Table 1.
Study design.
Fig 1.
Experimental set-up with two test-lungs A and B (Part I) and three test-lungs (Part II). Paw: airway pressure, HEPA: high-efficiency particulate air filter, : flow. Red and blue arrows indicate inspiration and expiration, respectively.
Fig 2.
Method to measure the pendelluft air volume during inspiration and expiration in case of a double circuit and two test-lungs with uneven compliance and resistance ventilated (volume control, step 2, V500 ventilator).
Recording of airway pressure (Paw, top) and flow , middle and bottom) leaving the ventilator during a breathing cycle. Paw and
are distributed in parallel to the test-lung A (red) (PawA and
) and the test-lung B (green) (PawB and
). The vertical broken lines indicate the corresponding ends of insufflation for the ventilator and each test-lung. The lower panel is a magnification of the end of insufflation.
Table 2.
Summary of pendelluft occurrence.
Fig 3.
Stacked plots of inspired tidal volume in test-lung A (blue), B (orange), and C (grey) in volume and pressure control ventilation during the 4 steps for each ventilator in the design with two (panels A and B) and three test-lungs (panels C and D). Step1 = C50-R5 for each test-lung, Step2 = A C50-R20 and B C20-R20, Step3 = A C20-R20 and B C10-R20, Step4 = A C50-R20 and B C20-R5. C 10-R20 for test-lung C at each step. Bars are median and the interquartile range (3rd minus 1st quartile) are indicated above bars. The horizontal broken black lines indicate the target tidal volume the ventilator should deliver to each test-lung. *P<0.05 as compared to V500.
Table 3.
Pendelluft air volume to each lung.
Fig 4.
Box-and-Whisker plots of minimal expiratory resistance in double (panel A and B) and triple circuits (panel C and D) with Elisée 350 (yellow) and V500 (white) ventilators during the different steps. Panels A and C are volume control and B and D pressure control. Whiskers denote median ± 1.58 x IQR x √3, where IQR is the interquartile range. *P<0.05 vs. V500.
Table 4.
Sex, anthropometric characteristics, ventilator settings and respiratory mechanics of 20 patients with COVID-19 related ARDS.
Table 5.
Summary of the bench studies on shared ventilation between two test-lungs.