Lung Recruitment Assessed by Respiratory Mechanics and Computed Tomography in Patients with Acute Respiratory Distress Syndrome. What Is the Relationship?

Chiumello, Davide; Marino, Antonella; Brioni, Matteo; Cigada, Irene; Menga, F; Colombo, Andrea; Crimella, Francesco; Algieri, Ilaria; Cressoni, Massimo; Carlesso, Eleonora; Gattinoni, Luciano

doi:10.1164/rccm.201507-1413oc

Cited by 122 publications

(117 citation statements)

References 25 publications

Supporting

Mentioning

106

Contrasting

Unclassified

Order By: Relevance

“…If we define, as we believe correct, the recruitment as the mass of pulmonary units regaining and maintaining inflation, it is convenient to estimate how much of the gas volume due to the presence of PEEP is distributed in the newly recruited units and how much is distributed in already open units. As shown in Figure 2, most of the PEEP volume enters the units already inflated (35). Therefore, the effect of PEEP is dual: on one side, it maintains a minimal amount of gas in newly opened units; on the other side, it increases the aeration of the units already open, even causing an overstretch.…”

Section: Recruitment Versus Inflationmentioning

confidence: 99%

See 1 more Smart Citation

Positive end-expiratory pressure: how to set it at the individual level

Gattinoni¹,

Collino²,

Maiolo³

et al. 2017

Ann. Transl. Med.

Self Cite

View full text Add to dashboard Cite

Abstract:The positive end-expiratory pressure (PEEP), since its introduction in the treatment of acute respiratory failure, up to the 1980s was uniquely aimed to provide a viable oxygenation. Since the first application, a large debate about the criteria for selecting the PEEP levels arose within the scientific community. Lung mechanics, oxygen transport, venous admixture thresholds were all proposed, leading to PEEP recommendations from 5 up to 25 cmH 2 O. Throughout this period, the main concern was the hemodynamics. This paradigm changed during the 1980s after the wide acceptance of atelectrauma as one of the leading causes of ventilator induced lung injury. Accordingly, the PEEP aim shifted from oxygenation to lung protection. In this framework, the prevention of lung opening and closing became an almost unquestioned dogma. Consequently, as PEEP keeps open the pulmonary units opened during the previous inspiratory phase, new methods were designed to identify the 'optimal' PEEP during the expiratory phase.The open lung approach requires that every collapsed unit potentially openable is opened and maintained open. The methods to assess the recruitment are based on imaging (computed tomography, electric impedance tomography, ultrasound) or mechanically-driven gas exchange modifications. All the latest assume that whatever change in respiratory system compliance is due to changes in lung compliance, which in turn is uniquely function of the recruitment. Comparative studies, however, showed that the only possible approach to measure the amount of collapsed tissue regaining inflation is the CT scan. In fact, all the other methods estimate as recruitment the gas entry in pulmonary units already open at lower PEEP, but increasing their compliance at higher PEEP. Since higher PEEP is usually more indicated (also for oxygenation) when the recruitability is higher, as occurs with increasing severity, a meaningful PEEP selection requires the assessment of recruitment. The Berlin definition may help in this assessment.

show abstract

Section: Recruitment Versus Inflationmentioning

confidence: 99%

“…This is the volume on which the tidal volume (V T ) is superimposed. The recruitment of new tissue and expansion of previously inflated lung accounts for the large difference reported in literature where recruitment is assessed (35). The CT scan allows to exactly quantify the amount of lung tissue regaining by inflation.…”

Section: Recruitment Versus Inflationmentioning

confidence: 99%

Positive end-expiratory pressure: how to set it at the individual level

Gattinoni¹,

Collino²,

Maiolo³

et al. 2017

Ann. Transl. Med.

Self Cite

View full text Add to dashboard Cite

show abstract

“…This US aeration score has been shown to correlate with PEEP-induced recruited lung volume obtained from the pressure-volume curve [4] and with weaning failure during spontaneous breathing trial [5]. Recently, however, it was shown that recruitment measured by CT scan (as re-inflation of previously not inflated regions) is not correlated with recruitment measured by the pressure-volume curve [6]. This last method and, by inference the US method, actually measure together both the aeration of previously non-aerated regions and a better inflation of lung regions already aerated.…”

mentioning

confidence: 99%

Assessment of oxygenation response to prone position ventilation in ARDS by lung ultrasonography

Guérin

Gattinoni

2016

Intensive Care Med

Self Cite

View full text Add to dashboard Cite

Acute respiratory distress syndrome (ARDS) is of major concern for the intensivist, as ARDS can only be treated in the intensive care unit (ICU). A cornerstone treatment is mechanical ventilation in order to buy time while the disease leading to ARDS can be cured. Therefore, the first aim of mechanical ventilation is to maintain a viable gas exchange. Over the years we realized that the cost of mechanical ventilation, as measured by the occurrence of ventilator-induced lung injury (VILI) [1], was too high if the target of the mechanical ventilation was normal blood gases. From there, permissive hypercapnia and oxygen saturation between 85 and 90 % were accepted to decrease the risk of VILI.To better tailor the ventilator settings, particularly to avoid potentially dangerous intratidal collapse and decollapse, increased attention was devoted to the characterization of the pathology underlying ARDS. To date, lung CT scan is the gold standard to assess the distribution of strain and from there to make inferences to minimize the occurrence of VILI. It should be mentioned, however, that no study demonstrated that patient outcome can be influenced from lung CT scan findings, essentially because no study has been done with this objective. Since ARDS lung characteristics cannot be monitored using CT imaging, methods feasible at the bedside are very attractive and lung ultrasound (US) is one of them [2]. One limitation of lung US is that the measurements do not quantify physical findings. Even though an aeration score has been developed, it is not quantitative as the Hounsfield units are for CT [3]. This US aeration score has been shown to correlate with PEEP-induced recruited lung volume obtained from the pressure-volume curve [4] and with weaning failure during spontaneous breathing trial [5]. Recently, however, it was shown that recruitment measured by CT scan (as re-inflation of previously not inflated regions) is not correlated with recruitment measured by the pressure-volume curve [6]. This last method and, by inference the US method, actually measure together both the aeration of previously non-aerated regions and a better inflation of lung regions already aerated. The regional hyperinflation, however, cannot be measured accurately either with CT (because of the mass increase of the ARDS lung) or lung US.Haddam et al.[7] performed a multicenter study in 51 ARDS patients with the aim to predict the oxygenation response to the prone position session from using lung US aeration score. The patients included suffered equally from either primary or secondary lung injury and received appropriate lung-protective mechanical ventilation. The authors found that changes in PaO 2 /F I O 2 ratio and lung aeration score did not correlate in either early or late stage of prone position regardless of the focal or nonfocal nature of ARDS. The same was true for changes in PaCO 2 . For the oxygenation to increase, and for the PaCO 2 to decrease, from increased regional lung aeration the blood should continue to flow towards those rea...

show abstract

“…In consequence, the "open lung strategy" has never been tested as a whole in the published randomized clinical trials. One may wonder how a mechanical ventilation protocol aimed at the "open lung strategy" should be designed and if it would reduce mortality, as the effect on lung inhomogeneity is limited/nonexistent [10,13,18]. To really apply the "open lung" strategy, a PEEP level sufficient to overcome the lung superimposed pressure [14,21,33], to keep the lung parenchyma open thorough the whole respiratory cycle, and to lift the chest wall is needed [9,14].…”

Section: Discussionmentioning

confidence: 99%

“…This would happen in a pure atelectasis model where all recruited lung units would re-gain normal gas/tissue status and normal mechanical properties; in ARDS, this does not happen, as the recruited lung units mainly become poorly inflated [10]. Upon recruitment, especially in the more severe patients, one may see an increase in poorly inflated tissue, [10], which is strongly related to the lung inhomogeneity [15]. The lung inhomogeneity itself is not completely abolished, but is slightly reduced or may paradoxically increase [18].…”

Section: Is Opening and Closing Real And What Is The "Real" Effect Ofmentioning

confidence: 99%