The following information is provided to assist the reader to understand the devices, systems and/or methods described herein and the environment in which such devices, systems and/or methods will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless clearly stated otherwise in this document. References set forth herein may facilitate understanding of the devices, systems and/or methods or the background. The disclosure of all references cited herein are incorporated by reference.
In many medical procedures, such as drug delivery, it is desirable to inject a fluid into a patient. Likewise, numerous types of contrast media (often referred to simply as contrast) are injected into a patient for many diagnostic and therapeutic imaging procedures. For example, contrast media are used in diagnostic procedures such as X-ray procedures (including, for example, angiography, venography and urography), CT scanning, magnetic resonance imaging (MRI), and ultrasonic imaging. Contrast media are also used during therapeutic procedures, including, for example, angioplasty and other interventional radiological procedures. Regardless of the type of procedure, any fluid injected into the patient must be sterile and contain a minimum of pyrogens.
In the case of relatively high pressure applications, such as CT and angiography, mechanized syringe injectors are often used. In general, syringe pumps can deliver a fluid with good control of both pressure and flow rate. However, flow rate acceleration of syringe injectors is limited by the inertia of the extensive drive train required to translate motor rotation into syringe plunger motion. Moreover, syringe pumps are limited in that the maximum volume that can be injected at one time is the volume of the syringe.
Various pump systems for generally continuous delivery of fluids from large volume sources of fluid are available. However, it is often difficult to accurately control the pressure and flow rate of the fluid exiting the pumping system. In relatively low pressure applications, for example, peristaltic pumps have long been used. However, peristaltic pumps are difficult to control with accuracy.
Cost-effective and efficient pumping systems including a plurality of pressurizing members actuated in a timed manner to provide pressurization for injection of contrast and other liquid media are, for example, described in U.S. Pat. Nos. 6,197,000 and 5,916,197. Although such pumps provide good control of pressure and flow rate, some variance in the pressure and/or flow rate can be experienced. Timed or sequential actuation of a plurality of pressurizing member or elements (for example, pistons, vanes, etc.) can, for example, result in pulsatile variations in pressure and/or flow rate. In general, pulsatile variations are repetitive variations or variations that occur with a certain frequency (for example, the frequency of activation of the pressurizing member(s)). U.S. patent application Ser. No. 12/974,549 discloses a number of compensating systems to reduce pulsatile flow in pump systems including a plurality of pressurizing members actuated in a timed manner.