Electrochemical Sensors for the Continuous Monitoring of Blood Gases and Electrolytes

Abstract

The demand for sensor technologies capable of continuously monitoring blood gas and electrolyte levels at the bedside of critically ill patients has increased considerably in recent years. Renewed interest in this area stems from the need to provide clinicians with better guidance for treating and managing such unstable patients, many of whom experience abrupt changes in the levels of these physiologically important parameters.

Improving the Thromboresistivity of Chemical Sensors via Nitric Oxide Release: Fabrication and in Vivo Evaluation of NO-Releasing Oxygen-Sensing Catheters

“…However, despite this barrier, platelet adhesion/activation on the surface of this outer tubing coupled with vasoconstriction at the implant site can result in significant analytical accuracy problems, 10-15 thus limiting the use of intravascular catheter sensors in humans. 34,35 The initial studies of NO-releasing catheter-style PO 2 sensors were based on SR coatings doped with the water-soluble diazeniumdiolate MAHMA/N 2 O 2 . This diazeniumdiolate is stable as a solid, but reacts spontaneously with water 36 to produce NO and a residual diamine, as shown in Figure 3.…”

“…The purpose of the silicone outer tube is to prevent both fouling of the working electrode by biological molecules and electrochemical reduction of interfering species. However, despite this barrier, platelet adhesion/activation on the surface of this outer tubing coupled with vasoconstriction at the implant site can result in significant analytical accuracy problems, − thus limiting the use of intravascular catheter sensors in humans. , …”

Thromboresistant Chemical Sensors Using Combined Nitric Oxide Release/Ion Sensing Polymeric Films

“…Efforts to develop implantable chemical sensors, both optical and electrochemical, capable of monitoring physiologically important ions (H + , K + , Na + , etc.) and gases (CO 2 and O 2 ) continuously via intra-arterial catheters have met with only limited success owing to the difficulties in fabricating fully functional analytical devices that are nonthrombogenic. , At the same time, placement of such miniaturized sensors within blood vessels can lead to vasoconstriction of arteries, thereby reducing blood flow which, in turn, can lead to sensor output signals that do not correlate with the true ion and/or gas levels within the bulk blood. Herein we demonstrate that it is now possible to fabricate chemical sensors that emit low levels of nitric oxide (NO), a potent platelet antiaggregation and vasodilating agent, over extended periods (days) without impairing the analytical performance of the sensing devices, and that the surfaces of the resulting sensors show a marked decrease in thrombogenic properties, as measured by in vitro platelet adhesion studies.…”