Invasive diagnostic techniques for pneumonia: protected specimen brush, bronchoalveolar lavage, and lung biopsy methods

Comparative Evaluation of the Role of Nonbronchoscopic and Bronchoscopic Techniques of Distal Airway Sampling for the Diagnosis of Ventilator-Associated Pneumonia

Background:

The diagnosis of ventilator-associated pneumonia (VAP) remains a challenge, with clinicians mainly relying on clinical, radiological, and bacteriologic strategies to manage patients with VAP.

Aims:

To compare the results of non-bronchoscopic and bronchoscopic techniques of distal airway sampling for the diagnosis of VAP.

Settings and Design:

This was a single-center prospective diagnostic accuracy study done in the 14-bedded intensive care unit of a tertiary care referral hospital.

Materials and Methods:

Patients aged ≥18 years, on mechanical ventilation for ≥48 h, and with clinical suspicion of VAP (fever, leukocytosis, and increased tracheal secretions) either on admission or during their stay were included. Every patient underwent both procedures for sample collection, first non-bronchoscopic protected bronchoalveolar lavage (NP-BAL) and then bronchoscopic BAL (B-BAL). Clinical Pulmonary Infection Score (CPIS) was calculated for each patient and the collected samples were evaluated in laboratory using standard microbiological techniques.

Statistical Analysis Used:

The sensitivity, specificity, positive predictive value, and negative predictive value of NP-BAL and B-BAL for the diagnosis of VAP were calculated taking CPIS score of >6 as index test for the diagnosis of VAP.

Results:

Sixty patients were included in the study. Both NP-BAL and B-BAL had concordance with the CPIS at 69.1%. The concordance between NP-BAL and B-BAL was better at 67.6% with a kappa coefficient of 0.064 (P = −0.593). The yield and sensitivity of NP-BAL were comparable to that of B-BAL.

Conclusions:

The blind NP-BAL is an equally effective method of airway sampling and could be a better alternative to replace more invasive B-BAL for microbiologic diagnosis of VAP.

Life-Threatening Everolimus-Associated Pneumonitis: A Case Report and a Review of the Literature

INTRODUCTION

Noninfective pneumonitis is a class-related effect within mammalian target of rapamycin (mTOR) inhibitors, including everolimus, and can occasionally be severe.

CASE REPORT

A 62-year-old man, medicated with everolimus due to a heart transplantation 17 years previously and with chronic kidney disease, was admitted to the intensive care unit (ICU) with acute respiratory failure, cardiovascular shock, and impaired renal function requiring dialysis. Computed tomography (CT) scan revealed right upper lobe consolidation. Extensive microbiological workup, autoimmune testing, and cytology were negative and echocardiography showed preserved heart function. Everolimus levels were normal (5.7-6.1 ng/mL) and the drug was suspended at day 9. The patient was difficult to ventilate and responded poorly to broad-spectrum antibiotic and antifungal therapy. On day 25, CT scan and bronchoscopy revealed left-sided alveolar hemorrhage, and corticosteroid pulses were performed. The patient gradually improved. After discharge and 6 months of follow-up, clinical recovery was complete and chest imaging substantially improved.

DISCUSSION

Pneumonitis occurs in up to 4.3% of transplant recipients using everolimus for immunosuppression. Despite usually presenting as a mild and self-limited disease, severe cases have been described. Alveolar hemorrhage can occur and is associated with poor outcome. Everolimus levels do not seem to accurately predict toxicity. Corticosteroid therapy has been used with success in severe disease. We review the pathophysiological, clinical, and management-related aspects of this entity with emphasis on its potential severity.

CONCLUSION

Our case was a rare occurrence of severe life-threatening pulmonary disease related to everolimus. Awareness of the potential severity of this entity is important for the management of patients using mTOR inhibitors.

The value of antibody-coated bacteria in tracheal aspirates for the diagnosis of ventilator-associated pneumonia: a case-control study

Objective:

Ventilator-associated pneumonia (VAP) is the leading type of hospital-acquired infection in ICU patients. The diagnosis of VAP is challenging, mostly due to limitations of the diagnostic methods available. The aim of this study was to determine whether antibody-coated bacteria (ACB) evaluation can improve the specificity of endotracheal aspirate (EA) culture in VAP diagnosis.

Methods:

We conducted a diagnostic case-control study, enrolling 45 patients undergoing mechanical ventilation. Samples of EA were obtained from patients with and without VAP (cases and controls, respectively), and we assessed the number of bacteria coated with FITC-conjugated monoclonal antibodies (IgA, IgM, or IgG) or an FITC-conjugated polyvalent antibody. Using immunofluorescence microscopy, we determined the proportion of ACB among a fixed number of 80 bacteria.

Results:

The median proportions of ACB were significantly higher among the cases (n = 22) than among the controls (n = 23)-IgA (60.6% vs. 22.5%), IgM (42.5% vs. 12.5%), IgG (50.6% vs. 17.5%), and polyvalent (75.6% vs. 33.8%)-p < 0.001 for all. The accuracy of the best cut-off points for VAP diagnosis regarding monoclonal and polyvalent ACBs was greater than 95.0% and 93.3%, respectively.

Conclusions:

The numbers of ACB in EA samples were higher among cases than among controls. Our findings indicate that evaluating ACB in EA is a promising tool to improve the specificity of VAP diagnosis. The technique could be cost-effective and therefore useful in low-resource settings, with the advantages of minimizing false-positive results and avoiding overtreatment.

Comparison of bronchoscopic and non-bronchoscopic techniques for diagnosis of ventilator associated pneumonia

Background:

The diagnosis of ventilator associated pneumonia (VAP) remains a challenge because the clinical signs and symptoms lack both sensitivity and specificity and the selection of microbiologic diagnostic procedure is still a matter of debate.

Aims and Objective:

To study the role of various bronchoscopic and non-bronchoscopic diagnostic techniques for diagnosis of VAP.

Settings and Design:

This prospective comparative study was conducted in a medical ICU of a tertiary care center.

Materials and Methods:

Twenty-five patients, clinically diagnosed with VAP, were evaluated by bronchoscopic and non-bronchoscopic procedures for diagnosis. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of various bronchoscopic and non-bronchoscopic techniques were calculated, taking clinical pulmonary infection score (CPIS) of ≥6 as reference standard.

Results:

Our study has shown that for the diagnosis of VAP, bronchoscopic brush had a sensitivity, specificity, PPV and NPV of 94.9% [confidence interval (CI): 70.6–99.7], 57.1% (CI: 13.4–86.1), 85% (CI: 61.1–96) and 80% (CI: 21.9–98.7), respectively. Bronchoscopic bronchoalveolar lavage (BAL) had a sensitivity, specificity, PPV and NPV of 77.8% (CI: 51.9–92.6), 71.8% (CI: 24.1–94), 87.3% (CI: 60.4–97.8) and 55.5% (CI: 17.4–82.6), respectively. Sensitivity, specificity, PPV and NPV for non–bronchoscopic BAL (NBAL) were 83.3% (CI: 57.7–95.6), 71.43% (CI: 24.1–94), 88.2% (CI: 62.3–97.4) and 62.5% (CI: 20.2–88.2), respectively. Endotracheal aspirate (ETA) yield was only 52% and showed poor concordance with BAL (κ-0.351; P-0.064) and NBAL (k-0.272; P-0.161). There was a good microbiologic concordance among different bronchoscopic and non-bronchoscopic distal airway sampling techniques.

Conclusion:

NBAL is an inexpensive, easy, and useful technique for microbiologic diagnosis of VAP. Our findings, if verified, might simplify the approach for the diagnosis of VAP.

Diagnostic accuracy of bronchoalveolar lavage samples in immunosuppressed patients with suspected pneumonia: analysis of a protocol

BACKGROUND

Fast and accurate etiologic diagnosis of pneumonia in immunocompromised patients is essential for a good outcome. Utility of bronchoalveolar lavage (BAL) samples has already been established, but studies about them are scarce and limited to few countries. We aimed to evaluate the accuracy of a diagnostic protocol, emphasizing on local epidemiology, rapidity, and yield of different techniques.

METHODS

One year prospective study of 101 consecutive immunosuppressed patients admitted with suspected pneumonia to a university hospital. They all had bronchoscopic BAL (n=109) and respiratory sampling. Conventional microbiological studies, cytomegalovirus pp65 antigenemia and transbronchial biopsy (TBB), whenever considered pertinent, were done. Results were analyzed along with other diagnostic procedures, clinical course and final outcome.

RESULTS

HIV/AIDS infection was the most frequent cause of inclusion (n=80). Infections accounted for 79 out of 122 final diagnoses (64.8%). Our protocol identified 60 infectious and 3 noninfectious pathologies (general yield: 51.6%). Sensitivity in pulmonary infections was 75.9% (IC95%: 64.8-84.6%), specificity 86.0% (72.6-93.7%), positive predictive value 89.6% (79.1-95.3%), negative predictive value 69.4% (56.2-80.1%), accuracy 79.8% (71.7-86.2%). Mycobacterium spp. (n=27), bacteria (n=19), Pneumocystis jirovecii (n=18) and other fungi (histoplasmosis: 6, aspergillosis: 5, cryptococosis: 3) were the most common infectious pathogens. Direct microscopy allowed an early definite/presumptive diagnosis in 36/49 fungal and mycobacterial infections (73.5%). Up to 30% of mycobacterial infections were missed.

CONCLUSIONS

Systematical study of BAL samples has a high diagnostic yield in our immunocompromised patients with suspected pneumonia. As economical and epidemiological conditions of regions are different, it should be tried everywhere.

[Management of ventilator acquired pneumonia]

Ventilator-associated pneumonia occurs in the evolution of 8 to 70% of patients in the Intensive Care Unit. It is the main site of nosocomial infection for mechanically ventilated patients. Nosocomial pneumonia represents an important cause of morbidity and mortality, despite progresses in antibiotic prescription, use of intensive care and prevention. This review is based on the ATS guidelines, and reviews epidemiology, diagnosis and treatment of ventilator-acquired pneumonia, in non-immunocompromised adults.

Neumonías comunitarias graves del adulto

Las neumonías agudas comunitarias son causa frecuente de hospitalización y mortalidad. El reconocimiento inmediato de las formas graves según criterios simples, clínicos, radiológicos y de laboratorio, es una etapa esencial para un tratamiento rápido en el servicio de reanimación con el fin de controlar los fallos orgánicos. La obtención de muestras apropiadas para realizar estudios microbiológicos precede al tratamiento antibiótico, que se debe instaurar con rapidez después de diagnosticar la neumonía. Pese a las técnicas de identificación, sólo la mitad de las neumonías se documentan adecuadamente. El tratamiento antibiótico, en principio empírico, integra los gérmenes patógenos, tanto extracelulares como intracelulares, que producen neumonías con mayor frecuencia; siempre debe ser activo contra el neumococo, la bacteria implicada más a menudo. La asociación de un betalactámico y un macrólido o una fluoroquinolona es la que mejor responde a este objetivo. En las recomendaciones más comunes, las fluoroquinolonas activas contra los neumococos sustituyen a los fármacos precedentes. En el caso excepcional de los pacientes con factores de riesgo especiales, el tratamiento empírico debe tener en cuenta Pseudomonas aeruginosa. La gravedad de parte de las neumonías comunitarias justifica el que se recurra a tratamientos complementarios. Se debe evaluar de nuevo el tratamiento antibiótico en las 72 horas siguientes a su instauración, a fin de valorar su eficacia, adaptar el tratamiento en caso necesario y simplificarlo. El mantenimiento de antibióticos de amplio espectro expone al paciente a efectos secundarios y contribuye a producir resistencias bacterianas. En cuanto a las neumonías neumocócicas, las fluoroquinolonas activas contra el neumococo podrían representar una alternativa en caso de que el neumococo desarrolle resistencia a los betalactámicos. La mortalidad persistente de las neumonías sigue siendo notable. Esto debe fomentar la mejora del tratamiento inicial y la búsqueda de nuevas opciones terapéuticas.

Pneumonies communautaires graves de l'adulte

Les pneumonies aiguës communautaires sont des causes fréquentes d'hospitalisation et de mortalité. La reconnaissance immédiate des formes sévères sur des critères simples, cliniques, radiologiques et biologiques, est une étape importante pour une prise en charge rapide en réanimation afin de contrôler les défaillances d'organes. Les prélèvements appropriés microbiologiques précèdent l'antibiothérapie qui doit être instituée très rapidement après le diagnostic de pneumonie. Malgré les techniques d'identification, la moitié seulement des pneumonies sont documentées. Cette antibiothérapie, initialement probabiliste, intègre les germes pathogènes les plus souvent responsables, extra- et intracellulaires ; elle doit toujours être active sur le pneumocoque, bactérie la plus fréquente. L'association d'une β-lactamine et d'un macrolide ou d'une fluoroquinolone répond le mieux à cet objectif. Les fluoroquinolones actives sur le pneumocoque se sont substituées aux précédentes dans les plus récentes recommandations. Dans le cas exceptionnel des patients ayant des facteurs de risque particuliers, le traitement probabiliste doit prendre en compte Pseudomonas aeruginosa. La gravité d'une partie des pneumonies communautaires justifie le recours à des traitements adjuvants. L'antibiothérapie doit être réévaluée dans les 72 heures dans le but d'apprécier son efficacité, de l'adapter éventuellement et de la simplifier. La poursuite des antibiotiques à large spectre expose le patient à des effets indésirables et contribue aux résistances bactériennes. Pour les pneumonies dues au pneumocoque, les fluoroquinolones actives sur le pneumocoque pourront constituer une alternative en cas d'évolution importante des résistances du pneumocoque aux β-lactamines. La mortalité persistante des pneumonies reste sévère. Ceci doit stimuler l'amélioration de la prise en charge initiale et faire rechercher de nouvelles thérapeutiques.

Decision analysis of antibiotic and diagnostic strategies in ventilator-associated pneumonia

The optimal strategy for ventilator-associated pneumonia remains controversial. To clarify the tradeoffs involved, we performed a decision analysis. Strategies evaluated included antibiotic therapy with and without diagnostic testing. Tests that were explored included endotracheal aspirates, bronchoscopy with protected brush or bronchoalveolar lavage, and nonbronchoscopic mini-bronchoalveolar lavage (mini-BAL). Outcomes included dollar cost, antibiotic use, survival, cost-effectiveness, antibiotic use per survivor, and the outcome perspective of financial cost-antibiotic use per survivor. Initial coverage with three antibiotics was better than expectant management or one or two antibiotic approaches, leading to both improved survival (54% vs. 66%) and decreased cost (US dollars 55447 vs. US dollars 41483 per survivor). Testing with mini-BAL did not improve survival but did decrease costs (US dollars 41483 vs. US dollars 39967) and antibiotic use (63 vs. 39 antibiotic days per survivor). From the perspective of minimizing cost, minimizing antibiotic use, and maximizing survival, the best strategy was three antibiotics with mini-BAL.

Aspiración endotraqueal, cepillado y lavado broncoalveolar

The aim of endotracheal aspiration is to eliminate secretions in patients with an artificial airway. All children with mechanical ventilation must undergo this procedure periodically. The frequency of aspiration depends on the type and quantity of the respiratory secretions and on the patient's clinical status. Aspiration should be performed by two people to maintain a greater degree of asepsis and to optimize stability of the airway and ventilation. Closed aspiration systems are available that allow aspiration without the need to disconnect the patient through a single probe that is constantly protected by a plastic sleeve and isolated from external environment. The most important risks of endotracheal aspiration are hypoxemia, mucosal injury, bronchospasm, arrhythmias, perforation of the airway with development of pneumothorax, accidental extubation, and infections. Bronchial brushing with a protected catheter and brochoalveolar lavage are used to analyze pulmonary infections. These techniques can be performed blind or through fibrobronchoscopy. They can also be used for the diagnosis of noninfectious pulmonary diseases such as alveolar proteinosis, alveolar hemorrhage or histiocytosis. Their adverse effects are similar to those of endotracheal aspiration.

Ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) continues to complicate the course of 8 to 28% of patients receiving mechanical ventilation (MV). In contrast to infections of more frequently involved organs (e.g., urinary tract and skin), for which mortality is low, ranging from 1 to 4%, the mortality rate for VAP ranges from 24 to 50% and can reach 76% in some specific settings or when lung infection is caused by high-risk pathogens. The predominant organisms responsible for infection are Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacteriaceae, but etiologic agents widely differ according to the population of patients in an intensive care unit, duration of hospital stay, and prior antimicrobial therapy. Because appropriate antimicrobial treatment of patients with VAP significantly improves outcome, more rapid identification of infected patients and accurate selection of antimicrobial agents represent important clinical goals. Our personal bias is that using bronchoscopic techniques to obtain protected brush and bronchoalveolar lavage specimens from the affected area in the lung permits physicians to devise a therapeutic strategy that is superior to one based only on clinical evaluation. When fiberoptic bronchoscopy is not available to physicians treating patients clinically suspected of having VAP, we recommend using either a simplified nonbronchoscopic diagnostic procedure or following a strategy in which decisions regarding antibiotic therapy are based on a clinical score constructed from seven variables. Selection of the initial antimicrobial therapy should be based on predominant flora responsible for VAP at each institution, clinical setting, information provided by direct examination of pulmonary secretions, and intrinsic antibacterial activities of antimicrobial agents and their pharmacokinetic characteristics. Further trials will be needed to clarify the optimal duration of treatment and the circumstances in which monotherapy can be safely used.

Microbial investigation in ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is a serious infectious condition in intensive care unit (ICU) patients, currently related to a high mortality rate. Therefore, this complication of mechanical ventilation requires a prompt diagnosis and adequate antibiotic treatment. The detection of the causative organism is imperative for guiding an appropriate therapy as there is strong evidence of the adverse effect of inadequate empirical treatment on outcome. The major difficulty of the microbial investigation is to obtain the sample from the lower respiratory tract, mainly because of the potential contamination with upper airways flora, which may result in a misinterpretation of the cultures. Microbial investigation in VAP is based on the culture of samples obtained from lower respiratory tract by noninvasive or invasive methods. The most common techniques of sampling are the endotracheal aspirate (ETA), which is considered a noninvasive method, the protected specimen brush (PSB) and the bronchoalveolar lavage (BAL), both being invasive methods of investigation. The latter were designed as an attempt to avoid the colonizing flora of the upper airways. The best of these diagnostic approaches is still controversial. In terms of outcome, there is strong evidence that the impact of both invasive and noninvasive methods seems to be similar. In terms of cost, however, the endotracheal aspirate is less expensive compared to BAL or PSB. On the other hand, invasive methods could be particularly beneficial in patients who are not responding to the initial empirical antibiotic treatment. The rationale for the quantitative culture of the respiratory samples is to differentiate between infection and colonization of lower airways, because the bacterial colonization is a frequent event in mechanically ventilated patients. The thresholds currently employed for the diagnosis of the pneumonia are the following: ETA samples, > or = 10(5)-10(6) colony forming units (cfu).mL(-1); PSB samples, > or =10(3) cfu.mL(-1); and BAL samples, > or =10(4) cfu.mL(-1). Intending to provide a practical approach to the issue, the present manuscript reviews the available noninvasive (blood culture, endotracheal aspirate) and invasive (protected specimen brush, bronchoalveolar lavage, blinded methods and lung biopsy) techniques used for the diagnosis of ventilator-associated pneumonia.