Department of Anesthesiology and Intensive Care Medicine, Emergency Medicine and Pain Management, Dresden Friedrichstadt Hospital, Technical University Dresden Teaching Hospital, Friedrichstrasse 41, 01067, Dresden, Germany.
Faculty of Mechanical Engineering, University of Applied Sciences Dresden, Dresden, Germany.
BMC Pulm Med. 2022 Dec 21;22(1):484. doi: 10.1186/s12890-022-02277-4.
Tracheostomy tube capping is a commonly used test to determine if the tracheostomy tube can be removed. The success of the capping trial depends on the patient's ability to maintain sufficient spontaneous breathing with an occluded tracheostomy tube. The impact of an occluded tracheotomy tube on airway resistance is currently unknown. The aim of this study was to investigate tracheal pressure during capping or stoma button insertion and potential determinants concerning cuff.
Eight cuffed and uncuffed tracheostomy tubes and three stoma buttons of various manufacturers and sizes were inserted into the trachea model. Cuffs were completely deflated or contained atmospheric pressure. The trachea was ventilated bidirectional with a respirator in volume-controlled mode and volume flows 15-60 L/min. Tracheal pressure drop during inspiration as a parameter of pressure required to move gas through the airway was measured.
Tracheal pressure drops occurred linearly or irregularly during capping trials to a maximum of 4.2 kPa at flow rates of 60 L/min for atmospheric pressure cuffs. In tracheostomy tubes with completely deflated cuffs, pressure drop in the trachea reaches a maximum of 3.4 kPa at a flow rate of 60 L/min. For tracheostomy tubes with cuff smaller inner or outer diameters do not regularly result in lower tracheal pressure drop. The pressure drop varies between different tracheostomy tubes depending on the manufacturer. In cuffed tracheostomy tubes, we observed three phenomena: sail-like positioning, folding over, and tightening of the cuff during flow. The maximum tracheal pressure drop during stoma button insertion reaches 0.014 kPa.
The cuff is a central element for the pressure drop in the airway and thus airway resistance during spontaneous translaryngeal breathing with a capped TT. Complete deflation reduces the pressure drop in the trachea. Due to deformation of the cuff, measured pressures are irregular as the volume flow is increased. Incomplete deflated cuffs and material characteristics of tracheostomy tubes and cuffs in addition to anatomical and clinical variables may cause unsuccessful capping trials due to increased airway resistance. All stoma buttons showed that pressure drop and thus airway resistance due to stoma buttons has no clinical relevance.
气管造口管封管是一种常用的测试方法，用于确定是否可以拔除气管造口管。封管试验的成功取决于患者在气管造口管被堵塞的情况下维持足够自主呼吸的能力。目前尚不清楚堵塞气管造口管对气道阻力的影响。本研究旨在探讨封管或插入造口塞时的气管压力以及与气袖相关的潜在决定因素。
将 8 个带和不带套囊的气管造口管和 3 个不同制造商和尺寸的造口塞插入气管模型中。套囊完全放气或保持大气压。气管通过呼吸机在容量控制模式下双向通气，容量流量为 15-60 L/min。测量吸气时气管压力下降作为通过气道输送气体所需压力的参数。
在流量为 60 L/min 时，带套囊的气管造口管的套囊完全放气或保持大气压时，封管试验中气管压力下降呈线性或不规则下降，最大可达 4.2 kPa。在完全放气的气管造口管中，当流量为 60 L/min 时，气管内压力下降最大可达 3.4 kPa。对于套囊较小内或外径的气管造口管，不一定会导致较低的气管压力下降。不同制造商的气管造口管之间的压力下降值有所不同。在带套囊的气管造口管中，我们观察到三种现象：在气流过程中套囊呈帆状定位、折叠和收紧。插入造口塞时最大的气管压力下降达到 0.014 kPa。
套囊是气道压力下降和自主经气管呼吸时气道阻力的核心因素。完全放气可降低气管内压力下降。由于套囊变形，随着体积流量的增加，测量的压力不规则。不完全放气的套囊以及气管造口管和套囊的材料特性以及解剖学和临床变量可能会由于气道阻力增加而导致封管试验失败。所有造口塞的结果均表明，由于造口塞引起的压力下降和气道阻力无临床意义。
