101,968 research outputs found
Respective role of tidal volume and PEEP on global and regional opening closing in ALI/ARDS
No full textRESPECTIVE ROLE OF TIDAL VOLUME AND PEEP ON GLOBAL AND REGIONAL OPENING CLOSING IN ALI/ARDS
No full textINTRODUCTION. Repeated opening and closing (O/C) of unstable alveoli in ALI/ARDS patients
can induce ventilator induced lung injury. We analyze the role of both tidal volume (Vt) and positive
end-expiratory pressure (PEEP) in producing atelectrauma, assessed by CT-scan.
METHODS. Observational CTscan study in ten patients with ALI/ARDS. Single CT slices were taken
during inspiratory and expiratory pauses with Vt 6 and 10 ml/kg at PEEP 10, 5, 15 and 20 cmH2O.
Non-aerated tissue (NAT) was measured by Maluna®. Global O/C was calculated for each PEEP/Vt
combination as (NAT weight/Total weight at expiration)-(NAT weight/Total weight at inspiration). Regional
O/C was evaluated splitting CT slices in ten compartments in the sterno-vertebral axis.
RESULTS. At Vt 6, increasing PEEP levels decrease O/C, reaching significance at PEEP 20
(2.2±2.7% vs 6.1±5.8% at PEEP 5, p<0.03). At both PEEP 5 and 15, higher Vt did not increase
global O/C. Regional O/C, at PEEP 5 and Vt 6, increased from ventral to middle levels (reaching
10±12.5% at level 7, p<0.04 vs level 1), and then decreased at posterior levels (Figure). Increasing
PEEP up to 20, regional O/C decreased in middle zones (p<0.02 for level 6 vs PEEP 5). Increasing Vt
from 6 to 10, at PEEP 5, regional O/C persisted higher in CT middle zones and at PEEP 15, regional
O/C decreased in middle zones, but significantly increased in dorsal zones.
CONCLUSION. Global O/C is higher at lower PEEP levels. Regional O/C at PEEP 5 is higher in
middle CT zones and can be reversed at higher PEEP levels. High Vt associated with PEEP 15 induced
higher O/C at more dependent zones
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
Key role of the potentially recruitable lung on the mechanical effects of PEEP during ARDS
No full textKEY ROLE OF THE POTENTIALLY RECRUITABLE LUNG ON THE MECHANICAL EFFECTS OF PEEP DURING ARDS
No full textINTRODUCTION. In acute respiratory distress syndrome (ARDS), the effect of high level of positive
end-expiratory pressure (PEEP) on outcome likely depends on the balance between its beneficial and
detrimental effects (reduction of intra-tidal lung opening-closing [O/C] vs. increase of alveolar strain).
We hypothesized that these effects may extensively vary according to the amount of the potentially
recruitable lung (PRL) of each patient.
METHODS. Sixty-eight patients underwent a whole lung CT-scan at 5 and 15 cmH2O PEEP, and
at airway plateau pressure of 45 cmH2O. End-inspiratory non-aerated lung tissue was estimated from
the CT pressure-volume curve. Intra-tidal lung O/C was defined as the difference between the endexpiratory
and end-inspiratory non-aerated lung tissue at each PEEP step, while keeping tidal-volume
(VT) constant (8-10ml/kg). Alveolar strain was calculated as the ratio between the end-inspiratory lung
inflation and end-expiratory lung volume. The amount of PRL was defined as the proportion of lung
tissue regaining aeration between 5 and 45 cmH2O airway pressures.
RESULTS. Patients were divided into those with a lower- and those with a higher-PRL, according to its
median value (9 percent). At 5 cmH2O PEEP, lung O/C in patients with a higher-PRL was greater than
that of patients with a lower-PRL (141±85 [SD] vs. 20±22 gr, P<0.01), which was almost negligible
(2±2% of the lung weight). In contrast, alveolar strain was identical in the two groups (0.38±0.17 vs.
0.41±0.15). Increasing PEEP to 15 cmH2O reduced the lung O/C only in patients with a higher-PRL
(down to 63±87 gr, P<0.01), and increased the alveolar strain at the same extent in both groups (up
to 0.68±0.33 and 0.84±0.26, respectively, P<0.01 for both). Regardless the same VT (9±2 vs. 9±2
ml/kg) and PEEP (12±3 vs. 11±3 cmH2O) clinically employed, patients with a higher-PRL showed a
greater clinical lung O/C (200±106 vs. 36±26 gr, P<0.01), and a higher mortality rate at ICU discharge
(41 vs. 15%, P=0.02), than patients with a lower-PRL.
CONCLUSION. The use of high level of PEEP appears to be physiologically advantageous only in
patients with a higher-PRL, where the beneficial effects may exceed the harmful ones
Anatomical and functional intrapulmonary shunt in acute respiratory distress syndrome
No full textOBJECTIVES:
The lung-protective strategy employs positive end-expiratory pressure to keep open otherwise collapsed lung regions (anatomical recruitment). Improvement in venous admixture with positive end-expiratory pressure indicates functional recruitment to better gas exchange, which is not necessarily related to anatomical recruitment, because of possible global/regional perfusion modifications. Therefore, we aimed to assess the value of venous admixture (functional shunt) in estimating the fraction of nonaerated lung tissue (anatomical shunt compartment) and to describe their relationship.
DESIGN:
Retrospective analysis of a previously published study.
SETTING:
Intensive care units of four university hospitals.
PATIENTS:
Fifty-nine patients with acute lung injury/acute respiratory distress syndrome.
INTERVENTIONS:
Positive end-expiratory pressure trial at 5 and 15 cm H2O positive end-expiratory pressures.
MEASUREMENTS AND MAIN RESULTS:
Anatomical shunt compartment (whole-lung computed tomography scan) and functional shunt (blood gas analysis) were assessed at 5 and 15 cm H2O positive end-expiratory pressures. Apparent perfusion ratio (perfusion per gram of nonaerated tissue/perfusion per gram of total lung tissue) was defined as the ratio of functional shunt to anatomical shunt compartment. Functional shunt was poorly correlated to the anatomical shunt compartment (r2 = .174). The apparent perfusion ratio at 5 cm H2O positive end-expiratory pressure was widely distributed and averaged 1.25 +/- 0.80. The apparent perfusion ratios at 5 and 15 cm H2O positive end-expiratory pressures were highly correlated, with a slope close to identity (y = 1.10.x -0.03, r2 = .759), suggesting unchanged blood flow distribution toward the nonaerated lung tissue, when increasing positive end-expiratory pressure.
CONCLUSIONS:
Functional shunt poorly estimates the anatomical shunt compartment, due to the large variability in apparent perfusion ratio. Changes in anatomical shunt compartment with increasing positive end-expiratory pressure, in each individual patient, may be estimated from changes in functional shunt, only if the anatomical-functional shunt relationship at 5 cm H2O positive end-expiratory pressure is known
The Right to Strike under the United States Constitution: Theory, Practice, and Possible Implications for Canada
No full textAnswering critics of the Canadian Supreme Court's judgment in B.C. Health, the author argues that the Court laid the foundation for a principled and durable doctrine protecting constitutional labour rights, one that goes directly to the heart of the matter — the inequality of workers’ power in the employment relation. In the author’s view, two paths could lead from B.C. Health to the recognition of Charter protec- tion for a right to strike: one that treats the right as an accessory to col- lective bargaining, and one that upholds the right directly on the basis of the Charter values of equality and participation. The author supports the latter approach, contending that constitutional rights should be defined in relation to fundamental values, in a way that is not contingent on time-bound or fact-sensitive assessments about the role of strikes within a particular collective bargaining regime. Although a Charter right to strike may involve the courts in difficult choices about when to defer to legislative policy decisions, and courts may lack the institutional capac- ity to deal effectively with labour law issues, the author points out that judges can look to ILO standards for expert guidance. Noting that the U.S. experience in this area might be of considerable use to Canadians, the author concludes by providing an overview of American case law concerning a constitutional right to strike.Peer reviewe
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