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Atraumatic spinal needle indicates correct CSF opening pressure


Online survey results

Forty-four out of 60 participants who were medical professionals of different experience levels and specialties completed the online survey. For details, see Table 1. For lumbar puncture without need for measuring the CSF opening pressure, most participants (77.3%) indicated to use atraumatic needles, whereas 20.5% indicated to use traumatic needles for this purpose and 2.2% indicated to use another technique without specification. In contrast, if CSF opening pressure was to be measured, 86.4% stated to use traumatic needles. In total, 68.1% of the participants believed that atraumatic needles could adequately assess the CSF pressure including 40.9% who stated that this would take more time. However, 31.8% of all participants still believed that the CSF pressure by lumbar punctures can be assessed correctly only by traumatic needles (Table 1).

Table 1 Questionnaire results.

Effect of needle type on time-to-equilibrium

In our experimental setup, both traumatic and atraumatic needle types reached the peak level of pressure correctly. Taken all experimental conditions together, we observed only slight but not significant (P = 0.07) differences in terms of the time to reach the peak level between the 20G traumatic (20 cm H2O, mean 12.4 s/SD 3.8 s; 30 cm H2O, mean 12.5 s/SD 2.8 s; 50 cm H2O, mean 11.2 s/SD 2.1 s) and 22G atraumatic (20 cm H2O, mean 14.7 s/SD 4.4 s; 30 cm H2O, mean 15.1 s/SD 4.1 s; 50 cm H2O, mean 14.8 s/SD 2.9 s). However, using the small 26G atraumatic needle it took significantly longer to reach the peak pressure (P < 0.0001; 20 cm H2O, mean 59.9 s/SD 29.8 s; 30 cm H2O, mean 59.8 s/SD 13.9 s; 50 cm H2O, mean 63.0 s/SD 9.6 s) (Fig. 2A).

Figure 2
figure 2

CSF opening pressure time-to-equilibrium depends from needle type and liquid. The impact of different needle types on CSF opening pressure measurements by lumbar puncture. (A) The time (in seconds) until the respective pressures were shown across all experimental liquid compositions. (B) The time (in seconds) until the respective pressures were shown, divided by needle types and different experimental liquids and CSF from healthy patients and patients who suffered from SAH.

Effect of CSF composition and pressure on time-to-equilibrium

Subsequently, the effect of the different liquid compositions and pressure levels on the time-to-peak were analysed. Thus, we used water with different milk powder protein concentrations (0, 0.4 and 10 g/L), glucose levels (0, 0.7 and 7 g/L) as well as different pressure levels (20 cm H2O, 30 cm H2O, 50 cm H2O). We found that neither the pressure levels (P = 0.84) nor the glucose concentration (P = 0.96) significantly impacted the time to peak. In contrast, high levels of protein (P = 9.5e−07) prolonged the time to peak across all needles (Fig. 2B, descriptive statistics for all conditions are provided in supplementary Table 2). Notably, further analysis revealed no significant differences between 20 and 22G needles across all pressure levels and protein concentrations (20 cm H2O, 0 g/L P = 0.08, 0.4 g/L P = 0.07, 10 g/L P = 0.08; 30 cm H2O, 0 g/L P = 0.08, 0.4 g/L P = 0.08, 10 g/L P = 0.1; 50 cm H2O, 0 g/L P = 0.08, 0.4 g/L P = 0.1, 10 g/L P = 0.1).

To translate our findings into clinical practice, we compared anonymized CSF samples from patients with idiopathic intracranial hypertension (IIH) and subarachnoid haemorrhages (SAH) in our experimental setup. Similar to the results in our experimental liquid compositions we did not observe significant differences in the time to peak between the 20G traumatic (20 cm H2O, mean 9 s/SD 1.4 s; 30 cm H2O, mean 9.7 s/SD 0.8 s; 50 cm H2O, mean 11.5 s/SD 3.14 s) and 22G atraumatic (20 cm H2O, mean 9.3 s/SD 1.2 s; 30 cm H2O, mean 11 s/SD 1.5 s; 50 cm H2O, mean 11.7 s/SD 3.3 s) needles (P = 0.92). In contrast, the 26G (20 cm H2O, mean 83 s/SD 47.9 s; 30 cm H2O, mean 64.3 s/SD 21.6 s; 50 cm H2O, mean 60 s/SD 12.7 s) significantly (P = 3.1e−13) significantly prolonged the time to peak (Fig. 2B, descriptive statistics for all conditions are provided in supplementary Table 2). Finally, we analysed the impact of haemoglobin on time to peak. High amounts of haemoglobin significantly impaired the time to peak across all applied pressures (P = 0.04). Subsequent analysis revealed no significant differences between the 20G traumatic and 22G atraumatic needles across all pressure levels in human CSF with or without haemoglobin (20 cm H2O, Hb negative P = 0.99, Hb positive P = 0.64; 30 cm H2O, Hb negative P = 0.81, Hb positive P = 0.07; 50 cm H2O, Hb negative P = 0.99, Hb positive P = 0.62).



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