Electrical impedance tomography to titrate positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome

Tuffet, Samuel; Maraffi, Tommaso; Alcala, Glasiele Cristina; Victor, Marcus; Haudebourg, Anne-Fleur; Razazi, Keyvan; Prost, Nicolas de; Amato, M; Carteaux, Guillaume; Dessap, Armand Mekontso

doi:10.1186/s13054-020-03414-3

Cited by 44 publications

(37 citation statements)

References 23 publications

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“…We found a comparable median response to PEEP in both patients with a low and high respiratory system compliance and with high and low PaO 2 /FiO 2 in whom the oxygenation improved, the mechanical power significantly increased while the ventilatory ratio and respiratory mechanics, although deteriorating, showed high heterogeneity. Perier et al, comparing two CARDS subgroups based on the compliance of the respiratory system assessed at low PEEP level, found a similar behavior in terms of collapse, hyperdistention and oxygenation by applying a range of PEEP from 6 to 18 cmH 2 O [ 44 ]. In our population, the more hypoxemic group, which seems to improve the oxygenation when PEEP was increased from 5 to 15 cmH 2 O, showed the same quantitative radiological features at the CT scan at 5 cmH 2 O compared with less hypoxemic group.…”

Section: Discussionmentioning

confidence: 99%

Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

et al. 2021

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Background We hypothesized that as CARDS may present different pathophysiological features than classic ARDS, the application of high levels of end-expiratory pressure is questionable. Our first aim was to investigate the effects of 5–15 cmH2O of PEEP on partitioned respiratory mechanics, gas exchange and dead space; secondly, we investigated whether respiratory system compliance and severity of hypoxemia could affect the response to PEEP on partitioned respiratory mechanics, gas exchange and dead space, dividing the population according to the median value of respiratory system compliance and oxygenation. Thirdly, we explored the effects of an additional PEEP selected according to the Empirical PEEP-FiO2 table of the EPVent-2 study on partitioned respiratory mechanics and gas exchange in a subgroup of patients. Methods Sixty-one paralyzed mechanically ventilated patients with a confirmed diagnosis of SARS-CoV-2 were enrolled (age 60 [54–67] years, PaO2/FiO2 113 [79–158] mmHg and PEEP 10 [10–10] cmH2O). Keeping constant tidal volume, respiratory rate and oxygen fraction, two PEEP levels (5 and 15 cmH2O) were selected. In a subgroup of patients an additional PEEP level was applied according to an Empirical PEEP-FiO2 table (empirical PEEP). At each PEEP level gas exchange, partitioned lung mechanics and hemodynamic were collected. Results At 15 cmH2O of PEEP the lung elastance, lung stress and mechanical power were higher compared to 5 cmH2O. The PaO2/FiO2, arterial carbon dioxide and ventilatory ratio increased at 15 cmH2O of PEEP. The arterial–venous oxygen difference and central venous saturation were higher at 15 cmH2O of PEEP. Both the mechanics and gas exchange variables significantly increased although with high heterogeneity. By increasing the PEEP from 5 to 15 cmH2O, the changes in partitioned respiratory mechanics and mechanical power were not related to hypoxemia or respiratory compliance. The empirical PEEP was 18 ± 1 cmH2O. The empirical PEEP significantly increased the PaO2/FiO2 but also driving pressure, lung elastance, lung stress and mechanical power compared to 15 cmH2O of PEEP. Conclusions In COVID-19 ARDS during the early phase the effects of raising PEEP are highly variable and cannot easily be predicted by respiratory system characteristics, because of the heterogeneity of the disease.

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Section: Discussionmentioning

confidence: 99%

Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

et al. 2021

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“…The novelty of our study is that we performed a decremental CPAP trial in awake SARS-CoV-2 patients and used EIT, a non-invasive, bedside tool that does not require specific competencies in respiratory mechanic assessment, to assess the changes in lung volume. Thus, we applied in our patients the same physiological principle used in intubated and mechanically ventilated patients to discriminate between recruiters and non-recruiters ( Perier et al, 2020 ; van der Zee et al, 2020 ; Kotani and Shono, 2021 ; Shono et al, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

A Pilot Study on Electrical Impedance Tomography During CPAP Trial in Patients With Severe Acute Respiratory Syndrome Coronavirus 2 Pneumonia: The Bright Side of Non-invasive Ventilation

et al. 2021

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Background: Different severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia phenotypes were described that match with different lung compliance and level of oxygenation, thus requiring a personalized ventilator setting. The burden of so many patients and the lack of intensive care unit (ICU) beds often force physicians to choose non-invasive ventilation (NIV) as the first approach, even if no consent has still been reached to discriminate whether it is safer to choose straightforward intubation, paralysis, and protective ventilation. Under such conditions, electrical impedance tomography (EIT), a non-invasive bedside tool to monitor lung ventilation and perfusion defects, could be useful to assess the response of patients to NIV and choose rapidly the right ventilatory strategy.Objective: The rationale behind this study is that derecruitment is a more efficient measure of positive end expiratory pressure (PEEP)-dependency of patients than recruitment. We hypothesized that patients who derecruit significantly when PEEP is reduced are the ones that do not need early intubation while small end-expiratory lung volume (ΔEELV) variations after a single step of PEEP de-escalation could be predictive of NIV failure.Materials and Methods: Consecutive patients admitted to ICU with confirmed SARS-CoV-2 pneumonia ventilated in NIV were enrolled. Exclusion criteria were former intubation or NIV lasting > 72 h. A trial of continuos positive airway pressure (CPAP) 12 was applied in every patient for at least 15 min, followed by the second period of CPAP 6, either in the supine or prone position. Besides standard monitoring, ventilation of patients was assessed by EIT, and end-expiratory lung impedance (ΔEELI) (%) was calculated as the difference in EELI between CPAP12 and CPAP6. Tidal volume (Vt), Ve, respiratory rate (RR), and FiO2 were recorded, and ABGs were measured. Data were analyzed offline using the dedicated software. The decision to intubate or continue NIV was in charge of treating physicians, independently from study results. Outcomes of patients in terms of intubation rate and ICU mortality were recorded.Results: We enrolled 10 male patients, with a mean age of 67 years. Six patients (60%) were successfully treated by NIV until ICU discharge (Group S), and four patients failed NIV and were intubated and switched to MV (Group F). All these patients died in ICU. During the supine CPAP decremental trial, all patients experienced an increase in RR and Ve. ΔEELI was < 40% in Group F and > 50% in Group S. In the prone trial, ΔEELI was > 50% in all patients, while RR decreased in Group S and remained unchanged in Group F.Conclusion: ΔEELI < 40% after a single PEEP de-escalation step in supine position seems to be a good predictor of poor recruitment and CPAP failure.

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“…Electrical impedance tomography (EIT) is a novel noninvasive, radiation-free, bedside method for monitoring ventilation changes related to different lung conditions. These include lung regional recruitment and overdistension during positive end-expiratory pressure (PEEP) titration in patients with acute respiratory distress syndrome (8)(9)(10)(11). Various EIT-based parameters were proposed to evaluate the status of ventilation in patients with spontaneous breathing (12,13).…”

Section: Introductionmentioning

confidence: 99%

First Attempt at Using Electrical Impedance Tomography to Predict High Flow Nasal Cannula Therapy Outcomes at an Early Phase

Zhang

Xia

et al. 2021

Front. Med.

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Objective: Spatial and temporal ventilation distributions in patients with acute respiratory failure during high flow nasal cannula (HFNC) therapy were previously studied with electrical impedance tomography (EIT). The aim of the study was to explore the possibility of predicting HFNC failure based on various EIT-derived parameters.Methods: High flow nasal cannula failure was defined reintubation within 48 h after HFNC. EIT was performed with the patients spontaneously breathing in the supine position at the start of HFNC. EIT-based indices (comprising the global inhomogeneity index, center of ventilation, ventilation delay, rapid shallow breathing index, minute volume, and inspiration to expiration time) were explored and evaluated at three time points (prior to HFNC, T1; 30 min after HFNC started, T2; and 1 h after, T3).Results: A total of 46 subjects were included in the final analysis. Eleven subjects had failed HFNC. The time to failure was 27.8 ± 12.4 h. The ROX index (defined as SpO2/FiO2/respiratory rate) for HFNC success patients was 8.3 ± 2.7 and for HFNC failure patients, 6.2 ± 1.8 (p = 0.23). None of the investigated EIT-based parameters showed significant differences between subjects with HFNC failure and success. Further subgroup analysis indicated that a significant difference in ventilation inhomogeneity was found between ARDS and non-ARDS [0.54 (0.37) vs. 0.46 (0.28) as evaluated with GI, p < 0.01]. Ventilation homogeneity significantly improved in ARDS after 60-min HFNC treatment [0.59 (0.20) vs 0.57 (0.19), T1 vs. T3, p < 0.05].Conclusion: Spatial and temporal ventilation distributions were slightly but insignificantly different between the HFNC success and failure groups. HFNC failure could not be predicted by changes in EIT temporal and spatial indexes of ventilation distribution within the first hour. Further studies are required to predict the outcomes of HFNC.

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Electrical impedance tomography to titrate positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome

Cited by 44 publications

References 23 publications

Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

A Pilot Study on Electrical Impedance Tomography During CPAP Trial in Patients With Severe Acute Respiratory Syndrome Coronavirus 2 Pneumonia: The Bright Side of Non-invasive Ventilation

First Attempt at Using Electrical Impedance Tomography to Predict High Flow Nasal Cannula Therapy Outcomes at an Early Phase

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