Arterial and transcutaneous variability and agreement between multiple successive measurements of carbon dioxide in patients with chronic obstructive lung disease.

PURPOSE: This study evaluates agreement between carbon dioxide measured arterial (PaCO2) and transcutaneous (PtcCO2) over time, by repeated successive measures, taking into consideration the inherent variability of arterial measurements. METHODS AND RESULTS: 11 patients receiving LTOT, with severe to very severe COPD in a stable phase were studied. Repeated arterial blood samples were drawn and PtcCO2 measured simultaneously at the ear lobe. Bland-Altman analysis was used to evaluate 95 % limits of agreement (LoA). 194 paired samples were analysed. Following correction for bias, the difference between PaCO2 and PtCO2 during dynamic conditions was 0.02 kPa and LoA 0.94 to -0.90 kPa while 29 % of PtCO2 measurements were outside the range of variability for arterial measurements. CONCLUSION: PtcCO2 corrected for intra-patient bias provide reasonable description of PaCO2 values within but not outside steady state conditions. Our results suggest that PtcCO2 is a valuable method for monitoring in chronic rather than acute conditions when bias can be removed.

The majority of participants with abnormal spirometry at walk-in consult their general practitioner as recommended.

INTRODUCTION: A number of studies inviting citizens to perform spirometry without need for a previous appointment have been performed to determine the need for general screening of the population for chronic obstructive pulmonary disease (COPD). Yet, no studies have examined how many of the participants follow the advice given to consult their general practitioner (GP) afterwards. METHODS: A walk-in spirometry was carried out on the island of Laesoe. All habitants above the age of 18 years were invited. In total, 142 were eligible for the study. Participants with an abnormal spirometry were recommended to consult their GP immediately, whereas smokers with symptoms, but with a normal spirometry, were recommended to consult their GP within a year for another spirometry. A follow-up was performed to investigate whether the participants had followed this advice. RESULTS: In total, 52% (74/142) of the participants were advised to contact their GP: 34 due to an abnormal spirometry and 40 due to smoking and respiratory symptoms. Among the participants with an abnormal spirometry, 79% saw their GP within three months, whereas 30% of the current smokers saw their GP within 9-15 months. Lung disease was diagnosed in 56% (19/34) of the participants who initially had an abnormal spirometry. CONCLUSIONS: Among the participants who had an abnormal spirometry at screening, 79% consulted their GP as recommended. Furthermore, 52% of the participants who had an abnormal spirometry were subsequently diagnosed with pulmonary disease by their GP. We conclude that walk-in spirometry is a useful tool for early diagnosis of COPD. FUNDING: none. TRIAL REGISTRATION: not relevant.