Dodds Jarron M, Appelqvist Dylan I, Paleologos Michael S, Downey Ryan G
Department of Anaesthesia and Acute Pain Medicine, St Vincent's Hospital, Melbourne, Australia.
The University of Notre Dame, Sydney, Australia.
Anaesth Intensive Care. 2023 Mar;51(2):130-140. doi: 10.1177/0310057X221119824. Epub 2023 Jan 31.
A bag-valve-mask (BVM) is a portable handheld medical device commonly used in airway management and manual ventilation. Outside of the operating theatre, BVM devices are often used to pre-oxygenate spontaneously breathing patients before intubation to reduce the risk of hypoxaemia. Pre-oxygenation is considered adequate when the end-tidal expiratory fraction of oxygen is greater than 0.85. There are reports that some BVM devices fail to deliver a satisfactory inspired oxygen (FiO) in spontaneously breathing patients due to variability in design. The primary aim of this study was to evaluate the efficacy of oxygen delivery of a broad range of adult and paediatric BVM devices at increasing tidal volumes using a mechanical lung to simulate spontaneous ventilation. The secondary aim was to evaluate the effect of BVM design on performance.Forty BVM devices were evaluated in a laboratory setting as part of a safety assessment requested by HealthShare New South Wales. The oxygen inlet of each BVM device was primed with 100% oxygen (15 l/min) for two min. The BVM device was then attached to the mechanical lung and commenced spontaneous breathing at a fixed respiratory rate of 12 breaths/min with an inspiratory: expiratory ratio of 1:2. For each device FiO was measured after two min of spontaneous breathing. This process was repeated with small (250 ml), medium (500 ml) and large (750 ml) tidal volumes simulating adult breathing in adult BVM devices, and small (150 ml), medium (300 ml) and large (450 ml) tidal volumes simulating paediatric breathing in paediatric BVM devices. The test was repeated using up to five BVM devices of the same model (where supplied) at each tidal volume as a manufacturing quality control measure.Eight of the 40 devices tested failed to deliver a FiO above 0.85 for at least one tidal volume, and five models failed to achieve this at any measured tidal volume. Concerningly, three of these devices delivered a FiO below 0.55. Six of the eight poorly performing devices delivered reducing concentrations of inspired oxygen with increasing tidal volumes. Devices which performed the worst were those with a duckbill non-rebreather valve and without a dedicated expiratory valve.Several BVM devices available for clinical use in Australia did not deliver sufficient oxygen for reliable pre-oxygenation in a spontaneously breathing in vitro model. Devices with a duckbill non-rebreather valve and without a dedicated expiratory valve performed the worst. It is imperative that clinicians using BVM devices to deliver oxygen to spontaneously breathing patients are aware of the characteristics and limitations of the BVM devices, and that the standards for manufacture are updated to require safe performance in all clinical circumstances.
袋阀面罩（BVM）是一种便携式手持医疗设备，常用于气道管理和手动通气。在手术室之外，BVM设备常用于在插管前对自主呼吸的患者进行预给氧，以降低低氧血症的风险。当呼气末氧分数大于0.85时，预给氧被认为是充分的。有报道称，由于设计的差异，一些BVM设备在自主呼吸的患者中无法提供令人满意的吸入氧浓度（FiO）。本研究的主要目的是使用机械肺模拟自主通气，评估一系列成人和儿童BVM设备在增加潮气量时的氧输送效果。次要目的是评估BVM设计对性能的影响。
作为新南威尔士州HealthShare要求的安全评估的一部分，在实验室环境中对40台BVM设备进行了评估。每个BVM设备的氧气入口用100%氧气（15升/分钟）灌注两分钟。然后将BVM设备连接到机械肺，并以12次/分钟的固定呼吸频率开始自主呼吸，吸呼比为1:2。在自主呼吸两分钟后，测量每个设备的FiO。对于成人BVM设备，用小（250毫升）、中（500毫升）和大（750毫升）潮气量模拟成人呼吸，对于儿童BVM设备，用小（150毫升）、中（300毫升）和大（450毫升）潮气量模拟儿童呼吸，重复这个过程。作为制造质量控制措施，在每个潮气量下，使用多达五台相同型号的BVM设备（如果有提供）重复测试。
在测试的40台设备中，有8台在至少一个潮气量下未能提供高于0.85的FiO，有5个型号在任何测量的潮气量下都未能达到这一水平。令人担忧的是，其中3台设备提供的FiO低于0.55。在8台表现不佳的设备中，有6台随着潮气量增加，吸入氧浓度降低。表现最差的设备是那些带有鸭嘴式非重复呼吸阀且没有专用呼气阀的设备。
澳大利亚临床上可用的几种BVM设备在体外自主呼吸模型中未能提供足够的氧气进行可靠的预给氧。带有鸭嘴式非重复呼吸阀且没有专用呼气阀的设备表现最差。使用BVM设备为自主呼吸患者输送氧气的临床医生必须了解BVM设备的特点和局限性，并且必须更新制造标准，以要求在所有临床情况下都具备安全性能。
