Corrections of Enghoffs dead space formula for shunt effects still overestimate Bohr's dead space
2013 (English)In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 189, no 1, 99-105 p.Article in journal (Refereed) Published
Dead space ratio is determined using Enghoffs modification (VDB-E/V-T) of Bohr's formula (V-DBohr/V-T) in which arterial is used as a surrogate of alveolar PCO2. In presence of intrapulmonary shunt Enghoffs approach overestimates dead space. In 40 lung-lavaged pigs we evaluated the Kuwabara's and Niklason's algorithms to correct for shunt effects and hypothesized that corrected VDB-E/V-T should provide similar values as V-DBohr/V-T. We analyzed 396 volumetric capnograms and arterial and mixed-venous blood samples to calculate V-DBohr/V-T and VDB-E/V-T. Thereafter, we corrected the latter for shunt effects using Kuwabara's (K) VDB-E/V-T and Niklason's (N) VDB-E/V-T algorithms. Uncorrected VDB-E/V-T (mean +/- SD of 0.70 +/- 0.10) overestimated V-DBohr/V-T (0.59 +/- 0.12) (p < 0.05), over the entire range of shunts. Mean (K) VDB-E/V-T was significantly higher than V-DBor/V-T (0.67 +/- 0.08, bias 0.085, limits of agreement 0.232 to 0.085; p< 0.05) whereas (N)VDB-E/V-T showed a better correction for shunt effects (0.64 +/- 0.09, bias 0.048, limits of agreement -0.168 to 0.072; p < 0.05). Neither Kuwabara's nor Niklason's algorithms were able to correct EnghofFs dead space formula for shunt effects.
Place, publisher, year, edition, pages
2013. Vol. 189, no 1, 99-105 p.
Dead space, Shunt, PEEP, Acute lung injury, Bohr's formula, V-D/V-T
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-211465DOI: 10.1016/j.resp.2013.06.020ISI: 000326059100014OAI: oai:DiVA.org:uu-211465DiVA: diva2:667150