Smith I E, Shneerson J M
The Respiratory Support and Sleep Centre, Papworth Hospital, Cambridge, UK.
Eur Respir J. 1996 Nov;9(11):2410-5. doi: 10.1183/09031936.96.09112410.
Four brands of ventilator used for noninvasive positive pressure ventilation in the home were assessed to determine their performance on a patient simulator. We tested the tidal volume (VT) preset Companion 2801 (Puritan Bennett), minute volume preset Monnal D (Taema), and two pressure preset ventilators, the Nippy (Friday Medical) and the Bilevel Positive Airway Pressure (BiPAP) (Respironics). A patient simulator was employed to investigate the relationships between VT, peak airway pressure (PAP) and mean airway pressure (MAP), the responses to an additional leak in the circuit and patient effort of a variable duration, which was modelled using a negative pressure pump. For equivalent VTs, >300 mL, the Monnal D and Nippy generated a PAP up to 100% greater than the Companion 2801 and BiPAP. When an additional leak was introduced to the circuit, the VT of the Companion 2801 and Monnal D fell by >50%, while the Nippy and the BiPAP responded by increasing flow and maintained VT close to the level achieved with no leak. When the ventilators were triggered by a simulated patient effort of 0.25 s duration with a frequency 33% greater than that of the ventilator, the minute volume increased by 41% for the Companion 2801, by 18% for the Monnal D (no change expected), and by 17% for the Nippy (less than expected), and fell by 7% for the BiPAP due to irregular triggering. When patient effort was prolonged to 1.5 s, a similar length to the inspiratory time of the ventilators, there was no further change in the minute volume of the Companion 2801 and Monnal D, while that of the Nippy and of the BiPAP increased by 38 and 71%, respectively, compared to baseline. These results show that distinct brands of ventilator respond to changes in the patient and patient circuit in different ways, which are not always predictable from a simple description of their operating principles. This should be borne in mind when choosing a positive pressure ventilator for noninvasive ventilation.
对用于家庭无创正压通气的四个品牌的呼吸机进行了评估，以确定它们在患者模拟器上的性能。我们测试了潮气量（VT）预设的Companion 2801（伟康公司）、分钟通气量预设的Monnal D（泰玛公司）以及两款压力预设的呼吸机，即Nippy（星期五医疗公司）和双水平气道正压通气（BiPAP）呼吸机（瑞思迈公司）。使用患者模拟器研究VT、气道峰值压力（PAP）和平均气道压力（MAP）之间的关系，以及回路中额外漏气和持续时间可变的患者用力的反应，后者使用负压泵进行模拟。对于等效VT（>300 mL），Monnal D和Nippy产生的PAP比Companion 2801和BiPAP高出多达100%。当回路中引入额外漏气时，Companion 2801和Monnal D的VT下降超过50%，而Nippy和BiPAP则通过增加流量做出反应，并将VT维持在接近无漏气时达到的水平。当呼吸机由持续时间为0.25 s且频率比呼吸机高33%的模拟患者用力触发时，Companion 2801的分钟通气量增加了41%，Monnal D增加了18%（预期无变化），Nippy增加了17%（低于预期），而BiPAP由于触发不规则，分钟通气量下降了7%。当患者用力延长至1.5 s（与呼吸机吸气时间相似的长度）时，Companion 2801和Monnal D的分钟通气量没有进一步变化，而Nippy和BiPAP的分钟通气量分别比基线增加了38%和71%。这些结果表明，不同品牌的呼吸机对患者和患者回路变化的反应方式不同，从其工作原理的简单描述中并不总是能够预测。在选择用于无创通气的正压呼吸机时应牢记这一点。
