Abstract

Introduction Large scale epidemiological data of pleural fluid characteristics are lacking. We are an established pleural center with high rates of pleural malignancy in the North East of England. We aim to follow the British Thoracic Guidelines and sought to add to the body of evidence. Methodology All pleural aspirations done between January 1st 2014 and December 31st 2015 were analyzed for fluid biochemistry, microbiology and cytology and final diagnoses. Light's criteria were applied wherever possible. Results º Population: 264 patients º Average age: 74 years º Gender: 61% Male º Lung Cancer (n = 44) º 26/44 (59%) had positive first cytology º 15 had more than one sample taken, and in 6 patients, this provided the diagnosis (14%) º 36/44 (82%) were exudates º 4/44 (9%) were transudates º 3/44 had a pH < 7.21 º Heart Failure (n = 36) º 9/36 were exudates º Empyema (n = 16) º Only 2/16 (13%) had positive microbiology º 12/16 (75%) had a pH < 7.21 (2 did not have a pH sent) º 16/16 were exudates º Mesothelioma (n = 24) º 12/24 (50%) had positive first cytology º 19 went on to have further sampling (done at thoracoscopy). Only 2 further sample provided diagnosis º 2/24 had a protein < 25 º 14/24 went on to have a biopsy º 13/14 had a thoracoscopy and 1/14 had a CT guided biopsy º All Malignancies (Lung Primary/Lung Secondary/Meso) (n = 96) º 80/95 (84%) were exudates º 8/95 (8%) had a protein < 25 AND a LDH < 200 º Audit: º 217/264 didn't meet the BTS guidance stating that every pleural tap should be sent for, microbiology, cytology, protein, LDH º pH < 7.21 (n = 19) º 12 were empyemas º But also: • 3 adenocarcinomas of the lung • 2 mesothelioma • 1 metastatic ovarian carcinoma • 1 haemothorax º Microbiology: • Only positive in 5/241 samples sent in universal bottles • 3 were empyemas • 1 was a biliary fistula • 1 was an infected indwelling pleural catheter Discussion Our findings are consistent with current literature. We found 60% positivity for cytology in lung cancer, dropping to 50% in mesothelioma, with further sampling helping in the former only. Tissue biopsy should be de rigeur if mesothelioma is suspected, rather than repeat cytology. 8% of all malignant effusions are transudates, and clinical as well as radiological correlation is vital in those cases. We fail in adherence to BTS guidelines- local guidelines have just been updated and all respiratory doctors have been reminded of them. We will also aim to increase microbiological yield by sending fluid in blood culture bottles.

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