PEDIATRICS Vol. 89 No. 5 May 1992, pp. 895-897
This Article
Right arrow Full Text (PDF)
Right arrow P3Rs: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when P3Rs are posted
Right arrow Alert me if a correction is posted
Services
Right arrow E-mail this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My File Cabinet
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ellis, R. W.
Right arrow Articles by Ellis, R. W.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ellis, R. W., III
Right arrow Articles by Ellis, R. W., Jr.

A Simple Method of Estimating Cerebrospinal Fluid Pressure During Lumbar Puncture

Robert W. Ellis III MD, USAF, MC, FS1, Lewis C. Strauss MD1, Joseph M. Wiley MD1, Thomas M. Killmond PA-C1, and Robert W. Ellis Jr. PhD, PE2

1 From the Department of Oncology and Pediatrics, Johns Hopkins University, Baltimore, MD
2 From the School of Engineering, Lawrence Technological University, Detroit, Michigan

It is often difficult to measure cerebrospinal fluid (CSF) pressure in children. CSF flow through a spinal needle is described by the equation: Flow = pressure/(needle constant x relative viscosity). Thus, CSF flow rate during lumbar puncture can be used to estimate CSF pressure. Because the viscosity of CSF is approximately the same as that of normal saline, 0.9% NaCl was used to model CSF flow in vitro. Flow of saline through various spinal needles was measured as pressure and temperature were varied to determine needle constants and variation in viscosity with temperature. Counting periods for which the number of drops counted equals the pressure (in centimeters of H2O) then were determined for each needle size. At patient temperatures less than 40°C, counting periods were calculated at 21, 39, and 12 seconds, for 22-gauge 1.5-inch, 22-gauge 3.5-inch, and 20-gauge 3.5-inch spinal needles, respectively. Viscosity decreased slightly above 40°C, and counting periods became 20, 37, and 11 seconds. Finally, the method was tested prospectively in 12 patients by comparing drop count (over the calculated counting period) to manometric pressure measurement. Drop counts were within 15% of manometric pressure in all patients. This method allows simple and rapid estimation of CSF pressure during lumbar puncture.

Key Words: cerebrospinal fluid • pressure • lumbar puncture • spinal tap • viscosity

Submitted on July 1, 1991
Accepted on August 26, 1991