Relationship between gas exchange response to prone position and lung recruitability during acute respiratory failure

Protti, Alessandro; Chiumello, Davide; Cressoni, Massimo; Carlesso, Eleonora; Mietto, Cristina; Berto, Virna; Lazzerini, M.; Quintel, Michael; Gattinoni, Luciano

doi:10.1007/s00134-009-1411-x

Cited by 61 publications

(46 citation statements)

References 26 publications

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“…At the very end, the present lung US findings are consistent with two previous CT studies [9,10]. The change in oxygenation in the prone position did not correlate with either the static distribution of densities in the dorsal lung regions [10] or with lung recruitability in the supine position [9].…”

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confidence: 91%

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

Guérin

Gattinoni

2016

Intensive Care Med

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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...

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confidence: 91%

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

Guérin

Gattinoni

2016

Intensive Care Med

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“…56 Nevertheless, a substantial number of studies have reported decreased P aCO 2 with PP. 28,93,98,42,104,115,[124][125][126] Romero et al 98 found an initial decrement in P aCO 2 after 30 min in PP (from 54 to 45 mm Hg) that continued to improve over 55 h (39 mm Hg). Protti et al 104 studied subjects ventilated with either volume or pressure control ventilation.…”

Section: Alveolar Ventilation and Recruitment During Pp In Ardsmentioning

confidence: 98%

“…Another mechanism that may sometimes explain drastic reductions in P aCO 2 with PP is the reduction in pulmonary hypertension and associated intracardiac shunt-ing in patients with ARDS and cor pulmonale (see effects of PP on right heart function). 125 Recently, several investigators 93,95,104,126 have classified subjects treated with PP as either P aO 2 or P aCO 2 responders. Protti et al 104 observed that improved P aCO 2 rather than P aO 2 was associated with the magnitude of lung injury and recruitment potential.…”

Section: Alveolar Ventilation and Recruitment During Pp In Ardsmentioning

confidence: 99%

“…125 Recently, several investigators 93,95,104,126 have classified subjects treated with PP as either P aO 2 or P aCO 2 responders. Protti et al 104 observed that improved P aCO 2 rather than P aO 2 was associated with the magnitude of lung injury and recruitment potential. What distinguished P aCO 2 responders from nonresponders was the amount of non-aerated tissue.…”

Section: Alveolar Ventilation and Recruitment During Pp In Ardsmentioning

confidence: 99%

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A Comprehensive Review of Prone Position in ARDS

2015

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Prone position (PP) has been used since the 1970s to treat severe hypoxemia in patients with ARDS because of its effectiveness at improving gas exchange. Compared with the supine position (SP), placing patients in PP effects a more even tidal volume distribution, in part, by reversing the vertical pleural pressure gradient, which becomes more negative in the dorsal regions. PP also improves resting lung volume in the dorsocaudal regions by reducing the superimposed pressure of both the heart and the abdomen. In contrast, pulmonary perfusion remains preferentially distributed to the dorsal lung regions, thus improving overall alveolar ventilation/perfusion relationships. 1660RESPIRATORY CARE • NOVEMBER 2015 VOL 60 NO 11Moreover, the larger tissue mass suspended from a wider dorsal chest wall effects a more homogeneous distribution of pleural pressures throughout the lung that reduces abnormal strain and stress development. This is believed to ameliorate the severity or development of ventilator-induced lung injury and may partly explain why PP reduces mortality in severe ARDS. Over 40 years of clinical trials have consistently reported improved oxygenation in approximately 70% of subjects with ARDS. Early initiation of PP is more likely to improve oxygenation than initiation during the subacute phase. Maximal oxygenation improvement occurs over a wide time frame ranging from several hours to several days. Meta-analyses of randomized controlled trials suggest that PP provides a survival advantage only in patients with relatively severe ARDS (P aO 2 /F IO 2 <150 mm Hg). Moreover, survival is enhanced when patients are managed with a smaller tidal volume (<8 mL/kg), higher PEEP (10 -13 cm H 2 O), and longer duration of PP sessions (>10 -12 h/session). Combining adjunctive therapies (high PEEP, recruitment maneuvers, and inhaled vasodilators) with PP has an additive effect in improving oxygenation and may be particularly helpful in stabilizing gas exchange in very severe ARDS.

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“…Sir: We read with interest Dr. Protti et al's [1] investigation into the decrease of PaCO 2 during ventilation in the prone position and its relationship with lung recruitability measured via whole-lung computed tomography scanning (CT).…”

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confidence: 99%

Comment on “Relationship between gas exchange response to prone position and lung recruitability during acute respiratory failure”

2009

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Relationship between gas exchange response to prone position and lung recruitability during acute respiratory failure

Abstract: During prone position, changes in PaCO(2), but not in oxygenation, are associated with lung recruitability which, in turn, is associated with the severity of lung injury.

Cited by 61 publications

References 26 publications

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

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

A Comprehensive Review of Prone Position in ARDS

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