title: Assessments for oxygen therapy in COPD: are we under correcting arterial oxygen tensions?
abstract: There is little data about the use of different oxygen sources during assessment for long-term oxygen therapy (LTOT) and how this impacts upon blood oxygen tensions and prescribed flow rates. Patients with chronic obstructive pulmonary disease (COPD), n=30, had assessments for LTOT using both an oxygen-concentrator and piped hospital oxygen (wall-oxygen) as supply sources. In addition, a random survey of 64 hospitals was conducted to determine what source of oxygen supply was used during assessments. Wall-oxygen was used by 89% of hospitals to perform assessments. During assessments, the median oxygen flow required to achieve an arterial oxygen tension (Pa,O2) >8 kPa was significantly greater for an oxygen-concentrator than for wall-oxygen, with a median difference (range) in flow of 1 (0-3) L. This difference was most likely in those with an forced expiratory volume <30% of predicted. At an oxygen flow of 1 L.min(-1), the mean P(a,O2) using an oxygen-concentrator was significantly lower than that of the wall-oxygen value, with a difference of 1.32+/-1.19 kPa (mean+/-SD). The common practice of using wall-oxygen to perform assessments significantly underestimates the required oxygen-concentrator flow rate. This may have implications for the long-term effect of domiciliary oxygen therapy.
authors.affiliation: Dept of Respiratory and HIV Medicine, Royal Free Hospital, Pond Street, London, UK. k.dheda@ucl.ac.uk
authors.forename: K
authors.initials: K
authors.lastname: Dheda
authors.forename: K
authors.initials: K
authors.lastname: Lim
authors.forename: B
authors.initials: B
authors.lastname: Ollivere
authors.forename: J
authors.initials: J
authors.lastname: Leftley
authors.forename: F C
authors.initials: FC
authors.lastname: Lampe
authors.forename: A
authors.initials: A
authors.lastname: Salisbury
authors.forename: J P
authors.initials: JP
authors.lastname: Dilworth
authors.forename: R K
authors.initials: RK
authors.lastname: Rajakulasingam
authors.forename: R K
authors.initials: RK
authors.lastname: Rajakulasingum
mesh_terms: D001784:Blood Gas Analysis; D003430:Cross-Sectional Studies; D006801:Humans; D010100:Oxygen / Q000097:blood*; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy*; D018709:Statistics, Nonparametric
chemical_list: D010100:Oxygen