Validity of arterialised-venous P CO2, pH and bicarbonate in obesity hypoventilation syndrome

Abstract

This prospective study investigated the validity of arterialised-venous blood gases (AVBG) for estimating arterial carbon dioxide P CO2, pH and bicarbonate (HCO3(-)) in people with obesity hypoventilation syndrome (OHS). AVBGs were obtained from an upper limb vein, after heating the skin at 42-46°C. Arterial blood gas (ABG) and AVBG samples were taken simultaneously and compared using Bland Altman analysis. Between-group differences were assessed with independent t-tests or Mann-Whitney U tests. Forty-two viable paired samples were analysed, including 27 paired samples from 15 OHS participants, and 15 paired samples from 16 controls. AVBG-ABG agreement was not different between groups, or between dorsal hand, forearm and antecubital AVBG sampling sites, and was clinically acceptable for P Co2: mean difference (MD) 0.4 mmHg (0.9%), limits of agreement (LOA) -2.7-3.6 mmHg (± 6.6%); pH: MD -0.008 (-0.1%), LOA -0.023-0.008 (± 0.2%); and HCO3(-): MD -0.3 mmol L(-1) (-1.0%), LOA -1.8-1.2 mmol L(-1) (± 5.3%). AVBG provides valid measures of [Formula: see text] , pH, and HCO3(-) in OHS.

Keywords: %bias; %error; ABG; AVBG; Arterialised-venous; Blood gas; CI; CO(2); Carbon dioxide; HCO(3)(−); HRF; LOA; MD; O(2); OHS; Obesity; Obesity hypoventilation syndrome; Oxygen; PAP; SD; Validation; arterial blood gas; arterial partial pressure of carbon dioxide; arterialised-venous blood gas; arterialised-venous partial pressure of carbon dioxide; bicarbonate; confidence interval; degrees celsius; hypercapnic respiratory failure; limits of agreement; limits of agreement represented as a percentage; mean difference; mean difference represented as a percentage; obesity hypoventilation syndrome; partial pressure of carbon dioxide; positive airway pressure; standard deviation; °C.