scholarly journals Physiological effects of different recruitment maneuvers in a pig model of ARDS

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Feiping Xia ◽  
Chun Pan ◽  
Lihui Wang ◽  
Ling Liu ◽  
Songqiao Liu ◽  
...  
Keyword(s):  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Pig Model ◽  
Physiological Effects ◽  
Impedance Tomography ◽  
Arterial Blood ◽  
Recruitment Maneuvers ◽  
Sustained Inflation ◽  
Significant Difference ◽  
Inhomogeneity Index

Abstract Background In acute respiratory distress syndrome (ARDS), lung recruitment maneuvers can recruit collapsed alveoli in gravity-dependent lung regions, improving the homogeneity of ventilation distribution. This study used electrical impedance tomography to investigate the physiological effects of different recruitment maneuvers for alveolar recruitment in a pig model of ARDS. Methods ARDS was induced in ten healthy male pigs with repeated bronchoalveolar lavage until the ratio of arterial partial pressure of oxygen (PaO2) of fraction of inspired oxygen (P/F) was < 100 mmHg and remained stable for 30 min (TARDS). ARDS pigs underwent three sequential recruitment maneuvers, including sustained inflation, increments of positive end-expiratory pressure (PEEP), and pressure-controlled ventilation (PCV) applied in random order, with 30 mins at a PEEP of 5 cmH2O between maneuvers. Respiratory mechanics, hemodynamics, arterial blood gas, and electrical impedance tomography were recorded at baseline, TARDS, and before and after each recruitment maneuver. Results In all ten pigs, ARDS was successfully induced with a mean 2.8 ± 1.03 L bronchoalveolar lavages. PaO2, P/F, and compliance were significantly improved after recruitment with sustained inflation, increments of PEEP or PCV (all p < 0.05), and there were no significant differences between maneuvers. Global inhomogeneity index significantly decreased after recruitment with sustained inflation, increments of PEEP, or PCV. There were no significant differences in global inhomogeneity before or after recruitment with the different maneuvers. The decrease in global inhomogeneity index (ΔGI) was significantly greater after recruitment with increments of PEEP compared to sustained inflation (p = 0.023), but there was no significant difference in ΔGI between increments of PEEP and PCV or between sustained inflation and PCV. Conclusion Sustained inflation, increments of PEEP, and PCV increased oxygenation, and regional and global compliance of the respiratory system, and decreased inhomogeneous gas distribution in ARDS pigs. Increments of PEEP significantly improved inhomogeneity of the lung compared to sustained inflation, while there was no difference between increments of PEEP and PCV or between sustained inflation and PCV.

scholarly journals Physiological Effects of Different Recruitment Maneuvers in a Pig Model of ARDS

2020 ◽  
Author(s):  
Feiping Xia ◽  
Chun Pan ◽  
Lihui Wang ◽  
Ling Liu ◽  
Songqiao Liu ◽  
...  
Keyword(s):  
Random Order ◽  
Pig Model ◽  
Physiological Effects ◽  
Impedance Tomography ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Recruitment Maneuvers ◽  
Sustained Inflation ◽  
Significant Difference ◽  
Before And After

Abstract Background: In acute respiratory distress syndrome (ARDS), lung recruitment maneuvers can recruit collapsed alveoli in gravity-dependent lung regions, improving the homogeneity of ventilation distribution. This study used electrical impedance tomography (EIT) to investigate the physiological effects of different recruitment maneuvers for alveolar recruitment in a pig model of ARDS. Methods: ARDS was induced in ten healthy male pigs with repeated bronchoalveolar lavage until the arterial partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) (P/F ratio) was < 100 mmHg and remained stable for 30 minutes (TARDS). ARDS pigs underwent three sequential recruitment maneuvers, including sustained inflation (SI), increments of positive end-expiratory pressure (PEEP) (IP), and pressure-controlled ventilation (PCV) applied in random order, with 30 mins at a PEEP of 5 cmH2O between maneuvers. Respiratory mechanics, hemodynamics, arterial blood gas, and EIT were recorded at baseline, TARDS, and before and after each recruitment maneuver.Results: In all ten pigs, ARDS was successfully induced with a mean 2.8±1.03L (2800±1032.80ml) bronchoalveolar lavages. PaO2, SO2, P/F, and compliance were significantly improved after recruitment with SI, IP or PCV (all p<0.05), and there were no significant differences between maneuvers. Global inhomogeneity (GI) was significantly decreased after recruitment with SI, IP, or PCV. There were no significant differences in GI before or after recruitment with the different maneuvers. The decrease in GI (ΔGI) was significantly greater after recruitment with IP compared to SI (p=0.023), but there was no significant difference in ΔGI between IP and PCV.Conclusion: SI, IP, and PCV increased oxygenation, and regional and global compliance of the respiratory system, and decreased inhomogeneous gas distribution in ARDS pigs. IP significantly improved inhomogeneity of the lung compared to SI.

scholarly journals Physiological Effects of Different Recruitment Maneuvers for Improved Lung Inhomogeneity in a Pig Model of ARDS

2020 ◽  
Author(s):  
Feiping Xia ◽  
Chun Pan ◽  
Lihui Wang ◽  
Ling Liu ◽  
Songqiao Liu ◽  
...  
Keyword(s):  
Random Order ◽  
Pig Model ◽  
Physiological Effects ◽  
Impedance Tomography ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Recruitment Maneuvers ◽  
Sustained Inflation ◽  
Significant Difference ◽  
Before And After

Abstract Background: In acute respiratory distress syndrome (ARDS), lung recruitment maneuvers can recruit collapsed alveoli in gravity-dependent lung regions, improving the homogeneity of ventilation distribution. This study used electrical impedance tomography (EIT) to investigate the physiological effects of different recruitment maneuvers for alveolar recruitment in a pig model of ARDS. Methods: ARDS was induced in ten healthy male pigs with repeated bronchoalveolar lavage until the arterial partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) (P/F ratio) was < 100 mmHg and remained stable for 30 minutes (TARDS). ARDS pigs underwent three sequential recruitment maneuvers, including sustained inflation (SI), increments of positive end-expiratory pressure (PEEP) (IP), and pressure-controlled ventilation (PCV) applied in random order, with 30 mins at a PEEP of 5 cmH2O between maneuvers. Respiratory mechanics, hemodynamics, arterial blood gas, and EIT were recorded at baseline, TARDS, and before and after each recruitment maneuver.Results: In all ten pigs, ARDS was successfully induced with a mean 2.8±1.03L (2800±1032.80ml) bronchoalveolar lavages. PaO2, SO2, P/F, and compliance were significantly improved after recruitment with SI, IP or PCV (all p<0.05), and there were no significant differences between maneuvers. Global inhomogeneity (GI) was significantly decreased after recruitment with SI, IP, or PCV. There were no significant differences in GI before or after recruitment with the different maneuvers. The decrease in GI (ΔGI) was significantly greater after recruitment with IP compared to SI (p=0.023), but there was no significant difference in ΔGI between IP and PCV.Conclusion: SI, IP, and PCV increased oxygenation, and regional and global compliance of the respiratory system, and decreased inhomogeneous gas distribution in ARDS pigs. IP significantly improved inhomogeneity of the lung compared to SI.

scholarly journals Efficacy of Different Recruitment Maneuvers for Improved Lung Inhomogeneity in a Pig Model of ARDS

2020 ◽  
Author(s):  
Feiping Xia ◽  
Chun Pan ◽  
Lihui Wang ◽  
Ling Liu ◽  
Songqiao Liu ◽  
...  
Keyword(s):  
Random Order ◽  
Lung Compliance ◽  
Pig Model ◽  
Impedance Tomography ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Recruitment Maneuvers ◽  
Sustained Inflation ◽  
Significant Difference ◽  
Before And After

Abstract Background: In acute respiratory distress syndrome (ARDS), lung recruitment maneuvers can recruit collapsed alveoli in gravity-dependent lung regions, improving the homogeneity of ventilation distribution. This study used electrical impedance tomography (EIT) to investigate the efficacy of different recruitment maneuvers for alveolar recruitment in a pig model of ARDS. Methods: ARDS was induced in ten healthy male pigs with repeated bronchoalveolar lavage until the arterial partial pressure of oxygen (PaO 2 )/fraction of inspired oxygen (FiO 2 ) (P/F ratio) was < 100 mmHg and remained stable for 30 minutes (TARDS). ARDS pigs underwent three sequential recruitment maneuvers, including sustained inflation (SI), increments of positive end-expiratory pressure (PEEP) (IP), and pressure-controlled ventilation (PCV) applied in random order, with 30 mins at a PEEP of 5 cmH 2 O between maneuvers. Respiratory mechanics, hemodynamics, arterial blood gas, and EIT were recorded at baseline, TARDS, and before and after each recruitment maneuver.Results: In all ten pigs, ARDS was successfully induced with a mean 2.8±1.03 (2800±1032.80ml) bronchoalveolar lavages. PaO 2 , SO 2 , P/F, and compliance were significantly improved after recruitment with SI, IP or PCV (all p<0.05), and there were no significant differences between maneuvers. Global inhomogeneity (GI) was significantly decreased after recruitment with SI, IP, or PCV. There were no significant differences in GI before or after recruitment with the different maneuvers. The decrease in GI (ΔGI) was significantly greater after recruitment with IP compared to SI (p=0.023), but there was no significant difference in ΔGI between IP and PCV. Conclusion: SI, IP, and PCV increased oxygenation, regional compliance and lung compliance, and decreased inhomogeneous gas distribution with no adverse effects on hemodynamics in ARDS pigs. IP significantly improved inhomogeneity of the lung compared to SI.

Monitoring of Pneumothorax Appearance with Electrical Impedance Tomography during Recruitment Maneuvers

2017 ◽  
Vol 195 (8) ◽  
pp. 1070-1073 ◽  
Author(s):  
Caio C. A. Morais ◽  
Roberta R. De Santis Santiago ◽  
José R. B. de Oliveira Filho ◽  
Adriana S. Hirota ◽  
Pedro H. D. Pacce ◽  
...  
Keyword(s):  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Impedance Tomography ◽  
Recruitment Maneuvers

scholarly journals Imaging fascicular organization of peripheral nerves with fast neural Electrical Impedance Tomography (EIT)

2020 ◽  
Author(s):  
Enrico Ravagli ◽  
Svetlana Mastitskaya ◽  
Nicole Thompson ◽  
Francesco Iacoviello ◽  
Paul R Shearing ◽  
...  
Keyword(s):  
Electrical Impedance Tomography ◽  
Peripheral Nerves ◽  
Electrical Impedance ◽  
Electrode Array ◽  
Compound Action Potential ◽  
Micro Computed Tomography ◽  
Impedance Tomography ◽  
Tissue Impedance ◽  
Significant Difference ◽  
Stimulation Of

Imaging of the compound action potential (CAP) in fascicles in peripheral nerves could help avoid side effects in neuromodulation by selective stimulation of identified fascicles. Existing methods have low resolution, limited imaging depth, or are invasive. We propose fast neural electrical impedance tomography (EIT), which allows fascicular CAP imaging with a high resolution of ∼200 μm, <1 ms. This uses a non-penetrating flexible cuff electrode array with 14 circumferential electrodes. This has been validated in rat sciatic nerve by comparison to micro-computed tomography (microCT) and histology with fluorescent dextran tracers (n=5). With EIT, there were reproducible localized changes in tissue impedance in response to stimulation of individual fascicles (tibial, peroneal and sural). The reconstructed EIT images corresponded to microCT scans and neural tracer histology, with significant separation between the fascicles (p<0.01), and no significant difference between techniques. The standard deviation from the mean fascicle position for EIT was 86 μm (6% of nerve diameter). This suggests fast neural EIT can reliably image the functional fascicular anatomy of the nerves and so aid selective neuromodulation.

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

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhe Li ◽  
Zhiyun Zhang ◽  
Qian Xia ◽  
Danling Xu ◽  
Shaojie Qin ◽  
...  
Keyword(s):  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Final Analysis ◽  
High Flow ◽  
Nasal Cannula ◽  
Time To Failure ◽  
High Flow Nasal Cannula ◽  
Impedance Tomography ◽  
Rapid Shallow Breathing Index ◽  
Significant Difference

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 &lt; 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 &lt; 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.

scholarly journals COMPARISON OF END-EXPIRATORY LUNG VOLUME MEASUREMENT BY ELECTRICAL IMPEDANCE TOMOGRAPHY AND NITROGEN WASHOUT METHOD IN PIGS

2020 ◽  
Vol 50 (4) ◽  
pp. 146-151
Author(s):  
Karel Roubík ◽  
Martin Muller
Keyword(s):  
Linear Relationship ◽  
Electrical Impedance Tomography ◽  
Lung Volume ◽  
Normal Saline ◽  
Electrical Impedance ◽  
Impedance Tomography ◽  
Baseline Phase ◽  
Nitrogen Washout ◽  
Saline Bolus ◽  
Significant Difference

End-expiratory lung volume (EELV) can be determined using several methods that allow clinically accurate measurements, but it is difficult to apply these methods to the patient's bedside. Electrical impedance tomography (EIT) is offered as another method for measuring EELV. The aim of the study is to compare changes in EELV measured by nitrogen washout method with changes of EELV calculated from the change in end-expiratory lung impedance (EELI) measured by EIT and to determine whether changes in EELV calculated from changes in chest impedance can be used as one of the parameters for EIT data analysis and description. The prospective interventional animal study was performed on ten pigs. The animals received total intravenous anesthesia with muscle relaxation. Mechanical lung ventilation was conducted in the volume-controlled mode. 16-electrode EIT system was used for data acquisition. End-expiratory lung volume was measured by a modified nitrogen wash-in/wash-out technique developed by Olegard et al. The study protocol consisted of the baseline phase, two incremental PEEP steps, two decremental PEEP steps and from normal saline i. v. administration. For each animal, a reference frame (baseline frame) was selected from the initial baseline phase and was used for the reconstruction of EIT images and impedance waveforms. For each breath cycle, tidal variation image was calculated as a difference between the end-inspiratory and the previous end-expiratory EIT image. An equivalent end-expiratory volume change (ΔEELVequiv) was calculated from EELI. The values of ΔEELVequiv were compared with reference EELV data measured by a modified nitrogen wash-in/wash-out technique (ΔEELVmeas). The measured and the estimated changes in EELV were statistically compared and correlation between ΔEELVequiv and ΔEELVmeas was calculated. Statistically significant difference between ΔEELVequiv and ΔEELVmeas was observed only in administration of normal saline bolus. Pearson’s correlation coefficients were 0.29 for increase in PEEP, 0.45 for decrease in PEEP and -0.1 during administration of normal saline bolus. The study showed that during changes in PEEP in the porcine model, there was no linear relationship between ΔEELVequiv and ΔEELVmeas. Although there was no linear relationship between ΔEELVequiv and ΔEELVmeas with changes in PEEP, no statistically significant difference was demonstrated between these two methods, which justifies the use of ΔEELVequiv as a parameter suitable for description and evaluation of EIT data.

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