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PEEP trial after lung injury (pig)

Methods and Data

The measurements were performed in the same pig after induction of acute lung injury by repeated bronchoalveolar lavage (p1130107.get) and after administration of surfactant (p1130122.get). Both measurements were acquired at a rate of 13 scans/s, a total of 1500 frames were obtained. The excitation current was 50 kHz. The data was acquired during an incremental and decremental PEEP trial (stepwise increase and decrease of positive end-expiratory pressure).

Data were published in Frerichs, I., Dargavillle, P.A., Dudykevych, T., Rimensberger, P.M. (2003) Electrical Impedance Tomography − a method for monitoring regional lung aeration and tidal volume distribution? Intensive Care Med. 29:2312-2316, 2003.

Results

The key results are shown in Fig.3 from the paper
figure 3

EIDORS Analysis

  1. Download the data and save it to your working directory.
  2. Create a FEM model of the pig
    % Create Model $Id: if_peep_trial01.m 3371 2012-07-02 09:08:43Z bgrychtol $
    
    fmdl = mk_library_model('pig_23kg_16el');
    [fmdl.stimulation fmdl.meas_select] = mk_stim_patterns(16,1,'{ad}','{ad}');
    fmdl = mdl_normalize(fmdl, 1);  % Use normalized difference imaging
    opt.noise_figure = 0.5; opt.imgsz = [64 64];
    imdl = mk_GREIT_model(fmdl, 0.25, [], opt);
    
    % subplot(211);
    show_fem(imdl.fwd_model, [0,1,0]);
    axis equal; axis off
    
    hh=text(-1.1,0,'Right');
    set(hh,'Rotation',90,'HorizontalAlignment','Center');
    hh=text(0,-1.15,'Ventral');
    set(hh,'HorizontalAlignment','Center');
    
    print_convert if_peep_trial01.png
    
    

    Figure: 3D FEM of pig thorax
  3. Reconstruct images
    % Reconstruct Images $Id: if_peep_trial02.m 1535 2008-07-26 15:36:27Z aadler $
    
    v_injury = eidors_readdata('p1130107.get');
    r_injury = mean(v_injury(:,1:10),2); % reference meas
    v_treat  = eidors_readdata('p1130122.get');
    r_treat  = mean(v_treat(:,1:10),2); % reference meas
    
    i_injury = inv_solve(imdl, r_injury, v_injury);
    i_treat  = inv_solve(imdl, r_treat , v_treat );
    
    
  4. Select Regions of interest to plot
    % Select ROI's
    
    img = i_injury; img.elem_data = img.elem_data(:,700);
    rimg = calc_colours( calc_slices( img ), img);
    
    np= calc_colours('npoints');
    xlocn= 5/16 * np;
    ylocn= [4:2:10]/16 * np; 
    for yl = 1:4;
       rimg(ylocn(yl) + (-2:2), xlocn + (-2:2) ) = 1;
    end
    image(rimg); axis square
    
    for yl = 1:4;
       text(xlocn-1, ylocn(yl), num2str(yl));
    end
    
    axis off
    print_convert if_peep_trial03.png
    
    

    Figure: Image of ventilation and 4 identified points to analyse regional ventilation
  5. Normalized Impedance Change (ΔZ) at each ROI
    % Display Times courses $Id: if_peep_trial04.m 2765 2011-07-14 16:13:38Z aadler $
    
    for loop = 1:2;
       if loop == 1; img = i_injury;
       else          img = i_treat;
       end
    
       subplot(2,2,loop);
       time = (0:size(img.elem_data,2)-1)/13; % Frame rate = 13/s
    
       raster= calc_slices( img );
       ROIs  = raster(ylocn, xlocn, :);
       ROIs  = permute(ROIs, [3,1,2]);
    
       %Normalize to its maximum
       for i=1:length(ylocn)
          ROIs(:,i) = - ROIs(:,i) / max(abs(ROIs(:,i)));
       end
       plot(time, ROIs);
       axis([0, max(time), -0.1, 1]);
       legend('1','2','3','4',2)
       xlabel('time (s)')
       ylabel('normalized \Delta Z')
    end
    
    print_convert if_peep_trial04.png '-density 175'
    
    

    Figure: Normalized ΔZ time course for different lung ROIs. Left Lung Injury Right Treated
  6. Animate Output for each condition This function creates a video of the sample sequences.
    % Show images $Id: if_peep_trial05.m 1535 2008-07-26 15:36:27Z aadler $
    
    for loop = 1:2;
       if loop == 1; img = i_injury; fn= 'a';
       else          img = i_treat;  fn= 'b';
       end
    
       % image properties
       img.calc_colours.npoints     = 32;
       img.calc_colours.window_range= .5;
       img.calc_colours.ref_level   = 0;
       img.calc_colours.greylev     = 0.01;
       img.calc_colours.backgnd     = [1,1,1];
       img.animate_reconstructions.show_times = 1;
    
       animate_reconstructions(['if_peep_trial05',fn], img);
    end
    
    

    Figure: Video of sample sequences Left Lung Injury Right Treated

Last Modified: $Date: 2017-02-28 13:12:08 -0500 (Tue, 28 Feb 2017) $ by $Author: aadler $