Influence of Positive End-Expiratory Pressure Titration on the Effects of Pronation in Acute Respiratory Distress Syndrome: A Comprehensive Experimental Study

Scaramuzzo, Gaetano; Ball, Lorenzo; Pino, Fabio; Ricci, Lucia; Larsson, Anders; Guérin, Claude; Pelosi, Paolo; Perchiazzi, Gaetano

doi:10.3389/fphys.2020.00179

Cited by 25 publications

(24 citation statements)

References 31 publications

(38 reference statements)

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“…In trials, PEEP level in prone was found lower than expected [41], even though a low PEEP level may have contributed to the clinical benefit [24]. An attempt to use the esophageal pressure-guided strategy in prone failed, on average, to show physiological benefit as compared to a PEEP and FiO 2 table in humans [74] in line with experimental data [75].…”

Section: Unanswered Questions New Avenues Of Research and Conclusionsupporting

confidence: 52%

Prone position in ARDS patients: why, when, how and for whom

et al. 2020

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Section: Unanswered Questions New Avenues Of Research and Conclusionsupporting

confidence: 52%

Prone position in ARDS patients: why, when, how and for whom

et al. 2020

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“…The distribution of aeration in severe COVID-19 patients was similar to that observed in ARDS, while the distribution of blood volume followed a reverse gravitational pattern—namely, higher blood volume in aerated, ventral lung regions. This distribution of blood volume was thus different from those seen in healthy individuals and non-COVID ARDS [ 32 , 33 ]. This might be explained by the presence of large non-perfused areas affecting predominantly the middle and dorsal lung regions.…”

Section: Discussionmentioning

confidence: 76%

Lung distribution of gas and blood volume in critically ill COVID-19 patients: a quantitative dual-energy computed tomography study

et al. 2021

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Background Critically ill COVID-19 patients have pathophysiological lung features characterized by perfusion abnormalities. However, to date no study has evaluated whether the changes in the distribution of pulmonary gas and blood volume are associated with the severity of gas-exchange impairment and the type of respiratory support (non-invasive versus invasive) in patients with severe COVID-19 pneumonia. Methods This was a single-center, retrospective cohort study conducted in a tertiary care hospital in Northern Italy during the first pandemic wave. Pulmonary gas and blood distribution was assessed using a technique for quantitative analysis of dual-energy computed tomography. Lung aeration loss (reflected by percentage of normally aerated lung tissue) and the extent of gas:blood volume mismatch (percentage of non-aerated, perfused lung tissue—shunt; aerated, non-perfused dead space; and non-aerated/non-perfused regions) were evaluated in critically ill COVID-19 patients with different clinical severity as reflected by the need for non-invasive or invasive respiratory support. Results Thirty-five patients admitted to the intensive care unit between February 29th and May 30th, 2020 were included. Patients requiring invasive versus non-invasive mechanical ventilation had both a lower percentage of normally aerated lung tissue (median [interquartile range] 33% [24–49%] vs. 63% [44–68%], p < 0.001); and a larger extent of gas:blood volume mismatch (43% [30–49%] vs. 25% [14–28%], p = 0.001), due to higher shunt (23% [15–32%] vs. 5% [2–16%], p = 0.001) and non-aerated/non perfused regions (5% [3–10%] vs. 1% [0–2%], p = 0.001). The PaO2/FiO2 ratio correlated positively with normally aerated tissue (ρ = 0.730, p < 0.001) and negatively with the extent of gas-blood volume mismatch (ρ = − 0.633, p < 0.001). Conclusions In critically ill patients with severe COVID-19 pneumonia, the need for invasive mechanical ventilation and oxygenation impairment were associated with loss of aeration and the extent of gas:blood volume mismatch. Graphic abstract

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“…Globally, the lowest PaO 2 /FiO 2 ratio observed during the first 5 days of ICU stay was 90 [11][12][13][14][15] cmH 2 O, P = 0.003). PFdiff was different between the two groups, as expected by study design, but DPdiff was not (Fig.…”

Section: Responders and Non-responders Comparabilitymentioning

confidence: 92%

“…The mechanisms by which PP improves oxygenation include the recruitment of atelectatic dorsal lung areas and the redistribution of lung ventilation toward still well perfused areas [10,11]. Moreover, PP may reduce the lung stress and strain associated with mechanical ventilation, thus decreasing the risk of ventilator-induced lung injury [12].…”

Section: Introductionmentioning

confidence: 99%

Sustained oxygenation improvement after first prone positioning is associated with liberation from mechanical ventilation and mortality in critically ill COVID-19 patients: a cohort study

Scaramuzzo

Gamberini

Tonetti

et al. 2021

Ann. Intensive Care

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Background Prone positioning (PP) has been used to improve oxygenation in patients affected by the SARS-CoV-2 disease (COVID-19). Several mechanisms, including lung recruitment and better lung ventilation/perfusion matching, make a relevant rational for using PP. However, not all patients maintain the oxygenation improvement after returning to supine position. Nevertheless, no evidence exists that a sustained oxygenation response after PP is associated to outcome in mechanically ventilated COVID-19 patients. We analyzed data from 191 patients affected by COVID-19-related acute respiratory distress syndrome undergoing PP for clinical reasons. Clinical history, severity scores and respiratory mechanics were analyzed. Patients were classified as responders (≥ median PaO2/FiO2 variation) or non-responders (< median PaO2/FiO2 variation) based on the PaO2/FiO2 percentage change between pre-proning and 1 to 3 h after re-supination in the first prone positioning session. Differences among the groups in physiological variables, complication rates and outcome were evaluated. A competing risk regression analysis was conducted to evaluate if PaO2/FiO2 response after the first pronation cycle was associated to liberation from mechanical ventilation. Results The median PaO2/FiO2 variation after the first PP cycle was 49 [19–100%] and no differences were found in demographics, comorbidities, ventilatory treatment and PaO2/FiO2 before PP between responders (96/191) and non-responders (95/191). Despite no differences in ICU length of stay, non-responders had a higher rate of tracheostomy (70.5% vs 47.9, P = 0.008) and mortality (53.7% vs 33.3%, P = 0.006), as compared to responders. Moreover, oxygenation response after the first PP was independently associated to liberation from mechanical ventilation at 28 days and was increasingly higher being higher the oxygenation response to PP. Conclusions Sustained oxygenation improvement after first PP session is independently associated to improved survival and reduced duration of mechanical ventilation in critically ill COVID-19 patients.

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Influence of Positive End-Expiratory Pressure Titration on the Effects of Pronation in Acute Respiratory Distress Syndrome: A Comprehensive Experimental Study

Cited by 25 publications

References 31 publications

Prone position in ARDS patients: why, when, how and for whom

Prone position in ARDS patients: why, when, how and for whom

Lung distribution of gas and blood volume in critically ill COVID-19 patients: a quantitative dual-energy computed tomography study

Sustained oxygenation improvement after first prone positioning is associated with liberation from mechanical ventilation and mortality in critically ill COVID-19 patients: a cohort study

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