The effects of prone and supine positions on the regional distribution of ventilation in infants and children using electrical impedance tomography

Background: Positioning of ill children is often used to optimise ventilation–perfusion matching, thereby improving oxygenation. Objectives: To determine the effects of supine and prone positions, and different head positions, on the distribution of ventilation in healthy, spontaneously breathing infants and children between the ages of 6 months and 9 years.Methods: Electrical impedance tomography measurements were recorded from participants in supine and prone positions. Head positions included the head turned to the left and right in supine and prone positions, and in the midline in the supine position. Distribution of ventilation was described using end-expiratory–end-inspiratory relative impedance change.Results: A total of 56 participants (boys = 31 [55%]; girls = 25 [45%]) were studied. The dorsal lung was significantly better ventilated than the ventral lung (P < 0.001) in both body positions. The majority of participants (83%) had greater ventilation in the dorsal lung in both positions, whilst five participants (10%) demonstrated consistently better ventilation in the non-dependent lung in both positions. Head position had no effect on the distribution of ventilation.Conclusions: This study demonstrates that the distribution of ventilation in healthy, spontaneously breathing infants and children in supine and prone positions is not as straightforward as previously thought, with no clear reversal of the adult pattern evident.

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Gravitational distribution of regional opening and closing pressures, hysteresis and atelectrauma in ARDS evaluated by electrical impedance tomography

Critical Care ◽

10.1186/s13054-020-03335-1 ◽

2020 ◽

Vol 24 (1) ◽

Author(s):

Gaetano Scaramuzzo ◽

Elena Spinelli ◽

Savino Spadaro ◽

Alessandro Santini ◽

Donatella Tortolani ◽

...

Keyword(s):

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Regional Distribution ◽

Low Flow ◽

Dependent Lung ◽

Impedance Tomography ◽

Lung Physiology ◽

Volume Curve ◽

Opening And Closing ◽

Closing Pressure

Abstract Background The physiological behavior of lungs affected by the acute respiratory distress syndrome (ARDS) differs between inspiration and expiration and presents heterogeneous gravity-dependent distribution. This phenomenon, highlighted by the different distribution of opening/closing pressure and by the hysteresis of the pressure–volume curve, can be studied by CT scan, but the technique expose the patient to radiations, cannot track changes during time and is not feasible at the bedside. Electrical impedance tomography (EIT) could help in assessing at the bedside regional inspiratory and expiratory mechanical properties. We evaluated regional opening/closing pressures, hysteresis and atelectrauma during inspiratory and expiratory low-flow pressure–volume curves in ARDS using electrical impedance tomography. Methods Pixel-level inspiratory and expiratory PV curves (PVpixel) between 5 and 40 cmH2O were constructed integrating EIT images and airway opening pressure signal from 8 ARDS patients. The lower inflection point in the inspiratory and expiratory PVpixel were used to find opening (OPpixel) and closing (CPpixel) pressures. A novel atelectrauma index (AtI) was calculated as the percentage of pixels opening during the inspiratory and closing during the expiratory PV curves. The maximal hysteresis (HysMax) was calculated as the maximal difference between normalized expiratory and inspiratory PV curves. Analyses were conducted in the global, dependent and non-dependent lung regions. Results Gaussian distribution was confirmed for both global OPpixel (r2 = 0.90) and global CPpixel (r2 = 0.94). The two distributions were significantly different with higher values for OPpixel (p < 0.0001). Regional OPpixel and CPpixel distributions were Gaussian, and in the dependent lung regions, both were significantly higher than in the non-dependent ones (p < 0.001). Both AtI and the HysMax were significantly higher in the dependent regions compared to the non-dependent ones (p < 0.05 for both). Conclusions Gravity impacts the regional distribution of opening and closing pressure, hysteresis and atelectrauma, with higher values in the dorsal lung. Regional differences between inspiratory and expiratory lung physiology are detectable at the bedside using EIT and could allow in-depth characterization of ARDS phenotypes and guide personalized ventilation settings. Graphic abstract

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Evaluation of Regional Pulmonary Ventilation in Spontaneously Breathing Patients with Idiopathic Pulmonary Fibrosis (IPF) Employing Electrical Impedance Tomography (EIT): A Pilot Study from the European IPF Registry (eurIPFreg)

Journal of Clinical Medicine ◽

10.3390/jcm10020192 ◽

2021 ◽

Vol 10 (2) ◽

pp. 192

Author(s):

Ekaterina Krauss ◽

Daniel van der Beck ◽

Isabel Schmalz ◽

Jochen Wilhelm ◽

Silke Tello ◽

...

Keyword(s):

Idiopathic Pulmonary Fibrosis ◽

Pulmonary Fibrosis ◽

Electrical Impedance Tomography ◽

Spontaneous Breathing ◽

Electrical Impedance ◽

Statistical Significance ◽

Pulmonary Ventilation ◽

Healthy Controls ◽

Impedance Tomography ◽

Spontaneously Breathing

Objectives: In idiopathic pulmonary fibrosis (IPF), alterations in the pulmonary surfactant system result in an increased alveolar surface tension and favor repetitive alveolar collapse. This study aimed to assess the usefulness of electrical impedance tomography (EIT) in characterization of regional ventilation in IPF. Materials and methods: We investigated 17 patients with IPF and 15 healthy controls from the University of Giessen and Marburg Lung Center (UGMLC), Germany, for differences in the following EIT parameters: distribution of ventilation (TID), global inhomogeneity index (GI), regional impedance differences through the delta of end-expiratory lung impedance (dEELI), differences in surface of ventilated area (SURF), as well as center of ventilation (CG) and intratidal gas distribution (ITV). These parameters were assessed under spontaneous breathing and following a predefined escalation protocol of the positive end-expiratory pressure (PEEP), applied through a face mask by an intensive care respirator (EVITA, Draeger, Germany). Results: Individual slopes of dEELI over the PEEP increment protocol were found to be highly significantly increased in both groups (p < 0.001) but were not found to be significantly different between groups. Similarly, dTID slopes were increasing in response to PEEP, but this did not reach statistical significance within or between groups. Individual breathing patterns were very heterogeneous. There were no relevant differences of SURF, GI or CGVD over the PEEP escalation range. A correlation of dEELI to FVC, BMI, age, or weight did not forward significant results. Conclusions: In this study, we did see a significant increase in dEELI and a non-significant increase in dTID in IPF patients as well as in healthy controls in response to an increase of PEEP under spontaneous breathing. We propose the combined measurements of EIT and lung function to assess regional lung ventilation in spontaneously breathing subjects.

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Electrical Impedance Tomography for Assessment of Pendelluft and Work of Breathing in Spontaneously Breathing Mechanically Ventilated Patients

10.1164/ajrccm-conference.2021.203.1_meetingabstracts.a2803 ◽

2021 ◽

Author(s):

E. Kistler ◽

M.S. Schaefer ◽

E. Baedorf Kassis

Keyword(s):

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Work Of Breathing ◽

Impedance Tomography ◽

Mechanically Ventilated ◽

Mechanically Ventilated Patients ◽

Spontaneously Breathing ◽

Ventilated Patients

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What hinders pulmonary gas exchange and changes distribution of ventilation in immobilized white rhinoceroses (Ceratotherium simum) in lateral recumbency?

Journal of Applied Physiology ◽

10.1152/japplphysiol.00359.2020 ◽

2020 ◽

Vol 129 (5) ◽

pp. 1140-1149

Author(s):

Martina Mosing ◽

Andreas D. Waldmann ◽

Muriel Sacks ◽

Peter Buss ◽

Jordyn M. Boesch ◽

...

Keyword(s):

Gas Exchange ◽

Electrical Impedance Tomography ◽

Electrical Impedance ◽

Breath Holding ◽

Dependent Lung ◽

Regional Ventilation ◽

Impedance Tomography ◽

Ventilation And Perfusion ◽

Lateral Recumbency ◽

Nondependent Lung

Electrical impedance tomography measurements of regional ventilation and perfusion applied to etorphine-immobilized white rhinoceroses in lateral recumbency revealed a pronounced disproportional shift of the measured ventilation and perfusion toward the nondependent lung. The dependent lung was minimally ventilated and perfused, but still aerated. Perfusion was found primarily around the hilum of the nondependent lung. These shifts can explain the gas exchange impairments found in this study. Breath holding can redistribute ventilation.

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