COPD patients. Our data are also in agreement with the suggestion by Z.L. Borrill and coworkers that a deaeration- caused pH change is a surrogate for CO 2 concentration to some extent; however, a simple pH measurement cannot give an estimate of the remaining CO 2 content that may still influence the pH reading. In summary, argon deaeration decreases the concentration and the variability of exhaled breath condensate partial pressure of CO 2 , but there is always some remaining CO 2 that may still be a confounding factor in pH assessment. CO 2 content has a marked influence on exhaled breath condensate pH and, since exhaled breath condensate partial pressure of CO 2 varies even after deaeration, it leaves some uncertainty in the exhaled breath condensate pH reading even after deaeration. It seems worthwhile to carry out some more research to define other potential modes of standardisation of this measurement, to learn more about the different factors that may influence exhaled breath condensate pH and the relationship between the pH of exhaled breath condensate and that of the airways. I. Horvath, B. Szili and T. Kullmann Dept of Pathophysiology, National Koranyi Institute for Pulmonology, Budapest, Hungary. A physiological–social score for triaging of pandemic influenza patients To the Editors: We read with interest the endorsement of ‘‘barefoot medicine’’ by EWIG et al. [1] in a recent issue of the European Respiratory Journal. As with NIEDERMAN et al. [2], we recognise the limitations of CURB-65 (confusion, urea .7 mmol?L -1 , respira- tory rate o30?min -1 , low blood pressure, and aged o65 yrs) scoring but the importance of its simplicity and ease of use. As part of the planning for a potential H5N1 influenza pandemic, using Dept of Health and Health Protection Agency projections [3], we have been forced to acknowledge that our urban emergency department, which normally sees ,250 patients?day -1 , will see 450 excess attenders?day -1 with influenza symptoms at a pandemic peak. We aimed to develop a rapidly applicable, purely clinical scoring system for use in primary and secondary care, to identify those in need of hospital admission and to reassure those fit for discharge. We suggest that the ideal score should reflect acute physiological derangement, as well as accommodating age, comorbidities and social factors, and could be used to triage and track for admission, intensive care unit (ICU) treatment and mortality. We believe that our proposed system has gone some way towards addressing this. We modified our hospital pandemic medical early warning score (PMEWS) [4] to include transcutaneous oxygen satura- tion. We also concur with EWIG et al. [1] and NIEDERMAN et al. [2] that comorbidities and social factors have to be taken into account when making admission and discharge decisions, and our score incorporates an extra point for being aged o65 yrs and another single point for any of the following: 1) social isolation (defined as living alone or having no fixed abode); 2) chronic disease (respiratory, cardiac, renal, diabetes mellitus or immunosuppression of any cause); or 3) performance status of limited activity or worse (modified Karnofsky .2 [5]). The validation of 195 adult patients (101 aged ,65 yrs) with a diagnosis of lower respiratory tract infection presenting to our emergency department (South Manchester University Hospitals Trust, Manchester, UK) between February and December 2005 showed good discrimination for the physio- logical section of the score, which was further improved by the addition of age and social factors. We retrospectively calcu- lated PMEWS, CURB-65 and CRB-65 scores from emergency department medical and nursing notes, and constructed receiver-operating characteristics (ROC) curves for the predic- tion of admission (fig. 1). PMEWS without the transcutaneous oxygen saturation component is shown as we recognise that not all primary care providers will have access to a pulse oximeter. We extended this to assess the value of the PMEWS score in predicting requirements for higher levels of care. Figure 2 shows the ROC curves for discrimination of need for high                                       FIGURE 2. The effect of gas standardisation on exhaled breath condensate (EBC) pH. This study was supported by the Hungarian National Research Foundation (T43396). c EUROPEAN RESPIRATORY JOURNAL VOLUME 28 NUMBER 1 253