Abstract
Introduction: We are interested in using the change in gas transfer from sitting to supine in patients with various lung diseases, but were unable to find any published studies showing how long a subject should be supine before a stable representative measurement could be made. We looked at this in healthy subjects first.
Method: We measured single breath gas transfer (TLCO & KCO) using a MasterScreen lung function system (Jaeger Ltd, Hochburg, Germany) 3 times sitting at rest and then after approximately 10, 15, 20, 25 & 30 minutes respectively, lying supine in 14 healthy subjects (11F:3M; Ages: 22-51 years).
Results: The results (Table 1) show that TLCO and KCO increase by about 9% and 15% respectively and VAeff decreases by 5% from sitting to supine. Stability is reached after 15 minutes.
Discussion: We have shown that changes in gas transfer when supine stabilise after 15 minutes. Unexpectedly, not all subjects showed an increase gas transfer, with 6 showing no increase or a slight decrease when supine. This result needs further explanation.
Conclusion: Supine gas transfer should be measured after 15minutes lying supine. Not all subjects produced an increase in gas tarnsfer when supine.
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