeat voluntary donor, replacement blood donor were defined as per the definition given by National AIDS Control Organisation, India.
Exclusions and inclusions
The donors were selected on the basis of donor selection criteria as per the Drugs and Cosmetics Act, Government of India. The donors' predonation Hb was determined by the CuSO4 method using the finger-prick blood and subsequently confirmed through a predonation sample collected from the sample collection pouch and analyzed by an automated blood cell counter (ORION 60, Ocean Medical Technologies, New Delhi, India). The lower and upper cut-offs for predonation Hb were 12.5 and 18 g/dl, respectively, in both sexes. The lower and upper age limits for the donors were 18–65 years, respectively. All-female donors and male donors weighing less than 60 Kg and more than 45 Kg donated 350 ml, while male donors weighing more than 60 Kg donated 450 ml of whole blood. Donors were categorized as body weight <60 Kg versus ≥60 Kg. Donors who had diploma, Graduate and Post Graduate were included in college-level education and rest of the others were categorized as below college-level education.
All 450 ml donations were collected into quadruple SAGM (additive solution) bag (Macopharma) and triple bag without additive solution (Terumo penpol Ltd., Trivandrum, India). All 350 ml donations were collected into double blood bags without additive solution (Terumo penpol Ltd., Trivandrum, India). All double (350 ml) and triple PRBC (450 ml) units were, nonleucodepleted and without RBC additive solution. All quadruple bags PRBC (450 ml) with the additive solution were Buffy coat removed (manual) without the filter. During whole blood collection, up to ± 10% variation in the volume of whole blood is acceptable in accordance with the Drugs and Cosmetics Act, Government of India. In addition, as per the standard policy of the department, bags with 10%–30% variation (lower volume collection) in whole blood volume were converted into blood components, however, only PRBC was taken in inventory as per the American Association of Blood Banks. Hence, for 450 ml blood bag 300–404 ml and for 350 ml blood bag 250–315 ml blood collection was considered low collection volume, and only PRBC was taken in inventory from such blood bags at our center.
Hemoglobin content of packed red cell units
Collection of representative samples from the packed red blood cell unit
After three times stripping, one ml Ethylenediaminetetraacetic acid sample was drawn from the PRBC unit for analysis in hematology analyzer.
Volume estimation of packed red blood cell unit
The weight of the empty PRBC unit bag was measured. The weight of the filled PRBC unit was measured after the separation of PRBC.
- Weight of PRBC = weight of filled PRBC unit bag–weight of empty PRBC unit bag
- Volume of PRBC = weight of PRBC/specific gravity of PRBC (1.094).
Measurement of blood loss due to buffy coat removal
The weight of the empty Buffy coat bag was measured. After buffy coat removal, the weight of the filled buffy coat bag was measured.
- To calculate the volume of blood (blood loss)
=weight of blood in buffy coat bag/specific gravity of whole blood (1.053).
Measurement of net hemoglobin content in the unit
Hb content in unit = Hb value of the PRBC unit (g/dL) × volume of PRBC unit (ml)/100.
Collected data were entered in the MS Excel spreadsheet, coded appropriately, and later cleaned for any possible errors in SPSS (Statistical Package for the Social Studies) for Windows version 22 (IBM, Chicago, USA) and online GraphPad software (Prism 5 for Windows) version 5.01 (San Diego, CA, USA).
Pearson's Chi-square test was used to evaluate differences between groups for categorized variables. Normally distributed data are presented as means and standard deviation, or 95% confidence intervals (CI). Kolmogorov–Smirnov test (KS) was used to check for normality of data. Unpaired and paired Student's t-test for independent samples was used for comparisons between quantitative data. Repeated measures analysis of variance (ANOVA) (Tuckeys) was used for before-after comparison of more than two groups. Binary logistic regression analysis (stepwise method) was used to evaluate the independent associations of various factors. All tests were performed at a 5% level significance; thus, an association was statistically significant if the value was <0.05.
| Results|| |
The donors' demographics, education, and hemoglobin levels
In the present study, out of 900 whole blood donors, 882 (98%) were male and 18 (2%) were female. The mean age of the donor irrespective of gender was 30.03 ± 9.77 years. Descriptive data of blood donors are mentioned in [Table 1].
The donors' Hb range was 12.5–18 g/dL; mean Hb was 14.63 ± 1.33 g/dL [Table 2]. The mean Hb of male donors was 14.66 ± 1.32 g/dL and the mean Hb of female donors was 13.25 ± 0.63 g/dL. This difference of 1.41 g/dL in the mean Hb of the two genders was statistically significant (P < 0.001).
|Table 2: Descriptive statistics of the tested packed red blood cell units (n=900)|
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The correlation of donor's Hb was analyzed with donor's age, weight, diet, and education. In the present study, mean Hb level decreased with increasing age of the blood donor (β = −0.68)(P = 0.041). There was no statistically significant correlation between donors' weight (P > 0.05), diet (vegetarian/nonvegetarian) (P > 0.05), donor education (P = 0.928), and donors' predonation Hb. Linear regression analysis was done to evaluate the independent effect and it shows that all three factors female gender, advanced age, and lower body weight, were independent and statistically significant (P < 0.05) predictors of a lower mean Hb in the donors however female gender was a stronger predictor (standardized coefficient, β = −0.155) of a lower Hb in the donors as compared to higher age (β = −0.051) or lower weight (β = −0.069).
Hemoglobin concentration, volume, hemoglobin loss (during buffy removal), and net hemoglobin content in the red cell units
Hb concentration testing of 900 PRBC units was done and Hb range of PRBC was 14.2–29.6 g/dl; mean Hb was 21.02 ± 2.90 g/dL [Table 2]. The volume range of PRBC was 155-370 ml; the mean volume was 253.82 ± 44.02 ml. Prospective testing of 300 buffy units was done and found that Hb loss during buffy removal was in the range of 0.79–10.20 g; mean loss of Hb was 3.34 ± 1.75 g. Net Hb content was calculated in 900 PRBC units and found that the Net Hb content range of PRBC was 30.77–87.36 g; mean was 52.91 ± 9.99 g [Table 2]. The maximum number of PRBCs (34.5%) was Hb content range of 50–60 g [Figure 1]. The mean Hb content of PRBC prepared from male donors was 53.20 ± 9.87 g. and from female donors was 38.67 ± 3.79. This difference of 14.53 g in the mean Hb content of the two genders was statistically significant (P = 0.001) [Figure 2]. Mean Hb content of PRBC unit was comparable between Q450 and T450 blood bags (P > 0.05) in all types of blood donors and it was significantly lower in D350 blood bags compared to Q450 and T450 bags (P = 0.001) [Figure 3].
|Figure 2: Box and whisker plot of hemoglobin content in red cell units derived from all Blood donors, male donors and female donors|
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|Figure 3: Box and whisker plot of hemoglobin content in red cell units derived from 350 ml double bag (D350), 450 ml triple bag without SAGM (T450), 450 ml quadruple bag with SAGMl eucodepleted (Q450)|
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Comparison of packed red blood cell parameters between different types of blood donors
PRBC unit mean volume was lower in RD as compared to units prepared from FTVD (P = 0.001) and RTVD (P = 0.014). However, it was similar between FTVD and RTVD (P = 0.733) [Table 3]. Hb loss (g) was similar in PRBC prepared from Q450 ml bags in all three-study group (P = 0.977), (P = 0.349), and (P = 0.465), respectively. Net Hb content was lower in PRBC prepared from RD as compared to FTVD (P = 0.001) and RTVD (P = 0.022). However, it was similar between FTVD and RTVD (P = 0.133) [Table 3]. When we applied ANOVA test for comparing three groups the difference in mean was found to be statistically significant for donor's Hb (P = 0.027), volume of PRBC (P = 0.0009), and net Hb content (P = 0.0001).
|Table 3: Donors' and mean packed red blood cell variables in three groups of blood donors (three categories of blood donors and three types of blood bags used)|
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Correlation of net hemoglobin content of packed red blood cell with various parameters
The net Hb content of all the 900 PRBC units was analyzed to see if there was any correlation with the donor and collection-related parameters. The correlation coefficient showed that the strongest association of net Hb content of the PRBC unit existed with the overall volume of PRBC (r = 0.730, P = 0.001). The correlation of net Hb with Hb concentration in the PRBC units and the donors' Hb was also significant, but the association was weaker, (r = 0.406) and (r = 0.351), respectively.
| Discussion|| |
Transfusion medicine has been in practice for many years. Still, RBC transfusions are given as “number of units” without knowing the Hb content of these units. This is in contrast to other drugs where composition and “salt content” administered is known to the last milligram. In 2000, Gorlin and Cable proposed that an “RBC unit” should be defined by its therapeutic equivalent of the RBC mass, which is better expressed in terms of total Hb content per unit. Current transfusion practice ignores the fact that net Hb content varies among the individual PRBC units. Net Hb content of unit depends on donors' predonation Hb, Hb concentration of PRBC, and volume of PRBC. These factors vary depending upon the different types of donors, different types of component separation methods, loss of Hb due to leukoreduction, and different types of blood bags used.
In 2000, Hog man and Knutson also advocated for the implementation of standardized units of RBC. In 2005, Davenport also advocated labeling of RBC units with their total Hb content. Knowledge of actual Hb content can be used to optimize RBC transfusion. In 2006, Hogman and Meryman defined the concept of the standard unit. They mentioned other than specifying the volume of blood; current standards do not mention the Hb content of an RBC unit after processing.
In the present study, most of the blood donors were males while females comprised only a small number. Similar proportion of gender was noted in other studies from the same region.,,, This low contribution of female donors might also be due to high deferral rates observed by Bahadur et al. in female blood donors (34.2%) as compared to men (1.2%) because of anemia.
The mean Hb was significantly higher in RD compared to RTVD and comparable between RTVD and FTVD. This may be due to strict screening of blood donors in accordance with Departmental SOP, accepting only fit donors and deferral of donors with low Hb. Furthermore, there are few studies which show that regular voluntary donors may have Hb values on the lower side of normal. In one such study by Dara et al. the mean Hb (g/dL) value of regular voluntary donors presenting for blood donation was 12.9 ± 1.3 (10.8–16.1 g/dL).
In our study, mean Hb of PRBC was 21.02 ± 2.90 g/dL. In the study by Agnihotri et al. mean Hb of the PRBC unit was 18.94 ± 2.04 g/dL. This lower mean Hb of PRBC in the study by Agnihotri et al. may be due to RBC additive solution blood bags used in the study. In our study, mean volume of PRBC was 253.82 ± 44.02 ml. The mean volume of PRBC in the study by Agnihotri et al. and Arslan et al. were 323.92 and 425 ml, respectively [Table 4].,
|Table 4: Summary of packed red blood cell parameters and type of blood bag in the present and previous studies|
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The final Hb (Net Hb) content of the PRBC unit is the most important parameter for the quality of the product. In our study, Net Hb content of the PRBC range was 30.77-87.36 g; the mean was 52.91 ± 9.99 g/unit. Mean Hb content of PRBC in the study by Agnihotri et al., Arslan et al., and Reikvam et al. were 61.3, 78, and 49.05 g, respectively [Table 4].,, Significant difference in Hb content and volume of PRBC in the different studies was because different types of blood bags (350/450 ml) (with or without RBC additive solution) (filter bags/Nonfilter bags) and different types of component separation methods (manual/automated) were used. In the present study, a significant difference in Hb content and volume of PRBC was due to our study design where 300 blood units were 350 ml collection and 600 blood units were 450 ml collection and the policy of inclusion of low volume PRBC in inventory is responsible for the high variation in volume and Hb content of PRBC. Use of both SAGM (RBC additive solution) and NonSAGM bags with manual component separation method were other reasons for variable Hb content and volume. In contrast to a study done by Agnihotri et al., exactly numbers of 350/450 ml bag was not mentioned. A study done by Arslan et al., all the units transfused were 500 ml whole blood generated RBCs and study done by Reikvam et al. they have not mentioned type of blood bag (350/450 ml) [Table 4]. Although there was a large variation with regard to the Hb content of PRBC, mostly PRBC could pass quality control criteria because our quality control criteria are based on volume and hematocrit and only 1% of packed red cells may be tested for quality control.
In our study, there was a wide range of Hb content with more than two times a difference in the higher and lower limit of Hb content of the unit. Now, we can consider the theoretical effect of this variable Hb content in PRBC units on patients. Formula for total Hb needed to achieve target Hb (g) = (Targeted Hb–Actual Hb) g/dl × TBV
When given to 70Kg, nonbleeding, euvolemic, adult, male patient, a PRBC unit containing 30.77 g Hb would be expected to increase his Hb by 0.627 g/dL. Another PRBC unit with Hb content 87.36 g, given to a clinical similar 60 Kg female patient, would raise her Hb by 2.24 g/dL. Thus, an assumption of 1 g/dl increase in the recipient Hb per PRBC unit transfused could be an under-estimate or an over-estimate. Previous studies highlight the clinical benefits of quantifying the net Hb content of PRBC units.,,
| Conclusion|| |
We conclude that there is a wide range of Hb content of PRBC units and we studied the factors causing this variability. Characteristics such as age, gender affect the donors' predonation Hb. We also showed that characteristics such as donors' predonation Hb, Hb concentration of PRBC unit, Hb loss due to buffy removal, and PRBC volume are the main causes of the variable Hb content of PRBC units. The main limitation of our study was clinical benefits of Hb content-based transfusion policy was not done. Another limitation was Cell Counter linearity, which could be lost at high Hb concentration. In our study, we explained the importance of the Hb content of the PRBC unit which decides recipients' posttransfusion Hb increment. Hence, we recommend to label the RBC unit with Hb content. Labeling Hb content of the PRBC unit help in better inventory management for patients and may help in decision making for the release of units for pediatric/low weight versus adults/higher-weight patients. This would help further in the clinical transfusion practices based on evidence.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]