Broberg Ellen, Pierre Leif, Fakhro Mohammed, Malmsjö Malin, Lindstedt Sandra, Hyllén Snejana
Department of Clinical Sciences, Lund University, Lund, Sweden.
Department of Cardiothoracic Anaesthesia and Intensive Care, Skåne University Hospital, Entrégatan 8, Level 8, 22241, Lund, Sweden.
Intensive Care Med Exp. 2023 Mar 17;11(1):12. doi: 10.1186/s40635-023-00498-3.
Detecting particle flow from the airways by a non-invasive analyzing technique might serve as an additional tool to monitor mechanical ventilation. In the present study, we used a customized particles in exhaled air (PExA) technique, which is an optical particle counter for the monitoring of particle flow in exhaled air. We studied particle flow while increasing and releasing positive end-expiratory pressure (PEEP). The aim of this study was to investigate the impact of different levels of PEEP on particle flow in exhaled air in an experimental setting. We hypothesized that gradually increasing PEEP will reduce the particle flow from the airways and releasing PEEP from a high level to a low level will result in increased particle flow.
Five fully anesthetized domestic pigs received a gradual increase of PEEP from 5 cmHO to a maximum of 25 cmHO during volume-controlled ventilation. The particle count along with vital parameters and ventilator settings were collected continuously and measurements were taken after every increase in PEEP. The particle sizes measured were between 0.41 µm and 4.55 µm.
A significant increase in particle count was seen going from all levels of PEEP to release of PEEP. At a PEEP level of 15 cmHO, there was a median particle count of 282 (154-710) compared to release of PEEP to a level of 5 cmHO which led to a median particle count of 3754 (2437-10,606) (p < 0.009). A decrease in blood pressure was seen from baseline to all levels of PEEP and significantly so at a PEEP level of 20 cmHO.
In the present study, a significant increase in particle count was seen on releasing PEEP back to baseline compared to all levels of PEEP, while no changes were seen when gradually increasing PEEP. These findings further explore the significance of changes in particle flow and their part in pathophysiological processes within the lung.
通过一种非侵入性分析技术检测气道中的颗粒流，可能成为监测机械通气的一种辅助工具。在本研究中，我们使用了一种定制的呼出空气中颗粒（PExA）技术，这是一种用于监测呼出空气中颗粒流的光学颗粒计数器。我们在增加和释放呼气末正压（PEEP）时研究颗粒流。本研究的目的是在实验环境中研究不同水平的PEEP对呼出空气中颗粒流的影响。我们假设逐渐增加PEEP会减少气道中的颗粒流，而将PEEP从高水平释放到低水平会导致颗粒流增加。
五只完全麻醉的家猪在容量控制通气期间，PEEP从5 cmH₂O逐渐增加到最大25 cmH₂O。连续收集颗粒计数以及生命体征参数和呼吸机设置，并在每次增加PEEP后进行测量。测量的颗粒大小在0.41 µm至4.55 µm之间。
从所有PEEP水平到释放PEEP时，颗粒计数显著增加。在PEEP水平为15 cmH₂O时，中位颗粒计数为282（154 - 710），而将PEEP释放到5 cmH₂O水平时，中位颗粒计数为3754（2437 - 10606）（p < 0.009）。从基线到所有PEEP水平血压均下降，在PEEP水平为20 cmH₂O时显著下降。
在本研究中，与所有PEEP水平相比，将PEEP释放回基线时颗粒计数显著增加，而逐渐增加PEEP时未见变化。这些发现进一步探讨了颗粒流变化的意义及其在肺内病理生理过程中的作用。
