An Evaluation of a New Analyser for Inhaled Nitric Oxide Administration

Abstract

We examined the ability of a new combined nitric oxide (NO)/nitrogen dioxide (NO₂) electrochemical analyser (PrinterNO_x, Micro Medical Limited, Chatham, Kent, England) to measure NO and NO₂ concentrations.

The PrinterNO_x was compared to a chemiluminescence analyser (42H, Thermo Environmental Instruments Inc, Franklin MA, U.S.A.). NO and NO₂ were generated in a standard ventilator circuit using a paediatric ventilator (900C, Siemens Elema, Sweden) connected to an artificial lung (260li, TTL Test Lung, Michigan Instruments, MI, U.S.A.). Forty-four paired NO measurements ranging from 2.56 ppm to 74.6 ppm and 50 paired NO₂ measurements ranging from 0.0 ppm to 5.39 ppm were obtained.

For the measurement of NO the PrinterNO_x showed a tendency to overestimate the chemiluminescence analyser. Regression analysis showed a close relationship between the two analysers with r²=0.9981 and a regression equation of y=1.1658 x +0.0197. In the more clinically important range of 0-25 ppm, r² increased to 0.9996 with a regression equation of y=1.1984 x -0.4657. Conversely the PrinterNO_x underestimated the chemiluminescence analyser for the measurement of NO₂. The regression equation describing this relationship was y=0.879 x -0.0447 (r²=0.9993).

We conclude that the PrinterNO_x is of sufficient accuracy to be of clinical use in the administration of NO.