Alveolar pentraxin 3 as an early marker of microbiologically confirmed pneumonia: a threshold-finding prospective observational study

Introduction: Timely diagnosis of pneumonia in intubated critically ill patients is rather challenging. Pentraxin 3 (PTX3) is an acute-phase mediator produced by various cell types in the lungs. Animal studies have shown that, during pneumonia, PTX3 participates in fine-tuning of inflammation (for example, microbial clearance and recruitment of neutrophils). We previously described an association between alveolar PTX3 and lung infection in a small group of intubated patients. The aim of the present study was to determine a threshold level of alveolar PTX3 with elevated sensitivity and specificity for microbiologically confirmed pneumonia. Methods: We recruited 82 intubated patients from two intensive care units (San Gerardo Hospital, Monza, Italy, and Massachusetts General Hospital, Boston, MA, USA) undergoing bronchoalveolar lavage (BAL) as per clinical decision. We collected BAL fluid and plasma samples, together with relevant clinical and microbiological data. We assayed PTX3 and soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) in BAL fluid and PTX3, sTREM-1, C-reactive protein (CRP) and procalcitonin (PCT) in plasma. Two blinded independent physicians reviewed patient data to confirm pneumonia. We determined the PTX3 threshold in BAL fluid for pneumonia and compared it to other biomarkers. Results: Microbiologically confirmed pneumonia of bacterial (n =12), viral (n =4) or fungal (n =8) etiology was diagnosed in 24 patients (29%). PTX3 levels in BAL fluid predicted pneumonia with an area under the receiving operator curve of 0.815 (95% CI =0.710 to 0.921, P <0.0001), whereas none of the other biomarkers were effective. In particular, PTX3 levels ≥1 ng/ml in BAL fluid predicted pneumonia in univariate analysis (β =2.784, SE =0.792, P <0.001) with elevated sensitivity (92%), specificity (60%) and negative predictive value (95%). Net reclassification index PTX3 values ≥1 ng/ml in BAL fluid for pneumonia indicated gain in sensitivity and/or specificity vs. all other mediators. These results did not change when we limited our analyses only to confirmed cases of bacterial pneumonia. Moreover, when we considered only the 70 patients who fulfilled the clinical criteria for the diagnosis of pneumonia at BAL fluid sampling, the diagnostic accuracy of PTX levels was confirmed in univariate and ROC curve analysis. Conclusions: In this hypothesis-generating convenience sample, a PTX3 level ≥1 ng/ml in BAL fluid was discriminative of microbiologically confirmed pneumonia in mechanically ventilated patients. Electronic supplementary material The online version of this article (doi:10.1186/s13054-014-0562-5) contains supplementary material, which is available to authorized users

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Topographic distribution of tidal ventilation in acute respiratory distress syndrome: Effects of positive end-expiratory pressure and pressure support

OBJECTIVE:: Acute respiratory distress syndrome is characterized by collapse of gravitationally dependent lung regions that usually diverts tidal ventilation toward nondependent regions. We hypothesized that higher positive end-expiratory pressure and enhanced spontaneous breathing may increase the proportion of tidal ventilation reaching dependent lung regions in patients with acute respiratory distress syndrome undergoing pressure support ventilation. DESIGN:: Prospective, randomized, cross-over study. SETTING:: General and neurosurgical ICUs of a single university-affiliated hospital. PATIENTS:: We enrolled ten intubated patients recovering from acute respiratory distress syndrome, after clinical switch from controlled ventilation to pressure support ventilation. INTERVENTIONS:: We compared, at the same pressure support ventilation level, a lower positive end-expiratory pressure (i.e., clinical positive end-expiratory pressure = 7 \uc2\ub1 2 cm H2O) with a higher one, obtained by adding 5 cm H2O (12 \uc2\ub1 2 cm H2O). Furthermore, a pressure support ventilation level associated with increased respiratory drive (3 \uc2\ub1 2 cm H2O) was tested against resting pressure support ventilation (12 \uc2\ub1 3 cm H2O), at clinical positive end-expiratory pressure. MEASUREMENTS AND MAIN RESULTS:: During all study phases, we measured, by electrical impedance tomography, the proportion of tidal ventilation reaching dependent and nondependent lung regions (Vt ep and Vt%nondep), regional tidal volumes (Vtdep and Vtnondep), and antero-posterior ventilation homogeneity (Vt%nondep/Vt ep). We also collected ventilation variables and arterial blood gases. Application of higher positive end-expiratory pressure levels increased Vt ep and Vtdep values and decreased Vt%nondep/Vt ep ratio, as compared with lower positive end-expiratory pressure (p &lt; 0.01). Similarly, during lower pressure support ventilation, Vt ep increased, Vtnondep decreased, and Vtdep did not change, likely indicating a higher efficiency of posterior diaphragm that led to decreased Vt%nondep/Vt ep (p &lt; 0.01). Finally, PaO2/FIO2 ratios correlated with Vt ep during all study phases (p &lt; 0.05). CONCLUSIONS:: In patients with acute respiratory distress syndrome undergoing pressure support ventilation, higher positive end-expiratory pressure and lower support levels increase the fraction of tidal ventilation reaching dependent lung regions, yielding more homogeneous ventilation and, possibly, better ventilation/ perfusion coupling. Copyright \uc2\ua9 2013 by the Society of Critical Care Medicine and Lippincott

Do spontaneous and mechanical breathing have similar effects on average transpulmonary and alveolar pressure? A clinical crossover study

Abstract Background Preservation of spontaneous breathing (SB) is sometimes debated because it has potentially both negative and positive effects on lung injury in comparison with fully controlled mechanical ventilation (CMV). We wanted (1) to verify in mechanically ventilated patients if the change in transpulmonary pressure was similar between pressure support ventilation (PSV) and CMV for a similar tidal volume, (2) to estimate the influence of SB on alveolar pressure (Palv), and (3) to determine whether a reliable plateau pressure could be measured during pressure support ventilation (PSV). Methods We studied ten patients equipped with esophageal catheters undergoing three levels of PSV followed by a phase of CMV. For each condition, we calculated the maximal and mean transpulmonary (ΔPL) swings and Palv. Results Overall, ΔPL was similar between CMV and PSV, but only loosely correlated. The differences in ΔPL between CMV and PSV were explained largely by different inspiratory flows, indicating that the resistive pressure drop caused this difference. By contrast, the Palv profile was very different between CMV and SB; SB led to progressively more negative Palv during inspiration, and Palv became lower than the set positive end-expiratory pressure in nine of ten patients at low PSV. Finally, inspiratory occlusion holds performed during PSV led to plateau and Δ PL pressures comparable with those measured during CMV. Conclusions Under similar conditions of flow and volume, transpulmonary pressure change is similar between CMV and PSV. SB during mechanical ventilation can cause remarkably negative swings in Palv, a mechanism by which SB might potentially induce lung injury

Pentraxin 3 in acute respiratory distress syndrome: An early marker of severity

OBJECTIVE: Pentraxin 3 is a fluid phase receptor involved in innate immunity. It belongs to the Pentraxins family, as C-reactive protein does. Pentraxin 3 is produced by a variety of tissue cells, whereas only the liver produces C-reactive protein. Pentraxin 3 plays a unique role in the regulation of inflammation. Acute lung injury and acute respiratory distress syndrome are characterized by an important inflammatory reaction. We investigated the role of pentraxin 3 as a marker of severity and outcome predictor of acute lung injury and acute respiratory distress syndrome. DESIGN: We measured circulating pentraxin 3 and C-reactive protein levels within 24 hrs from intubation (day 1), after 24 hrs from the first sample, then every 3 days for the first month and then once a week, until discharge from the intensive care unit. Pentraxin 3 was also measured in bronchoalveolar lavages, performed when clinically indicated. SETTING: One university medical center general intensive care unit. PATIENTS: The study included 21 patients affected by acute lung injury and acute respiratory distress syndrome (1994 Consensus Conference criteria). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Pentraxin 3 plasma levels were high with a peak on the first day (median 71.05 ng/mL, interquartile range 52.37-117.38 ng/mL, normal values &lt;2 ng/mL), declining thereafter. C-reactive protein peaked later and remained at relatively high values. Out of several day 1 parameters, pentraxin 3 was the only significant difference between survivors and nonsurvivors. Pentraxin 3 levels were positively correlated with lung injury score values (p &lt; 0.001) and number of organ failures (p &lt; 0.001). Pentraxin 3 was present in bronchoalveolar lavages fluids (5.03 ng/mL, interquartile range 1.52-8.48 ng/mL) and bronchoalveolar lavages positive to bacterial culture were associated with significantly higher pentraxin 3 values (p &lt; 0.05). CONCLUSIONS: The results presented here show that pentraxin 3 is elevated in acute lung injury and acute respiratory distress syndrome and that its levels correlate with parameters of lung injury and systemic involvement. The clinical and pathophysiological significance of pentraxin 3 in acute lung injury and acute respiratory distress syndrome deserves further scrutiny. \uc2\ua9 2008 by the Society of Critical Care Medicine and Lippincott Williams &amp; Wilkins

Elevated plasma and alveolar levels of soluble receptor for advanced glycation endproducts are associated with severity of lung dysfunction in ARDS patients

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) are severe forms of bilateral lung inflammation with poor clinical outcomes. However, the pathophysiology of ALI/ARDS remains largely obscure. Soluble receptor for advanced glycation endproducts (sRAGE) plays a key regulatory role during the acute phase of inflammation, and baseline plasma levels of sRAGE were recently found to be associated with severity of ALI/ARDS. We analyzed, in ALI/ARDS patients, plasma and alveolar levels of sRAGE over time and the association with severity of lung injury. We enrolled 21 ALI/ARDS patients admitted to our intensive care unit (ICU) and assayed plasma sRAGE on the first 2 days after diagnosis, every three days for the first month and then once a week, until ICU discharge or death. We also measured sRAGE levels in bronchoalveolar lavage fluids, obtained when clinically indicated. At each sampling time, we recorded physiological and clinical data of the patients. Plasma sRAGE levels peaked at day 1 and decreased over time. When all samples were considered, plasma and alveolar sRAGE levels were significantly higher in patients with worse oxygenation and higher need for ventilatory support (i.e., patients with more severe lung dysfunction). Moreover, the presence of lung infection yielded higher alveolar sRAGE levels. In conclusion, we show that the plasma and alveolar levels of sRAGE in ALI/ARDS patients are correlated to lung injury severity and to lung infection. Our findings may, in time, lead to the development of more effective therapies against ALI/ARDS. \uc2\ua9 2010 Tohoku University Medical Press

Clinical Assessment of Auto-positive End-expiratory Pressure by Diaphragmatic Electrical Activity during Pressure Support and Neurally Adjusted Ventilatory Assist

Background: Auto-positive end-expiratory pressure (auto-PEEP) may substantially increase the inspiratory effort during assisted mechanical ventilation. Purpose of this study was to assess whether the electrical activity of the diaphragm (EAdi) signal can be reliably used to estimate auto-PEEP in patients undergoing pressure support ventilation and neurally adjusted ventilatory assist (NAVA) and whether NAVA was beneficial in comparison with pressure support ventilation in patients affected by auto-PEEP. Methods: In 10 patients with a clinical suspicion of auto-PEEP, the authors simultaneously recorded EAdi, airway, esophageal pressure, and flow during pressure support and NAVA, whereas external PEEP was increased from 2 to 14 cm H2O. Tracings were analyzed to measure apparent "dynamic" auto-PEEP (decrease in esophageal pressure to generate inspiratory flow), auto-EAdi (EAdi value at the onset of inspiratory flow), and IDEAdi (inspiratory delay between the onset of EAdi and the inspiratory flow). Results: The pressure necessary to overcome auto-PEEP, auto-EAdi, and IDEAdi was significantly lower in NAVA as compared with pressure support ventilation, decreased with increase in external PEEP, although the effect of external PEEP was less pronounced in NAVA. Both auto-EAdi and IDEAdi were tightly correlated with auto-PEEP (r2 = 0.94 and r2 = 0.75, respectively). In the presence of auto-PEEP at lower external PEEP levels, NAVA was characterized by a characteristic shape of the airway pressure. Conclusions: In patients with auto-PEEP, NAVA, compared with pressure support ventilation, led to a decrease in the pressure necessary to overcome auto-PEEP, which could be reliably monitored by the electrical activity of the diaphragm before inspiratory flow onset (auto-EAdi)