Diagnostic and therapeutic lumbar puncture performed safely and efficiently with a thin blunt needle

The risk of postdural puncture headache following lumbar puncture can be reduced by choosing a blunt spinal needle or by using a smaller needle diameter. Reports indicate that lumbar puncture practiced outside of the anaesthetic discipline does not adhere to the current level of evidence. To examine the practice among haematologists in Denmark, we performed a national survey. In addition, we analysed the flow rate of a blunt 27-gauge (0.4 mm) spinal needle typically used for spinal anaesthesia by timing the tap duration of a diagnostic lumbar puncture.

An online survey was emailed to all twelve haematology departments in Denmark with questions regarding needle type and technique. A total of 64 patients undergoing lumbar puncture with a 27-gauge spinal needle (sitting position) had their sampling of 6 ml cerebrospinal fluid timed with a stopwatch.

Eleven sites participated. Only three (27%) reported routine use of blunt needles. Five (45%) departments used a large calibre needle (18-20 gauge; 1.2-0.9 mm), while the remaining six (55%) used smaller calibre needles (≥ 22-gauge; ≤ 0.7 mm). The mean sampling time was 11 min. 59 sec., which corresponds to a flow rate of 30 ml/h.

There is strong evidence in favour of the use of blunt spinal needles to reduce the risk of postdural puncture headache. In general, lumbar puncture practice among the haematologists in Denmark does not adhere to the literature's recommendations. The risk of headache may further be reduced by using a thin needle, even if this prolongs sampling time.

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