Josep Ramírez

Clinical diagnosis of ventilator associated pneumonia revisited: comparative validation using immediate post-mortem lung biopsies

BACKGROUND A study was undertaken to assess the diagnostic value of different clinical criteria and the impact of microbiological testing on the accuracy of clinical diagnosis of suspected ventilator associated pneumonia (VAP). METHODS Twenty five deceased mechanically ventilated patients were studied prospectively. Immediately after death, multiple bilateral lung biopsy specimens (16 specimens/patient) were obtained for histological examination and quantitative lung cultures. The presence of both histological pneumonia and positive lung cultures was used as a reference test. RESULTS The presence of infiltrates on the chest radiograph and two of three clinical criteria (leucocytosis, purulent secretions, fever) had a sensitivity of 69% and a specificity of 75%; the corresponding numbers for the clinical pulmonary infection score (CPIS) were 77% and 42%. Non-invasive as well as invasive sampling techniques had comparable values. The combination of all techniques achieved a sensitivity of 85% and a specificity of 50%, and these values remained virtually unchanged despite the presence of previous treatment with antibiotics. When microbiological results were added to clinical criteria, adequate diagnoses originating from microbiological results which might have corrected false positive and false negative clinical judgements (n = 5) were countered by a similar proportion of inadequate diagnoses (n = 6). CONCLUSIONS Clinical criteria had reasonable diagnostic values. CPIS was not superior to conventional clinical criteria. Non-invasive and invasive sampling techniques had diagnostic values comparable to clinical criteria. An algorithm guiding antibiotic treatment exclusively by microbiological results does not increase the overall diagnostic accuracy and carries the risk of undertreatment.

Characterization of pulmonary vascular remodelling in smokers and patients with mild COPD

Intimal enlargement of pulmonary arteries is an early change in chronic obstructive pulmonary disease (COPD). The cellular and extracellular components that are involved in this enlargement are unknown. The present study was designed to characterize the structural changes occurring in pulmonary muscular arteries in the initial disease stages. Lung specimens from patients with moderate COPD (n=8; forced expiratory volume in one second (FEV1), 66±10% predicted) and smokers without airflow obstruction (n=7; FEV1, 86±6% pred), were investigated by histochemistry to characterize extracellular matrix proteins and by immunohistochemistry to identify intrinsic cells of the vascular wall. In both COPD patients and smokers, the majority of cells present in the enlarged intimas were stained by specific smooth muscle cell (SMC) markers. No staining with endothelial or fibroblast markers was shown. A proportion of SMCs did not stain with desmin, suggesting cellular heterogeneity in this population. Elastin was the most abundant extracellular matrix protein and collagen was seen in a lower proportion. The amount of collagen was related to the intimal thickness (p<0.001). The findings demonstrated smooth muscle cell proliferation, as well as elastin and collagen deposition, in the thickened intimas of pulmonary arteries in moderate chronic obstructive pulmonary disease patients and smokers, suggesting that these abnormalities may originate at an early stage in cigarette smoke-induced respiratory disease.

Endothelial dysfunction in pulmonary arteries of patients with mild COPD

To investigate whether endothelial dysfunction of pulmonary arteries (PA) is present in patients with mild chronic obstructive pulmonary disease (COPD) and to what extent it is related to the morphological abnormalities of PA, we studied 41 patients who underwent lung resection. Patients were divided into the following groups: nonsmokers ( n = 7), smokers with normal lung function ( n = 13), and COPD ( n = 21). Endothelium-dependent relaxation mediated by nitric oxide was evaluated in vitro in PA rings exposed to cumulative concentrations of acetylcholine (ACh) and ADP. Structural abnormalities of PA were assessed morphometrically. PA of COPD patients developed lower maximal relaxation in response to ADP than both nonsmokers and smokers ( P < 0.05 each) and a trend to reduced relaxation in response to ACh ( P = 0.08). Maximal relaxation to ADP correlated with the degree of airflow obstruction ( r = 0.48, P < 0.01). Morphometrical analysis of PA revealed thicker intimas, especially in small arteries, in both smokers and COPD compared with nonsmokers ( P < 0.05 each). We conclude that endothelial dysfunction of PA is already present in patients with mild COPD. In these patients, as well as in smokers with normal lung function, small arteries show thickened intimas, suggesting that tobacco consumption may play a critical role in the pathogenesis of pulmonary vascular abnormalities in COPD.To investigate whether endothelial dysfunction of pulmonary arteries (PA) is present in patients with mild chronic obstructive pulmonary disease (COPD) and to what extent it is related to the morphological abnormalities of PA, we studied 41 patients who underwent lung resection. Patients were divided into the following groups: nonsmokers (n = 7), smokers with normal lung function (n = 13), and COPD (n = 21). Endothelium-dependent relaxation mediated by nitric oxide was evaluated in vitro in PA rings exposed to cumulative concentrations of acetylcholine (ACh) and ADP. Structural abnormalities of PA were assessed morphometrically. PA of COPD patients developed lower maximal relaxation in response to ADP than both nonsmokers and smokers (P < 0.05 each) and a trend to reduced relaxation in response to ACh (P = 0.08). Maximal relaxation to ADP correlated with the degree of airflow obstruction (r = 0.48, P < 0. 01). Morphometrical analysis of PA revealed thicker intimas, especially in small arteries, in both smokers and COPD compared with nonsmokers (P < 0.05 each). We conclude that endothelial dysfunction of PA is already present in patients with mild COPD. In these patients, as well as in smokers with normal lung function, small arteries show thickened intimas, suggesting that tobacco consumption may play a critical role in the pathogenesis of pulmonary vascular abnormalities in COPD.

Histopathologic and Microbiologic Aspects of Ventilator-associated Pneumonia

BackgroundThe relationship between microbiology and histology in patients with ventilator-associated pneumonia has been sparsely described.MethodsTwenty-five patients who died in the intensive care unit after their lungs had been mechanically ventilated for 72 h were studied. Twenty of the 25 died w

Intermittent hypoxia enhances cancer progression in a mouse model of sleep apnoea

To the Editors: Obstructive sleep apnoea (OSA) is a very prevalent syndrome that induces or aggravates cardiovascular, metabolic and neurocognitive disorders. Among the various challenges imposed on a patient by OSA as a consequence of apnoeas (sleep disruption, increased inspiratory efforts and recurrent hypoxaemia), intermittent hypoxia plays a major role in the pathophysiology of this sleep breathing disorder. It has been well established that hypoxia plays an important role in regulating the various stages of tumour formation and progression [1]. Accordingly, the aim of the experimental study reported here was to test the hypothesis that high-rate intermittent hypoxia with a time course similar to that found in OSA (one or more hypoxic event per minute) enhances tumour growth. To avoid the interaction of any comorbidity, this investigation was carried out in a well-controlled animal model where the main variable under study was intermittent hypoxia. This study, which was approved by the Ethical Committee for Animal Research of the University of Barcelona (Barcelona, Spain), was conducted in 15 pathogen-free male C57BL/6J mice (25–30 g) using a conventional murine melanoma model consisting of tumour induction by subcutaneous injection of 106 B16F10 melanoma cells (ATCC-CRL-6475; American Type Culture Collection, Manassas, VA, USA) in the left flank region of the mouse [2]. This is a widely used cancer model in experimental research [3, 4], which has a response to hypoxia that is representative of a variety of cancer types …

Sampling methods for ventilator-associated pneumonia: validation using different histologic and microbiological references.

ObjectiveTo validate sampling techniques (tracheobronchial aspirates, protected specimen brush, and bronchoalveolar lavage, both conventional and protected) for the detection of ventilator-associated pneumonia (VAP) and causative microorganisms according to different histologic and microbiological references. DesignImmediate, multiple bilateral lung biopsy, postmortem study. SettingRespiratory intensive care unit of a 1,000-bed teaching hospital. PatientsTwenty-five mechanically ventilated patients (>72 hrs) who died in our intensive care unit. MeasurementsLung tissue histologic examination and quantitative cultures (16 specimens/patient). The following four references for the diagnostic techniques were used: histology of guided lung biopsy, histology of blind lung biopsy, combined guided and blind lung biopsy histology and microbiology of lung tissue, and microbiology of lung tissue. ResultsSensitivities when histologic reference tests were used ranged from 16% to almost 40%, whereas specificity rates were always <80%. When we combined both lung histology of guided or blind specimens and microbiology of lung tissue, all diagnostic techniques achieved considerably higher but still limited diagnostic yields (sensitivity range 43% to 83%; specificity range 67% to 91%). Causative organisms were missed in a significant number of cases by all techniques (17% to 83%). ConclusionsThe diagnostic performances of different diagnostic techniques strongly depend on the reference used. All techniques for detecting VAP are of limited value. Finding a balance between clinical judgment and microbiological results is crucial to appropriately manage patients with VAP.

miR-141 and miR-200c as Markers of Overall Survival in Early Stage Non-Small Cell Lung Cancer Adenocarcinoma

Background Several treatments in non-small cell lung cancer (NSCLC) are histology-dependent, and the need for histology-related markers is increasing. MicroRNAs (miRNAs) are promising molecular markers in multiple cancers and show differences in expression depending on histological subtype. The miRNA family miR-200 has been associated with the regulation of epithelial-mesenchymal (EMT)/mesenchymal-epithelial transition (MET). EMT involves profound phenotypic changes that include the loss of cell-cell adhesion, the loss of cell polarity, and the acquisition of migratory and invasive properties that facilitates metastasis. A dual role for the miR-200 family in the prognosis of several tumors has been related to tumor cell origin. However, the prognostic role and function of miR-200 family in early-stage NSCLC adenocarcinoma and squamous cell carcinoma (SCC) have not been well established. Methods miRNA expression was determined using TaqMan assays in 155 tumors from resected NSCLC patients. Functional studies were conducted in three NSCLC cell lines: H23, A-549 and HCC-44. Results High miR-200c expression was associated with shorter overall survival (OS) in the entire cohort (p = 0.024). High miR-200c (p = 0.0004) and miR-141 (p = 0.009) expression correlated with shorter OS in adenocarcinoma – but not in SCC. In the multivariate analysis, a risk score based on miR-141 and miR-200c expression emerged as an independent prognostic factor for OS in the entire cohort (OR, 2.787; p = 0.033) and in adenocarcinoma patients (OR, 10.649; p = 0.002). Functional analyses showed that miR-200c, was related to mesenchymal-epithelial transition (MET) and affected cell migration and E-cadherin levels, while overexpression of miR-141 reduced KLF6 protein levels and produced an increase of secretion of VEGFA in vitro (H23, p = 0.04; A-549, p = 0.03; HCC-44, p = 0.02) and was associated with higher blood microvessel density in patient tumor samples (p<0.001). Conclusion High miR-141 and miR-200c expression are associated with shorter OS in NSCLC patients with adenocarcinoma through MET and angiogenesis.

Experimental reconstruction of the canine trachea with a free revascularized small bowel graft

Extensive tracheal stenotic lesions caused by tracheomalacia or neoplasms represent a surgical challenge. Segmental tracheal substitution is sometimes required to obtain radical cure. We present an experimental study of 27 dogs undergoing replacement of the cervical trachea using a vascularized small bowel segment as a tubular graft. A silicone stent was placed in the lumen of the intestinal fragment and was removed the second week after operation. Endoscopic and histological examinations were performed between the first week and second month after operation, and rigidity of the graft was assessed in all cases. No evidence of anastomotic stricture or mucous formation was found. Microscopic examination showed the substitution of bowel mucosa by squamous epithelium as well as the development of connective tissue favoring the fixation of the skeletal muscular structures of the neck to the serous layer of the graft, thus avoiding collapse of the new airway.

Value of intracellular bacteria detection in the diagnosis of ventilator associated pneumonia.

BACKGROUND: Markers of ventilator associated pneumonia are of interest for confirming the diagnosis and for guiding the initial management of this frequent complication of mechanical ventilation. The detection of intracellular organisms in the polymorphonuclear leucocytes (PMNLs) and/or macrophages of bronchoalveolar lavage (BAL) fluid has been suggested as a specific test for the early indication of an infectious pulmonary process. METHODS: The diagnostic value of detecting intracellular organisms in two types of BAL fluid--protected (P-BAL) and conventional (C-BAL)--in 25 patients who died in one unit was prospectively studied. Immediately after death both P-BAL and C-BAL were performed bilaterally. Through a minithoracotomy on both sides of the chest bilateral bronchoscopically guided open lung biopsy samples were obtained from the same area, and an average of eight open lung blind biopsy samples (not bronchoscopically guided) were taken from each lung for histological examination. BAL fluid was examined for quantitative cultures (threshold 10(4) cfu/ml) and for the presence of intracellular organisms and extracellular organisms, and differential cell counts were also performed. RESULTS: Using the histopathology of the bronchoscopically guided open lung biopsies as the gold standard, detection of intracellular organisms in P-BAL (> or = 5%) and C-BAL (> or = 5%) fluids yielded 75% and 57% positive predictive values, and 83% negative predictive values, respectively. Prior treatment with antibiotics decreased the positive and negative predictive values of intracellular organism detection for both types of BAL fluid. The presence of intracellular organisms was correlated with the quantitative cultures of P-BAL and C-BAL samples. Quantitative cultures from P-BAL fluid were less sensitive (22% versus 45%) and more specific (100% versus 55%) than those from C-BAL samples. The percentage of extracellular organisms and the differential cell count in P-BAL and C-BAL samples could not discriminate between the presence or absence of pneumonia. CONCLUSIONS: The presence of > or = 5% intracellular organisms infecting PMNLs or macrophages in P-BAL or C-BAL fluids is a specific marker of ventilator associated pneumonia.

Clinical and functional assessment of patients with idiopathic pulmonary fibrosis: results of a 3 year follow-up

The purpose of this study was to analyse the information provided by different techniques used in the assessment of patients with idiopathic pulmonary fibrosis (IPF) and their role in the prediction of lung function decline with the decline. Twenty seven subjects with IPF (55 +/- 14 (mean +/- SD) yrs) were studied at the initial staging. Nineteen of them (70%) were included in a follow-up over 3 yrs (32 +/- 6 months), whilst the remaining 8 patients were lost to follow-up. During the period of the study, 6 of the 19 patients died. A significant correlation between diffusing capacity of the lungs for carbon monoxide (DLCO) (and carbon monoxide transfer coefficient (KCO) = DLCO/alveolar volume (VA)) and the increase in alveolar-arterial oxygen tension difference (A-aPO2) during exercise (delta A-aPO2) was observed at diagnosis (r = -0.58). Despite the treatment with prednisone (1 mg.kg-1 daily during 4 weeks, tapered to an individualized maintenance daily dose of 15-30 mg), the 13 patients controlled throughout the whole period of the study showed a marked impairment in lung volumes; forced vital capacity (FVC) -0.46 +/- 0.09 l, from 69 +/- 16 to 52 +/- 11% of predicted, and total lung capacity (TLC) -0.39 +/- 0.11 l, from 75 +/- 16 to 62 +/- 14%, and in DLCO -0.6 +/- 0.2 mmol.min-1.kPa-1, from 56 +/- 15 to 47 +/- 18%, predicted. By contrast, both mean arterial oxygen tension (PaO2) and A-aPO2 at rest remained unchanged throughout the 3 yrs follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)