P65 Is serum N-terminal pro B type natriuretic peptide (NT-proBNP) measurement useful in the investigation of unilateral pleural effusions?--a prospective observational study

Abstract

variability of the artery were described and then analysed for association with clinical factors using a random effects regression model. Results 298 arteries were analysed from 48 patients (mean age 60 years). The mean lateral distance from the spine over which the artery was exposed within the intercostal space ('unsafe artery length') was 39 mm with wide variability (SD¼10 mm, 10th to 90th centile 28 mm to 51 mm, Abstract P64 Figure 1A). At 3 cm lateral distance from the spine 16.6% of arteries were shielded by the superior rib, compared to 96.6% at 6 cm. Unsafe artery length was not associated with age, sex, rib space or side. Using regression modelling, variability of arterial position (as SD and coefficient of variation) was significantly associated with age (coeff 0.91, p<0.001) and rib space number (coeff À2.60, p<0.001) (Abstract P64 Figure 1B). Variability of arterial position was strongly negatively correlated with lateral distance from the spine (Pearson's À0.77, p<0.001). Abstract P64 Figure 1 (A). Position of artery as proportion of inter-rib distance (%). (B). Position of intercostal artery as proportion of inter-rib distance (%).Conclusions The intercostal artery is exposed within the intercostal space in the first 6 cm lateral to the spine; variability of its vertical position is greater in older patients and more cephalad rib spaces. This implies that pleural interventions within 6 cm lateral to the spine should be conducted with caution and that the risk of intercostal artery laceration is potentially higher in older patients and more cephalad rib spaces. Measurement of serum NT-proBNP has been proposed in the investigation of pleural effusions, particularly in the diagnosis of cardiac failure in those misclassified as exudates by Light's criteria. Studies have reported excellent diagnostic accuracy for the test but have included both bilateral and unilateral effusions and applied short follow-up periods. We prospectively examined the diagnostic utility of serum NT-proBNP in a consecutive series of unilateral pleural effusions with robust follow-up and diagnostic criteria. Method Consecutive patients presenting to a UK teaching hospital with an undiagnosed unilateral pleural effusion underwent clinical assessment including CXR, ECG, echocardiogram, thoracentesis (and CTwhen appropriate). Light's criteria were applied. Serum NTproBNP was measured using point of care ELISA. Patients were followed up to histological/microbiological diagnosis, radiographic resolution or 12 months. Echocardiograms were double reported and diagnosis determined independently by two respiratory consultantsdall blind to NT-proBNP results. . At cut-off of age and sex adjusted 97.5th centile (healthy population) NT-proBNP had sensitivity 100%, Specificity 53%, PPV 30% and NPV 100% and all four cardiac exudates were correctly diagnosed. At an optimum cutoff of 1500 pg/mldsensitivity 75%, specificity 76%, PPV 38% and NPV 94%. Co-morbid cardiac disease was common in patients without a PCC for effusion with 70% having signif...