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Infusion Pumps are an effective pathway for delivering fluid, blood, and medicants to a patient's vital organs. Since the entire blood supply in a human body completely circulates within 60 seconds, substances introduced into the circulatory system are distributed rapidly. An infusion device typically consists of three major components: the fluid reservoir, a catheter system for transferring the fluids into the body, and most importantly, a device that combines electronics with a mechanism to generate and regulate flow. This regulation of the drug concentration in the body to achieve and maintain a desired result is highly critical, especially if prolonged underinfusion or overinfusion takes place. Although underinfusion may not provide sufficient therapy, overinfusion can produce even more serious toxic side effects.
The infusion of drugs requires high flow rate accuracy and flow uniformity. Sensors can be used to count the number of drops passing through the drip chamber to provide flow feedback for automatic rate adjustment and to detect any downstream occlusions directly below the pumping mechanism. However, flow rate accuracy remains limited by the rate and viscosity of the drip as well as improper angulation if in motion. Flow uniformity can also suffer at low flow rates from the discrete nature of the drop detector. Despite these limitations, a processor with an advanced graphical user interface, smart and real-time physiological processing, and wired and wireless connectivity options for patient monitoring and data logging applications provides an additional level of safety by quickly detecting complications and generating an alarm.
One alternative to the drop sensor is a volumetric metering chamber. A pump with a stepper or servo-controlled dc motor can be used to provide the driving force for the fluid by mechanized displacement of the contents in the volumetric chamber. The stepping resolution along with the chamber elasticity can influence the flow uniformity. When the volume is not uniform over the mechanism's cycle, software control can be used to compensate for the variation.
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