Prone position improves lung ventilation-perfusion matching in non-intubated COVID-19 patients: a prospective physiologic study.
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SUBMITTER: Liu L
PROVIDER: S-EPMC9241304 | biostudies-literature | 2022 Jun
REPOSITORIES: biostudies-literature
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Prone position improves lung ventilation-perfusion matching in non-intubated COVID-19 patients: a prospective physiologic study.
Liu Ling L Xie Jianfeng J Wang Changsong C Zhao Zhanqi Z Chong Yang Y Yuan Xueyan X Qiu Haibo H Zhao Mingyan M Yang Yi Y Slutsky Arthur S AS
Critical care (London, England) 20220629 1
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Project description: Not available
| S-EPMC7365368 | biostudies-literature
Project description:BackgroundProne positioning (PP) improves oxygenation in awake patients with acute hypoxemic respiratory failure (AHRF). However, the underlying mechanisms remain unclear in patients with diverse lung morphology. We aimed to determine the short-term effects of awake prone positioning (APP) in AHRF patients with focal and non-focal lung morphology.MethodsThis is a prospective physiological study. Twenty-four non-intubated patients with PaO2/FiO2 ≤ 300 mm Hg were included. Gas exchange, ventilation and perfusion distribution, and hemodynamics variables were recorded in the supine position (SP1), 2 h after PP, and 1 h after re-supine (SP2). Lung morphology was classified as focal and non-focal patterns using computed tomography.ResultsTwelve of the included patients were classified to the focal group and 12 to the non-focal group. PaO2/FiO2 improved after PP in all patients (161 [137, 227] mmHg vs. 236 [202, 275] mmHg, p < 0.001). Ventilation-perfusion (V/Q) matching increased after PP in all patients (61.9 [53.9, 66.5] vs. 77.5 [68.3, 80.0], p < 0.001). Shunt exhibited a significant decrease in patients of the non-focal group (28.6 [22.5, 30.3] vs. 11.3 [9.0, 14.5], p < 0.001), whereas no difference was found in the focal group after PP. Dead space decreased significantly in patients of the focal group (25.6 [21.5, 28.4] vs. 12.0 [10.8, 14.1], p < 0.001), whereas no difference was found in the non-focal group after PP.ConclusionsAPP improves V/Q matching, and large-scale, bias-free studies are needed to find more definitive differences between patients with focal and non-focal lung morphyology.Trial registrationThe study is registered in ClinicalTrials.gov (trial No. NCT04754113, date of registration: 2021-02-15).
| S-EPMC11633027 | biostudies-literature
Project description:BackgroundThe physiological effects of prone ventilation in ARDS patients have been discussed for a long time but have not been fully elucidated. Electrical impedance tomography (EIT) has emerged as a tool for bedside monitoring of pulmonary ventilation and perfusion, allowing the opportunity to obtain data. This study aimed to investigate the effect of prone positioning (PP) on ventilation-perfusion matching by contrast-enhanced EIT in patients with ARDS.DesignMonocenter prospective physiologic study.SettingUniversity medical ICU.PatientsTen mechanically ventilated ARDS patients who underwent PP.InterventionsWe performed EIT evaluation at the initiation of PP, 3 h after PP initiation and the end of PP during the first PP session.Measurements and main resultsThe regional distribution of ventilation and perfusion was analyzed based on EIT images and compared to the clinical variables regarding respiratory and hemodynamic status. Prolonged prone ventilation improved oxygenation in the ARDS patients. Based on EIT measurements, the distribution of ventilation was homogenized and dorsal lung ventilation was significantly improved by PP administration, while the effect of PP on lung perfusion was relatively mild, with increased dorsal lung perfusion observed. The ventilation-perfusion matched region was found to increase and correlate with the increased PaO2/FiO2 by PP, which was attributed mainly to reduced shunt in the lung.ConclusionsProlonged prone ventilation increased dorsal ventilation and perfusion, which resulted in improved ventilation-perfusion matching and oxygenation.Trial registrationClinicalTrials.gov, NCT04725227. Registered on 25 January 2021.
| S-EPMC9137443 | biostudies-literature
Project description:BackgroundARDS is a heterogeneous syndrome involving different subphenotypes with different clinical features and different responses to treatment strategies. The prone position (PP) is an effective treatment for ARDS; however, whether the effects of prone positioning vary among ARDS patients with different subphenotypes remains unknown.ObjectivesTo evaluated the impact of PP on ventilation-perfusion matching(VQ matching) by contrast-enhanced Electrical impedance tomography (EIT) in ARDS patients with different subphenotypes.MethodsThis was a prospective, observational study at the medical ICU of Zhongda Hospital, Southeast University. ARDS patients undergoing mechanical ventilation were screened and allocated to different subphenotypes based on lung morphology (focal/non-focal) and D-dimer level (low/high D-dimer). EIT was used in the supine position and 3 h, 6 h, and 12 h after the PP during the first PP session.ResultsFrom July 1, 2021, to July 1, 2022, 25 patients were included in this study. 10 patients (40%) were focal ARDS, and 15 were non-focal ARDS based on baseline morphology. 12 patients (48%) were high D-dimer ARDS, and 13 were low D-dimer ARDS based on baseline D-dimer levels. PaO2/FiO2 increased significantly 3 h after prone positioning in focal ARDS patients (130.30[109.94-147.30] vs. 213.50[176.00-256.50] mmHg, p < 0.001), while the effect of improved oxygenation was not apparent until 6 h after prone positioning in non-focal ARDS patients (104.60[95.20-127.00] vs. 190.20[160.10-213.20] mm Hg, p < 0.001). VQ matching improved after 3 h in the prone position in the focal ARDS group (69.93 ± 6.69 vs. 78.22 ± 5.07, p = 0.006) but improved after only 6 h in the prone position in the non-focal ARDS group (67.32 ± 4.78 vs. 78.70 ± 5.93, p < 0.001). In ARDS patients with varying levels of D-dimer, increased PaO2/FiO2 (126.60[99.30-146.20] vs. 185.20[112.10-236.00] mmHg, p = 0.013) and improved VQ matching (67.60 ± 4.60 vs. 72.97 ± 6.48, p = 0.023) were observed at 3 h in the PP in patients with low D-dimer ARDS. In contrast, increased PaO2/FiO2(105.20[95.20-124.10] vs. 195.2[183.20-213.20], p < 0.001) and improved VQ matching (67.19 ± 6.70 vs. 72.50 ± 6.37, p < 0.001) were revealed only after 6 h in the prone position in high D-dimer ARDS patients.ConclusionsFor moderate to severe ARDS patients, non-focal and high D-dimer ARDS patients need longer PP to improve oxygenation and VQmatching than the focal and low D-dimer patients.Clinical trial registrationThis was a prospective, observational study registered in the Chinese Clinical Trial Registry (ChiCTR2200055442, https://www.chictr.org.cn/ ), on June 30, 2021.
| S-EPMC11871685 | biostudies-literature
Project description:BackgroundProne position ventilation (PPV) is resource-intensive, yet the optimal strategy for PPV in intubated patients with COVID-19 is unclear.Research questionDoes a prolonged (24 or more h) PPV strategy improve mortality in intubated COVID-19 patients compared with intermittent (∼16 h with daily supination) PPV?Study design and methodsMulticenter, retrospective cohort study of consecutively admitted intubated COVID-19 patients treated with PPV between March 11 and May 31, 2020. The primary outcome was 30-day all-cause mortality. Secondary outcomes included 90-day all-cause mortality and prone-related complications. Inverse probability treatment weights (IPTW) were used to control for potential treatment selection bias.ResultsOf the COVID-19 patients who received PPV, 157 underwent prolonged and 110 underwent intermittent PPV. Patients undergoing prolonged PPV had reduced 30-day (adjusted hazard ratio [aHR], 0.475; 95% CI, 0.336-0.670; P < .001) and 90-day (aHR, 0.638; 95% CI, 0.461-0.883; P = .006) mortality compared with intermittent PPV. In patients with Pao2/Fio2 ≤ 150 at the time of pronation, prolonged PPV was associated with reduced 30-day (aHR, 0.357; 95% CI, 0.213-0.597; P < .001) and 90-day mortality (aHR, 0.562; 95% CI, 0.357-0.884; P = .008). Patients treated with prolonged PPV underwent fewer pronation and supination events (median, 1; 95% CI, 1-2 vs 3; 95% CI, 1-4; P < .001). PPV strategy was not associated with overall PPV-related complications, although patients receiving prolonged PPV had increased rates of facial edema and lower rates of peri-proning hypotension.InterpretationAmong intubated COVID-19 patients who received PPV, prolonged PPV was associated with reduced mortality. Prolonged PPV was associated with fewer pronation and supination events and a small increase in rates of facial edema. These findings suggest that prolonged PPV is a safe, effective strategy for mortality reduction in intubated COVID-19 patients.
| S-EPMC9635255 | biostudies-literature
Project description:ObjectivesProne positioning allows to improve oxygenation and decrease mortality rate in COVID-19-associated acute respiratory distress syndrome (C-ARDS). However, the mechanisms leading to these effects are not fully understood. The aim of this study is to assess the physiologic effects of pronation by the means of CT scan and electrical impedance tomography (EIT).DesignExperimental, physiologic study.SettingPatients were enrolled from October 2020 to March 2021 in an Italian dedicated COVID-19 ICU.PatientsTwenty-one intubated patients with moderate or severe C-ARDS.InterventionsFirst, patients were transported to the CT scan facility, and image acquisition was performed in prone, then supine position. Back to the ICU, gas exchange, respiratory mechanics, and ventilation and perfusion EIT-based analysis were provided toward the end of two 30 minutes steps (e.g., in supine, then prone position).Measurements and main resultsProne position induced recruitment in the dorsal part of the lungs (12.5% ± 8.0%; p < 0.001 from baseline) and derecruitment in the ventral regions (-6.9% ± 5.2%; p < 0.001). These changes led to a global increase in recruitment (6.0% ± 6.7%; p < 0.001). Respiratory system compliance did not change with prone position (45 ± 15 vs 45 ± 18 mL/cm H2O in supine and prone position, respectively; p = 0.957) suggesting a decrease in atelectrauma. This hypothesis was supported by the decrease of a time-impedance curve concavity index designed as a surrogate for atelectrauma (1.41 ± 0.16 vs 1.30 ± 0.16; p = 0.001). Dead space measured by EIT was reduced in the ventral regions of the lungs, and the dead-space/shunt ratio decreased significantly (5.1 [2.3-23.4] vs 4.3 [0.7-6.8]; p = 0.035), showing an improvement in ventilation-perfusion matching.ConclusionsSeveral changes are associated with prone position in C-ARDS: increased lung recruitment, decreased atelectrauma, and improved ventilation-perfusion matching. These physiologic effects may be associated with more protective ventilation.
| S-EPMC9005091 | biostudies-literature
Project description: Not available
| S-EPMC10621498 | biostudies-literature
Project description:BackgroundProne position has been shown to improve oxygenation and survival in patients with early acute respiratory distress syndrome (ARDS). These beneficial effects are partly mediated by improved ventilation/perfusion (V/Q) distribution. Few studies have investigated the impact of early versus delayed proning on V/Q distribution in patients with ARDS. The aim of this study was to assess the regional ventilation and perfusion distribution in early versus persistent ARDS after prone position.MethodsThis is a prospective, observational study from June 30, 2021, to October 1, 2022 at the medical ICU in Zhongda Hospital, Southeast University. Fifty-seven consecutive adult patients with moderate-to-severe ARDS ventilated in supine and prone position. Electrical impedance tomography was used to study V/Q distribution in the supine position and 12 h after a prone session.ResultsOf the 57 patients, 33 were early ARDS (≤ 7 days) and 24 were persistent ARDS (> 7 days). Oxygenation significantly improved after proning in early ARDS (157 [121, 191] vs. 190 [164, 245] mm Hg, p < 0.001), whereas no significant change was found in persistent ARDS patients (168 [136, 232] vs.177 [155, 232] mm Hg, p = 0.10). Compared to supine position, prone reduced V/Q mismatch in early ARDS (28.7 [24.6, 35.4] vs. 22.8 [20.0, 26.8] %, p < 0.001), but increased V/Q mismatch in persistent ARDS (23.8 [19.8, 28.6] vs. 30.3 [24.5, 33.3] %, p = 0.006). In early ARDS, proning significantly reduced shunt in the dorsal region and dead space in the ventral region. In persistent ARDS, proning increased global shunt. A significant correlation was found between duration of ARDS onset to proning and the change in V/Q distribution (r = 0.54, p < 0.001).ConclusionsProne position significantly reduced V/Q mismatch in patients with early ARDS, while it increased V/Q mismatch in persistent ARDS patients. Trial registration ClinicalTrials.gov (NCT05207267, principal investigator Ling Liu, date of registration 2021.08.20).
| S-EPMC10683149 | biostudies-literature
Project description:BackgroundThe efficacy and safety profiles of prone ventilation among intubated Coronavirus Disease 2019 (COVID-19) patients remain unclear. The primary objective was to examine the effect of prone ventilation on the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) in intubated COVID-19 patients.MethodsDatabases of MEDLINE, EMBASE and CENTRAL were systematically searched from inception until March 2021. Case reports and case series were excluded.ResultsEleven studies (n = 606 patients) were eligible. Prone ventilation significantly improved PaO2/FiO2 ratio (studies: 8, n = 579, mean difference 46.75, 95% CI 33.35‒60.15, p < 0.00001; evidence: very low) and peripheral oxygen saturation (SpO2) (studies: 3, n = 432, mean difference 1.67, 95% CI 1.08‒2.26, p < 0.00001; evidence: ow), but not the arterial partial pressure of carbon dioxide (PaCO2) (studies: 5, n = 396, mean difference 2.45, 95% CI 2.39‒7.30, p = 0.32; evidence: very low), mortality rate (studies: 1, n = 215, Odds Ratio 0.66, 95% CI 0.32‒1.33, p = 0.24; evidence: very low), or number of patients discharged alive (studies: 1, n = 43, Odds Ratio 1.49, 95% CI 0.72‒3.08, p = 0.28; evidence: very low).ConclusionProne ventilation improved PaO2/FiO2 ratio and SpO2 in intubated COVID-19 patients. Given the substantial heterogeneity and low level of evidence, more randomized- controlled trials are warranted to improve the certainty of evidence, and to examine the adverse events of prone ventilation.
| S-EPMC9259191 | biostudies-literature
Project description:RationaleThe prone position is used to improve gas exchange in patients with acute respiratory distress syndrome. However, the regional mechanism by which the prone position improves gas exchange in acutely injured lungs is still incompletely defined.MethodsWe used positron emission tomography imaging of [(13)N]nitrogen to assess the regional distribution of pulmonary shunt, aeration, perfusion, and ventilation in seven surfactant-depleted sheep in supine and prone positions.ResultsIn the supine position, the dorsal lung regions had a high shunt fraction, high perfusion, and poor aeration. The prone position was associated with an increase in lung gas content and with a more uniform distribution of aeration, as the increase in aeration in dorsal lung regions was not offset by loss of aeration in ventral regions. Consequently, the shunt fraction decreased in dorsal regions in the prone position without a concomitant impairment of gas exchange in ventral regions, thus leading to a significant increase in the fraction of pulmonary perfusion participating in gas exchange. In addition, the vertical distribution of specific alveolar ventilation became more uniform in the prone position. A biphasic relation between regional shunt fraction and gas fraction showed low shunt for values of gas fraction higher than a threshold, and a steep linear increase in shunt for lower values of gas fraction.ConclusionIn a surfactant-deficient model of lung injury, the prone position improved gas exchange by restoring aeration and decreasing shunt while preserving perfusion in dorsal lung regions, and by making the distribution of ventilation more uniform.
| S-EPMC2718529 | biostudies-literature