Dullenkopf A, Gerber A C, Weiss M
Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland.
Acta Anaesthesiol Scand. 2005 Sep;49(8):1072-6. doi: 10.1111/j.1399-6576.2005.00800.x.
The aim of this study was to evaluate the performance of a new cuff pressure release valve (CPRV), in which the release pressure can be adjusted from 10 to 25 cmH2O, particularly intended to control pressure in paediatric cuffed tracheal tubes and to avoid cuff hyperinflation caused by N2O diffusion.
In vitro: the PRV was set to 10, 15, 20 or 25 cmH2O release pressure and connected to a cuffed tube placed into a box flushed with 66% N2O in O2. The cuff pressure was monitored with and without CPRV for 60 min. Experiments were performed four times using two different CPRVs. In vivo: with Institutional Review Board approval, CPRV was studied in 50 children undergoing general anaesthesia with tracheal intubation and standardized anaesthesia technique (including 66% N2O in O2) and ventilator settings. Patients were randomized into two groups (with and without CPRV). The cuff pressure baseline was 20 cmH2O and CPRV was set to 25 cmH2O. If the cuff pressure exceeded 25 cmH2O, it was manually released to 20 cmH2O. The numbers of deflations in both groups were noted and compared by Mann-Whitney U-test (P<0.05).
In vitro: the cuff pressure exceeded 50 cmH2O after 60 min without CPRV, but did not exceed the settings with CPRV. In vivo: there was no need to manually deflate the cuff in the CPRV group but, in every patient in the control group, three (two to seven) deflating manoeuvres were required within the first hour of anaesthesia (P<0.0001).
The CPRV allows reliable cuff pressure release at various pressure levels and reliably prevents cuff pressure increases caused by N2O.
本研究旨在评估一种新型袖带压力释放阀（CPRV）的性能，该阀的释放压力可在10至25 cmH₂O之间调节，特别用于控制小儿带套囊气管导管的压力，并避免因氧化亚氮扩散导致的套囊过度充气。
体外实验：将PRV的释放压力设置为10、15、20或25 cmH₂O，并连接到置于充有66%氧化亚氮和氧气混合气的箱体内的带套囊导管上。分别在有和没有CPRV的情况下监测套囊压力60分钟。使用两种不同的CPRV进行了4次实验。体内实验：经机构审查委员会批准，对50例接受气管插管全身麻醉且采用标准化麻醉技术（包括66%氧化亚氮和氧气混合气）及呼吸机设置的儿童进行了CPRV研究。患者被随机分为两组（有和没有CPRV）。套囊压力基线为20 cmH₂O，CPRV设置为25 cmH₂O。如果套囊压力超过25 cmH₂O，则手动将其释放至20 cmH₂O。记录两组的放气次数，并通过曼-惠特尼U检验进行比较（P<0.05）。
体外实验：无CPRV时，60分钟后套囊压力超过50 cmH₂O，但有CPRV时未超过设定值。体内实验：CPRV组无需手动放气套囊，但对照组的每位患者在麻醉的第一小时内都需要进行三次（两到七次）放气操作（P<0.0001）。
CPRV可在不同压力水平可靠地释放袖带压力，并可靠地防止因氧化亚氮导致的袖带压力升高。
