Pleural fluid chemical analysis in parapneumonic effusions. A meta-analysis

Myeloid-derived suppressor cells in pleural effusion as a diagnostic marker for early discrimination of pulmonary tuberculosis from pneumonia

Introduction

Tuberculous pleural effusion (TPE) stands as one of the primary forms of extrapulmonary tuberculosis (TB) and frequently manifests in regions with a high prevalence of TB, consequently being a notable cause of pleural effusion in such areas. However, the differentiation between TPE and parapneumonic pleural effusion (PPE) presents diagnostic complexities. This study aimed to evaluate the potential of myeloid-derived suppressor cells (MDSCs) in the pleural fluid as a potential diagnostic marker for distinguishing between TPE and PPE.

Methods

Adult patients, aged 18 years or older, who presented to the emergency room of a tertiary referral hospital and received a first-time diagnosis of pleural effusion, were prospectively enrolled in the study. Various immune cell populations, including T cells, B cells, natural killer (NK) cells, and MDSCs, were analyzed in both pleural fluid and peripheral blood samples.

Results

In pleural fluid, the frequency of lymphocytes, including T, B, and NK cells, was notably higher in TPE compared to PPE. Conversely, the frequency of polymorphonuclear (PMN)-MDSCs was significantly higher in PPE. Notably, compared to traditional markers such as the neutrophil-to-lymphocyte ratio and adenosine deaminase level, the frequency of PMN-MDSCs emerged as a more effective discriminator between PPE and TPE. PMN-MDSCs demonstrated superior positive and negative predictive values and exhibited a higher area under the curve in the receiver operating characteristic curve analysis. PMN-MDSCs in pleural effusion increased the levels of reactive oxygen species and suppressed the production of interferon-gamma from T cells following nonspecific stimulation. These findings suggest that MDSC-mediated immune suppression may contribute to the pathology of both TPE and PPE.

Discussion

The frequency of PMN-MDSCs in pleural fluid is a clinically useful indicator for distinguishing between TPE and PPE.

Empyema Secondary to Pneumonia: Whom Should We Operate?

Introduction: Empyema secondary to pneumonia is a common condition. A significant number of patients will require surgical intervention for drainage and decortication. The aim of this study was to identify predictive factors for surgical intervention. Materials and Methods: The medical records of patients who were diagnosed with empyema secondary to pneumonia between the years 2010 and 2019 in a university hospital were included in the study. Patients who underwent surgical intervention were defined as group A and nonoperative treatment as group B. Clinical and laboratory data were collected from medical records and patients' chest computerized tomography (CT) scans were reviewed. Results: A total of 194 patients were included in the study-86 patients were included in group A and 108 patients in group B. Several parameters on admission were found to have a statistically significant correlation with surgical intervention: younger age, higher systolic blood pressure, and elevated white blood count. Multivariant analysis showed that younger age was found to have a statistically significant correlation with operative intervention (adjusted odds ratio = 0.971, P = .023). A statistically significant correlation between surgical intervention and survival (adjusted hazard ratio [HR] = 1.762, P = .046) and an inverse correlation between age and survival (adjusted HR = 0.050, P < .001) were found. Surgical intervention was associated with increased survival irrespective of age. A total of 42 CT scans were available for review. The mean density of the empyema fluid in group A was higher by 4.3 hounsfield units compared to group B (P < .067). Conclusions: Younger age was found to be associated with surgical intervention among patients suffering from empyema secondary to pneumonia. Surgical intervention was associated with increased long-term survival, irrespective of patients' age. Several radiologic characteristics were associated with the need for surgery in this study: empyema fluid density, pleural thickening, and fluid loculations. Additional prospective studies are required to ascertain these results.

Effect of sugammadex on postoperative complications in patients with severe burn who underwent surgery: a retrospective study

This retrospective study investigated the association of sugammadex with postoperative pulmonary complication risk between 2013 and 2021 in patients with severe burn of five hospitals. Postoperative pulmonary complications included atelectasis, pulmonary edema, pulmonary effusion, pneumothorax, pneumonia, pulmonary thromboembolism, respiratory failure and acute respiratory distress. To identify whether sugammadex reduced the risk of postoperative pulmonary complication in patients with severe burn who underwent surgery, Kaplan-Meier curve were used to check the difference of incidence according to surgical cases and time-varying Cox hazard regression were used to calculate the hazard ratio. The study included 1213 patients with severe burn who underwent 2259 surgeries. Postoperative pulmonary complications were occurred in 313 (25.8%) patients. Among 2259 surgeries, sugammadex was used in 649 (28.7%) surgeries. Cumulative postoperative pulmonary complication were 268 (16.6%) cases in surgeries without sugammadex, and 45 (6.9%) cases in surgeries with sugammadex, respectively (P < 0.005). The postoperative pulmonary complications risk was reduced significantly in patients who use sugammadex than those who did not use sugammadex. (Adjusted hazard ratio, 0.61; 95% confidence interval, 0.42-0.89; P = 0.011). In conclusion, sugammadex reduced risk of postoperative pulmonary complications compared with nonuse of sugammadex in patients with severe burn who underwent surgery.

Diagnosis and management of pleural infection

Pleural infection remains a medical challenge. Although closed tube drainage revolutionised treatment in the 19th century, pleural infection still poses a significant health burden with increasing incidence. Diagnosis presents challenges due to non-specific clinical presenting features. Imaging techniques such as chest radiographs, thoracic ultrasound and computed tomography scans aid diagnosis. Pleural fluid analysis, the gold standard, involves assessing gross appearance, biochemical markers and microbiology. Novel biomarkers such as suPAR (soluble urokinase plasminogen activator receptor) and PAI-1 (plasminogen activator inhibitor-1) show promise in diagnosis and prognosis, and microbiology demonstrates complex microbial diversity and is associated with outcomes. The management of pleural infection involves antibiotic therapy, chest drain insertion, intrapleural fibrinolytic therapy and surgery. Antibiotic therapy relies on empirical broad-spectrum antibiotics based on local policies, infection setting and resistance patterns. Chest drain insertion is the mainstay of management, and use of intrapleural fibrinolytics facilitates effective drainage. Surgical interventions such as video-assisted thoracoscopic surgery and decortication are considered in cases not responding to medical therapy. Risk stratification tools such as the RAPID (renal, age, purulence, infection source and dietary factors) score may help guide tailored management. The roles of other modalities such as local anaesthetic medical thoracoscopy and intrapleural antibiotics are debated. Ongoing research aims to improve outcomes by matching interventions with risk profile and to better understand the development of disease.

Expert Review on Nonsurgical Management of Parapneumonic Effusion: Advances, Controversies, and New Directions

Parapneumonic effusion and empyema are rising in incidence worldwide, particularly in association with comorbidities in an aging population. Also driving this change is the widespread uptake of pneumococcal vaccines, leading to the emergence of nonvaccine-type pneumococci and other bacteria. Early treatment with systemic antibiotics is essential but should be guided by local microbial guidelines and antimicrobial resistance patterns due to significant geographical variation. Thoracic ultrasound has emerged as a leading imaging technique in parapneumonic effusion, enabling physicians to characterize effusions, assess the underlying parenchyma, and safely guide pleural procedures. Drainage decisions remain based on longstanding criteria including the size of the effusion and fluid gram stain and biochemistry results. Small-bore chest drains appear to be as effective as large bore and are adequate for the delivery of intrapleural enzyme therapy (IET), which is now supported by a large body of evidence. The IET dosing regimen used in the UK Multicenter Sepsis Trial -2 has the most evidence available but data surrounding alternative dosing, concurrent and once-daily instillations, and novel fibrinolytic agents are promising. Prognostic scores used in pneumonia (e.g., CURB-65) tend to underestimate mortality in parapneumonic effusion/empyema. Scores specifically based on pleural infection have been developed but require validation in prospective cohorts.

Assessment and diagnosis of the acute hot joint: a systematic review and meta-analysis

OBJECTIVES

Prompt diagnosis of septic arthritis (SA) in acute native hot joints is essential for avoiding unnecessary antibiotics and hospital admissions. We evaluated the utility of synovial fluid (SF) and serum tests in differentiating causes of acute hot joints.

METHODS

We performed a systematic literature review of diagnostic testing for acute hot joints. Articles were included if studying ≥1 serum or SF test(s) for an acute hot joint, compared with clinical assessment and SF microscopy and culture. English-language articles only were included, without date restriction. The following were recorded for each test, threshold and diagnosis: sensitivity, specificity, positive/negative predictive values and likelihood ratios. For directly comparable tests (i.e. identical fluid, test and threshold), bivariate random-effects meta-analysis was used to pool sensitivity, specificity, and areas under the curves.

RESULTS

A total of 8443 articles were identified, and 49 were ultimately included. Information on 28 distinct markers in SF and serum, differentiating septic from non-septic joints, was extracted. Most had been tested at multiple diagnostic thresholds, yielding a total of 27 serum markers and 156 SF markers. Due to heterogeneity of study design, outcomes and thresholds, meta-analysis was possible for only eight SF tests, all differentiating septic from non-septic joints. Of these, leucocyte esterase had the highest pooled sensitivity [0.94 (0.70, 0.99)] with good pooled specificity [0.74 (0.67, 0.81)].

CONCLUSION

Our review demonstrates many single tests, individually with diagnostic utility but suboptimal accuracy for exclusion of native joint infection. A combination of several tests with or without a stratification score is required for optimizing rapid assessment of the hot joint.

Pleural Space Infections

Pleural space infections have been a well-recognized clinical syndrome for over 4000 years and continue to cause significant morbidity and mortality worldwide. However, our collective understanding of the causative pathophysiology has greatly expanded over the last few decades, as have our treatment options. The aim of this paper is to review recent updates in our understanding of this troublesome disease and to provide updates on established and emerging treatment modalities for patients suffering from pleural space infections. With that, we present a review and discussion synthesizing the recent pertinent literature surrounding the history, epidemiology, pathophysiology, diagnosis, and management of these challenging infections.

Diagnostic value of soluble biomarkers for parapneumonic pleural effusion

Parapneumonic pleural effusion (PPE) is a common complication in patients with pneumonia. Timely and accurate diagnosis of PPE is of great value for its management. Measurement of biomarkers in circulating and pleural fluid have the advantages of easy accessibility, short turn-around time, objectiveness and low cost and thus have utility for PPE diagnosis and stratification. To date, many biomarkers have been reported to be of value for the management of PPE. Here, we review the values of pleural fluid and circulating biomarkers for the diagnosis and stratification PPE. The biomarkers discussed are C-reactive protein, procalcitonin, presepsin, soluble triggering receptor expressed on myeloid cells 1, lipopolysaccharide-binding protein, inflammatory markers, serum amyloid A, soluble urokinase plasminogen activator receptor, matrix metalloproteinases, pentraxin-3 and cell-free DNA. We found that none of the available biomarkers has adequate performance for diagnosing and stratifying PPE. Therefore, further work is needed to identify and validate novel biomarkers, and their combinations, for the management of PPE.

Pleural fluid biochemical analysis: the past, present and future

Identifying the cause of pleural effusion is challenging for pulmonologists. Imaging, biopsy, microbiology and biochemical analyses are routinely used for diagnosing pleural effusion. Among these diagnostic tools, biochemical analyses are promising because they have the advantages of low cost, minimal invasiveness, observer independence and short turn-around time. Here, we reviewed the past, present and future of pleural fluid biochemical analysis. We reviewed the history of Light’s criteria and its modifications and the current status of biomarkers for heart failure, malignant pleural effusion, tuberculosis pleural effusion and parapneumonic pleural effusion. In addition, we anticipate the future of pleural fluid biochemical analysis, including the utility of machine learning, molecular diagnosis and high-throughput technologies. Clinical Chemistry and Laboratory Medicine (CCLM) should address the topic of pleural fluid biochemical analysis in the future to promote specific knowledge in the laboratory professional community.

Diagnostic utility of pleural cell-free nucleic acids in undiagnosed pleural effusions

Pleural effusion (PE) is a common sign caused by various disorders. Microbiology, histology and cytology are reference standards for these disorders. However, these diagnostic tools have limitations, including invasiveness, high cost, long turnaround time, and observer-dependent. Soluble biomarkers in pleural fluid (PF) are promising diagnostic tools because they are mininvasive, economical, and objective. Recent studies have revealed that some cell-free nucleic acids (e.g., DNA, mRNA, microRNA, and lncRNA) in PF are potential diagnostic markers for many disorders. Here, we review the performance of PF cell-free nucleic acids for differentiating and stratification of PE.

Recent Insights into the Management of Pleural Infection

Pleural infection in adults has considerable morbidity and continues to be a life-threatening condition. The term “pleural infection” encompasses complicated parapneumonic effusions and primary pleural infections, and includes but is not limited to empyema, which refers to collection of pus in the pleural cavity. The incidence of pleural infection in adults has been continuously increasing over the past two decades, particularly in older adults, and most of such patients have comorbidities. Management of pleural infection requires prolonged duration of hospitalization (average 14 days). There are recognized differences in microbial etiology of pleural infection depending on whether the infection was acquired in the community or in a health-care setting. Anaerobic bacteria are acknowledged as a major cause of pleural infection, and thus anaerobic coverage in antibiotic regimens for pleural infection is mandatory. The key components of managing pleural infection are appropriate antimicrobial therapy and chest-tube drainage. In patients who fail medical therapy by manifesting persistent sepsis despite standard measures, surgical intervention to clear the infected space or intrapleural fibrinolytic therapy (in poor surgical candidates) are recommended. Recent studies have explored the role of early intrapleural fibrinolytics or first-line surgery, but due to considerable costs of such interventions and the lack of convincing evidence of improved outcomes with early use, early intervention cannot be recommended, and further evidence is awaited from ongoing studies. Other areas of research include the role of routine molecular testing of infected pleural fluid in improving the rate of identification of causative organisms. Other research topics include the benefit of such interventions as medical thoracoscopy, high-volume pleural irrigation with saline/antiseptic solution, and repeated thoracentesis (as opposed to chest-tube drainage) in reducing morbidity and improving outcomes of pleural infection. This review summarizes current knowledge and practice in managing pleural infection and future research directions.

Levels of lactic acid's concordance with pH in pediatric parapneumonic pleural effusion

Purpose of the article: The indication of pleural drainage in parapneumonic pleural effusion (PPE) is still controversial. Pleural fluid's (PF) pH is widely used as an indicator of the need for pleural drainage. We hypothesized that PF's lactate will have a high concordance with pH, and thus, may be a valuable tool to determine the need for pleural drainage in pediatric PPE.

MATERIALS AND METHODS

We performed a descriptive, prospective study sequentially enrolling those pediatric patients admitted to a tertiary University Hospital with a PPE between 2008 and 2018. Patients were classified in two groups: drainable PPE (pH < 7) and non-drainable PPE (pH > 7). Correlation with the pH, the area under the curve (AUC), and the sensitivity and specificity values for lactate and other parameters (glucose, and LDH) were analysed too.

RESULTS

72 patients with a median age of 4 years (interquartile range 2.25-6) were included. Both groups were homogeneous. Lactate levels were higher in the drainable PPE group (p < 0.001), and a strong inverse correlation between pH and lactate was found (r: -0.7; p < 0.001). A lactate cut-off value of 60.5 mmol/L, exhibit an AUC of 0.86 with a sensitivity of 70% and a high specificity (97.9%) to predict a pH < 7.

CONCLUSIONS

Our data indicates that lactate in PF presents a strong correlation with pH and could potentially serve as a highly specific biomarker of the need for pleural drainage.

[Management of Adult Community-Acquired Pneumonia and Prevention - Update 2021 - Guideline of the German Respiratory Society (DGP), the Paul-Ehrlich-Society for Chemotherapy (PEG), the German Society for Infectious Diseases (DGI), the German Society of Medical Intensive Care and Emergency Medicine (DGIIN), the German Viological Society (DGV), the Competence Network CAPNETZ, the German College of General Practitioneers and Family Physicians (DEGAM), the German Society for Geriatric Medicine (DGG), the German Palliative Society (DGP), the Austrian Society of Pneumology Society (ÖGP), the Austrian Society for Infectious and Tropical Diseases (ÖGIT), the Swiss Respiratory Society (SGP) and the Swiss Society for Infectious Diseases Society (SSI)]

The present guideline provides a new and updated concept of the management of adult patients with community-acquired pneumonia. It replaces the previous guideline dating from 2016.The guideline was worked out and agreed on following the standards of methodology of a S3-guideline. This includes a systematic literature search and grading, a structured discussion of recommendations supported by the literature as well as the declaration and assessment of potential conflicts of interests.The guideline has a focus on specific clinical circumstances, an update on severity assessment, and includes recommendations for an individualized selection of antimicrobial treatment.The recommendations aim at the same time at a structured assessment of risk for adverse outcome as well as an early determination of treatment goals in order to reduce mortality in patients with curative treatment goal and to provide palliation for patients with treatment restrictions.

Management of Pleural Infection

Pleural infection is a millennia-spanning condition that has proved challenging to treat over many years. Fourteen percent of cases of pneumonia are reported to present with a pleural effusion on chest X-ray (CXR), which rises to 44% on ultrasound but many will resolve with prompt antibiotic therapy. To guide treatment, parapneumonic effusions have been separated into distinct categories according to their biochemical, microbiological and radiological characteristics. There is wide variation in causative organisms according to geographical location and healthcare setting. Positive cultures are only obtained in 56% of cases; therefore, empirical antibiotics should provide Gram-positive, Gram-negative and anaerobic cover whilst providing adequate pleural penetrance. With the advent of next-generation sequencing techniques, yields are expected to improve. Complicated parapneumonic effusions and empyema necessitate prompt tube thoracostomy. It is reported that 16-27% treated in this way will fail on this therapy and require some form of escalation. The now seminal Multi-centre Intrapleural Sepsis Trials (MIST) demonstrated the use of combination fibrinolysin and DNase as more effective in the treatment of empyema compared to either agent alone or placebo, and success rates of 90% are reported with this technique. The focus is now on dose adjustments according to the patient's specific 'fibrinolytic potential', in order to deliver personalised therapy. Surgery has remained a cornerstone in the management of pleural infection and is certainly required in late-stage manifestations of the disease. However, its role in early-stage disease and optimal patient selection is being re-explored. A number of adjunct and exploratory therapies are also discussed in this review, including the use of local anaesthetic thoracoscopy, indwelling pleural catheters, intrapleural antibiotics, pleural irrigation and steroid therapy.

Diagnostics in Pleural Disease

Pleural disease diagnostics represent a sprawling topic that has enjoyed a renaissance in recent years from humble beginnings. Whilst pleural patients are heterogeneous as a population and in the aetiology of the disease with which they present, we provide an overview of the typical diagnostic approach. Pleural fluid analysis is the cornerstone of the diagnostic pathway; however, it has many shortcomings. Strong cases have been made for more invasive upfront investigations, including image-guided biopsies or local anaesthetic thoracoscopy, in selected populations. Imaging can guide the diagnostic process as well as act as a vehicle to facilitate therapies, and this is never truer than with the recent advances in thoracic ultrasound.

Pleural Fluid suPAR Levels Predict the Need for Invasive Management in Parapneumonic Effusions

Rationale: Parapneumonic effusions have a wide clinical spectrum. The majority settle with conservative management but some progress to complex collections requiring intervention. For decades, physicians have relied on pleural fluid pH to determine the need for chest tube drainage despite a lack of prospective validation and no ability to predict the requirement for fibrinolytics or thoracic surgery.Objectives: To study the ability of suPAR (soluble urokinase plasminogen activator receptor), a potential biomarker of pleural fluid loculation, to predict the need for invasive management compared with conventional fluid biomarkers (pH, glucose, and lactate dehydrogenase) in parapneumonic effusions.Methods: Patients presenting with pleural effusions were prospectively recruited to an observational study with biological samples stored at presentation. Pleural fluid and serum suPAR levels were measured using the suPARnostic double-monoclonal antibody sandwich ELISA on 93 patients with parapneumonic effusions and 47 control subjects (benign and malignant effusions).Measurements and Main Results: Pleural suPAR levels were significantly higher in effusions that were loculated versus nonloculated parapneumonic effusions (median, 132 ng/ml vs. 22 ng/ml; P < 0.001). Pleural suPAR could more accurately predict the subsequent insertion of a chest tube with an area under the curve (AUC) of 0.93 (95% confidence interval, 0.89-0.98) compared with pleural pH (AUC 0.82; 95% confidence interval, 0.73-0.90). suPAR was superior to the combination of conventional pleural biomarkers (pH, glucose, and lactate dehydrogenase) when predicting the referral for intrapleural fibrinolysis or thoracic surgery (AUC 0.92 vs. 0.76).Conclusions: Raised pleural suPAR was predictive of patients receiving more invasive management of parapneumonic effusions and added value to conventional biomarkers. These results need validation in a prospective multicenter trial.

Pleural Effusion in Adults-Etiology, Diagnosis, and Treatment

BACKGROUND

Pleural effusion is common in routine medical practice and can be due to many different underlying diseases. Precise differential diagnostic categorization is essential, as the treatment and prognosis of pleural effusion largely depend on its cause.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed and on the authors' personal experience.

RESULTS

The most common causes of pleural effusion are congestive heart failure, cancer, pneumonia, and pulmonary embolism. Pleural fluid puncture (pleural tap) enables the differentiation of a transudate from an exudate, which remains, at present, the foundation of the further diagnostic work-up. When a pleural effusion arises in the setting of pneumonia, the potential devel- opment of an empyema must not be overlooked. Lung cancer is the most common cause of malignant pleural effusion, followed by breast cancer. Alongside the treatment of the underlying disease, the specific treatment of pleural effusion ranges from pleurodesis, to thoracoscopy and video-assisted thoracoscopy (with early consultation of a thoracic surgeon), to the placement of a permanently indwelling pleural catheter.

CONCLUSION

The proper treatment of pleural effusion can be determined only after meticulous differential diagnosis. The range of therapeutic options has recently become much wider. More data can be expected in the near future concerning diagnostic test- ing for the etiology of the effusion, better pleurodetic agents, the development of interventional techniques, and the genetic background of the affected patients.

Pleural fluid lactate as a point-of-care adjunct diagnostic aid to distinguish tuberculous and complicated parapneumonic pleural effusions during initial thoracentesis: Potential use in a tuberculosis endemic setting

BACKGROUND

Tuberculous pleural effusions (TBEs) and parapneumonic pleural effusion (PPEs) have similar clinical presentations and fluid biochemistry. A pleural biopsy is usually required to diagnose TBE but complete fluid evacuation may not be necessary, contrasting with complicated PPE (CPPE). A point-of-care test that distinguishes between TBE and CPPE enables the appropriate procedures to be performed during the initial diagnostic thoracentesis. Lactate is a metabolic product measurable by a blood-gas analyzer. This study measured pleural fluid (Pf) lactate levels in TBE and compared them with those in PPE/CPPE. We hypothesized that Pf lactate would be significantly higher in PPE because of active metabolic activities than in TBE which is driven by delayed hypersensitivity.

METHODS

All patients undergoing an initial diagnostic thoracentesis over 18 months with Pf lactate measured using a calibrated point-of-care blood gas analyzer were assessed.

RESULTS

The diagnoses of the enrolled patients (n = 170) included TBE (n = 49), PPE (n = 47), malignancy (n = 63), and transudate (n = 11). Pf lactate level in TBE, median 3.70 (inter-quartile range 2.65-4.90) mmol/l, was significantly lower than in PPE and CPPE. In the subgroup of TBE and CPPE patients whose initial Pf pH and glucose could suggest either condition, Pf lactate was significantly higher in those with CPPE. Pf lactate (cutoff ≥7.25 mmol/l) had a sensitivity of 79.3%, specificity 100%, positive predictive value 100%, and negative predictive value 89.1% for discriminating CPPE from TBE (area under the curve 0.947, p < 0.001, 95% confidence interval 0.89-0.99).

CONCLUSIONS

Point-of-care Pf lactate measurements may have practical value in early separation of TBE or CPPE during initial thoracentesis, and warrants further investigation.

Review of interference indices in body fluid specimens submitted for clinical chemistry analyses

Objectives

The aims of this study were to retrospectively investigate interference indices in a wide range of body fluid specimens and compare these indices to those found in serum/plasma.

Design and Methods

This retrospective study evaluated interference indices for hemolysis, icterus, and lipemia in 2752 body fluid specimens submitted for clinical chemistry testing.

Results

The distribution of interference indices for body fluid samples was generally similar to that of serum/plasma interference indices. Hemolysis of specimens submitted for lactate dehydrogenase (LD) represented the most common interference for body fluid chemistries. Body fluids collected from postsurgical drain sites had a higher proportion of tests exceeding both icterus and lipemic limits compared to serum/plasma specimens.

Conclusions

Overall, degrees of hemolysis, icterus, and lipemia observed in body fluid specimens were in large part similar to serum/plasma specimens, with a few notable differences. Body fluids exhibited a higher proportion of samples with severe icterus or lipemia. Severely lipemic body fluid samples were significantly less likely to also be hemolyzed relative to severely lipemic serum/plasma specimens. LD was the test most commonly affected by interference across all body fluid types. False elevations in pleural fluid LD induced by hemolysis can lead to mis-classification of transudative effusions as exudative using Light’s criteria. The possible impact of interferences on clinical chemistry testing in body fluids is an important post-analytical consideration.

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Hemolysis, icterus, and lipemia were evaluated in 2752 body fluid specimens.

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Distributions of interference indices in body fluids generally mimicked those of serum/plasma.

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Pancreatic and pericardial fluids had the highest proportion of tests exceeding the hemolysis index.

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Compared to serum/plasma, drain fluids had relatively more tests exceeding both icterus and lipemic limits.

Advances in pleural effusion diagnostics

Introduction: Pleural effusion is a common clinical problem. Yet, in a significant proportion of patients (~20%), the cause of pleural effusion remains unknown. Understanding the diagnostic value of pleural fluid tests is crucial for the development of accurate diagnostic models.Areas covered: This paper provides an overview of latest advances in the diagnosis of pleural effusion based on the best evidence available.Expert opinion: For pleural fluid tests to have a good diagnostic value, it is necessary that data obtained from clinical history, physical examination, and radiological studies are correctly interpreted. Thoracentesis and pleural biopsy should always be performed under image guidance to improve its diagnostic sensitivity and prevent complications. Nucleic acid amplification tests, pleural tissue cultures, and collection of pleural fluid in blood culture bottles improve the diagnostic yield of pleural fluid cultures. Although undiagnosed pleural effusions generally have a favorable prognosis, follow-up is recommended to prevent the development of a malignant pleural effusion.

Hepatic Hydrothorax: An Updated Review on a Challenging Disease

Hepatic hydrothorax is a challenging complication of cirrhosis related to portal hypertension with an incidence of 5-11% and occurs most commonly in patients with decompensated disease. Diagnosis is made through thoracentesis after excluding other causes of transudative effusions. It presents with dyspnea on exertion and it is most commonly right sided. Pathophysiology is mainly related to the direct passage of fluid from the peritoneal cavity through diaphragmatic defects. In this updated literature review, we summarize the diagnosis, clinical presentation, epidemiology and pathophysiology of hepatic hydrothorax, then we discuss a common complication of hepatic hydrothorax, spontaneous bacterial pleuritis, and how to diagnose and treat this condition. Finally, we elaborate all treatment options including chest tube drainage, pleurodesis, surgical intervention, Transjugular Intrahepatic Portosystemic Shunt and the most recent evidence on indwelling pleural catheters, discussing the available data and concluding with management recommendations.

Interpreting pleural fluid results

Interpreting pleural fluid results correctly requires an awareness of the possible aetiologies of a pleural effusion and an understanding of the reliability of the outcome of each investigation. All results must be interpreted within each different clinical context and knowledge of the pitfalls for each test is necessary when the diagnosis is unclear. This review aims to discuss the common aetiologies of a pleural effusion and some of the pitfalls in interpretation that can occur when the diagnosis is unclear.

Clinical Outcome and Risk Factors for Emergency Department Adult Patients with Thoracic Empyema after Video-Assisted Thoracic Surgical Procedure

Background: Empyema is a purulent infection of the pleural cavity that is most relevant to parapneumonia effusion. Video-assisted thoracoscopic surgery (VATS) is an option for stage 2 (fibrinopurulent) and stage 3 (organizational). Surgeons may see critically ill patients with pleural empyema who present to the emergency department (ED). The purpose of this work is to investigate the outcomes of ED adult patients with thoracic empyema undergoing a thoracoscopic surgical procedure and to identify possible risk factors for death. Methods: We reviewed retrospectively the clinical characteristics and treatment outcomes of patients with thoracic empyema who received this diagnosis at our center from January 2012 to June 2014. Patients <20 years old were excluded from this study. The prognostic values of age, sex, comorbidities, clinical presentations, location, stage, and laboratory examinations were evaluated. Uni-variable analysis and multi-variable modeling were performed to determine significant risk factors for post-operative death. Results: Seventeen of 160 patients died post-operatively. Two groups (survivors and non-survivors) significantly differed in age (p = 0.013), sex (p = 0.026), comorbidity (p = 0.017), cough (p = 0.024), chest pain (p = 0.016), serum hemoglobin (p = 0.001), and potassium (p = 0.004) levels. Further logistic regression analysis showed statistically significant differences in age, hemoglobin levels, and potassium levels. Conclusion: Among the ED patients with thoracic empyema, older age, lower hemoglobin levels, and higher potassium levels are associated with post-operative death after VATS. These findings underline the importance of careful peri-operative treatment in older patients with signs of empyema when they present to the ED.

Delafloxacin: an improved fluoroquinolone developed through advanced molecular engineering

The emergence of antimicrobial resistance threatens current clinical practice across a range of infection types. Delafloxacin, a non-zwitterionic fluoroquinolone recently approved by the US FDA for the treatment of acute bacterial skin and skin structure infections, has been developed to address some of these challenges. Uniquely delafloxacin has increased intracellular penetration and enhanced antibacterial activity under acidic conditions, an environment seen in many infection sites including abscesses. Delafloxacin is active against a wide range of Gram-positive and -negative species including methicillin-resistant Staphylococcus aureus and many fluoroquinolone-resistant strains. Additionally, according to preclinical and clinical trial data, well-known adverse events related to fluoroquinolone class do not appear to occur with this new molecule. Delafloxacin has been studied in acute bacterial skin and skin structure infections with >1400 patients exposed to both intravenous and oral formulation for up to 14 days and has shown noninteriority to vancomycin with or without aztreonam. For its interesting microbiological and pharmacokinetic/pharmacodynamics characteristics and for its safety profile, delafloxacin represents a very promising option for the treatment of infections caused by multidrug-resistant pathogens.

Predictors of Prolonged Hospitalizations in Pediatric Complicated Pneumonia

BACKGROUND

Pediatric community-acquired complicated pneumonia (PCACP) is characterized by a prolonged clinical course, but this may be highly variable.

METHODS

A multicenter observational study was conducted to develop and validate a clinical prediction tool for prolonged hospitalizations in PCACP. The derivation and validation cohorts consisted of 144 and 169 patients with PCACP, respectively, hospitalized between the years 1997 and 2017 in three tertiary care hospitals. Logistic regression analyses were used to identify parameters associated with a prolonged hospitalization and to develop and validate a prediction model for constructing a useful clinical tool.

RESULTS

Higher levels of lactate dehydrogenase (LDH) (P < .026) and lower levels of glucose (P = .018) in pleural fluid were significantly associated with prolonged hospitalization. A predictive stepwise logistic regression model was developed and applied to the validation cohort. The area under the receiver operating characteristic curve (AUROC) constructed indicated that the model retained good predictive value (AUROC for the derivation vs validation data, [0.77 (95% CI, 0.66-0.87) vs 0.82 (95% CI, 0.72-0.91)], respectively). From these data, a clinical tool was derived; the combination of pleural LDH >1,000 units/L and pleural glucose levels < 1 mmol/L or pleural LDH levels > 2,000 units/L and pleural glucose levels < 2 mmol/L or pleural LDH levels > 3,000 units/L and pleural glucose < 3 mmol/L predict prolonged hospitalization with positive and negative predictive values of 78% (95% CI, 0.71-0.85) and 73% (95% CI, 0.59-0.85), respectively.

CONCLUSIONS

In children, pleural fluid LDH and glucose levels are useful parameters for assessing the severity of PCACP. The model developed in this study accurately predicts patients who will have prolonged hospitalization.

A review of the management of complex para-pneumonic effusion in adults

A complex para-pneumonic effusion is a descriptive term for exudative effusions, which complicate or are likely to complicate the anatomy of the pleural space after pneumonia. We performed an online search was performed using the resources PubMed and Google Scholar to provide an update on the management of such effusions based on review of published literature. Search terms including pleural effusion (PE), parapneumonic effusion, and empyema were used. Relevant studies were identified and original articles were studied, compared and summarized. References in these articles were examined for relevance and included where appropriate. Studies involving pediatric patients were excluded. Management of para-pneumonic PE has changed tremendously over the last decade. As we accumulate more evidence in this area, approach to pleural fluid drainage is becoming more specific and guideline based. An example of a practice changing study in this aspect is the Multi-center Intrapleural Streptokinase Trial (MIST) 2 trial which demonstrated that a combination of intra-pleural tPA and DNAse improved outcomes in pleural infections compared to DNase or t-PA alone. More randomized control trials are needed to describe the role of surgical techniques like VATS (video-assisted thoracoscopic surgery) when MIST 2 protocol fails; this combination has revolutionized the management of empyema in recently.

Streptococcus Gordonii Empyema: A Case Report and Review of Empyema

Streptococcus gordonii (S. gordonii) is a pioneer oral bacteria that is recognized as an agent of bacterial endocarditis. However, an extensive review of the literature revealed no reported case of S. gordonii causing empyema. We present a case of a 65-year-old male who presented with respiratory distress. Physical examination revealed several dental caries with decreased breath sounds in the bibasilar regions. A computed tomography (CT) scan of the chest and abdomen demonstrated left-sided pleural effusion and a 4.3 cm x 2.8 cm splenic abscess. He received intravenous (IV) antibiotics, and his blood cultures remained negative. Drainage of the splenic abscess grew S. gordonii. A CT-guided thoracentesis yielded 450 ml of exudative fluid. Pleural fluid cultures grew S. gordonii. A CT scan of the head and neck ruled out an intra-oral abscess. He received six weeks of IV penicillin with a follow-up CT scan showing resolution of both the splenic abscess and the left parapneumonic effusion.

Ultrasound in the management of pleural disease

INTRODUCTION

Pleural disease encompasses a large range of conditions, is a common presentation to the acute medical take and often requires comprehensive investigation and treatment. Ultrasound is well recognised as a useful investigative tool in pleural disease especially in the field of pleural effusion, pleural thickening and interventional procedures. Thoracic ultrasound (TUS) has gained widespread use by physicians as evidence has shown a reduced rate of complications when performing pleural procedures with ultrasound guidance. Areas covered: This article will review studies assessing the role of TUS in the management of pleural disease and examine ongoing research into how TUS could advance our knowledge and understanding over the next decade. Expert commentary: Physician lead thoracic ultrasound has become commonplace over the last decade, and now represents a minimum standard of safety in conducting the majority of 'bedside' pleural procedures. The current evidence points to important diagnostic and procedural roles of the use of bedside thoracic ultrasound. In the future, research developments are likely to lead to the use of thoracic ultrasound in prognostication, targeted treatment and understanding pathogenesis in pleural disease.

Community Acquired Pneumonia

Early identification of patients with severe community-acquired pneumonia (CAP) who require ICU care is important as delayed transfer is associated with increased mortality. In such patients, aggressive diagnostic testing is warranted given the increased probability of detecting a pathogen resistant to usual empirical therapy. In the absence of risk factors for healthcare-associated pneumonia or drug resistant pathogens, adequate coverage of Streptococcus pneumoniae and Legionella pneumophila is crucial. When Pseudomonas is suspected, dual anti-pseudomonal therapy is required. When methicillin-resistant Staphylococcus aureus is suspected, linezolid is superior to vancomycin.

Several aspects of managing severe CAP remain without consensus and include the risks associated with multidrug resistant pathogens, antibiotic use to suppress toxin formation in the setting of pneumonia caused by S. aureus, and adjuvant assessment tools such as procalcitonin.

Diagnosis of complicated parapneumonic effusion by pleural pH measurement is jeopardized by inadequate physician knowledge and guideline-discordant laboratory practice

Pleural fluid pH is a crucial determinant of complicated parapneumonic effusion diagnosis and the need for drainage. It is best measured by blood gas analyzer. We examined whether physicians were aware of this, and whether their laboratories measured pleural pH according to their expectations. Only 53% of physicians understood the need for blood gas analyzer measurements, only 50% of laboratories used blood gas analyzers, and only 35% of physicians correctly identified the method performed in their laboratory. Diagnosis of complicated parapneumonic effusion is jeopardized by inadequate physician knowledge and guideline-discordant laboratory practice. We recommend cooperation between thoracic and biochemistry specialty societies to rectify this issue.

Trends in Pleural Effusion Research

Background:

Research in pleural diseases has traditionally been neglected but is now growing.

Objectives:

This study aimed to analyze scientific research trends on pleural effusions over the last decades.

Method:

We conducted a bibliometric analysis of the Scopus database from its inception to March 2016, searching for original articles and reviews on “pleural effusion” (key word). Journal, year of publication, number of citations, authors and their affiliations, and the Hirsch (H)-index for some of these variables were recorded and analyzed.

Results:

A total of 15 982 documents were retrieved, of which half have been published in the last 18 years and a quarter during the last 8 years. Chest ranked first regarding the number of documents on pleural effusions (both absolute number and yearly rate) and their scientific relevance (H-index of 76). The United States had contributed the most to pleural research productivity (23%). American pulmonologists Dr Richard Light and Dr Steven Sahn exhibited the highest number of papers (206 and 156, respectively) and author H-indexes (44 and 38, respectively).

Conclusion:

There is growing research activity in the field of pleural effusions, which has gained relevance and visibility in clinical respiratory journals. The United States is the leader in quantity and quality of research productivity in pleural medicine.

Metabolomic Profiling of Infectious Parapneumonic Effusions Reveals Biomarkers for Guiding Management of Children with Streptococcus pneumoniae Pneumonia

Metabolic markers in biofluids represent an attractive tool for guiding clinical management. The aim of this study was to identify metabolic mechanisms during the progress of pleural infection in children with Streptococcus pneumoniae pneumonia. Forty children diagnosed with pneumococcal pneumonia were enrolled and analysis of pleural fluid metabolites categorized by complicated parapneumonic effusions (CPE) and non-CPE was assessed by using ¹H-NMR spectroscopy. Multivariate statistical analysis including principal components analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) were performed. Metabolites identified were studied in relation to subsequent intervention procedures by receiver operating characteristic (ROC) curve analysis. Ten metabolites significantly different between CPE and non-CPE were identified. A significantly lower level of glucose for glycolysis was found in CPE compared to non-CPE. Six metabolites involving bacterial biosynthesis and three metabolites involving bacterial fermentation were significantly higher in CPE compared to non-CPE. Glucose and 3-hydroxybutyric acid were the metabolites found to be useful in discriminating from receiving intervention procedures. Metabolic profiling of pleural fluid using ¹H-NMR spectroscopy provides direct observation of bacterial metabolism in the progress of pneumococcal pneumonia. An increase in the metabolism of butyric acid fermentation of glucose could potentially lead to the need of aggressive pleural drainage.

Pleural infection: past, present, and future directions

Pleural space infections are increasing in incidence and continue to have high associated morbidity, mortality, and need for invasive treatments such as thoracic surgery. The mechanisms of progression from a non-infected, pneumonia-related effusion to a confirmed pleural infection have been well described in the scientific literature, but the route by which pathogenic organisms access the pleural space is poorly understood. Data suggests that not all pleural infections can be related to lung parenchymal infection. Studies examining the microbiological profile of pleural infection inform antibiotic choice and can help to delineate the source and pathogenesis of infection. The development of radiological methods and use of clinical indices to predict which patients with pleural infection will have a poor outcome, as well as inform patient selection for more invasive treatments, is particularly important. Randomised clinical trial and case series data have shown that the combination of an intrapleural tissue plasminogen activator and deoxyribonuclease therapy can potentially improve outcomes, but the use of this treatment as compared with surgical options has not been precisely defined, particularly in terms of when and in which patients it should be used.

Predictors of prolonged stay in patients with community-acquired pneumonia and complicated parapneumonic effusion

BACKGROUND AND OBJECTIVE

Development of CPE in CAP is associated with prolonged hospital stay and it may increase the morbidity and mortality. We aimed to identify microbiological and clinical factors that predicate a prolonged hospital admission in patients treated with a tube thoracostomy to control CPE.

METHODS

This retrospective cohort included patients with CPE requiring chest tube drainage in a tertiary referral Korean hospital from 1 January 2004 to 30 July 2012. After dichotomous grouping according to the mean duration of hospital stay, clinical, laboratory and microbiological parameters were compared.

RESULTS

The final analysis included 158 patients with CPE. The majority were male (130, 85.0%), and the mean age was 62.8 years. The mean duration of hospital stay was 17.7 (±10.2) days. The mean duration of chest tube drainage was 9.6 (±6.7) days. Streptococcus viridans (48.4%) was the most common pathogen. Intrapleural fibrinolysis was performed in 85 (53.8%); additional tube insertion was needed in 40 (25.3%) patients. In the multivariate analysis after adjusting for covariates, a prolonged hospital stay was associated with fever (aOR: 3.42, P = 0.02), lower PaO2 (aOR: 4.89, P = 0.007) and haemoglobin (aOR: 4.90, P = 0.003) levels, and an increased blood neutrophil fraction (aOR: 3.83, P = 0.01) on admission as well as the identification of microbes in CPE (aOR: 4.14, P = 0.03), and ineffective pleural drainage (aOR: 3.28, P = 0.03).

CONCLUSIONS

This study suggests that physicians should note the clinical symptoms and laboratory findings of severe infection and effectiveness of pleural drainage to predicate which patients with a CAP needing thoracostomy for CPE will have a prolonged hospital stay.

The diagnosis of pleural effusions

Pleural effusions arise from a variety of systemic, inflammatory, infectious and malignant conditions. Their precise etiological diagnosis depends on a combination of medical history, physical examination, imaging tests and pertinent pleural fluid analyses; including specific biomarkers (e.g., natriuretic peptides for heart failure, adenosine deaminase for tuberculosis, or mesothelin for mesothelioma). Invasive procedures, such as pleuroscopic biopsies, may be required for persistently symptomatic effusions which remain undiagnosed after the analysis of one or more pleural fluid samples. However, whenever parietal pleural nodularity or thickening exist, image-guided biopsies should first be attempted. This review addresses the current diagnostic approach to pleural effusions secondary to heart failure, pneumonia, cancer, tuberculosis and other less frequent conditions.

A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats

OBJECTIVE

To review the current literature in reference to the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats.

ETIOLOGY

Pyothorax, also known as thoracic empyema, is characterized by the accumulation of septic purulent fluid within the pleural space. While the actual route of pleural infection often remains unknown, the oral cavity and upper respiratory tract appear to be the most common source of microorganisms causing pyothorax in dogs and cats. In human medicine, pyothorax is a common clinical entity associated with bacterial pneumonia and progressive parapneumonic effusion.

DIAGNOSIS

Thoracic imaging can be used to support a diagnosis of pleural effusion, but cytologic examination or bacterial culture of pleural fluid are necessary for a definitive diagnosis of pyothorax.

THERAPY

The approach to treatment for pyothorax varies greatly in both human and veterinary medicine and remains controversial. Treatment of pyothorax has classically been divided into medical or surgical therapy and may include administration of antimicrobials, intermittent or continuous thoracic drainage, thoracic lavage, intrapleural fibrinolytic therapy, video-assisted thoracic surgery, and traditional thoracostomy. Despite all of the available options, the optimal treatment to ensure successful short- and long-term outcome, including the avoidance of recurrence, remains unknown.

PROGNOSIS

The prognosis for canine and feline pyothorax is variable but can be good with appropriate treatment. A review of the current veterinary literature revealed an overall reported survival rate of 83% in dogs and 62% in cats. As the clinical presentation of pyothorax in small animals is often delayed and nonspecific, rapid diagnosis and treatment are required to ensure successful outcome.

[Parapneumonic pleural effusions: Epidemiology, diagnosis, classification and management]

Parapneumonic pleural effusions represent the main cause of pleural infections. Their incidence is constantly increasing. Although by definition they are considered to be a "parapneumonic" phenomenon, the microbial epidemiology of these effusions differs from pneumonia with a higher prevalence of anaerobic bacteria. The first thoracentesis is the most important diagnostic stage because it allows for a distinction between complicated and non-complicated parapneumonic effusions. Only complicated parapneumonic effusions need to be drained. Therapeutic evacuation modalities include repeated therapeutic thoracentesis, chest tube drainage or thoracic surgery. The choice of the first-line evacuation treatment is still controversial and there are few prospective controlled studies. The effectiveness of fibrinolytic agents is not established except when they are combined with DNase. Antibiotics are mandatory; they should be initiated as quickly as possible and should be active against anaerobic bacteria except for in the context of pneumococcal infections. There are few data on the use of chest physiotherapy, which remains widely used. Mortality is still high and is influenced by underlying comorbidities.

Utility of measurement of interleukin-1ß and interleukin-8 in the diagnosis of complicated parapneumonic pleural effusions

OBJECTIVES

Thirty percent of patients with pneumonia develop pleural effusion, and of these, 20% have complicated effusion (CPPE), which may require a chest tube or surgery for resolution. The objective of the study is to compare the diagnostic yield of determining interleukin-1β and interleukin-8 in pleural fluid (PF) (PFIL-1β and PFIL-8) with respect to classic criteria (pH <7.2, lactate dehydrogenase [LD] >1,000 IU/mL, and/or glucose <60 mg/dL) in the early diagnosis of CPPE.

METHODS

Of the 559 patients studied, 40 had CPPE. All underwent PF analysis: pH, glucose (PFGLUC), LD (PFLD), PFIL-1β and PFIL-8, and PF/serum ratios (PF/SIL-1β and PF/SIL-8).

RESULTS

The diagnostic criterion that showed the best area under the curve was the combination of PF/SIL-8 and PFIL-1β (0.906), with a statistically significant difference (P < .05) compared with the classic criterion of pH and PFGLUC or PFLD (0.826). The combination of PF/SIL-8 and PFIL-1β (cutoffs >5.73 and >9.14 pg/mL, respectively) was significantly more sensitive (72.7%) and more specific (97.9%) (P < .05) than the rest of the parameters used.

CONCLUSIONS

Measurement of IL-1β and IL-8 in pleural fluid may be useful in the early diagnosis of CPPE, although individually, it may not improve the results obtained with the PFLD. Further studies are needed to more firmly establish what role these new parameters can play in the diagnosis of CPPE.

The role of interventional therapy for pleural diseases

Pleural diseases encompass a vast and heterogeneous group of diseases that have traditionally received relatively little attention from researchers, resulting in empiric approaches to patient management based largely on expert opinions and anecdotal evidence. Yet, paradoxically, pleural diseases represent a considerable burden for patients, providers, and the healthcare system as a whole, with a rising incidence of malignant pleural effusions and pleural space infections, in increasingly complex patients. Fortunately, the last decade has witnessed unprecedented research efforts from the pleural community, which have resulted in substantial advances in risk-stratification, patient selection, treatment efficacy and the development of evidence-based recommendations ultimately leading to improved patient care. In this review, we will present a summary of the current evidence for the management of pleural diseases with an emphasis on interventional procedures, and highlight the need for future research efforts in the field of malignant pleural effusions, pleural space infections and pneumothorax.

Recommendations of diagnosis and treatment of pleural effusion. Update

Although during the last few years there have been several important changes in the diagnostic or therapeutic methods, pleural effusion is still one of the diseases that the respiratory specialist have to evaluate frequently. The aim of this paper is to update the knowledge about pleural effusions, rather than to review the causes of pleural diseases exhaustively. These recommendations have a longer extension for the subjects with a direct clinical usefulness, but a slight update of other pleural diseases has been also included. Among the main scientific advantages are included the thoracic ultrasonography, the intrapleural fibrinolytics, the pleurodesis agents, or the new pleural drainages techniques.

Do we measure pleural fluid pH correctly?

PURPOSE OF REVIEW

This review analyzes the current literature available on appropriate measurement of pleural fluid pH and currently used methods of measurement.

RECENT FINDINGS

Current literature continues to support the superiority of blood gas analyzers (BGAs) in the accurate measurement of pleural fluid pH. Despite the compelling evidence, roughly 30-50% of the laboratories across the United States continue to use inaccurate methods for pleural fluid pH measurement. Nearly 40% of pulmonologists were incorrect in believing their laboratory uses BGA for the analysis of pleural fluid pH.

SUMMARY

It is apparent that the clinical utility of pleural fluid pH is often undermined by its inappropriate measurement. Physicians must be made aware of their laboratory's method of measurement if pleural fluid pH is to be used in the evaluation of pleural diseases. If pleural fluid pH measurement is not done accurately, then other pleural fluid characteristics may be used to aid the clinician.