Discontinuing noninvasive ventilation in severe chronic obstructive pulmonary disease exacerbations: a randomised controlled trial.

We assessed whether prolongation of nocturnal noninvasive ventilation (NIV) after recovery from acute hypercapnic respiratory failure (AHRF) in chronic obstructive pulmonary disease (COPD) patients with NIV could prevent subsequent relapse of AHRF.A randomised controlled trial was performed in 120 COPD patients without previous domiciliary ventilation, admitted for AHRF and treated with NIV. When the episode was resolved and patients tolerated unassisted breathing for 4 h, they were randomly allocated to receive three additional nights of NIV (n=61) or direct NIV discontinuation (n=59). The primary outcome was relapse of AHRF within 8 days after NIV discontinuation.Except for a shorter median (interquartile range) intermediate respiratory care unit (IRCU) stay in the direct discontinuation group (4 (2-6) versus 5 (4-7) days, p=0.036), no differences were observed in relapse of AHRF after NIV discontinuation (10 (17%) versus 8 (13%) for the direct discontinuation and nocturnal NIV groups, respectively, p=0.56), long-term ventilator dependence, hospital stay, and 6-month hospital readmission or survival.Prolongation of nocturnal NIV after recovery from an AHRF episode does not prevent subsequent relapse of AHRF in COPD patients without previous domiciliary ventilation, and results in longer IRCU stay. Consequently, NIV can be directly discontinued when the episode is resolved and patients tolerate unassisted breathing.

Efficacy of linezolid compared to vancomycin in an experimental model of pneumonia induced by methicillin-resistant Staphylococcus aureus in ventilated pigs.

OBJECTIVE: To assess the efficacy of linezolid compared with vancomycin in an experimental model of pneumonia induced by methicillin-resistant Staphylococcus aureus (MRSA) in ventilated pigs. METHODS: Forty pigs (30 kg) were intubated and challenged via bronchoscopy with a suspension of 106 colony forming units of MRSA into every lobe. Afterwards, pigs were ventilated up to 96 hours. Twelve hours after bacterial inoculation, the animals were randomized into 4 groups of treatment: group 1, control; group 2, vancomycin twice daily; group 3, continuous infusion of vancomycin; and group 4, linezolid. Clinical and laboratory parameters were monitored throughout the study. Bacterial cultures of bronchoalveolar lavage fluid and lung tissue samples were performed at the end of the study. Measurements of histopathology derangements of lung samples and studies of intrapulmonary drug penetration were performed. RESULTS: A total of 34 animals completed the study. No differences in clinical and laboratory parameters were observed. The percentage of bronchoalveolar lavage fluid and lung tissue samples with positive cultures for MRSA in controls and groups 2, 3, and 4 was respectively 75%, 11%, 11%, and 0% (p < .01); 52%, 9%, 24%, and 2.5% (p < .01). Histopathology studies demonstrated signs of pneumonia in 95%, 69%, 58%, and 57% and signs of severe pneumonia in 48%, 29%, 22%, and 0% of controls and groups 2, 3, and 4, respectively (p < .01). In addition, pharmacokinetics/pharmacodynamics profile in serum and lung tissue showed better results for linezolid compared with both vancomycin treatments. CONCLUSIONS: In this animal model of MRSA pneumonia, linezolid showed a better efficacy than vancomycin showed because of a better pharmacokinetics/pharmacodynamics index.

Linezolid limits burden of methicillin-resistant Staphylococcus aureus in biofilm of tracheal tubes.

OBJECTIVE: To evaluate the effects of systemic treatment with linezolid compared with vancomycin on biofilm formation in mechanically ventilated pigs with severe methicillin-resistant Staphylococcus aureus-induced pneumonia. DESIGN: Prospective randomized animal study. SETTING: Departments of Pneumology, Microbiology, and Pharmacy of the Hospital Clínic, Barcelona, and Scientific and Technological Services of the University of Barcelona. SUBJECTS: We prospectively analyzed 70 endotracheal tube samples. Endotracheal tubes were obtained from pigs either untreated (controls, n=20), or treated with vancomycin (n=32) or linezolid (n=18). INTERVENTIONS: The endotracheal tubes were obtained from a previous randomized study in tracheally intubated pigs with methicillin-resistant Staphylococcus aureus severe pneumonia, and mechanically ventilated for 69±16 hrs. MEASUREMENTS AND MAIN RESULTS: Distal and medial hemisections of the endotracheal tube were assessed to quantify methicillin-resistant Staphylococcus aureus burden, antibiotic biofilm concentration by high-performance liquid chromatography or bioassay, and biofilm thickness through scanning electron microscopy. We found a trend toward a significant variation in biofilm methicillin-resistant Staphylococcus aureus burden (log colony-forming unit/mL) among groups (p=.057), and the lowest bacterial burden was found in endotracheal tubes treated with linezolid (1.98±1.68) in comparison with untreated endotracheal tubes (3.72±2.20, p=.045) or those treated with vancomycin (2.97±2.43, p=.286). Biofilm linezolid concentration was 19-fold above the linezolid minimum inhibitory concentration, whereas biofilm vancomycin concentration (1.60±0.91 µg/mL) was consistently below or close to the vancomycin minimum inhibitory concentration. Biofilm was thicker in the vancomycin group (p=.077). CONCLUSIONS: Systemic treatment with linezolid limits endotracheal tube biofilm development and methicillin-resistant Staphylococcus aureus burden. The potential clinical usefulness of linezolid in decreasing the risk of biofilm-related respiratory infections during prolonged tracheal intubation requires further investigation.

Development and validation of a high performance liquid chromatography method to determine linezolid concentrations in pig pulmonary tissue.

BACKGROUND: Linezolid is the first synthetic compound of a new group of antimicrobials, the oxazolidinones, which inhibit protein synthesis. It shows a broad spectrum of activity against Gram positive organisms. With respect to its pharmacokinetics, linezolid shows a relatively high volume of distribution and good penetration into inflammatory fluids, bone, fat and muscle. METHODS: A reversed-phase isocratic high-performance liquid chromatographic method for linezolid analysis in piglet pulmonary tissue is described. Tissue samples and controls were prepared in 1 x TBE (1 M Tris, 0.9 M boric acid, 0.01 M EDTA). The mobile phase consisted of 20% ultrafiltered water and 80% of (A) 15 mM potassium monohydrogen phosphate buffer (pH = 5) with (B) acetonitrile (80%/20%; v/v). Samples were homogenized and precipitated with HClO(4) 3% (1/1, v/v). The injection volume was 100 microL. Ofloxacin was used as an internal standard. RESULTS: The assay was linear over a linezolid concentration range: 1.6-100 microg/mL. The method provided good validation data (n = 15): inaccuracy (3.6%), intra and inter-day variability (4.2% and 5.2%, respectively), recovery (91.8%), limit of detection (0.8 microg/mL) and quantitation (1.6 microg/mL) and acceptable stability within 24 h in the auto-sampler. CONCLUSIONS: The method offers a fast and simple approach to determine linezolid in pulmonary tissue which could be of use in pharmacokinetic studies.

[Transbronchial needle aspiration in the study of mediastinal lymph nodes: yield and cost-effectiveness]. / Punción transbronquial aspirativa en el estudio de las adenopatías mediastínicas: rentabilidad y coste-beneficio.

OBJECTIVE: The role of different techniques for mediastinal staging in patients with suspected lung cancer is a subject of debate. The aim of this study was to analyze the diagnostic yield and cost-effectiveness of transbronchial needle aspiration in the mediastinal staging of lung cancer in patients being evaluated in a tertiary hospital. PATIENTS AND METHODS: This was a retrospective, observational study of the results of transbronchial needle aspiration in patients with suspected lung cancer and mediastinal lymph node involvement. A cost-effectiveness analysis of the systematic use of this technique was also performed. RESULTS: One-hundred ninety-four patients (85% men, 15% women) were evaluated. The diagnosis of lung cancer was confirmed in 157 (81%). Cytology samples obtained by transbronchial needle aspiration were adequate in 147 (76%) of the 194 cases. When only the adequate samples were included in the analysis, transbronchial needle aspiration showed a sensitivity of 88%, specificity of 100%, positive predictive value of 100%, negative predictive value of 64%, and efficiency of 90%. Mediastinoscopy was avoided in 44 (34%) of the 127 patients with localized non-small cell lung cancer, with an estimated saving of euro 119,456. CONCLUSIONS: Transbronchial needle aspiration has a high diagnostic yield and obviates the need for mediastinoscopy in a significant percentage of cases. This finding is of diagnostic and economic significance.

Direct analysis of bacterial viability in endotracheal tube biofilm from a pig model of methicillin-resistant Staphylococcus aureus pneumonia following antimicrobial therapy.

Confocal laser scanning microscopy (CLSM) helps to observe the biofilms formed in the endotracheal tube (ETT) of ventilated subjects and to determine its structure and bacterial viability using specific dyes. We compared the effect of three different treatments (placebo, linezolid, and vancomycin) on the bacterial biofilm viability captured by CLSM. Eight pigs with pneumonia induced by methicillin-resistant Staphylococcus aureus (MRSA) were ventilated up to 96 h and treated with linezolid, vancomycin, or placebo (controls). ETT images were microscopically examined after staining with the live/dead(®) BacLight(™) Kit (Invitrogen, Barcelona, Spain) with a confocal laser scanning microscope. We analyzed 127 images obtained by CLSM. The median ratio of live/dead bacteria was 0.51, 0.74, and 1 for the linezolid, vancomycin, and control groups, respectively (P = 0.002 for the three groups); this ratio was significantly lower for the linezolid group, compared with the control group (P = 0.001). Images showed bacterial biofilm attached and non-attached to the ETT surface but growing within secretions accumulated inside ETT. Systemic treatment with linezolid is associated with a higher proportion of dead bacteria in the ETT biofilm of animals with MRSA pneumonia. Biofilm clusters not necessarily attach to the ETT surface.

Significance of the presence of lymphocytes in the cytological analysis of transbronchial needle aspiration.

AIM: To evaluate the clinical relevance of the presence of lymphocytes in transbronchial needle aspiration (TBNA) samples from pathological mediastinal lymph nodes in patients with suspected lung cancer. METHODS: Retrospective observational study evaluating the negative predictive value (NPV) of TBNA samples containing lymphocytes but not malignant cells. RESULTS: A total of 266 TBNA were performed in 252 patients with pathological lymph nodes. One hundred and fifteen TBNA samples had evidence of malignant cells (43%), and 94 (35%) samples were considered as inadequate (absence of adequate cytological material or exclusive presence of bronchial epithelial cells). Out of the 57 TBNA samples remaining (21%), 15 could not be confirmed; in 32, TBNA samples were confirmed with alternative diagnostic techniques and in 10, they were confirmed after clinical and radiological follow-up. The NPV of the 32 samples that were confirmed with alternative diagnostic techniques was 84% decreasing down to 76% when the 10 TBNA samples confirmed after clinical and radiological follow-up were included. CONCLUSIONS: The presence of lymphocytes in the TBNA sample does not exclude the neoplasic invasion of the specific lymph node analyzed.