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Open Access Research article

Effects of acute hypoventilation and hyperventilation on exhaled carbon monoxide measurement in healthy volunteers

Franco Cavaliere1*, Carmen Volpe1, Riccardo Gargaruti1, Andrea Poscia2, Michele Di Donato2, Giovanni Grieco2 and Umberto Moscato2

Author Affiliations

1 Institute of Anaesthesia and Intensive Care, Catholic University of the Sacred Heart, Rome, Italy

2 Institute of Hygiene, Catholic University of the Sacred Heart, Rome, Italy

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BMC Pulmonary Medicine 2009, 9:51  doi:10.1186/1471-2466-9-51

Published: 23 December 2009

Abstract

Background

High levels of exhaled carbon monoxide (eCO) are a marker of airway or lung inflammation. We investigated whether hypo- or hyperventilation can affect measured values.

Methods

Ten healthy volunteers were trained to achieve sustained end-tidal CO2 (etCO2) concentrations of 30 (hyperventilation), 40 (normoventilation), and 50 mmHg (hypoventilation). As soon as target etCO2 values were achieved for 120 sec, exhaled breath was analyzed for eCO with a photoacoustic spectrometer. At etCO2 values of 30 and 40 mmHg exhaled breath was sampled both after a deep inspiration and after a normal one. All measurements were performed in two different environmental conditions: A) ambient CO concentration = 0.8 ppm and B) ambient CO concentration = 1.7 ppm.

Results

During normoventilation, eCO mean (standard deviation) was 11.5 (0.8) ppm; it decreased to 10.3 (0.8) ppm during hyperventilation (p < 0.01) and increased to 11.9 (0.8) ppm during hypoventilation (p < 0.01). eCO changes were less pronounced than the correspondent etCO2 changes (hyperventilation: 10% Vs 25% decrease; hypoventilation 3% Vs 25% increase). Taking a deep inspiration before breath sampling was associated with lower eCO values (p < 0.01), while environmental CO levels did not affect eCO measurement.

Conclusions

eCO measurements should not be performed during marked acute hyperventilation, like that induced in this study, but the influence of less pronounced hyperventilation or of hypoventilation is probably negligible in clinical practice