Comparison of a Novel Thin-Walled 25-gauge Needle Push Button Blood Collection Set to a Standard 23-gauge Needle in a Cancer Patient Population

Abstract

Background:

Phlebotomy can be an uncomfortable and even painful experience which increases in likelihood in patients that require frequent blood draws such as those with cancer. The 25-gauge BD Vacutainer^® UltraTouch^™ Push Button Blood Collection Set has a smaller outer bore needle size and unique bevel configuration which in theory should reduce pain associated with phlebotomy. Smaller needles typically cause less pain, however, they have a higher incidence of compromising the specimen integrity. Innovative engineering allows this particular needle to maintain a larger inner bore size similar to a standard 23-gauge needle. This study compares pain and specimen integrity between this novel device to a standard 23-gauge needle.

Methods:

Two cohorts of 190 patients each had phlebotomy performed with either needle. Pain experienced was assessed by patient surveys, rating pain from 0 (low) to 10 (high). Sample integrity was assessed by determining the hemolysis index (Abbott Architect c8000).

Results:

No statistically significant difference in median pain scores was observed between the 2 cohorts, P-value: 0.068. The 23-gauge cohort more frequently reported 3+ pain than the 25-gauge cohort, 14/190 vs 5/190. Pain scoring 1 and 2 was more frequent in the 25-gauge cohort, 84/190 vs 54/190. Pain scores of 0 were more frequent in the 23-gauge cohort, 122/190 vs 101/190. This stratification is statistically significant, P-value: 0.003. The 25-gauge needle showed no increase in hemolysis rates, P-value: 0.5.

Conclusions:

Sample integrity was identical between both needles. The 25-gauge needle resulted in less 3+ pain, while pain scoring 1 and 2 was more frequent in the 25-gauge cohort.

INTRODUCTION

Despite advances in non-invasive testing techniques, phlebotomy remains the predominant method for the acquisition of clinical samples and is one of the most common invasive techniques performed within all of healthcare. Although commonly performed, phlebotomy is often met with considerable apprehension by both pediatric and adult patients alike (1, 2). One major source of this apprehension is due to pain felt during the phlebotomy procedure (3). Many strategies exist to mitigate pain felt during phlebotomy such as numbing agents, patient distraction, and cooling the venipuncture site, however, these strategiesdonot completely eliminate the pain felt by the patient (4–6). Pain felt during phlebotomy can also be reduced byusinga smaller diameter needle whenperforming the venipuncture (7). Phlebotomy needle outer diameter has been shown to correlate with pain felt during the venipuncture, where larger diameter needles are associated with greater amounts of pain (8). Needle diameter is represented in “gauges” where larger gauges are indicative of smaller outer diameters. Although the use of larger gauge needles during the venipuncture is seemingly advantageous to the patient, blood samples collected with larger gauge needles are more prone to hemolysis which adversely affect laboratory test results (9). Specimen integrity is critical in the clinical lab, as poor-quality samples can lead to aberrant patient results and canceled tests (10). This can result in the patient needing additional phlebotomy procedures, delaying patient care, and increasing costs to the hospital and patient alike (11). Prior studies have shown that 23 g needles are the largest gauge needle acceptable for routine phlebotomy (12).

The 25-gauge BD Vacutainer^® UltraTouch^™ Push Button Blood Collection Set (BD 25 g PentaPoint needle) is uniquely designed in that it has a thinner wall for the needle cannula. This allows for a larger inner bore while maintaining the same outer diameter as 23 g phlebotomy needles (13). This reportedly allows for phlebotomy to be performed using a 25 g needle without the specimen integrity issues typically associated with needles of this small diameter. The tip of this 25 g needle is redesigned to contain 5 bevels, as opposed to the standard 3 bevels. This design allows for a flatter needle profile. This, in conjunction with the larger needle gauge, has been reported by the manufacture to reduce painful venipunctures (13). This needle also contains a safety mechanism that allows for the retraction of the needle within the needle set with the push of a button, reducing the chance of accidental needle sticks (14).

Cancer patients undergoing chemotherapy or other oncologic treatments require frequent lab monitoring to both assess treatment effectiveness and monitor for drug toxicity. These patients require frequent phlebotomy, so minimizing phlebotomy-related pain would greatly improve patient experience. The goal of this study is to assess the efficacy of the BD 25 g PentaPoint needle in reducing pain felt during phlebotomy in cancer patients without compromising the sample quality as compared to a standard 23 g butterfly needle. We hypothesize that the smaller outer diameter of the BD 25 g PentaPoint needle will be less painful to patients than the standard 23 g needle, while sample quality will be identical.

MATERIALS AND METHODS

This study was reviewed by the Memorial Sloan Kettering Cancer Center Institutional Review Board (IRB) and determined not to need IRB oversight. A total of 380 patients, ages 18 and up, were voluntarily recruited for the study and enrolled sequentially into 2 cohorts of 190 patients each. Assuming a standard deviation (SD) of 2 for the 0 to 10 pain rating scale, we estimated 190 patients per arm would give us 80% power to detect a mean group difference in pain ratings as small as 0.58 using a 2-sided 2-sample t-test with significance threshold of P < 0.05. This difference of 0.58 on the 0 to 10 pain rating scale translated to a standardized effect size (in SD units) of 0.29. Each cohort had phlebotomy performed using either a standard 23 g butterfly needle (23 g BD Vacutainer Safety-Lok Blood Collection Set) in the first cohort or the BD 25 g PentaPoint needle in the second cohort. All study participants were outpatient cancer patients and had phlebotomy performed as part of their routine cancer treatment. All phlebotomy was performed by experienced phlebotomists having >10 years of experience with cancer patients. After phlebotomy, each participant was asked to fill out a survey ranking the pain they experienced during the procedure, how many needle sticks were required for a successful blood draw, and their overall satisfaction. Pain experienced was assessed from 0 to 10, where 0 is no pain and 10 is the worst pain imaginable. Patient satisfaction was also assessed from 0 to 10 where 0 is very dissatisfied and 10 is completely satisfied. Patients were asked to record how many venipunctures were required to complete the procedure and self-report whether they have “difficult veins”. Specimen integrity was assessed between the 2 collection systems by determining the presence of hemolysis in the sample by measuring the hemolysis index on the Abbott Architect c8000. The hemolysis index on the Abbott Architect c8000 is a numerical value from 0 to 4, where 0 represents no hemolysis and 4 represents gross hemolysis. Statistical analysis performed on the study results included chi-squared tests of independence and Fisher’s exact tests for categorical endpoints, and Wilcoxon rank-sum tests for continuous non-normal endpoints.

RESULTS

A total of 380 patients comprising 200 males and 180 females were recruited for the study. Patient ages ranged from 18 to 88 years, averaging 57 years (Table 1). No other demographics were recorded.

Table 1:

Study Cohort Demographics

Demographic	Standard 23g Needle (n = 190)	BD 25g PentaPoint needle (n = 190)	p-value
Female	83 (44%)	97 (51%)	0.2
Male	107 (56%)	93 (49%)
Age Range	18 – 85	18 – 88	0.7

Median pain scores were 0 for both groups, P-value 0.068. However, as pain scores were strongly right-skewed in both cohorts (Fig. 1) we subdivided the ratings into different categories to afford a better analysis. When comparing patients reporting no instances of pain (score: 0) to patients reporting any instances of pain (score: 1+) within each cohort, 101/190 and 122/190 patients reported feeling no pain with the BD 25 g PentaPoint needle and the standard 23 g needle, respectively, while 89/190 patients reported feeling any degree of pain (score: 1+) with the BD 25 g needle, compared to 68/190 patients with the 23 g needle. These differences are statistically significant, P-value: 0.037 (Table 2).

Figure 1:

Distribution of Pain Scores Across The 25-Gauge and 23-Gauge Cohorts. Note that pain scores of 3 and up have a higher association with the standard 23-gauge phlebotomy needle (p = 0.003).

Table 2:

Results of Pain Survey Comparing No Pain to Any Pain (1+)

Pain Score	Standard 23g Needle (n=190)	BD 25g PentaPoint needle (n=190)	p-value
No Pain (0)	122 (64%)	101 (53%)	0.037
Any Pain (1+)	68 (36%)	89 (47%)

Further stratification of pain felt during venipuncture with the BD 25 g PentaPoint needle yielded the following: 59/190 patients reported a pain score of 1, 25/190 patients reported a pain score of 2, and 5/190 patients reported a pain score of 3+. Pain during venipuncture with the 23 g needle was as follows: 122/190 patients reported a pain score of 0, 42/190 patients reported a pain score of 1, 12/190 reported a pain score of 2, and 14/190 patients reported a pain score of 3+. Differences between the 2 cohorts were statistically significant, P-value: 0.003 (Table 3).

Table 3:

Stratification of Pain Scores

Pain Score	Standard 23g Needle (n=190)	BD 25g PentaPoint needle (n=190)	p-value
No Pain (0)	122 (64%)	101 (53%)	0.003
Barely Pain (1)	42 (22%)	59 (31%)
Mild Pain (2)	12 (6%)	25 (13%)
Moderate to Severe Pain (3+)	14 (7%)	5 (3%)

No statistically significant differences in patient satisfaction were observed, P-value: 0.6. In patients having blood drawn with the 23 g needle, 159/190 reported a 10 for patient satisfaction, and 31/190 reported satisfaction of <10. From the patients drawn with the BD 25 g PentaPoint needle, 164/190 reported a satisfaction of 10 and 26/190 patients reported a satisfaction of <10.

Comparing the number of venipunctures, 186/190 patients reported that only one venipuncture was performed during their visit when being drawn with the 23 g needle compared to 189/190 patients drawn with the BD 25 g PentaPoint needle. Of the 23 g needle group, 3 patients required 2 attempts and 1 required >3 attempts (pain scores of 0, 1, 7, and 6, respectively). Of the 25 g PentaPoint needle group, only 1 patient required 2 attempts and reported a pain score of 3. In total, 99/380 patients self-reported having difficult veins, with 50/190 patients reporting difficult veins for the 23 g needle and 49/190 for the 25 g PentaPoint needle.

Lithium heparin samples were available for 172 patients from the 23 g cohort and 174 patients from the 25 g cohort which were used to evaluate for hemolysis on the chemistry analyzer. All 172 samples drawn with the 23 g needle had a hemolysis index of 0. Most samples (172/174) drawn with the BD 25 g PentaPoint needle had a hemolysis index of 0 with the remaining 2 having a hemolysis index of 1. There was no statistical difference in hemolysis between the 2 groups, P-value 0.5.

DISCUSSION

Our data shows that median pain scores were 0 for both cohorts. This low median pain score value can likely be attributed to the skill of the phlebotomists who participated in this study, and their ability to limit pain during venipuncture, regardless of needle gauge. Statistically, there was no difference in median pain scores across both cohorts, but as the entire data set was extremely right-skewed across both cohorts, further stratification of the data can provide additional insight. When looking at no pain (0) vs any pain (1+) categories, any pain is more frequently reported in patients drawn with the BD 25 g PentaPoint needle. This is a surprising finding and is contrary to both our hypothesis and prior published results (7). One possible reason for this can be found in the design of the retraction mechanism in the BD 25 g PentaPoint needle which was not present on our standard 23 g needle. The needle retraction mechanisms emits an audible click sound when activated and this sound may be misinterpreted as very mild pain (pain scores of 1 and 2) by our patients.

Although our data show that patients receiving venipunctures with the BD 25 g PentaPoint needle more frequently reported any instance of pain, mostly pain scores of 1 and 2, pain scores of 3 and above have a statistically significant higher association with the standard 23 g needle (Table 3). This may be an indicator that the 25 g needle reduces actual pain that would normally be reported as a score of 3 or more, and that this difference is being masked by perceived mild pain in reaction to the audible click from the needle retraction mechanism. Further investigations would have to be done to confirm or disprove this theory.

Despite these differences in pain levels, patients drawn with either needle were satisfied with their experience, with no statistical differences observed. This level of satisfaction can likely be attributed to the overall low levels of pain felt between both needles with 223/380 patients reporting no pain whatsoever, as well as the low incidence of multiple venipunctures needed (5/380) despite 99/380 patients reporting having difficult veins.

Overall, the phlebotomists were satisfied with the new device. They appreciated the safety features and noted that the smaller needle size was useful in patients with small veins. When asked, however, which device they prefer, they were still more comfortable with the standard 23 g since that is what they were accustomed to. This may be different if the phlebotomists were to use the new device for a longer period of time.

Both needle types in our study have nearly identical low rates of hemolysis with 172/172 (23 g) vs 172/174 (25 g) samples showing no hemolysis proving the manufacturer’s claim that the BD 25 g PentaPoint needle is effective in limiting hemolysis, similar to that of standard 23 g needles as compared to standard 25 g needles (13). The degree of hemolysis is measured by the Abbott Architect c8000 system by determining the concentration of hemoglobin (mg/dL) and categorizing it as a hemolysis index as follows: 0 ≤ 30, 1 = 30 to < 100, 2 = 100 to < 200, 3 = 200 to <500, and 4 = ≥ 500. The clinical laboratory uses the hemolysis index in all samples run on the Abbott Architect c8000 analyzer to evaluate specimen integrity and determine if hemolysis is at a level that would interfere with assay results. For example, a hemolysis index of 1 indicates a specimen to be slightly hemolyzed and would only affect a few analytes, while an index of 4 corresponds to severe hemolysis and interferes with many more analytes.

Although it is generally accepted that larger gauge needles are indicative of less pain felt during phlebotomy, research into pain reduction using 25 g needles has led to mixed results (7). A recent study has shown that the BD 25 g PentaPoint needle was effective in reducing pain during phlebotomy in children ages 3 to 12 when compared to a 23 g needle. However, this same study found no difference in pain felt between either needle in children ages 13 to 18 (15). Another study focusing on arterial blood gas samples found no difference in pain felt when acquiring the sample using either a 23 g or 25 g needle. It should be noted that the 25 g needle used in this arterial blood gas study was not the same 25 g needle used in our study (16). An additional study comparing the BD 25 g needle to a 23 g thin-walled needle found that patients drawn with the BD 25 g PentaPoint needle generally felt less pain (17). In this study, as noted by Padoan et al., patients were drawn using both needles in opposite arms and not representative of a typical phlebotomy experience (15, 17). Our study builds on these prior works by comparing BD 25 g PentaPoint needle to a standard 23 g needle in a cancer patient population which has not been previously reported. Cancer patients frequently experience phlebotomy to monitor cancer treatment side effects and response to therapy, so it is beneficial for them to use equipment that makes the procedure as comfortable as possible.

One limitation of our study is that it was conducted exclusively using a limited number of our most experienced and most skilled phlebotomists all having more than 10 years of experience with cancer patients. This was done purposefully to ensure that the phlebotomists were able to adapt quickly to the new device and to keep the skill level constant throughout the study. This, however, introduces an issue where the majority of patients from both cohorts demonstrate very mild to no pain due to the high skill of the phlebotomist. This may be further compounded in both cohorts since these particular phlebotomists are often requested by name by the patient since they already have a standing relationship with them. Testing the device with less experienced phlebotomists or with individuals who do not perform venipuncture every day (i.e., doctors and nurses) may elucidate different results. Also, using a pain assessment tool validated to be more sensitive in distinguishing different low levels of pain may have provided better information. In our study we found that the verbal anchors for the 0 to 10 pain rating scale we used (i.e., 0 = “no pain at all” and 10 = “worst pain imaginable”) was most sensitive at distinguishing moderate to severe levels of pain. Since our patients experienced predominantly no pain to very mild pain, this scale may not have been ideal. We recommend future studies of phlebotomy-related pain use a validated pain assessment that is most sensitive to pain experiences in the mild range.

Another limitation was the comparison of devices where one had an automatic retraction mechanism whereas the control group did not. This was because the novel 25 g PentaPoint needle was only available with the retraction mechanism and our standard 23 g needles did not have that feature. This introduced a bias where the retraction mechanism had an audible click that may have been interpreted as mild pain. For future studies we recommend using a needle with a retraction mechanism in the control group to cover this bias.

Furthermore, our study assessed sample quality by looking strictly at semi-quantitative hemolysis index rates. No other sample quality indicators, such as instances of underfilled samples, were examined.

It is important to note that one of the possible barriers to implementing this new technology is the cost. Since the new device has additional safety features and innovative engineering it takes more resources to produce. This translates into a higher cost for the device, about 2.5 times the amount that the standard 23 g needle setup costs. It was for this reason that our institution did not convert over to the new phlebotomy device.

In conclusion, we believe our study demonstrates that the BD 25 g PentaPoint needle is effective in reducing moderate to severe pain during phlebotomy in cancer patients without increasing the rate of hemolyzed samples. It is important to note that instances of mild pain (scores 1 and 2) were reported more often for this device than the standard 23 g needle. This mild pain may be due to the audible click of the retraction mechanism that is perceived as pain; however, additional studies are necessary to confirm or disprove this possibility.

IMPACT STATEMENT.

Phlebotomy-related pain is a source of apprehension in many patients. Small diameter 25 g needles are typically less painful to the patient, but can produce poor quality blood specimens, potentially affecting lab results. In this study, we evaluated The BD Vacutainer^® UltraTouch^™ Push Button Blood Collection Set, a uniquely designed 25 g needle, which is reportedly less painful to patients without compromising specimen integrity. Our study focused on oncology patients but may benefit any patient receiving phlebotomy.

Abbreviations:

BD 25g PentaPoint needle

BD Vacutainer^® UltraTouch^™ Push Button Blood Collection Set

23g

23-gauge