Correction: Nitrogen washout/washin, helium dilution and computed tomography in the assessment of end expiratory lung volume

INTRODUCTION: End expiratory lung volume (EELV) measurement in the clinical setting is routinely performed using the helium dilution technique. A ventilator that implements a simplified version of the nitrogen washout/washin technique is now available. We compared the EELV measured by spiral computed tomography (CT) taken as gold standard with the lung volume measured with the modified nitrogen washout/washin and with the helium dilution technique. METHODS: Patients admitted to the general intensive care unit of Ospedale Maggiore Policlinico Mangiagalli Regina Elena requiring ventilatory support and, for clinical reasons, thoracic CT scanning were enrolled in this study. We performed two EELV measurements with the modified nitrogen washout/washin technique (increasing and decreasing inspired oxygen fraction (FiO2) by 10%), one EELV measurement with the helium dilution technique and a CT scan. All measurements were taken at 5 cmH2O airway pressure. Each CT scan slice was manually delineated and gas volume was computed with custom-made software. RESULTS: Thirty patients were enrolled (age = 66 +/- 10 years, body mass index = 26 +/- 18 Kg/m2, male/female ratio = 21/9, partial arterial pressure of carbon dioxide (PaO2)/FiO2 = 190 +/- 71). The EELV measured with the modified nitrogen washout/washin technique showed a very good correlation (r2 = 0.89) with the data computed from the CT with a bias of 94 +/- 143 ml (15 +/- 18%, p = 0.001), within the limits of accuracy declared by the manufacturer (20%). The bias was shown to be highly reproducible, either decreasing or increasing the FiO2 being 117+/-170 and 70+/-160 ml (p = 0.27), respectively. The EELV measured with the helium dilution method showed a good correlation with the CT scan data (r2 = 0.91) with a negative bias of 136 +/- 133 ml, and appeared to be more correct at low lung volumes. CONCLUSIONS: The EELV measurement with the helium dilution technique (at low volumes) and modified nitrogen washout/washin technique (at all lung volumes) correlates well with CT scanning and may be easily used in clinical practice. TRIAL REGISTRATION: Current Controlled Trials NCT00405002

Transpulmonary pressure monitoring during mechanical ventilation: a bench-to-bedside review

Different ventilation strategies have been suggested in the past in patients with acute respiratory distress syndrome(ARDS). Airway pressure monitoring alone is inadequate to assure optimal ventilatory support in ARDS patients. Theassessment of transpulmonary pressure (PTP) can help clinicians to tailor mechanical ventilation to the individualpatient needs. Transpulmonary pressure monitoring, defined as airway pressure (Paw) minus intrathoracic pressure(ITP), provides essential information about chest wall mechanics and its effects on the respiratory system and lungmechanics. The positioning of an esophageal catheter is required to measure the esophageal pressure (Peso), which isclinically used as a surrogate for ITP or pleural pressure (Ppl), and calculates the transpulmonary pressure. The benefitsof such a ventilation approach are avoiding excessive lung stress and individualizing the positive end-expiratory pressure (PEEP) setting. The aim is to prevent over-distention of alveoli and the cyclic recruitment/derecruitment or shear stress of lung parenchyma, mechanisms associated with ventilator-induced lung injury (VILI). Knowledge of the real lung distending pressure, i.e. the transpulmonary pressure, has shown to be useful in both controlled and assistedmechanical ventilation. In the latter ventilator modes, Peso measurement allows one to assess a patient’s respiratoryeffort, patient-ventilator asynchrony, intrinsic PEEP and the calculation of work of breathing. Conditions that havean impact on Peso, such as abdominal hypertension, will also be discussed briefly.Different ventilation strategies have been suggested in the past in patients with acute respiratory distress syndrome(ARDS). Airway pressure monitoring alone is inadequate to assure optimal ventilatory support in ARDS patients. Theassessment of transpulmonary pressure (PTP) can help clinicians to tailor mechanical ventilation to the individualpatient needs. Transpulmonary pressure monitoring, defined as airway pressure (Paw) minus intrathoracic pressure(ITP), provides essential information about chest wall mechanics and its effects on the respiratory system and lungmechanics. The positioning of an esophageal catheter is required to measure the esophageal pressure (Peso), which isclinically used as a surrogate for ITP or pleural pressure (Ppl), and calculates the transpulmonary pressure. The benefitsof such a ventilation approach are avoiding excessive lung stress and individualizing the positive end-expiratory pressure (PEEP) setting. The aim is to prevent over-distention of alveoli and the cyclic recruitment/derecruitment or shear stress of lung parenchyma, mechanisms associated with ventilator-induced lung injury (VILI). Knowledge of the real lung distending pressure, i.e. the transpulmonary pressure, has shown to be useful in both controlled and assistedmechanical ventilation. In the latter ventilator modes, Peso measurement allows one to assess a patient’s respiratoryeffort, patient-ventilator asynchrony, intrinsic PEEP and the calculation of work of breathing. Conditions that havean impact on Peso, such as abdominal hypertension, will also be discussed briefly

Autologous transfusion of stored red blood cells increases pulmonary artery pressure

RATIONALE: Transfusion of erythrocytes stored for prolonged periods is associated with increased mortality. Erythrocytes undergo hemolysis during storage and after transfusion. Plasma hemoglobin scavenges endogenous nitric oxide leading to systemic and pulmonary vasoconstriction.OBJECTIVES: We hypothesized that transfusion of autologous blood stored for 40 days would increase the pulmonary artery pressure in volunteers with endothelial dysfunction (impaired endothelial production of nitric oxide). We also tested whether breathing nitric oxide before and during transfusion could prevent the increase of pulmonary artery pressure.METHODS: Fourteen obese adults with endothelial dysfunction were enrolled in a randomized crossover study of transfusing autologous, leukoreduced blood stored for either 3 or 40 days. Volunteers were transfused with 3-day blood, 40-day blood, and 40-day blood while breathing 80 ppm nitric oxide.MEASUREMENTS AND MAIN RESULTS: The age of volunteers was 41 ± 4 years (mean ± SEM), and their body mass index was 33.4 ± 1.3 kg/m(2). Plasma hemoglobin concentrations increased after transfusion with 40-day and 40-day plus nitric oxide blood but not after transfusing 3-day blood. Mean pulmonary artery pressure, estimated by transthoracic echocardiography, increased after transfusing 40-day blood (18 ± 2 to 23 ± 2 mm Hg; P &lt; 0.05) but did not change after transfusing 3-day blood (17 ± 2 to 18 ± 2 mm Hg; P = 0.5). Breathing nitric oxide decreased pulmonary artery pressure in volunteers transfused with 40-day blood (17 ± 2 to 12 ± 1 mm Hg; P &lt; 0.05).CONCLUSIONS: Transfusion of autologous leukoreduced blood stored for 40 days was associated with increased plasma hemoglobin levels and increased pulmonary artery pressure. Breathing nitric oxide prevents the increase of pulmonary artery pressure produced by transfusing stored blood. Clinical trial registered with www.clinicaltrials.gov (NCT 01529502).<br/

Carta Geologica d'Italia alla scala 1:50.000 con note illustrative: Foglio 082 Asiago.

Il Foglio n. 082 ASIAGO della Carta Geologica d’Italia, alla scala 1:50.000, è stato realizzato nell’ambito del Progetto CARG (Legge 305/89), con una convenzione tra il Servizio Geologico Nazionale (ora APAT) e la Regione Veneto. La carta è stata realizzata dalla Regione Veneto e dal Dipartimento di Geologia, Paleontologia e Geofisica dell’Università degli Studi di Padova, con la collaborazione del personale delle citate strutture; per la Regione del Veneto (Segreteria all’Ambiente e Territorio, segretario regionale Roberto Casarin; Direzione Geologia e Attività Estrattive, dirigente regionale Andrea Costantini): F. Toffoletto responsabile del progetto, E. Schiavon direttore per la parte applicativa, coadiuvato da F. Mastellone; R. Campana responsabile dell’informatizzazione coadiuvato da V. Perna; per l’Università degli Studi di Padova: G. Barbieri coordinatore scientifico sostituito al suo pensionamento (1.10.2003) da P. Grandesso, già direttore di rilevamento. I rilievi geologici sono stati eseguiti da: G. Barbieri, R. Campana, M. Cucato, P. Gianolla, P. Grandesso, A. Guermani, B. Monopoli, G. Paiero, G. Roghi, A. Schiavo, G.L. Trombetta e D. Zampieri, con contributi di G. Dalla Valle, M. Franceschi, A. Gillarduzzi, M. Scarano, e M. Zannol. I sondaggi geognostici sono stati realizzati a cura del Servizio Forestale Regionale di Belluno (dirigente F. Cristofoletti coadiuvato da C. Gnech). Le Note Illustrative sono state curate da G. Barbieri e P. Grandesso, alla stesura delle quali hanno contribuito A. Zanferrari (basamento cristallino), V. De Zanche, P. Gianolla, G. Roghi (successioni permo-triassiche), M. Cucato (geologia del Quaternario), D. Zampieri (tettonica), W. Del Piero, P. Mietto, E. Schiavon (aspetti applicativi). 8 Il Foglio ricade quasi interamente nella Provincia di Vicenza e comprende territori dei Comuni di Arsiero, Asiago, Bassano del Grappa, Caltrano, Calvene, Campolongo sul Brenta, Cogollo del Cengio, Conco, Enego, Foza, Gallio, Lugo di Vicenza, Lusiana, Pedemonte, Roana, Rotzo, Tonezza del Cimone, Valdastico e Valstagna e parzialmente nella Provincia di Trento, nei Comuni di Borgo Valsugana, Grigno, Lavarone, Levico, Luserna. L’area studiata comprende in tutto o in parte le seguenti tavolette I.G.M., alla scala 1:25.000: “M. Verena”, “Rotzo”, “Arsiero”, “Conco”, “Caltrano”, “M. Lisser”, “Valstagna”, “Asiago”, “Cima Dodici”. Per i rilievi di campagna sono state utilizzate le sezioni della carta tecnica regionale, alla scala 1:10.000: “Cima Manderiolo”, “Cima Portule”, “Spitz Keserle”, “Passo della Forcellona”, “Cascina di Campovecchio”, “Monte Meatta”, “Monte Longara”, “Monte Tonderecar”, “Valdastico”, “Roana”, “Asiago”, “Valstagna”, “Arsiero”, “Cesuna”, “Monte Gusella” e “Conco”. I rilievi geologici sono stati eseguiti negli anni 2000-2003