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

Chiumello, Davide; Cressoni, Massimo; Chierichetti, Monica; Tallarini, Federica; Botticelli, Marco; Berto, Virna; Mietto, Cristina; Gattinoni, Luciano

doi:10.1186/cc7139

Cited by 108 publications

(98 citation statements)

References 25 publications

(22 reference statements)

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“…This finding has potential clinical relevance because it supports the evidence (45,46) that, to set the appropriate VT, end-expiratory lung volume should be taken into account. In this study we used CT to measure end-expiratory lung volumes, whose measurements are in tight agreement with those obtained by bedside methods (15,47). In contrast to normally aerated tissue, the metabolic activity of the poorly aerated tissue was not associated with its distending volume.…”

Section: Discussionsupporting

confidence: 63%

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

Bellani¹,

Guerra²,

Musch³

et al. 2011

Am J Respir Crit Care Med

190

159

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Rationale: During acute lung injury (ALI), mechanical ventilation can aggravate inflammation by promoting alveolar distension and cyclic recruitment-derecruitment. As an estimate of the intensity of inflammation, metabolic activity can be measured by positron emission tomography imaging of [ 18 F]fluoro-2-deoxy-D-glucose. Objectives: To assess the relationship between gas volume changes induced by tidal ventilation and pulmonary metabolic activity in patients with ALI. Methods: In 13 mechanically ventilated patients with ALI and relatively high positive end-expiratory pressure, we performed a positron emission tomography scan of the chest and three computed tomography scans: at mean airway pressure, end-expiration, and end-inspiration. Metabolic activity was measured from the [ 18 F]fluoro-2-deoxy-D-glucose uptake rate. The computed tomography scans were used to classify lung regions as derecruited throughout the respiratory cycle, undergoing recruitment-derecruitment, and normally aerated. Measurements and Main Results: Metabolic activity of normally aerated lung was positively correlated both with plateau pressure, showing a pronounced increase above 26 to 27 cm H 2 O, and with regional VT normalized by end-expiratory lung gas volume. This relationship did not appear to be caused by a higher underlying parenchymal metabolic activity in patients with higher plateau pressure. Regions undergoing cyclic recruitment-derecruitment did not have higher metabolic activity than those collapsed throughout the respiratory cycle. Conclusions: In patients with ALI managed with relatively high endexpiratory pressure, metabolic activity of aerated regions was associated with both plateau pressure and regional VT normalized by end-expiratory lung gas volume, whereas no association was found between cyclic recruitment-derecruitment and increased metabolic activity.Keywords: acute lung injury; respiration, artificial; tomography, X-ray computed; positron emission tomographyWe reported (1) that positron emission tomography (PET) with [ 18 F]fluoro-2-deoxy-D-glucose ( 18 FDG) shows diffuse increase in metabolic activity in the lungs of patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).In keeping with previous evidence, we interpreted the increased metabolic activity as indicating the presence of an inflammatory process (2-5). The cross-registration of dynamic PET images with computed tomography (CT) scans allowed us to show that the increased metabolic activity was not confined to regions with abnormal density but also involved normally aerated regions (1, 6).Mechanical ventilation can be a powerful inflammatory stimulus and ventilator-induced lung injury (VILI) has been the object of extensive research. Two main mechanisms have been advocated for VILI, the first being the cyclic recruitment and derecruitment of alveolar units (sometimes referred to as ''atelectrauma'') (7, 8) and the second being the (over)distension of aerated alveolar units (9, 10). Most of the data on VILI derive from animal ...

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Section: Discussionsupporting

confidence: 63%

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

Bellani¹,

Guerra²,

Musch³

et al. 2011

Am J Respir Crit Care Med

190

159

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“…Using bedside measurements (EELV, Cstat, and PEEP) all provided by an intensive care ventilator, we were able to separate high from low recruiters and to estimate PEEP-induced recruitment with imperfect but reasonable accuracy. Nitrogen (or oxygen) washout/washin correlates sufficiently well with helium dilution to be suitable for lung volume measurement in everyday practice [28,29]. Other advantages of EELV are the lack of need for ventilator discontinuation and the PEEP stability during the measurement.…”

Section: Discussionmentioning

confidence: 98%

PEEP-induced changes in lung volume in acute respiratory distress syndrome. Two methods to estimate alveolar recruitment

Dellamonica¹,

Lerolle²,

Sargentini³

et al. 2011

Intensive Care Med

137

128

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“…[83][84][85] A modified nitrogen washout technique is available on one commercially available ventilator. If EELV is measured on 0 PEEP and then again after PEEP is added, it is possible to calculate strain, an important determinant of lung injury.…”

Section: Lung Volumementioning

confidence: 99%

Recruitment Maneuvers and PEEP Titration

2015

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The injurious effects of alveolar overdistention are well accepted, and there is little debate regarding the importance of pressure and volume limitation during mechanical ventilation. The role of recruitment maneuvers is more controversial. Alveolar recruitment is desirable if it can be achieved, but the potential for recruitment is variable among patients with ARDS. A stepwise recruitment maneuver, similar to an incremental PEEP titration, is favored over sustained inflation recruitment maneuvers. Many approaches to PEEP titration have been proposed, and the best method to choose the most appropriate level for an individual patient is unclear. A PEEP level should be selected that balances alveolar recruitment against overdistention. The easiest approach to select PEEP might be according to the severity of the disease: 5-10 cm H 2 O PEEP in mild ARDS, 10 -15 cm H 2 O PEEP in moderate ARDS, and 15-20 cm H 2 O PEEP in severe ARDS. Recruitment maneuvers and PEEP should be used within the context of lung protection and not just as a means of improving oxygenation.

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

Cited by 108 publications

References 25 publications

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

PEEP-induced changes in lung volume in acute respiratory distress syndrome. Two methods to estimate alveolar recruitment

Recruitment Maneuvers and PEEP Titration

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