Kinnear W J, Shneerson J M
Thorax. 1985 Sep;40(9):677-81. doi: 10.1136/thx.40.9.677.
A new electronically controlled pump has been developed for use with a cuirass in providing external negative pressure ventilation. It is smaller, lighter, and more versatile than currently available pumps and operates on a servo principle. A rotary valve between the pump and the cuirass varies the rate of extraction of air from the cuirass. The pressure within the cuirass is sensed by a pressure transducer, and the output of this is used to control the position of the rotary valve by means of a motor so that the pressure within the cuirass follows a predetermined half sine wave pattern. The respiratory rate varies from 10 to 30 per minute and the inspiratory to expiratory time (I/E) ratio from 3:2 to 2:3. Inspiratory pressure varies from 0 to -50 cm H2O and an expiratory pressure of 0 to +50 cm H2O can be imposed. The performance of the new pump was assessed in 21 patients with nocturnal hypoxaemia who were accustomed to external negative pressure ventilation. The mean tidal volume achieved increased with increase in cuirass suction pressure, and changing the I/E ratio from 1:1 to 3:2 produced a small increase at a cuirass negative pressure at 20 cm water. Comparison of the Newmarket pump with the Cape pump in 14 patients showed that similar tidal volumes were achieved. Overnight monitoring of cuirass pressure in one patient showed more even control of peak negative pressure with the Newmarket pump than with the Cape pump. Ten pumps are in use in patients' homes; five have been in service for more than six months and no important problems have been encountered. The new pump seems to offer advantages that make external negative pressure ventilation more acceptable.
一种新型电子控制泵已被开发出来，用于与胸甲配合提供外部负压通气。它比目前可用的泵体积更小、重量更轻且用途更广泛，并且基于伺服原理运行。泵与胸甲之间的旋转阀可改变从胸甲抽出空气的速率。胸甲内的压力由压力传感器感应，其输出通过电机用于控制旋转阀的位置，以便胸甲内的压力遵循预定的半正弦波模式。呼吸频率为每分钟10至30次，吸气与呼气时间（I/E）比为3:2至2:3。吸气压力为0至 -50 cm H2O，呼气压力可为0至 +50 cm H2O。对21名习惯外部负压通气的夜间低氧血症患者评估了这种新型泵的性能。随着胸甲吸引压力的增加，平均潮气量增加，在胸甲负压为20 cm水柱时，将I/E比从1:1改为3:2会使潮气量略有增加。对14名患者将纽马克特泵与开普泵进行比较，结果显示二者潮气量相似。对一名患者进行的胸甲压力夜间监测表明，与开普泵相比，纽马克特泵对峰值负压的控制更为均匀。有十台泵正在患者家中使用；五台已使用超过六个月，未遇到重大问题。这种新型泵似乎具有一些优势，使得外部负压通气更容易被接受。
