A Calibration Technique for the Estimation of Lung Volumes in Nonintubated Subjects by Electrical Impedance Tomography

Sosio, Simone; Bellani, Giacomo; Villa, Silvia; Lupieri, Ermes; Mauri, Tommaso

doi:10.1159/000499159

Cited by 12 publications

(15 citation statements)

References 26 publications

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“…However, we based our calculations on the ratio of V T measurements from the ventilator and from the EIT device which are known to be correlating strongly. 29 While this approach is limited in its generalizability, our data clearly show a loss in FRC of considerable magnitude which may contribute to physiological instability during and after extubation. This is underlined in the strong correlation of ΔEELI with ΔSpO 2 and ΔSpO 2 /FiO 2 ratio in our study.…”

Section: Discussionmentioning

confidence: 66%

The DELUX study: development of lung volumes during extubation of preterm infants

et al. 2021

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Objective To measure changes in end-expiratory lung impedance (EELI) as a marker of functional residual capacity (FRC) during the entire extubation procedure of very preterm infants. Methods Prospective observational study in preterm infants born at 26–32 weeks gestation being extubated to non-invasive respiratory support. Changes in EELI and cardiorespiratory parameters (heart rate, oxygen saturation) were recorded at pre-specified events during the extubation procedure compared to baseline (before first handling of the infant). Results Overall, 2912 breaths were analysed in 12 infants. There was a global change in EELI during the extubation procedure (p = 0.029). EELI was lowest at the time of extubation [median (IQR) difference to baseline: −0.30 AU/kg (−0.46; −0.14), corresponding to an FRC loss of 10.2 ml/kg (4.8; 15.9), padj = 0.004]. The biggest EELI loss occurred during adhesive tape removal [median change (IQR): −0.18 AU/kg (−0.22; −0.07), padj = 0.004]. EELI changes were highly correlated with changes in the SpO2/FiO2 ratio (r = 0.48, p < 0.001). Forty per cent of FRC was re-recruited at the tenth breath after the initiation of non-invasive ventilation (p < 0.001). Conclusions The extubation procedure is associated with significant changes in FRC. This study provides novel information for determining the optimal way of extubating a preterm infant. Impact This study is the first to examine the development of lung volumes during the entire extubation procedure including the impact of associated events. The extubation procedure significantly affects functional residual capacity with a loss of approximately 10 ml/kg at the time of extubation. Removal of adhesive tape is the major contributing factor to FRC loss during the extubation procedure. Functional residual capacity is regained within the first breaths after initiation of non-invasive ventilation and is further increased after turning the infant into the prone position.

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Section: Discussionmentioning

confidence: 66%

The DELUX study: development of lung volumes during extubation of preterm infants

et al. 2021

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“…The correct position and signal quality were assessed on the monitor screen as described ( Cinnella et al, 2015 ). At every study step, the EIT images were divided into four quadrants, to obtain two ventral and two dorsal regions of interest (ROIs), as already described ( Cinnella et al, 2015 ; Sosio et al, 2019 ). Real-time impedance curves represent ventilation over time.…”

Section: Methodsmentioning

confidence: 99%

“…The operator was always the same. We recorded EELI according to a validated method ( Sosio et al, 2019 ). Later, the patient was connected to a V60 Philips Respirator, and the recordings were taken in the four study steps ( Figure 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…Electrical impedance tomography (EIT) is a non-invasive and easy to use bedside tool that dynamically shows regional tidal volume (Vt) distribution. EIT has been demonstrated a valid instrument to assess regional ventilation and PEEP-induced recruitment in many experimental and clinical studies ( Cinnella et al, 2015 ; Sosio et al, 2019 ). However, to our knowledge, no data are available on the use of EIT to monitor lung recruitability under non-invasive ventilation in patients with COVID-19.…”

Section: Introductionmentioning

confidence: 99%

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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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“…The transferability of the approach shown here is uncertain as the physiology of positive pressure ventilation and spontaneous breathing is very different. This transfer to non-ventilated patients would be very useful, because volume calibration for spontaneous breathing requires extra effort [28]. Additionally, this would yield great benefits considering the technical advances in remote patient monitoring with wearable EIT [29].…”

Section: Discussionmentioning

confidence: 99%

Inferring Respiratory and Circulatory Parameters from Electrical Impedance Tomography With Deep Recurrent Models

Strodthoff

Strodthoff²,

Becher³

et al. 2021

IEEE J. Biomed. Health Inform.

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Electrical impedance tomography (EIT) is a noninvasive imaging modality that allows a continuous assessment of changes in regional bioimpedance of different organs. One of its most common biomedical applications is monitoring regional ventilation distribution in critically ill patients treated in intensive care units. In this work, we put forward a proofof-principle study that demonstrates how one can reconstruct synchronously measured respiratory or circulatory parameters from the EIT image sequence using a deep learning model trained in an end-to-end fashion. For this purpose, we devise an architecture with a convolutional feature extractor whose output is processed by a recurrent neural network. We demonstrate that one can accurately infer absolute volume, absolute flow, normalized airway pressure and within certain limitations even the normalized arterial blood pressure from the EIT signal alone, in a way that generalizes to unseen patients without prior calibration. As an outlook with direct clinical relevance, we furthermore demonstrate the feasibility of reconstructing the absolute transpulmonary pressure from a combination of EIT and absolute airway pressure, as a way to potentially replace the invasive measurement of esophageal pressure. With these results, we hope to stimulate further studies building on the framework put forward in this work. Index Terms-bioimpedance, time series analysis, regression analysis, recurrent neural networks This work was supported by the Bundesministerium für Bildung und Forschung through the BIFOLD -Berlin Institute for the Foundations of Learning and Data (ref. 01IS18025A and ref 01IS18037A) and by the Faculty of Medicine of the Christian Albrechts University in Kiel, Germany (intramural research funding of research rotation positions). Nils Strodthoff is with

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A Calibration Technique for the Estimation of Lung Volumes in Nonintubated Subjects by Electrical Impedance Tomography

Cited by 12 publications

References 26 publications

The DELUX study: development of lung volumes during extubation of preterm infants

The DELUX study: development of lung volumes during extubation of preterm infants

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

Inferring Respiratory and Circulatory Parameters from Electrical Impedance Tomography With Deep Recurrent Models

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