Premium
Oxygraphy in spontaneously breathing subjects
Author(s) -
LARSEN V. H.,
WALDAU T.,
ØBERG B.
Publication year - 1995
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1995.tb04338.x
Subject(s) - medicine , arterial blood , airway , breathing , anesthesia , partial pressure , exhalation , oxygen , respiratory system , cardiology , chemistry , organic chemistry
Background: Continuous monitoring of O 2 and CO 2 in the airways of spontaneously breathing patients can be carried out by sampling air to a gas monitor through a catheter placed in the upper airway. The graphical display of O 2 (oxygraphy) is a rather new facility. Objective: To describe the photo‐acoustic and magneto‐acoustic technique for CO 2 and O 2 monitoring in the open unintubated airway, to evaluate the efficacy of oxygen therapy by oxygraphy and to determine alveolar gas tensions and alveolar‐arterial partial pressure gradients. Data sources: O 2 and CO 2 fractions in the airways were monitored in 9 healthy subjects. Blood samples were drawn from the radial artery. Methods: The Multigas Monitor 1304 (Brüel and Kjær, Naerum, Denmark) was used; end‐expiratory measurements were considered as representative for the alveolar gas composition. Arterial blood was analysed by ABL™520 (Radiometer Medical A/S, Copenhagen, Denmark). Results: Reliable tracings of gas fractions ( F CO 2 and F O 2 ) were obtained during the respiratory cycle in all subjects. When oxygen was supplied, F O 2 of the airway varied considerably during the inspiratory phase whereas it remained almost constantly during the expiratory phase. The end‐expiratory F O 2 increased from 0. 15 breathing atmospheric air to 0. 41 breathing oxygen 15 L/min through a Hudson mask. Alveolar‐arterial partial pressure differences were: p O 2 (A‐a): 1. 07 ± 0. 85 kPa and p CO 2 (A‐a): ‐0. 04 ± 0. 33 kPa during norrnoventilation in atmospheric air. Conclusion: Continuous monitoring of CO 2 and O 2 in the airway gives information about the pulmonary gas exchange and the efficacy of oxygen supply. Combined with arterial blood gas analysis the method allows determination of alveolar‐arterial CO 2 or O 2 gradients.