Improved <i>in Vivo</i> Performance of Amperometric Oxygen (<i>P</i>O₂) Sensing Catheters via Electrochemical Nitric Oxide Generation/Release

Abstract

A novel electrochemically controlled release method for nitric oxide (NO) (based on electrochemical reduction of nitrite ions) is combined with an amperometric oxygen sensor within a dual lumen catheter configuration for the continuous <i>in vivo</i> sensing of the partial pressure of oxygen (<i>P</i>O₂) in blood. The on-demand electrochemical NO generation/release method is shown to be fully compatible with amperometric <i>P</i>O₂ sensing. The performance of the sensors is evaluated in rabbit veins and pig arteries for 7 and 21 h, respectively. Overall, the NO releasing sensors measure both venous and arterial <i>P</i>O₂ values more accurately with an average deviation of −2 ± 11% and good correlation (<i>R</i>² = 0.97) with <i>in vitro</i> blood measurements, whereas the corresponding control sensors without NO release show an average deviation of −31 ± 28% and poor correlation (<i>R</i>² = 0.43) at time points >4 h after implantation in veins and >6 h in arteries. The NO releasing sensors induce less thrombus formation on the catheter surface in both veins and arteries (<i>p</i> < 0.05). This electrochemical NO generation/release method could offer a new and attractive means to improve the biocompatibility and performance of implantable chemical sensors