Assessing the accuracy of pleural puncture sites as determined by clinic-radiological examination versus Lung Ultrasound- a prospective study.

Introduction: Ultrasound is the gold standard for determination of pleural puncture sites. The utility of clinico-radiological examination and its performance with reference to ultrasound has not been studied extensively. Physical signs of pleural effusion have not been studied with respect to ultrasound. Methods: Patients were examined clinicoradiologically by multiple physicians and a pleural puncture site was proposed and was confirmed via ultrasound. Response was characterized as true positive, true negative, false positive, or false negative. Upper and lower limits of pleural effusions were mapped and the distance of the first appearance of physical signs consistent with pleural effusion from the upper limit of pleural effusion was noted as a percentage of the total distance. Results: We enrolled 115 patients and 345 physician observations. Overall accuracy of the clinico-radiological examination was 94.8% with a sensitivity, specificity, PPV, NPV of 96.8 %, 92.4%, 93.8% and of 96% respectively. BMI (OR - 1.19) and lower zone pleural effusions (OR – 4.99) demonstrated significant role when adjusted for age, gender, side of effusion, and experience of examining doctors. Least accuracy was seen in lower zone pleural effusions, loculated pleural effusion and mid-zone pleural effusion. Conclusion: Clinico-radiologic determination of pleural puncture sites have reasonable overall accuracy. BMI and lower zone pleural effusions are significant factors of accuracy. We suggest use of ultrasound in lower zones limited effusions and/or patients with BMI > 23.15 kg/m2.