A new way of monitoring mechanical ventilation by measurement of particle flow from the airways using Pexa method in vivo and during ex vivo lung perfusion in DCD lung transplantation

Abstract

BackgroundDifferent mechanical ventilation settings are known to affect lung preservation for lung transplantation. Measurement of particle flow in exhaled air may allow online assessment of the impact of ventilation before changes in the tissue can be observed. We hypothesized that by analyzing the particle flow, we could understand the impact of different ventilation parameters.MethodsParticle flow was monitored in vivo, post mortem, and in ex vivo lung perfusion (EVLP) in six porcines with the Pexa (particles in exhaled air) instrument. Volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) were used to compare small versus large tidal volumes. The surfactant lipids dipalmitoylphosphatidylcholine (DPPC) and phosphatidylcholine (PC) were quantified by mass spectrometry.ResultsIn vivo the particle mass in VCV1 was significantly lower than in VCV2 (p = 0.0186), and the particle mass was significantly higher in PCV1 than in VCV1 (p = 0.0322). In EVLP, the particle mass in VCV1 was significantly higher than in PCV1 (p = 0.0371), and the particle mass was significantly higher in PCV2 than in PCV1 (p = 0.0127). DPPC was significantly higher in EVLP than in vivo.ConclusionsHere, we introduce a new method for measuring particle flow during mechanical ventilation and confirm that these particles can be collected and analyzed. VCV resulted in a lower particle flow in vivo but not in EVLP. In all settings, large tidal volumes resulted in increased particle flow. We found that DPPC was significantly increased comparing in vivo with EVLP. This technology may be useful for developing strategies to preserve the lung and has a high potential to detect biomarkers.

Increased particle flow rate from airways precedes clinical signs of ARDS in a porcine model of LPS-induced acute lung injury

“…PExA. A customized PExA 2.0 device (PExA, Gothenburg, Sweden) was used in conjunction with mechanical ventilation, described previously by us (3,4). PExA measurements were recorded continuously throughout the experiment and were presented as particle flow rate (particles/minute).…”

“…EBPs are transmitted in exhaled air during the opening and closing of small airways and measured as PFR but could also be generated by shear forces produced by air flow acting on the RTLF (1). We used a customized particles in exhaled air (PExA) device, which is an optical particle counter that can detect, measure, and quantify EBPs in real time during mechanical ventilation, as we have shown previously in large animal studies and clinically in the ICU following lung transplantation (3,4). We aimed to determine PFR alterations in a lipopolysaccharide (LPS)-induced porcine model of ARDS and whether we could detect changes in the PFR before any changes in conventional parameters indicating ARDS occurred, such as a decrease in blood gases and alterations in ventilator parameters.…”

Mechanically ventilated patients exhibit decreased particle flow in exhaled breath as compared to normal breathing patients

“…The PExA 2.0 device (PExA, Gothenburg, Sweden) contain an optical particle counter (OPC) connected to an impactor for collection of PEx [9,10,14]. PEx in the diameter range of 0.41-4.55 µm can be measured continuously using the OPC and the impactor samples particles in the size range 0.4-7.2 µm.…”

“…PEx in the diameter range of 0.41-4.55 µm can be measured continuously using the OPC and the impactor samples particles in the size range 0.4-7.2 µm. In the present study, the PExA 2.0 instrument was customised to be able to be used in conjunction with mechanical ventilation as we have described previously in preclinical in vivo settings [14,15]. The device was connected to the outflow air of the mechanical respiratory circuit, as seen in figure 3.…”

“…Particle collection and membrane preparation with the PExA device Particles in exhaled air were collected using a two-stage inertial impactor, described in previous articles [9,10,14]. Mass spectrometry was used to quantify the phospholipids di-palmitoyl-phosphatidyl-choline (DPPC) and palmitoyl-oleoyl-phosphocholine (POPC).…”