Abstract: A pumping mechanism moving in movement increments is controlled to space those movement increments in direct proportion to the volume resulting from each movement increment. In a further aspect, movement increments are grouped to result in approximately equal volumes per group. The mechanism moves continuously through the movement increments in each group. Groups are spaced to result in approximately equal flow volumes per group. The number of groups decreases as the flow rate increases. The number of movement increments in each group and the volume of each group increase as the flow rate increases.

Abstract: A device for mounting a tonometry sensor upon a patient's wrist includes a base portion that is specifically adapted to generally conform to the patient's wrist while providing a stable placement of the tonometry sensor relative to a preselected artery. A sensor housing is movably mounted upon the base portion and configured such that the mounting device has an essentially equal thickness at each end of the device. A strap member is provided for releasably securing the mounting device to a patient's wrist. The mounting device facilitates more accurate, non-invasive blood pressure measurement by providing a stable placement of the tonometry sensor relative to the tissue overlying a preselected artery at a measurement location and, further, limits undesirable movement by the patient to thereby reduce undesirable error in the blood pressure measurement.

Abstract: An infusion system with an air-in-line sensor is provided with improved apparatus and method for quickly and easily clearing small quantities of undissolved gas such as air from the sensor detection field. The infusion system includes an infusion pump having control components responsive to the air-in-line sensor to activate an alarm and/or to cease pump operation when undissolved gas is detected. A "clear air" key or switch is provided on the pump for actuation by medical personnel to operate the pump in a manner delivering a small pulse of the infusion liquid to move a small detected quantity of gas past the air-in-line sensor. The system can be adapted for actuation of the "clear air" key up to a selected number of times, while monitoring and accumulating the total fluid quantity delivered to a patient.

Abstract: Impedance to fluid flow in a fluid delivery line is measured. Two techniques are used depending on the flow rate selected. For high flow rates, the pump is controlled to vary the flow rate and the change in pressure is divided by the change in flow to directly determine the resistance. For low flow rates, a processor controls the pump to pump flow quantities in accordance with a pseudo-random binary code. The resulting pressure signal sensed at the conduit is decoded in accordance with that code. Pressures received during code periods of no flow are subtracted from pressures received during code periods of flow. Pressure offset is also removed and a least squares estimation approach is used with a linear prediction model to determine impedance. The coefficients determined in the model are used to calculate the resistance to fluid flow of the system. A quality supervisor monitors the resistance determination process and controls the display of resistance depending on the quality determined.

Abstract: An interlock, latching and retaining mechanism for use in an infusion system, embodying a latch arm mounted to a rotatable shaft having a plurality of cams and gears attached thereto, a rectangular faceplate with a plurality of apertures formed therethrough, and a clamp. Rotating the latch arm functions to engage fluid monitoring, flow control and pumping structure of the infusion system with a pumping segment for control of fluid flow through the segment and also causes the clamp to hold the pumping segment in a required position. In another aspect, rotation of the latch arm additionally causes an air-in-line sensor to rotate into position on the pumping segment.

Abstract: An engineered pumping segment for facilitating efficient and accurate peristaltic pumping of fluids, providing regulation of fluid flow and providing an effective interface for sensing fluid line pressure in a peristaltic pump system. The engineered pumping segment includes an elastomeric membrane sandwiched between a rigid base and a rigid cover and a slider adapted to slidably mount about the base and cover. The membrane and base define a channel for fluid flow and the membrane, base and cover cooperate to facilitate peristaltic pumping of fluids through the engineered pumping segment and to provide a pressure sensing interface, and in combination with the slider, cooperate to regulate fluid flow.