The development of specific connections to guarantee safety in infiltrations has been a demand of anesthesiologists and other medical specialists for at least two decades. Today, new standards for neuraxial and significant regional anaesthesia have finally been developed, such as ISO 80369-6 (NRFit), and manufacturers are redesigning their products to fit the new standard.
Precisely along these lines, the independent study Strength of commonly used spinal needles: the ability to deform and resist deformation was carried out in 2017, led by Dr Arani Pillai from the Anesthesia Service of Nottingham University Hospital. This research, published by the journal Anesthesia, tested the strength and resistance of the most common spinal needles on the market. This comparison shows the differences between manufacturers but also compares each hand with its new version adapted to the new regulations.
The authors carried out an investigation focused on measuring the force of the most used spinal needles about the deformation they suffer. The study also examines the effect of the internal style in terms of needle force. All tests were performed on equipment designed to achieve them in horizontal and axial planes, reflecting standard industrial testing and clinical use.
WHAT DATA DOES THIS STUDY COMPARE?
Needles from four commonly used manufacturers (Vygon, Becton Dickinson, B Braun, and Pajunk) were used. The 25G and 27G needles were tested in lengths of 90 and 120mm. The study focused on comparing:
- The size of the deformation and “hardness”/resistance to a deformation between needles of different brands.
- The behaviour of the different needles in the horizontal tests was carried out as an industry standard, and the axial test was carried out by the researchers. Significant differences may be due to the clinic’s incidence of flexion and breakage.
- The role of the internal stylet, which resulted in significantly higher hardness in many needles, had little effect on the degree of deformation.
- In addition, Luer and non-Luer (NRFit) needles of the same brand and size were compared. In this case, they showed few significant differences in strength. This result is reassuring, given the imminent change from Luer to non-Luer needles due to the appearance of the ISO 80369-6 standard, which will change the neuraxial connections to reduce connection errors, which can be fatal for patients.
WHAT TYPES OF NEEDLES HAVE BEEN TESTED
To carry out this study, we used:
29 types of needles from 4 brands:
- vygon
- BD (27G 120mm, luer and non-luer not tested as they were not available at the time of the study)
- Braun ( 25G 120mm, luer not tested as it was not available at the time of the survey)
- Pajunk
The needles were tested in 4 sizes:
- 25G 90mm
- 27G 90mm
- 25G 120mm
- 27G 120mm
The connection types tested were:
- Luer
- No Luer: new connectors that comply with ISO 80369-6, NRFit
METHODOLOGY
To carry out this comparison between needles, the researchers carried out three types of tests:
Horizontal test – 3-point curve – 25G and 27G 90mm needles, Luer without stylet
Axial Test – Needles 25G and 27G 90mm and 120mm, luer and non-luer
Measurement of the final deviation
SPINAL NEEDLE DEFORMATION COMPARISON RESULTS
The results showed significant differences between the needles of the different commercial houses, both in the horizontal and the axial tests, in terms of absolute deviation and hardness of the hands.
“Overall, the results of this independent study showed that the Vygon needles show little ultimate deformation and the highest hardness, while the B Braun needles show the highest ultimate deformation and the least hardness.”
The study also found that needles of the same brand did not behave the same in different sizes. For example, the 25G 120mm Vygon needle showed more significant final deformation than the exact size of the BD and Pajunk brands, while the 27G 90mm size did not show this difference.
HORIZONTAL TEST VS AXIAL TEST
Each needle showed similar behaviours in the horizontal and axial tests. For example, in both tests, Vygon’s 27G 90mm Luer needle showed significantly higher hardness than the same needles from BD and B Braun.
However, there were also some differences in the results of the same needle in these two tests. This is the case of the B Braun 27G 90mm Luer needle, which showed a significantly more significant final deviation than the needles of the other brands in the axial test and did not do so in the horizontal test.
In addition, there were also differences between brands in terms of the absolute deviation and the hardness of the needles.
In the case of B Braun’s 25G 90mm Luer needle, it showed more significant final deformation than Pajunk but also greater hardness in the same test.
DIFFERENCES BETWEEN LUER AND NRFIT
One of the most exciting results of this study is the little difference found in final deformation between Luer and Non-Luer needles of the same brand and size when faced with the same test. These tests were performed with and without an interior style, and the results were similar.
The most significant difference between the same Luer and Non-Luer needle was found in the final deformation of the 27G 120mm Pajunk needle in the axial test.
In addition, the most significant differences in hardness between Luer and Non-Luer needles were found in BD, B Braun and Pajunk hands, at least in one size.
The relevance of this comparison between Luer and Non-Luer needles is exceptionally high since many countries, such as the United Kingdom, have already begun to change Luer-type spinal hands for those that comply with ISO 80369-6 (NRFit ).
This regulation “specifies the requirements for connectors used in neuraxial applications intended to deliver medications to neuraxial sites, wound infiltration, administration of anaesthesia, other regional anaesthesia procedures, and to monitor or withdraw cerebrospinal fluid for therapeutic or diagnostic purposes. Using the standard will thus reduce the risk of the wrong product being administered, which could save lives,” explains Scott Colburn, director of the FDA Center for Devices and Radiological Health (CDRH) Standards Program.
Finally, all the needles showed greater hardness in the horizontal test, and most did so in the axial test when the tests were performed with the stylet inserted.
The conclusions of the authors of the independent study Strength of commonly used spinal needles: the ability to deform and resist deformation were:
- There are significant differences between brands regarding final deformation, hardness or resistance to deformation in needles of the same G and length.
- In some axial tests, on the same needle size, the deformation of the needles of one brand was twice that of another.
- Although a direct clinical comparison of these results is difficult, they suggest differences between brands in incidence and degree of needle flexibility during use.
- Current changes in needle grip design (the move from Luer to Non-Luer) do not significantly influence needle strength in terms of needle deformation and needle hardness.
