José Diego Santotoribio

What are the biochemical parameters of pleural fluid that best identify parapneumonic effusions

To the Editor, In the recent review of the British Thoracic Society guidelines for the investigation of unilateral pleural effusion in adults, 1 there was no mention of biochemical analysis of pleural fluid for the diagnosis of parapneumonic pleural effusions (PPE). PPE is an exudate associated with pneumonia, abscess or bronchiectasis, called empyema when it contains pus. 2 The biochemical analysis of pleural fluid is important for the diagnosis of PPE. The aim of our study was to determine the accuracy of biochemical parameters of pleural fluid for the diagnosis of PPE, using receiveroperating characteristic (ROC) techniques by analysing the area under the ROC curve (AUC) and determining the optimal cut-off value. We studied 207 pleural fluids obtained anaerobically by thoracocentesis using gasometry syringes in 110 men and 97 women aged between 1 and 90 y (average 58 y), from June 2005 to July 2006. The following variables were analysed: protein, glucose, lactate dehydrogenase (LDH), lactate and amylase by INTEGRA 400 (Roche Diagnostics S.L w , Barcelona, Spain), adenosine deaminase (ADA) by Modular P (Roche Diagnostics S.L w ), pH and pCO2 by gasometer IL-1620 (Izasa S.A. w , Barcelona, Spain), and the aetiological diagnosis of pleural effusion discharged from hospital after evaluating clinical and radiological data and laboratory tests. Protein was analysed by Biuret reaction, glucose by enzymatic reference method with hexokinase, LDH, lactate, amylase and ADA by enzymatic colorimetric methods according to the International Federation of Clinical Chemistry. The serum LDH reference range was 135 –225 U/L. The diagnosis of PPE required an acute febrile illness with purulent sputum and pulmonary infiltrates in association with a pleural effusion or positive pleural fluid culture or positive pleural fluid Gram stain or purulent pleural fluid. Pleural fluids were classified into two groups: PPE and non-PPE. Statistical analysis was performed using the software Medcalc w . Forty-six of 207 pleural fluids studied were PPE (14 uncomplicated PPE, eight complicated PPE and 24

Indicación de tratamiento con tubo de drenaje endotorácico en derrames pleurales paraneumónicos, según la presión parcial de anhídrido carbónico de líquido pleural

Fundamento y objetivo: Los derrames pleurales paraneumonicos (DPP) con un pH menor de 7,20 o glucosa menor de 0,40 g/l o lactatodeshidrogenasa (LDH) mayor de 1.000 U/l tienen indicacion de tratamiento con tubo de drenaje endotoracico (TDE). El objetivo del presente estudio ha sido medir la exactitud que presenta la determinacion de la presion parcial de anhidrido carbonico (pCO2) del liquido pleural para la indicacion de tratamiento con TDE en los DPP mediante el calculo del area bajo la curva (ABC) de eficacia diagnostica, ademas de determinar su punto de corte optimo. Pacientes y metodo: Se analizaron 207 liquidos pleurales, en los que se determinaron pCO2, pH, glucosa y LDH. Se recogio asimismo el diagnostico etiologico del derrame pleural con que se dio el alta hospitalaria al paciente y si fue necesario tratamiento con TDE. Resultados: De los 207 liquidos pleurales estudiados, 46 fueron DPP, de los que 32 requirieron tratamiento con TDE. La ABC obtenida de la pCO2 fue 0,888 (p < 0,0001); la del pH, 0,890 (p < 0,0001); la de la glucosa, 0,816 (p < 0,0001), y la de la LDH, 0,801 (p < 0,0001). Las diferencias de las ABC carecieron de significacion estadistica. El punto de corte optimo de la pCO2 resulto un valor superior a 48,6 mmHg, con una sensibilidad del 90,6% y una especificidad del 78,6%. Todos los DPP con una pCO2 mayor de 60,9 mmHg fueron tratados con TDE. De los 46 DPP, 3 (6,5%) serian tratados incorrectamente segun el pH, la glucosa o la LDH; en cambio, hubieran sido correctamente tratados segun la pCO2. Conclusiones: La pCO2 de liquido pleural presenta una exactitud para la indicacion de tratamiento con TDE similar al pH, la glucosa y la LDH, y mejora el criterio de indicacion de tratamiento con TDE en los DPP.

Evaluation of Pleural Fluid Lactate for Diagnosis and Management of Parapneumonic Pleural Effusion

BACKGROUND The aim was to measure the accuracy of pleural fluid lactate concentration for diagnosis of parapneumonic pleural effusion (PPE) and to discriminate between uncomplicated (UPPE) and complicated PPE (CPPE). METHODS Pleural fluid lactate was measured in patients with pleural effusion. Patients were classified into two groups according to the etiology of pleural effusion: PPE and NOT PPE. RESULTS We studied 173 patients. Thirty patients were PPE (10 UPPE and 20 CPPE) and 143 were NOT PPE. The AUC value was 0.831 (p < 0.0001) and the optimal cutoff value was 5.6 mmol/L exhibiting 70% sensitivity and 90.9% specificity for diagnosis of PPE. Also, pleural fluid lactate could be used to discriminate between UPPE and CPPE, the AUC value was 0.740 (p = 0.0089) and the optimal cutoff value was 10.2 mmol/L, exhibiting 45% sensitivity and 90% specificity. CONCLUSIONS Pleural fluid lactate has a high accuracy for diagnosis and management of PPE.

Pleural fluid cell-free DNA in parapneumonic pleural effusion☆

OBJECTIVES To measure the accuracy of pleural fluid cell-free DNA (cfDNA) concentration for diagnosis of parapneumonic pleural effusions (PPE). DESIGN AND METHODS We studied pleural fluids obtained by thoracocentesis in patients with pleural effusion. DNA was automatically extracted from pleural fluid using the MagNa Pure Compact instrument (Roche Diagnostics), and was measured by a real-time quantitative PCR assay for the β-globin gene using a Light-Cycler 480 Real-Time PCR instrument (Roche Diagnostics). Patients were classified into two groups according to the etiology of pleural effusion: PPE and NOT PPE. The diagnostic accuracy was determined using receiver operating characteristic (ROC) techniques by analyzing the area under the ROC curve (AUC). RESULTS We studied 78 patients with ages between 1 and 86 years old (median=64). Sixteen patients were PPE and 62 were NOT PPE (24 transudative, 30 malignant and 8 other etiology). Pleural fluid cfDNA concentration was higher in patients with PPE (median=46,240 ng/mL) than in those with NOT PPE (median=224 ng/mL). The AUC value was 0.907 (p<0.0001) and the optimal cut-off value was 6740 ng/mL exhibiting 87.5% sensitivity and 80.6% specificity. Also, there were significant differences between transudative and exudative effusions according to pleural fluid cfDNA concentration (p<0.0001). The AUC value was 0.994 and the optimal cut-off value was 162ng/mL exhibiting 100% sensitivity and 96.3% specificity. CONCLUSIONS Pleural fluid cfDNA concentration showed high accuracy for diagnosis of PPE and to discriminate between transudative and exudative effusions.

Rendimiento diagnóstico de la determinación del antígeno carcinoembrionario en el líquido pleural

1. Gamboa Antiñolo F. Limitación del esfuerzo terapéutico. ¿Es lo mismo retirar un tratamiento de soporte vital que no iniciarlo? Med Clin (Barc). 2009. May 21. [Epub ahead of print]. doi:10.1016/j.medcli.2009.02.046. 2. Iribarren-Diarasarri S, Latorre-Garcı́a K, Muñoz-Martı́nez T, Poveda-Hernández Y, Dudagoitia-Otaolea JL, Martı́nez-Alutiz S, et al. Limitación del esfuerzo terapéutico tras el ingreso en una unidad de medicina intensiva. Análisis de los factores asociados. Med Intensiva. 2007;31:68–72. 3. Hofhuis JG, Spronk PE, Van Stel HF, Schrijvers AJ, Bakker J. Quality of life before intensive care unit admission is a predictor of survival. Crit Care. 2007;11:R78. 4. Rivera-Fernández R, Sánchez-Cruz JJ, Abizanda-Campos R, Vázquez-Mata G. Quality of life before intensive care unit admission and its influence on resource utilization and mortality rate. Crit Care Med. 2001;29:1701–9. 5. Garrouste-Orgeas M, Montuclard L, Timsit JF, Reignier J, Desmettre T, Karoubi P; French ADMISSIONREA Study Group. Predictors of intensive care unit refusal in French intensive care units: A multiple-center study. Crit Care Med. 2005;33:750–5.

Influence of reduction in the elution times on HPLC glycohaemoglobin results

OBJECTIVES To compare HPLC methods with short and long elution times for HbA1c measurement in blood. METHODS Comparison between G7-Tosoh (1.2 min); Bio-Rad-Variant-II-Turbo (1.3 min) and Arkray-HA-8160 (2.9 min). RESULTS Passing-Bablok regression equations were: Y=0.17+0.96X; Y=-0.39+1.01X; Y=-0.40+1.0X and the means of the differences using Bland-Altman Plot were 0.02; -0.34; 0.32 for HA-8160/G7-Tosoh, HA-8160/Variant-II-Turbo and G7-Tosoh/Variant-II-Turbo, respectively. CONCLUSIONS Faster elution methods had no problems on reproducibility of results obtained by slower elution methods.