A randomized controlled trial of ultrasound-assisted lumbar puncture

Evidence showing the systematic utility of ultrasound imaging during lumbar puncture (LP) in the emergency department is lacking. Our hypothesis was that ultrasound-assisted LP would increase the success rate and ease of performing LP with a greater benefit in obese patients.

This was an Institutional Review Board-approved, randomized, prospective, double-blind study conducted at the emergency department of a teaching institution. Patients undergoing LP from January to December 2004 were eligible for enrollment. Patients were randomized to undergo LP using palpation landmarks (PLs) or ultrasound landmarks (ULs). Data collected included age, body mass index, number of attempts, ease of performance and patient comfort on a 10-cm Visual Analog Scale, procedure time, success, and traumatic LP. Statistical analysis of data included relative risk (RR), the Mann-Whitney U test, and the Student t test.

A total of 46 patients were enrolled, 22 randomized to PLs and 24 to ULs. There were no differences between the groups in mean age or body mass index. Six of 22 attempts failed with PLs versus 1 of 24 with ULs (RR, 1.32; 95% confidence interval, 1.01-1.72). In 12 obese patients, 4 of 7 PL attempts failed versus 0 of 5 UL attempts (RR, 2.33; 95% confidence interval, 0.99-5.49). The ease of the procedure was better with ULs versus PLs. There were no statistical differences in the number of attempts, traumatic LPs, patient comfort, or procedure length.

The use of ultrasound for LP significantly reduced the number of failures in all patients and improved the ease of the procedure in obese patients.