Limits...
Improved in vivo performance of amperometric oxygen (PO2) sensing catheters via electrochemical nitric oxide generation/release.

Ren H, Coughlin MA, Major TC, Aiello S, Rojas Pena A, Bartlett RH, Meyerhoff ME - Anal. Chem. (2015)

Bottom Line: 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 in vivo sensing of the partial pressure of oxygen (PO2) in blood.The on-demand electrochemical NO generation/release method is shown to be fully compatible with amperometric PO2 sensing.This electrochemical NO generation/release method could offer a new and attractive means to improve the biocompatibility and performance of implantable chemical sensors.

View Article: PubMed Central - PubMed

Affiliation: †Departments of Chemistry and ‡Surgery, University of Michigan, Ann Arbor, Michigan 48109-1055, United States.

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 in vivo sensing of the partial pressure of oxygen (PO2) in blood. The on-demand electrochemical NO generation/release method is shown to be fully compatible with amperometric PO2 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 PO2 values more accurately with an average deviation of -2 ± 11% and good correlation (R(2) = 0.97) with in vitro blood measurements, whereas the corresponding control sensors without NO release show an average deviation of -31 ± 28% and poor correlation (R(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 (p < 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.

Show MeSH

Related in: MedlinePlus

Performanceof electrochemical NO generating/releasing PO2 sensors implanted in rabbit veins for 7 h:(a) representative sensor response for a NO releasing sensor (black)and a control sensor (red) compared with blood draw in vitro test values (blue square); the FiO2 levels were changedpurposely between 100% and 21% (dash dot) to vary venous PO2; (b) representative photo illustrating the degree ofclot formation on the surface of the control and the NO releasingsensors after being explanted; (c) average thrombus coverage percentageon NO releasing sensors vs control sensors (n = 5rabbits, p < 0.05); (d) average deviation of theNO releasing sensors (black) and control sensors (red) from the referencemethod (blue). Error bars indicate standard deviation.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4556045&req=5

fig2: Performanceof electrochemical NO generating/releasing PO2 sensors implanted in rabbit veins for 7 h:(a) representative sensor response for a NO releasing sensor (black)and a control sensor (red) compared with blood draw in vitro test values (blue square); the FiO2 levels were changedpurposely between 100% and 21% (dash dot) to vary venous PO2; (b) representative photo illustrating the degree ofclot formation on the surface of the control and the NO releasingsensors after being explanted; (c) average thrombus coverage percentageon NO releasing sensors vs control sensors (n = 5rabbits, p < 0.05); (d) average deviation of theNO releasing sensors (black) and control sensors (red) from the referencemethod (blue). Error bars indicate standard deviation.

Mentions: The catheter-type PO2 sensors were first studied in rabbit veinsover a 7 h period. The sensors were purposely challenged with lowervenous PO2 levels during the latter periodof the experiment, by switching the FiO2 from 100% to 21%.The NO releasing sensors measured the PO2 levels accurately and were able to follow both the decrease of PO2 at the ∼4 h time point and the recoveryof PO2 at the ∼5.5 h time point(see Figure 2a as representativeexample). In contrast, the signal from the control sensors startedto deviate negatively during the latter time period of the experiment,and although the sensors responded to a decrease of PO2 at ca. the ∼4 h mark, the levels measured werenot accurate (negative deviation from in vitro blood-gasinstrument values) and the responses were not able to fully recoverwhen the PO2 is changed to the higherlevel via increasing the FiO2 level. This was due to theformation of the large blood clots on the control sensor (see Figure 2b, as an example).Thrombus formation around the catheter surface can create a localenvironment that has lower O2 level because of the consumptionof oxygen by platelets and other cells within the clot.9 Overall, the NO releasing sensors induced lessclot formation than the control sensors as measured by imaging thesurface of the catheters after explantation from the rabbit after7 h (see Figure 2cfor data for n = 5 rabbits, p <0.05).


Improved in vivo performance of amperometric oxygen (PO2) sensing catheters via electrochemical nitric oxide generation/release.

Ren H, Coughlin MA, Major TC, Aiello S, Rojas Pena A, Bartlett RH, Meyerhoff ME - Anal. Chem. (2015)

Performanceof electrochemical NO generating/releasing PO2 sensors implanted in rabbit veins for 7 h:(a) representative sensor response for a NO releasing sensor (black)and a control sensor (red) compared with blood draw in vitro test values (blue square); the FiO2 levels were changedpurposely between 100% and 21% (dash dot) to vary venous PO2; (b) representative photo illustrating the degree ofclot formation on the surface of the control and the NO releasingsensors after being explanted; (c) average thrombus coverage percentageon NO releasing sensors vs control sensors (n = 5rabbits, p < 0.05); (d) average deviation of theNO releasing sensors (black) and control sensors (red) from the referencemethod (blue). Error bars indicate standard deviation.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556045&req=5

fig2: Performanceof electrochemical NO generating/releasing PO2 sensors implanted in rabbit veins for 7 h:(a) representative sensor response for a NO releasing sensor (black)and a control sensor (red) compared with blood draw in vitro test values (blue square); the FiO2 levels were changedpurposely between 100% and 21% (dash dot) to vary venous PO2; (b) representative photo illustrating the degree ofclot formation on the surface of the control and the NO releasingsensors after being explanted; (c) average thrombus coverage percentageon NO releasing sensors vs control sensors (n = 5rabbits, p < 0.05); (d) average deviation of theNO releasing sensors (black) and control sensors (red) from the referencemethod (blue). Error bars indicate standard deviation.
Mentions: The catheter-type PO2 sensors were first studied in rabbit veinsover a 7 h period. The sensors were purposely challenged with lowervenous PO2 levels during the latter periodof the experiment, by switching the FiO2 from 100% to 21%.The NO releasing sensors measured the PO2 levels accurately and were able to follow both the decrease of PO2 at the ∼4 h time point and the recoveryof PO2 at the ∼5.5 h time point(see Figure 2a as representativeexample). In contrast, the signal from the control sensors startedto deviate negatively during the latter time period of the experiment,and although the sensors responded to a decrease of PO2 at ca. the ∼4 h mark, the levels measured werenot accurate (negative deviation from in vitro blood-gasinstrument values) and the responses were not able to fully recoverwhen the PO2 is changed to the higherlevel via increasing the FiO2 level. This was due to theformation of the large blood clots on the control sensor (see Figure 2b, as an example).Thrombus formation around the catheter surface can create a localenvironment that has lower O2 level because of the consumptionof oxygen by platelets and other cells within the clot.9 Overall, the NO releasing sensors induced lessclot formation than the control sensors as measured by imaging thesurface of the catheters after explantation from the rabbit after7 h (see Figure 2cfor data for n = 5 rabbits, p <0.05).

Bottom Line: 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 in vivo sensing of the partial pressure of oxygen (PO2) in blood.The on-demand electrochemical NO generation/release method is shown to be fully compatible with amperometric PO2 sensing.This electrochemical NO generation/release method could offer a new and attractive means to improve the biocompatibility and performance of implantable chemical sensors.

View Article: PubMed Central - PubMed

Affiliation: †Departments of Chemistry and ‡Surgery, University of Michigan, Ann Arbor, Michigan 48109-1055, United States.

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 in vivo sensing of the partial pressure of oxygen (PO2) in blood. The on-demand electrochemical NO generation/release method is shown to be fully compatible with amperometric PO2 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 PO2 values more accurately with an average deviation of -2 ± 11% and good correlation (R(2) = 0.97) with in vitro blood measurements, whereas the corresponding control sensors without NO release show an average deviation of -31 ± 28% and poor correlation (R(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 (p < 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.

Show MeSH
Related in: MedlinePlus