A disposable, closed fluid sampling
system for use with a medical conduit line (70), especially for taking blood samples from a
pressure monitoring line. The conduit line (70) has at least one fluid sampling site (100, 102) interposed between a
distal segment of tubing and a proximal segment of tubing. The
system includes a disposable subsystem (96) having a bypass cannula (110) adapted to engage the sampling site, a reservoir (112) for drawing a prime volume of fluid past the sampling site, and a fluid sampling container (114). A 3-way
stopcock (116) may connect the reservoir, bypass cannula, and sampling vessel for controlling the sampling procedure. The bypass cannula (110) may simultaneously place the subsystem into fluid communication with an inner chamber (136) of the sampling site and exclude the proximal segment of the conduit line. Alternatively, a
stopcock immediately adjacent the sampling site in the proximal segment may be utilized. A method of using the
system includes attaching the disposable subsystem, opening the reservoir to the
distal segment while excluding the proximal segment, drawing a prime volume of fluid into the reservoir, opening the sampling vessel to the
distal segment and drawing a sample, re-infusing the prime volume into the distal segment, and removing and discarding the subsystem. The reservoir remains attached between the prime volume draw and re-infusion and is thus 'closed'.