Elsevier

Clinical Biochemistry

Prevention of hemolysis in blood samples collected from intravenous catheters

Abstract

Objectives

Samples drawn through intravenous catheters are frequently hemolyzed. We planned a prospective, randomized study to establish whether hemolysis in samples drawn from intravenous catheters may be reduced using S-Monovette® tubes collected by manual aspiration as compared with standard vacuum tubes.

Design and Methods

We studied 52 consecutive patients admitted to the ED. Blood was drawn through a 20-gauge intravenous catheter. A 5.0   mL, Becton Dickinson Vacutainer® SST II Plus serum tube was collected and discarded. In the odd group of patients (i.e., n. 1, 3, 5, etc.), a second SST II tube was drawn with vacuum ("BD-V"), followed by a 5.5 mL S-Monovette® serum tube collected with manual aspiration ("SD-A") and an identical S-Monovette collected by vacuum ("SD-V"). In the pair group of patients (i.e., n. 2, 4, 6, etc.), the sequence was modified to "SD-A", "SD-V" and "BD-V". Serum was separated and tested for lactate dehydrogenase (LDH), potassium and cell-free hemoglobin.

Results

The mean concentration of potassium (+   2.7% in BD-V and +   1.7% in SD-V, respectively), LDH (+   15% in BD-V and +   7% in SD-V, respectively) and cell-free hemoglobin was significantly increased when samples were collected with vacuum tubes as compared with manual aspiration. No significant differences were observed between SD-V and BD-V. The frequency of hemolyzed samples was higher when blood was collected with the vacuum as compared with SD-A (i.e., 2%), but did not differ between BD-V and SD-V (i.e., 29 versus 31%; p   =   0.70).

Conclusion

S-Monovette can be used with vacuum or aspiration collection. This latter approach allows blood drawing with limited shear stress and less likelihood of generating spuriously hemolysis.

Highlights

► Samples drawn through intravenous catheters are frequently hemolyzed. ► Hemolysis was higher in vacuum tubes than in S-Monovette collected in manual mode. ► S-Monovette can be used with vacuum or aspiration collection ► This approach allows limited shear stress and less likelihood of spurious hemolysis

Introduction

Laboratory diagnostics is an essential part of the clinical decision making, provided that a high degree of quality is established throughout the total testing process [1]. Several lines of evidence attest that the manually intensive activities of the preanalytical phase are more prone to uncertainties and errors than those belonging to the analytical and post-analytical phases [2], [3]. This inherent vulnerability is mostly attributable to inappropriate, incorrect or mishandled procedures used for obtaining blood specimens. Among the various preanalytical problems, spurious hemolysis largely prevails in terms of prevalence, especially in samples referred from specific hospital wards such as the emergency department (ED), where their frequency can be as high as 10 to 30% of all blood samples being referred to the central laboratory for diagnostic testing [4], [5], [6]. Although artifactual (in vitro) hemolysis recognizes several patient- and operator-dependent causes that have been comprehensively reviewed elsewhere [7], several lines of evidence consistently attest that collection of blood tubes using intravenous catheters may be associated with a high likelihood to generate erythrocyte injury [6], [8], [9], [10]. Nevertheless, the use of intravenous catheters is almost unavoidable in the ED and other short stay or procedural units, wherein nurses frequently draw the blood from newly established intravenous lines because this practice is faster and more convenient than searching for another venipuncture site. In a recent critical review of the literature, Halm and Gleaves reported that spurious hemolysis occurs in 3.3 to 77% of blood samples obtained through intravenous catheters, whereas the frequency is nearly 20 times lower when blood specimens are drawn by direct venipuncture [9]. Even more interestingly, artifactual hemolysis can be as high as 77% when intravenous catheters and vacuum tubes are combined, while the use of syringe draw is effective to decrease the rate of hemolyzed specimens by nearly half [9]. Regardless of the specific cause, the generation of catheter-related hemolysis generates a variety of clinical, organizational and economical issues, which are mainly attributable to specimen rejection and/or recollection, suppression of those tests most sensitive to artifactual hemolysis, delayed diagnosis and overcrowding due to increasing length of stay of patients in ED, as well as frequent inquiring between the ED and laboratory personnel [10].

The collection of blood through a syringe and subsequent transferral of blood into primary blood collection tubes [6], as well as the use of low volume vacuum tubes [11], [12] have both been proposed as potential approaches to prevent catheter-related hemolysis. However, neither solution appears suitable to completely prevent hemolysis. The use of primary tubes adapted for drawing blood from intravenous line would hence represent a breakthrough for decreasing the rate of hemolyzed samples and lowering healthcare costs and patient discomfort. A prospective, randomized study was thereby planned to establish whether spurious hemolysis in samples collected in the ED from intravenous catheters may be reduced using the S-Monovette® serum tubes collected by manual aspiration as compared with the use of standard vacuum serum tubes.

Section snippets

Materials and Methods

This investigation was settled in a large urban ED, averaging ~   90,000 visits per year. The study population consisted in all consecutive patients admitted to the ED from 8:00   AM to 2:00   PM of a single working day, who required blood collection for diagnostics purposes, including assessment of potassium and lactate dehydrogenase (LDH). According to our experimental design, blood was drawn by the nurse in duty at the ED through a 1.0   ×   3.2   mm, 20-gauge catheter (Neo DELTA VEN, Viadana, MN, Italy; ref.

Results

The final study population consisted in 52 consecutive patients (21 males and 31 females; mean age 69   ±   3   years, 95% CI from 63 to 75   years). The reasons for ED admission were as follows: dyspnea (n. 12), abdominal pain (n. 11), syncope (n. 5), arrhythmias (n. 4), renal or biliary colic (n. 3), chest pain (n. 3), cerebrovascular disease (n. 3), low back pain (n. 2), vertigo (n. 2), epilepsy (n. 1), hypertensive crisis (n. 1), trauma (n. 1), epistaxis (n. 1), diabetes (n. 1), drug poisoning (n. 1)

Discussion

Blood collection is the most vulnerable step throughout the testing process [16]. Although sample collection via venipuncture rather than through intravenous catheters should be considered as a standard of care throughout the healthcare [17], the latter procedure is virtually unavoidable in procedural or short-stay units such as the ED or the cardiac intensive care unit. Several explanations have been offered to support the hemolytic propensity of intravenous catheters, including the presence

Author Contributions

All authors confirmed that they have contributed to the intellectual content of this paper and have met the following 3 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; and (c) final approval of the published article.

Acknowledgments

The authors acknowledge the nurses Catia Caleffi, Caterina Colombo and Davide Caputo for the skill assistance during blood collection in the emergency department.

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    Lippi et al. also investigated the frequency of in vitro hemolysis in samples obtained via intravenous catheters by manual aspiration compared to standard vacuum tubes [23]. The mean levels of K, LDH and free Hb were significantly lower when the sample was aspirated manually as compared to the vacuum technique [23]. A subsequent study demonstrated that the introduction of Sarstedt S-monovette® blood tubes reduced the rate of hemolysis in the emergency department (ED) compared to the previously used BD Vacutainer® SST II Plus plastic serum tubes [24].

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    Evidence also recommends the use of primary tubes adapted for drawing blood from IV lines,13 whereby the use of an access device with the vacuum tubes enables direct collection into blood tube from the intravenous catheter.14 The use of a syringe to draw blood is not recommended because it may create a higher risk of needle-stick injury and blood contamination and also may be associated with additional erythrocyte injury and identification errors, because the syringe cannot be equipped with labels or other patient identifiers.15 Allowing nurses to draw blood will reduce the number of venipunctures when using these primary tube adaptors.

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    Unlike these options, blood drawing through intravenous catheters should be usually discouraged, since this practice may lead to a significantly higher risk of spurious hemolysis compared with standard blood collections using straight needles [17]. Interestingly, it has been reported that reducing the negative pressure for aspirating blood from catheters by means of slow manual aspiration or low vacuum tubes [18] can be effective to limit the burden of spurious hemolysis from intravenous catheters [19], and this may therefore be seen as a potential opportunity in short stay units (e.g., emergency departments) or other healthcare settings (e.g., oncology or hematology wards), where the number of patients bearing these devices is considerably high. The use of unsuitable containers cannot be easily identified by the laboratory.

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