The effect of needle size on cerebrospinal fluid collection time and post-dural puncture headache: A retrospective cohort study

Objective The main objective of this study was to compare cerebrospinal fluid (CSF) collection time and patient's discomfort between 20G (a)traumatic and 22G atraumatic needles. Background Risk of post-dural puncture headache (PDPH) is decreased using atraumatic needles. Smaller needles may give lower risk but possibly at the cost of increased CSF collection time (due to lower flow), leading to additional patient's discomfort. Methods We performed a retrospective study of lumbar puncture data from a research program on CSF metabolomics and compared traumatic 20G (n = 210) with atraumatic 20G (n = 39) and 22G (n = 105) needles. In this cohort, incidence of PDPH was prospectively registered with other procedure details. Primary outcome was CSF collection time (time to fill the tube). Secondary outcomes were pain and stress scores during procedure, and incidence of PDPH. Results The time to collect 10 mL of CSF was longer for 22G needles (6.1 minutes; 95% CI 5.8-6.5) than for 20G traumatic (2.2 minutes; 95% CI 2.1-2.2) and 20G atraumatic needles (2.9 minutes; 95% CI 2.8-3.1). There were no differences in pain and stress scores. PDPH was lower for 22G atraumatic needles: odds ratio 0.41 (95% CI 0.25-0.66) versus 20G traumatic needles and 0.53 (95% CI 0.40-0.69) versus 20G atraumatic needles. Absolute PDPH rates were 69/210 (32.9%) for 20G traumatic, 13/39 (33.3%) for 20G atraumatic, and 19/105 (18.1%) for 22G atraumatic needles. Conclusions CSF collection time is slightly longer for smaller 22G needles, but this does not lead to more discomfort for the patient.