Dialyzers coil dialyzer

Kolf s first tubular dialyzer, shown in Figure 12.2, required several liters of blood to prime the system, a major operational problem. In the 1950s, tubular dialyzers were replaced with coil (spiral) devices, also developed by Kolf and coworkers. This coil system was the basis for the first disposable dialyzer produced commercially in the early 1960s. The blood volume required to prime the device was still excessive, however, and during the 1960s the plate-and-frame and hollow fiber devices shown in Figure 12.3 were developed. In the US in 1975, about 65 % of all dialyzers were coil, 20 % hollow fiber systems and 15 % plate-and-frame. Within 10 years the coil dialyzer had essentially disappeared, and the market was divided two-thirds hollow fibers and one-third plate-and-frame. By 1996, hollow fiber dialyzers had more than 95 % of the market. 

The fact that dialysis is slow does not mean that it cannot be used efficiently or quickly. For example, the Autoanalyzer contains a dialyzer unit for biological materials. If you pass the sample through the dialyzer coils, only a few percent of the ions or molecules transfer before the sample passes through. However, this is a very reproducible few percent, and it is easy to quantitate these materials. 

Based on the membrane design and configuration, there are three types of dialyzers available. The design of the membrane is crucial to determine the efficiency of the dialysis (how much and how sufficiently the blood can be filtered). The basic membrane designs for dialyzers are hollow fiber, parallel plate and coil dialyzers, and each one has its own disadvantages and advantages over the other, but all of them ultimately have the same function. 

Dialysis patients do not produce much urine. As a result, they retain large amounts of water between dialysis treatments, which produces a strain on the heart. The intake of fluids for a dialysis patient may be lestrieted to as little as a few teaspoons of water a day. In the dialysis procedure, the pressure of the blood is increased as it circulates through the dialyzing coil so water can be squeezed out of the blood. For some dialysis patients, 2 to 10 L of water may be removed... 

FIGURE 21.1-2 Basic dialyzer configurations (A) plate-and-franie, (B) coil and (C) hollow fiber. (Courtesy ofTravenol Laboratories, Deerfield. IL.)... 

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