title: Capillary blood gases in acute exacerbations of COPD.
abstract: OBJECTIVE
  To assess the correlation and agreement between measurements of PO(2), PCO(2), H(+) and HCO(3)(-) in arterial and capillary blood in patients with acute exacerbations of COPD. To assess the repeatability of capillary measurements.
  
  
  METHODS
  Method comparison study.
  
  
  METHODS
  Accident and emergency department in a university teaching hospital.
  
  
  METHODS
  Measurements of PO(2), PCO(2), H(+) and HCO(3)(-) in one arterial and two capillary samples taken from consecutive patients with acute exacerbations of COPD.
  
  
  RESULTS
  The agreement between measurements of PCO(2), H(+) and HCO(3)(-) in arterial and capillary blood was good with mean differences of 0.087 kPa, 1.044 nmol/l and 0.513 mmol/l, respectively. The corresponding 95% limits of agreement were narrow. The agreement between measurements of PO(2) was poor with a mean difference of 1.256 kPa and wide 95% limits of agreement. There was good repeatability between capillary samples with mean differences of 0.094 kPa, 0.674 nmol/l and 0.028 mmol/l for measurements of PCO(2), H(+) and HCO(3) respectively and narrow coefficients of repeatability.
  
  
  CONCLUSIONS
  Capillary blood gas measurements provide an accurate assessment of PCO(2), H(+) and HCO(3)(-) and can be used to reliably measure the ventilatory status of patients. Combined with continuous pulse oximetry they can be used as an alternative to arterial blood gas measurements in patients with acute exacerbations of COPD.
authors.affiliation: Department of Accident and Emergency Medicine, The Royal Infirmary of Edinburgh, Old Dalkeith Road, Little France, Edinburgh EH16 4SU, UK.
authors.forename: Ross
authors.initials: R
authors.lastname: Murphy
authors.forename: Sanjeet
authors.initials: S
authors.lastname: Thethy
authors.forename: Simon
authors.initials: S
authors.lastname: Raby
authors.forename: Jean
authors.initials: J
authors.lastname: Beckley
authors.forename: John
authors.initials: J
authors.lastname: Terrace
authors.forename: Christine
authors.initials: C
authors.lastname: Fiddler
authors.forename: Michelle
authors.initials: M
authors.lastname: Craig
authors.forename: Colin
authors.initials: C
authors.lastname: Robertson
mesh_terms: D000208:Acute Disease; D001784:Blood Gas Analysis / Q000379:methods; D002196:Capillaries; D004423:Ear / Q000098:blood supply; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood*; D017534:Radial Artery; D015203:Reproducibility of Results