The advance of technology as a prelude to the laboratory of the twenty-first century.

Technological changes in the clinical laboratory are usually driven by the goal of patient care optimization. In the last decade, the trend appeared to be directed at clinical laboratory decentralization. A new generation of analytical instruments, the biosensors, is redirecting laboratory testing closer to the patient, at the bedside, in the physician's office, and by the patient at home. These miniaturized biosensors are easy to operate, require small specimen size, and provide reliable results with rapid TAT. Thus far, bedside testing using biosensor technology appears to offer unique opportunities for earlier availability of clinical laboratory data, decision making, and more specific diagnosis, and faster and more frequent monitoring; these may translate into improved patient care and reduced hospital costs. It is likely that this trend will continue into the twenty-first century. Electrochemical sensors (e.g., for electrolytes, glucose, urea, and hematocrit) and pulse oximetry, having gained clinical acceptance, will probably be the leading instrumentation for bedside testing. Continuous monitoring either by near-infrared sensing technology or with an implantable sensor is valuable in the care of the critically ill patient. Acceptance for clinical use will depend on complete data integration and a favorable cost-benefit ratio.