Blood gas monitors

In vitro blood gas analysis requires limitation of the frequency of serial blood gas measurements for two major reasons--blood loss and cost. In vivo or ex vivo blood gas monitors eliminate these factors because the measurements are available continuously, or as frequently as deemed desirable, without permanently removing blood or imparting additional cost. For patients with arterial catheters in place, the propriety of blood gas monitors is obvious as long as there is no requirement to alter the size, location, or placement of the arterial catheter and the routine use of the arterial catheter system is unaffected. Further, personnel exposure to the patient's blood, and the risk of nosocomial infection from contaminated arterial catheters, should be reduced because the integrity of the arterial catheter and tubing system is not interrupted to obtain blood gas values. Blood gas monitors and point-of-care analyzers should significantly reduce therapeutic decision time (the interval from ordering the test to initiating a therapeutic action based on the test results), thereby enabling rapid titration of common therapeutic modalities such as oxygen administration, positive pressure ventilation, positive end-expiratory pressure, and manipulation of acid-base balance. The transfer of blood gas measurements from laboratory analyzers to the combination of blood gas monitors and point-of-care analyzers should have as profound an impact on acute care medicine as did the introduction of laboratory-based blood gas analysis over 30 years ago. In the current medico-economic environment, however, we must be certain that these devices are reliable, consistent, and cost beneficial in order to avoid widespread application of yet another technology that provides more data, greater costs, and only questionable patient benefits.