Elsevier

The Lancet

Volume 391, Issue 10126, 24–30 March 2018, Pages 1197-1204
The Lancet

Articles
Atraumatic versus conventional lumbar puncture needles: a systematic review and meta-analysis

https://doi.org/10.1016/S0140-6736(17)32451-0Get rights and content

Summary

Background

Atraumatic needles have been proposed to lower complication rates after lumbar puncture. However, several surveys indicate that clinical adoption of these needles remains poor. We did a systematic review and meta-analysis to compare patient outcomes after lumbar puncture with atraumatic needles and conventional needles.

Methods

In this systematic review and meta-analysis, we independently searched 13 databases with no language restrictions from inception to Aug 15, 2017, for randomised controlled trials comparing the use of atraumatic needles and conventional needles for any lumbar puncture indication. Randomised trials comparing atraumatic and conventional needles in which no dural puncture was done (epidural injections) or without a conventional needle control group were excluded. We screened studies and extracted data from published reports independently. The primary outcome of postdural-puncture headache incidence and additional safety and efficacy outcomes were assessed by random-effects and fixed-effects meta-analysis. This study is registered with the International Prospective Register of Systematic Reviews, number CRD42016047546.

Findings

We identified 20 241 reports; after exclusions, 110 trials done between 1989 and 2017 from 29 countries, including a total of 31 412 participants, were eligible for analysis. The incidence of postdural-puncture headache was significantly reduced from 11·0% (95% CI 9·1–13·3) in the conventional needle group to 4·2% (3·3–5·2) in the atraumatic group (relative risk 0·40, 95% CI 0·34–0·47, p<0·0001; I2=45·4%). Atraumatic needles were also associated with significant reductions in the need for intravenous fluid or controlled analgesia (0·44, 95% CI 0·29–0·64; p<0·0001), need for epidural blood patch (0·50, 0·33–0·75; p=0·001), any headache (0·50, 0·43–0·57; p<0·0001), mild headache (0·52, 0·38–0·70; p<0·0001), severe headache (0·41, 0·28–0·59; p<0·0001), nerve root irritation (0·71, 0·54–0·92; p=0·011), and hearing disturbance (0·25, 0·11–0·60; p=0·002). Success of lumbar puncture on first attempt, failure rate, mean number of attempts, and the incidence of traumatic tap and backache did not differ significantly between the two needle groups. Prespecified subgroup analyses of postdural-puncture headache revealed no interactions between needle type and patient age, sex, use of prophylactic intravenous fluid, needle gauge, patient position, indication for lumbar puncture, bed rest after puncture, or clinician specialty. These results were rated high-quality evidence as examined using the grading of recommendations assessment, development, and evaluation.

Interpretation

Among patients who had lumbar puncture, atraumatic needles were associated with a decrease in the incidence of postdural-puncture headache and in the need for patients to return to hospital for additional therapy, and had similar efficacy to conventional needles. These findings offer clinicians and stakeholders a comprehensive assessment and high-quality evidence for the safety and efficacy of atraumatic needles as a superior option for patients who require lumbar puncture.

Funding

None.

Introduction

Postdural-puncture headache is the most common complication after lumbar puncture, affecting up to 35% of patients.1 This type of headache is postural and can be debilitating in some patients, resulting in discomfort that results in patients returning to hospital for controlled analgesia or invasive therapy. Postdural-puncture headache is presumed to be due to sustained leakage of cerebrospinal fluid from the dural defect, which is created by the spinal needle during puncture.2 The incidence of headache after lumbar puncture is thought to be influenced by multiple factors, including needle gauge, needle tip design, patient position, use of prophylactic intravenous fluid or bed rest, and experience of the clinician.3 To date, needle tip design has received the most attention in view of the proposed mechanism of postdural-puncture headache.

Spinal needles can be broadly classified as atraumatic or conventional on the basis of their tip configuration.4 Conventional needles are the most frequently used in clinical practice and have a sharp slanted tip designed to cut through the dura with a distal opening that enables the injection of therapeutics or collection of cerebrospinal fluid. In comparison, atraumatic needles are blunt with a closed pencil point tip and a side port for injection or collection (figure 1).5 Post-mortem studies6 have shown that conventional needles cut through tissues, causing irregular lacerations that can increase the potential for cerebrospinal fluid leakage. By contrast, atraumatic needles separate and dilate dural fibres, resulting in a smaller pinpoint opening after needle removal and contracture of the dura.6 Therefore, atraumatic needles are postulated to reduce the incidence of postdural-puncture headache by limiting the leakage of cerebrospinal fluid after lumbar puncture. In-vitro studies7 that further support this theory have shown that the rate of cerebrospinal fluid leakage due to dural perforations is decreased with atraumatic needles compared with the conventional needle type.

Research in context

Evidence before this study

Several surveys show that clinicians' knowledge about the existence of atraumatic needles and their adoption in clinical practice is poor. More than 100 trials have compared atraumatic needles and conventional needles, but these trials were largely single-centre with a small sample size, which even if powered to detect the effect of needle tip design for the primary outcome of postdural-puncture headache, were not sufficiently powered to examine key additional outcomes. Moreover, previous trials were underpowered to detect interactions between needle tip design and important clinical subgroups. Previously published meta-analyses also failed to reach consensus on this topic because of methodological limitations.

Added value of this study

To the best of our knowledge, our systematic review and meta-analysis is the most broad and robust analysis comparing atraumatic and conventional needles to date. Our study was not only powered to detect a difference in the primary outcome of postdural-puncture headache, but also 11 additional outcomes. Moreover, evidence from this study was not limited to a single clinical discipline and was obtained from a large sample size (>30 000 participants), which enhanced generalisability and enabled the interaction between needle tip design and key predefined patient subgroups and procedural characteristics to be assessed. Prespecified subgroup analyses for the primary outcome revealed no interactions between needle type and patient and care delivery characteristics suggesting that our findings indicate a true effect of the atraumatic tip design.

Implications of all the available evidence

Evidence from this study suggests that atraumatic needles are associated with significant reductions in the risk of postdural-puncture headache and other complications, with similar efficacy to their conventional counterparts. Additionally, atraumatic needles reduced the need for patients to return to hospital for medical or invasive therapy. Our findings offer clinicians and health-care policy makers a comprehensive assessment and high-quality evidence for the safety and efficacy of atraumatic needles as a superior option for patients who require lumbar puncture.

Although atraumatic needles were first developed nearly 70 years ago,8 they are not routinely used in clinical practice.9 In fact, few surveyed clinicians reported awareness of their existence because evidence describing the safety and efficacy of atraumatic needles has not reached consensus.10, 11 Previous studies have largely been single centre trials with a small sample size, only powered to detect the effect of needle tip design on the primary outcome of postdural-puncture headache. Additionally, these trials were not powered to assess the true effect of needle tip design and whether it interacts with important clinical subgroups. Therefore, we did a systematic review and meta-analysis of randomised controlled trials to compare atraumatic and conventional lumbar puncture needles across important outcomes and prespecified subgroups of patient and procedural characteristics.

Section snippets

Search strategy and selection criteria

For this systematic review and meta-analysis, we searched 13 databases, including MEDLINE, Embase, and Web of Science from inception to Aug 15, 2017, using a combination of relevant keywords and medical subject heading terms. We searched for randomised controlled trials that compared the use of atraumatic needles with conventional needles for any lumbar puncture indication. Full search terms and search strategy are provided in the appendix (p 1). Database searching was supplemented by manually

Results

Our systematic search of the literature identified 20 241 records. Of these, 110 trials totalling 31 412 patients, done between 1989 and 2017 in 29 different countries, met our inclusion criteria (figure 2). Eight (7%) of 110 eligible studies were conference abstracts and the remainder were full-text articles. All articles were written in English with the exception of 25 that were published in German (n=7), Spanish (n=5), Mandarin (n=4), Turkish (n=3), Danish (n=2), Dutch (n=1), Japanese (n=1),

Discussion

Our study indicates that patients who have lumbar puncture with atraumatic needles have a significantly lower incidence of postdural-puncture headache than those punctured with the conventional type. Furthermore, the need for patients to return to hospital for controlled analgesia or intravenous fluid was reduced in patients punctured with atraumatic needles. Need for invasive therapy (ie, epidural blood patch) was also significantly decreased in the atraumatic group compared with the

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