RT Journal Article
SR Electronic
T1 Time required for PaO2 equilibration in patients with severe COPD
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP p255
VO 38
IS Suppl 55
A1 Lars Pilegaard Thomsen
A1 Stephen Rees
A1 Ulla Weinreich
YR 2011
UL http://erj.ersjournals.com/content/38/Suppl_55/p255.abstract
AB Adjusting the inspired oxygen level in patients with COPD can be time consuming. Typically 30 minutes are waited before drawing an arterial sample to verify the PaO2 level.Consensus does not exist as to whether 30 minutes is a necessary period. Sherter et al. (Sherter, CB et al. Chest 1975; 67:259-261) showed that 20 minutes were required to return to baseline PaO2 after increased O2 in spontaneously breathing patients with COPD. In contrast, Sasse et al. (Sasse, SA et al. Am J Respir Crit Care Med 1995; 152(1):148-52) showed that 7 minutes were required to reach 90% of baseline PaO2 after an increase in O2 in mechanically ventilated patients with COPD. To the authors knowledge no study has investigated PaO2 equilibrium time following clinically relevant de- and increases in O2 in spontaneously breathing patients with COPD.This study investigated PaO2 equilibration time in 5 patients with severe COPD in stable state (mean FEV1% 26, mean MRC-score 4.2), by analysis of consecutively drawn ABG samples. The initial PaO2 level was measured by 2 ABG's at the patient's LTOT level (1-2 l/min). Hereafter, LTOT was discontinued or reduced. Blood samples were drawn after 1, 2, 4, 8, 12, 17, 22, 32, and 33 minutes to analyse the reduction in PaO2. Hereafter LTOT was set to the initial level and increase in PaO2 was analysed at the same time periods. The 90% equilibrium times for PaO2 were 5.3 (±2.8) min for the decrease and 5.4 (±0.4) min for the increase in O2.These results show a faster response to changes in FiO2 than seen previously, with similar response times for de- and increase in O2. Results indicate that it may be possible to reduce the time waited before evaluating ABG following changes in inspired oxygen.