Construction and uses of a concentric catheter for gas sampling in lung airways

N. Gavriely*, J. Solway, D. Elad, Y. Shabtai-Musih, D. P. Gaver, J. B. Grotberg, J. M. Drazen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A catheter for intra-airway sampling of gas concentrations was constructed from concentric polyethylene tubes. The internal tube (0.58 mm ID, 0.91 mm OD) was connected to a gas analyzer while the external tube (1.20 mm ID, 1.75 mm OD) was constantly flushed by air or a calibration gas, except during sampling. Injection and sampling dead spaces were 0.35 and 0.28 ml, respectively. Delay at 4-ml/min sampling rate was 4.0 ± 0.2 s. The 0-90% step response to a sudden change in gas composition was 0.24 s when connected to a mass spectrometer. This catheter was used to assess tracer gas dispersion during oscillatory flow (1-20 Hz) in a straight long tube. Local concentrations measured through the catheter, after a small bolus of tracer gas was injected through the external tube, compared favorably with direct measurements through needles inserted via the tube wall and with theoretical predictions. The catheter was also used to measure intra-airway gas concentrations in dog airways during spontaneous breathing, conventional mechanical ventilation, high-frequency ventilation, high-frequency vibration ventilation, and constant-flow ventilation. It was placed by a fiber-optic bronchoscope and used to measure local quasi-steady concentrations of CO2 and local dispersion with the bolus method. The occurrence of catheter clogging with secretions was substantially reduced with flow through the external tube. Transmitting a calibration gas through the external tube facilitated in situ recalibration of the gas analyzer without removing the catheter. The use of this catheter improved the efficiency and accuracy of measurements of gas concentrations inside lung airways.

Original languageEnglish
Pages (from-to)3063-3067
Number of pages5
JournalJournal of Applied Physiology
Volume74
Issue number6
DOIs
StatePublished - 1993
Externally publishedYes

Funding

FundersFunder number
National Heart, Lung, and Blood InstituteP01HL033009

    Keywords

    • alternative modes of ventilation
    • artificial ventilation
    • cardiogenic oscillations
    • high-frequency ventilation
    • pulmonary gas transport

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