Relationship between inhaling oxygen's flowing rate and respiratory depression in patients with chronic obstructive pulmonary disease plus carbon dioxide retention / 中华全科医师杂志

ABSTRACT

We observed 38 patients' breath frequency after different oxygen therapy according to their visit sequences and tolerance conditions.All patients with chronic obstructive pulmonary.disease (COPD) plus carbon dioxide retention from April 2008 to June 2011 were recruited at our hospital.Twentythree patients who could maintain SpO2≥92％ through inspiring O2 at ≤3.5 L/min were assigned into the first group.And another 15 subjects whose SpO2 could not reach 92％ at the same oxygen flow for 5 hours were assigned into the second group.The second group received an elevated oxygen flow until their SpO2 attained 92％ or so.But the maximal rate did not exceed 8 L/min even if SpO2 was below 92％.The state was maintained for 5 hours.Paired t-test showed PaO2 became elevated and PaCO2 decreased significantly on onset and termination of low oxygen flow in both groups.But the frequency of the second group's breaths per minute (BPM) had no significant differences.After elevating oxygen flow,the second group's BPM and PaCO2 on onset and termination were (19.4 ± 3.4) and (18.1 ± 2.6) perminute (P =0.038),(55.0 ±8.1) and (52.0 ±7.9) mm Hg (1 mm Hg =0.133 kPa) (P =0.030) respectively and the results showed significant decreases.But SpO2 was elevated [(85.8 ± 4.1) and (90.7 ± 2.4) mm Hg (P =0.000)].