Smith I E, King M A, Shneerson J M
Respiratory Support and Sleep Centre, Papworth Hospital, Cambridge, UK.
Eur Respir J. 1995 Oct;8(10):1792-5. doi: 10.1183/09031936.95.08101792.
Five negative pressure ventilator pumps were assessed to determine whether there were any differences in performance which were likely to be of clinical importance. The pumps tested were the NEV-100 (Lifecare Inc.), the Negavent Respirator DA-1 (Dima Italia), the Thompson Maxivent (Puritan Bennett), the CCP-001 and Newmarket pumps (Si-Plan Electronics Research Ltd). A patient model was employed to investigate the relationship between the pressure waveform of each pump and the tidal volume generated, the stability of performance on a continuous 8 h test, and the response to a change in leak. On the continuous tests, the stability was better than +/- 1% for the inspiratory/expiratory (I:E) ratio and rate, and better than +/- 10% for the peak negative pressure for all of the pumps. The Negavent and NEV-100 pumps generated a square wave of pressure and for the same peak negative pressure produced a tidal volume up to 30% greater than the CCP-001 and the Newmarket pumps, which produced a half sine wave. The Maxivent produced an intermediate waveform, with a plateau at peak negative pressure but a curved decay back to atmospheric pressure. It is argued that if the pressure of the pumps producing a half sine wave is made more negative to compensate and produce an equivalent tidal volume, they are more likely to induce upper airway obstruction. The leak compensation of the NEV-100 and Negavent pumps was nearly complete but took several breaths to develop, the CCP-001 and Newmarket pumps had a very rapid compensation but this was less complete, whilst the Maxivent has no mechanism for leak compensation. From these results, it seems that in patients liable to upper airway obstruction the NEV-100 and Negavent pumps would be advantageous, whilst when rapidly changing leaks impair the efficiency of negative pressure ventilation the CCP-001 and Newmarket pumps would be preferable. The Maxivent pump seems to offer no advantages.
对五台负压呼吸机泵进行了评估，以确定其性能是否存在可能具有临床重要性的差异。所测试的泵包括NEV - 100（Lifecare公司）、Negavent呼吸仪DA - 1（意大利迪马公司）、汤普森Maxivent（普里默斯·贝内特公司）、CCP - 001和纽马克特泵（Si - Plan电子研究有限公司）。采用患者模型来研究各泵的压力波形与产生的潮气量之间的关系、连续8小时测试中性能的稳定性以及对漏气变化的反应。在连续测试中，所有泵的吸气/呼气（I:E）比率和速率的稳定性优于±1%，峰值负压的稳定性优于±10%。Negavent和NEV - 100泵产生方形压力波，在相同的峰值负压下，其产生的潮气量比产生半正弦波的CCP - 001和纽马克特泵大30%。Maxivent产生中间波形，在峰值负压处有一个平台，但向大气压力的衰减呈曲线状。有人认为，如果使产生半正弦波的泵的压力更负以进行补偿并产生等效潮气量，它们更有可能导致上呼吸道阻塞。NEV - 100和Negavent泵的漏气补偿几乎是完全的，但需要几次呼吸才能形成，CCP - 001和纽马克特泵的补偿非常迅速，但不太完全，而Maxivent没有漏气补偿机制。从这些结果来看，对于易发生上呼吸道阻塞的患者，NEV - 100和Negavent泵可能具有优势，而当快速变化的漏气损害负压通气效率时，CCP - 001和纽马克特泵可能更可取。Maxivent泵似乎没有优势。
