Use of atraumatic needles rather than conventional needles for lumbar puncture more than halves the rate of post-procedure headache. Moreover, this improvement does not come at the expense of procedure success rates.
Lumbar puncture involves inserting a needle in the lower back into the spinal canal to collect cerebrospinal fluid for diagnosis, or to inject a treatment or anaesthetic into it.
A common side effect is a headache, often from leakage of fluid from the puncture. Atraumatic needles leave a smaller puncture. After piercing the skin with an introducer needle, the atraumatic needle is inserted through the introducer. This spreads apart the fibres of the canal lining rather than cutting through it with a conventional needle.
This review provides high-quality evidence endorsing consensus guideline recommendations to use atraumatic needles. There may be training requirements to increase their use outside of the anaesthetic setting.
Why was this study needed?
Over 67,000 diagnostic and nearly 15,000 therapeutic lumbar punctures are performed in England each year. A common side-effect is a headache, estimated to affect up to a third of patients (10% in this review, perhaps reflecting the setting and experience of the clinicians). One probable cause is leakage of cerebrospinal fluid from the puncture causing reduced intracranial pressure.
Conventional needles have a sharp-angled open tip which cuts through the spinal canal lining the width of the whole needle. Atraumatic needles have a solid pencil point blunt tip with the hole on the side. The tip pushes through the canal lining, spreading the fibres apart rather than cutting them, allowing them to shrink back on needle removal. This leaves a smaller hole and less leakage.
Atraumatic needles are not always used - surveys indicate some clinicians are unclear on their safety and clinical effectiveness.
This review aimed to pool together all the evidence comparing atraumatic versus conventional needles for lumbar puncture.
What did this study do?
This systematic review and meta-analysis included 110 randomised controlled trials with 31,412 participants comparing atraumatic and conventional needles for lumbar puncture. Six trials were conducted in the UK. The average age was around 38, and a small proportion of participants were under 18. Injecting spinal anaesthetic was the reason for lumbar puncture in 91% of the trials. Only 5% were performed for diagnostic purposes. Epidurals were excluded as the needle does not pierce the spinal canal lining (dura).
Although there were differences found between the studies contributing to the primary outcome of post-procedure headache, overall the quality of evidence was rated high. Anaesthetists were the group most likely to perform the lumbar puncture in these trials, reflecting the high proportion of trials investigating the technique in spinal anaesthesia.
What did it find?
- Post-procedure headache was experienced by 4% of people after an atraumatic needle compared to 9.8% after conventional needles (relative risk [RR] 0.40, 95% confidence interval [CI] 0.34 to 0.47; 24,901 participants).
- The incidence of a severe headache was also lower, at 1.2% of people after an atraumatic needle compared to 4.2% after a conventional needle (RR 0.41, 95% CI 0.28 to 0.59; 5,178 participants).
- Fewer people needed intravenous fluid or controlled pain relief after atraumatic needles, 1.6% compared to 3.9% after conventional needles (RR 0.44, 95% 0.29 to 0.64; 7,183 participants).
- There was no difference in first attempt success rate, which was 86% for atraumatic needles compared to 88% for conventional needles (RR 0.99, 5% CI 0.96 to 1.02; 8,782 participants).
- Failure rates were similar, 3.2% for atraumatic needles and 3.8% for conventional needles (RR 0.86, 95% CI 0.58 to 1.27; 5,514 participants).
What does current guidance say on this issue?
Atraumatic needles are recommended for lumbar punctures in 2017 Consensus guidelines for lumbar puncture in people with neurological diseases.
What are the implications?
The evidence is consistent with previous studies; however, most cases were performed for spinal anaesthetic. There is less evidence on the safety and effectiveness of atraumatic needles for other indications such as diagnostic lumbar puncture for suspected meningitis or for delivering chemotherapy. But perhaps there is no reason for the benefits to be any different following these.
Nevertheless, the available evidence backs up current guidance to use atraumatic needles. If local use is low, protocols could be put in place to increase their use and reduce variation in care.
Citation and Funding
Nath S, Koziarz A, Badhiwala JH, et al. Atraumatic versus conventional lumbar puncture needles: a systematic review and meta-analysis. Lancet. 2018;391:1197-204.
There was no funding source for this study.
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