Capillary blood gases in acute exacerbations of COPD.
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.
Murphy
Ross
R
Department of Accident and Emergency Medicine, The Royal Infirmary of Edinburgh, Old Dalkeith Road, Little France, Edinburgh EH16 4SU, UK.
Thethy
Sanjeet
S
Raby
Simon
S
Beckley
Jean
J
Terrace
John
J
Fiddler
Christine
C
Craig
Michelle
M
Robertson
Colin
C
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