A self-powered constant infusion device for use in unrestrained rats

We developed a device that delivers fluid through a catheter at a constant rate and can be used in conscious animals to solve a variety of problems. F or example, this device can be used for delivering drugs and maintaining in travascular catheter patency. The device provides infusions at low flows (1 .0-1.5 ml/day), so that experimental agents may be administered with minima l volume loading of the rat. Arterial and venous catheter patency is mainta ined by infusion of heparinized saline through indwelling catheters attache d to the device. The catheters exit from the rat in the intrascapular area and are routed through a protective spring to the device, which is suspende d above the cage. The catheters may be attached to pressure transducers, bl ood may be sampled, and injections or infusions may be made without disturb ing the rat. Because the device is self-contained, it can be suspended by a fluid-free swivel that rotates through 360 degrees, providing minimal rest raint. The device has been used successfully to measure arterial and centra l venous blood pressures in two studies using rats.