Effects of prone position and positive end-expiratory pressure on lung perfusion and ventilation*

Richard, Jean-Christophe; Brégeon, Fabienne; Costes, Nicolas; Bars, Didier Le; Tourvieille, Christian; Lávenne, F.; Janier, Marc; Bourdin, Gaël; Gimenez, G.; Guérin, Claude

doi:10.1097/ccm.0b013e31818094a9

Cited by 44 publications

(39 citation statements)

References 42 publications

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“…Prone positioning makes the following more homogeneously distributed in the anterior-toposterior direction throughout the lungs: lung densities ( fig. 3) [7,21], as previously discussed; intrapulmonary shunt [22]; lung ventilation [23]; and transpulmonary pressure [24]. By favouring such a homogenisation, prone positioning prepares the lung to receive the strain imposed by mechanical ventilation [25], and hence makes the distribution of the resulting stress more homogeneous across the lung.…”

Section: Ventilator-induced Lung Injurymentioning

confidence: 83%

Prone ventilation in acute respiratory distress syndrome

Guérin

2014

Eur Respir Rev

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Prone positioning has been used for many years in patients with acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS), with no clear benefit for patient outcome. Meta-analyses have suggested better survival in patients with an arterial oxygen tension (PaO 2 )/inspiratory oxygen fraction (FIO 2 ) ratio ,100 mmHg. A recent randomised controlled trial was performed in ARDS patients after a 12-24 h stabilisation period and severity criteria (PaO 2 /FIO 2 ,150 mmHg at a positive end-expiratory pressure o5 cmH 2 O). This trial has demonstrated a significant reduction in mortality from 32.8% in the supine group to 16% in the prone group (p,0.001). The reasons for this dramatic effect are not clear but probably involves a reduction in ventilator-induced lung injury due to prone positioning, for which there is ample evidence in experimental and clinical studies.The aims of this article are to discuss: the rationale of prone positioning in patients with ALI/ARDS; the evidence of its use based on trial analysis; and the limitations of its use as well as the current place of prone positioning in the management of patients with ALI/ARDS.From the currently available data, prone positioning should be used as a first-line therapy in patients with severe ALI/ARDS. @ERSpublications Prone positioning and low tidal volume should be the first-line therapy in patients with continued ARDS and severity criteria

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Section: Ventilator-induced Lung Injurymentioning

confidence: 83%

Prone ventilation in acute respiratory distress syndrome

Guérin

2014

Eur Respir Rev

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“…PP improves oxygenation over a variable time course that may reach a plateau after 12-24 h, 26,79,88,89 but in some cases, improvement continues for 30 -55 h 97,98 This has been attributed to the interplay between several factors, including increased IAP and abnormal C CW , compression atelectasis, and persistent small airway closure despite high levels of PEEP (ie, 14 cm H 2 O). 168 Airway closure is both asynchronous in onset and unevenly distributed, particularly in dependent lung regions that delay in opening, close quickly, and have a lower EELV.…”

Section: Incorporating Pp Into Bundled Carementioning

confidence: 99%

“…78 In another experimental ARDS study, application of moderate-level PEEP (10 cm H 2 O) resulted in significant alveolar recruitment in both SP and PP. 79 PEEP caused a redistribution of both ventilation and perfusion toward the dependent lung in both SP and PP. However in SP, PEEPinduced alveolar recruitment occurred only in the dorsal lung, whereas applying PEEP during PP affected alveolar recruitment diffusely down the dorsoventral aspects of the lung.…”

Section: Airway Closure and V A /Q Matching In Experimental Ards And mentioning

confidence: 99%

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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“…For example, it has been shown that PEEP redistributes the pulmonary blood flow toward dorsal and caudal lung regions in the supine position. 14 In some instances in the present study the values of the P15/P5 ratios were greater than 1. The role of perfusion redistribution may be accounted for in this finding.…”

Section: Relationships Between Change In Density and V Recmentioning

confidence: 84%

Evaluation of Recruited Lung Volume at Inspiratory Plateau Pressure With PEEP Using Bedside Digital Chest X-ray in Patients With Acute Lung Injury/ARDS

et al. 2013

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BACKGROUND:We wanted to assess whether there was a significant relationship between recruited lung volume (V rec ) and change in density on digital processed chest x-ray measured at 2 different levels of inspiratory plateau pressure corresponding to 2 PEEP levels in patients with acute lung injury or ARDS. METHODS: In 14 subjects, PEEP 5 cm H 2 O and 15 cm H 2 O were prospectively applied in a random order for 10 min. At the end of each period, chest x-ray was taken using a digital portable device, and a pressure-volume curve of the respiratory system was performed. We also assessed P aO 2 , and the static and the dynamic (C dyn,rs ) compliance of the respiratory system. Change in end-expiratory lung volume between tidal breath and relaxation volume of the respiratory system was determined. Radiological attenuation was measured on chest x-rays in 4 regions of interest in the right lung, and in 3 regions of interest in the left lung, drawn in posterior intercostal spaces from top to bottom, by using dedicated software. The ratio of lung density in each region between PEEP 15 and PEEP 5 (rP15/P5) and their arithmetic mean (P15/P5) were computed. V rec was determined from the pressure-volume curves. RESULTS: The median value of rP15/P5 in the 98 lung levels was 0.91 (0.80 -1.01), which was significantly different from 1 (P < .001). The values of rP15/P5 were not significantly different between the lung levels. The median values of V rec and P15/P5 were 288 (173-402) mL and 0.90 (0.80 -0.97), respectively. There was a significant negative correlation between V rec and P15/P5 (R ‫؍‬ ؊0.77, P ‫؍‬ .01). The reduction in P15/P5 tended to correlate with the increase in C dyn,rs (R ‫؍‬ ؊0.49, P ‫؍‬ .077) or in P aO 2 (R ‫؍‬ ؊0.53, P ‫؍‬ .05) between PEEP 15 cm H 2 O and PEEP 5 cm H 2 O. CONCLUSIONS: Digital chest x-ray done at the bedside in acute lung injury/ARDS subjects was able to detect a reduction in density between PEEP 5 cm H 2 O and PEEP 15 cm H 2 O, which correlated with V rec .

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Effects of prone position and positive end-expiratory pressure on lung perfusion and ventilation*

Abstract: Positive end-expiratory pressure and posture act synergistically by redistributing lung regional perfusion toward ventral regions, but have antagonistic effects on regional ventilation.

Cited by 44 publications

References 42 publications

Prone ventilation in acute respiratory distress syndrome

Prone ventilation in acute respiratory distress syndrome

A Comprehensive Review of Prone Position in ARDS

Evaluation of Recruited Lung Volume at Inspiratory Plateau Pressure With PEEP Using Bedside Digital Chest X-ray in Patients With Acute Lung Injury/ARDS

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