Capnography reflects ventilation/perfusion distribution in a model of acute lung injury
2011 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 55, no 5, 597-606 p.Article in journal (Refereed) Published
Background: Changes in the shape of the capnogram may reflect changes in lung physiology. We studied the effect of different ventilation/perfusion ratios (V/Q) induced by positive end-expiratory pressures (PEEP) and lung recruitment on phase III slope (S(III) ) of volumetric capnograms. Methods: Seven lung-lavaged pigs received volume control ventilation at tidal volumes of 6 ml/kg. After a lung recruitment maneuver, open-lung PEEP (OL-PEEP) was defined at 2 cmH(2) O above the PEEP at the onset of lung collapse as identified by the maximum respiratory compliance during a decremental PEEP trial. Thereafter, six distinct PEEP levels either at OL-PEEP, 4 cmH(2) O above or below this level were applied in a random order, either with or without a prior lung recruitment maneuver. Ventilation-perfusion distribution (using multiple inert gas elimination technique), hemodynamics, blood gases and volumetric capnography data were recorded at the end of each condition (minute 40). Results: S (III) showed the lowest value whenever lung recruitment and OL-PEEP were jointly applied and was associated with the lowest dispersion of ventilation and perfusion (Disp(R-E) ), the lowest ratio of alveolar dead space to alveolar tidal volume (VD(alv) /VT(alv) ) and the lowest difference between arterial and end-tidal pCO(2) (Pa-ETCO(2) ). Spearman's rank correlations between S(III) and Disp(R-E) showed a ρ=0.85 with 95% CI for ρ (Fisher's Z-transformation) of 0.74-0.91, P<0.0001. Conclusion: In this experimental model of lung injury, changes in the phase III slope of the capnograms were directly correlated with the degree of ventilation/perfusion dispersion.
Place, publisher, year, edition, pages
2011. Vol. 55, no 5, 597-606 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-151480DOI: 10.1111/j.1399-6576.2011.02404.xISI: 000289365000015PubMedID: 21342153OAI: oai:DiVA.org:uu-151480DiVA: diva2:410083