Artificial Circulatory Setup.

<p>Artificial circulatory setup with two independent circuits filled with human packed red blood cells (haematocrit of 30%). A switching valve between the circuits enabled a step-change between highly oxygenated (circuit 1: purged with pure oxygen) and oxygen free blood (circuit 2: purged with nitrogen). Black arrows represent direction of blood flow. Adapting the settings of the rollerpumps and the heating-cooling device (heat exchanger) allowed blood-flow and temperature to be controlled. Via the O₂/N₂ blenders, oxygen content could be adapted at fixed sweep gas flow over the oxygenators. Measurement chamber contained 1.) ports for insertion of MFPF probes (Foxy-AL 300); 2.) a temperature probe and 3.) a sampling port for Clark-typed based (CTE) P_O2 analysis (ABL 700).</p

Influence of temperature and blood flow on MFPF P_O2 measurements: Linear regression model.

<p>Linear regression model: magnitude of P_O2 measurements, temperature and blood flow as independent variables, differences of P_O2 measurements as dependent variable. P_O2  =  oxygen partial pressure; MFPF  =  Multi Frequency Phase Fluorimetry; CTE  =  Clark-type electrode; CI  =  confidence interval.</p

Multi Frequency Phase Fluorimetry P_O2 vs. Clark-type Electrode P_O2 (porcine blood <i>in vitro</i>, normobaric range).

<p>Panel A: Linear regression plot, the solid line displays the line of best fit, the dashed line shows the line of identity; Panel B: Bland-Altman plot showing the differences (CTE-MFPF) versus the means for absolute P_O2 values. The dashed line represents the bias, the solid lines the 1.96 standard deviation interval.</p

Multi Frequency Phase Fluorimetry/FOXY-AL300 Probe Response Time.

<p>Example of an MFPF step-down manoeuvre in artificial circulatory setup (human blood-phase). The graph displays the absolute MFPF P_O2 values over the time course. The arrow marks the time when the switching valve was changed between the oxygenated (750 mmHg) and non-oxygenated blood (0 mmHg) circuit.</p

Multi Frequency Phase Fluorimetry P_O2 vs. Clark-type Electrode P_O2 (human blood <i>ex vivo</i>, normobaric range).

<p>Panel A: Linear regression plot, the solid line displays the line of best fit, the dashed line shows the line of identity; Panel B: Bland-Altman plot showing the differences (CTE-MFPF) versus the means for absolute P_O2 values. The dashed line represents the bias, the solid lines the 1.96 standard deviation interval.</p

Regional Ventilation Distribution as measured by VRI and EIT.

<p>Regional ventilation distribution as measured by VRI and EIT. Values are given as percentage of ventilation as assessed by EIT and VRI, itemized for the different measurement points and respective PEEP levels (BLH: baseline healthy; ALI-0: impaired lungs (ALI) at zero PEEP; ALI-5: ALI at PEEP 5 mbar; ALI-10: ALI at PEEP 10 mbar; ALI-15: ALI at PEEP 15 mbar). Panel A: within ventral and dorsal lung ROI. Panel B: within level 1 (upper ventral), level 2 (middle), and level 3 (lower dorsal) lung ROI.</p

Example of VRI and EIT side-by-side raw data recordings.

<p>Raw data waveforms of one representative breathing-cycle for each of the different measurement time points (BLH: baseline healthy; ALI-0: impaired lungs (ALI) at zero PEEP; ALI-5: ALI at PEEP 5 mbar; ALI-10: ALI at PEEP 10 mbar; ALI-15: ALI at PEEP 15 mbar). Panel A: Vibration energy (VE) over time by VRI. The parameter vibration energy amplitude (VEA) was assessed at the peak flow rate of the inspiratory phase of the breathing cycle. Panel B: Relative impedance changes (rel.Z) over time by EIT. The amplitudes of rel.Z (rel.ΔZ) were assessed by tidal differences between minimum and maximum rel.Z values.</p

Agreement between estimated V_T by EIT and VRI for different lung regions: Linear correlation and Bland-Altman analysis.

<p>Agreement between estimated V_T by EIT and VRI for the different lung regions of interest (ROIs): linear correlation equation with the corresponding goodness of fit (left). Bias and 1.96-SD limits of the Bland-Altman analysis (right).</p

Influence of lung injury and PEEP on VRI V_T measurement: ANCOVA.

<p>Slopes and intercepts for the different measurement points (BLH: baseline healthy; ALI-0: impaired lungs (ALI) at zero PEEP; ALI-5: ALI at PEEP 5 mbar; ALI-10: ALI at PEEP 10 mbar; ALI-15: ALI at PEEP 15 mbar) are presented on the left. Descriptive measures of the differences in V_T measured by VRI and EIT, displayed as mean±SD (standard deviation) and range [ml] are presented on the right. To investigate the influence of lung damage and PEEP on EIT and VRI V_T measures, an ANCOVA was used to test the equality of slopes and intercepts (using an F test to compare a global model where slope is shared among the data sets, with a model where each dataset gets its own slope). The first <i>P</i>-value tested the null hypothesis that the slopes are all identical (the lines are parallel). The second <i>P</i>-value represents the results of testing the null hypothesis that the intercepts are identical.</p

Ventilatory, gas exchange and hemodynamic parameters in healthy baseline and injured lungs at different PEEP.

<p>N = 9. Values are means ± standard deviations. P_endinsp: end-inspiratory airway pressure; PEEP: positive end-expiratory pressure; RR: respiratory rate; V_T: tidal volume; Crs: respiratory system compliance; Flow: airway flow; F_IO₂: fraction of inspired oxygen; P_aO₂: arterial partial pressure of oxygen; P_aCO₂: arterial partial pressure of carbon dioxyde; S_pO₂: peripheral saturation; HR: heart rate; SAP, systolic arterial pressure; DAP, diastolic arterial pressure; MAP, mean arterial pressure; MPAP, mean pulmonary arterial pressure; CVP, central venous pressure.</p