Fauroux Brigitte, Louis Bruno, Hart Nicholas, Essouri Sandrine, Leroux Karl, Clément Annick, Polkey Michael Ian, Lofaso Frédéric
Pediatric Pulmonary Department and INSERM 213, Armand Trousseau Hospital, Assistance Publique-Hôpitaux de Paris, 28 avenue du Docteur Arnold Netter, 75012 Paris, France.
Intensive Care Med. 2004 Apr;30(4):673-81. doi: 10.1007/s00134-003-2126-z. Epub 2004 Jan 16.
The aim of the study was to evaluate the effect of the back-up rate on respiratory effort during non-invasive mechanical ventilation.
An in vitro study evaluated the inspiratory trigger in seven domiciliary ventilators. Then, a prospective, randomized, crossover trial compared the effect on respiratory effort of three different back-up rates during pressure support (PS) and assist-control/volume-targeted (AC/VT) ventilation.
A research unit and a tertiary referral pediatric center.
Ten patients with cystic fibrosis (CF).
During the in vivo study, the back-up rate was progressively increased to the maximum that patients could tolerate (Fmax) and respiratory effort, as judged by pressure/time product of the diaphragm (PTPdi/min), was compared between the two ventilatory modes.
Differences were observed between trigger pressure, trigger time delay, trigger pressure/time product and the slope between flow and pressure in the seven ventilators. PS and AC/VT ventilation were associated with a decrease in respiratory effort (PTPdi/min was 518+/-172, 271+/-119 and 291+/-138 cmH(2)O. s(-1). min(-1), for spontaneous breathing, PS and AC/VT ventilation, respectively, p=0.05). During the two modes, increasing the back-up rate to Fmax resulted in a greater reduction in PTPdi/min (p=0.001), which was more pronounced during AC/VT ventilation, due to the automatic adjustment of the inspiratory/expiratory time ratio.
Increasing the back-up rate during PS and AC/VT ventilation decreases respiratory effort in young patients with CF, but this effect was more marked with AC/VT ventilation.
本研究旨在评估备用频率对无创机械通气期间呼吸做功的影响。
一项体外研究评估了七台家用呼吸机的吸气触发情况。然后，一项前瞻性、随机、交叉试验比较了压力支持（PS）通气和辅助控制/容量目标（AC/VT）通气期间三种不同备用频率对呼吸做功的影响。
一个研究单位和一家三级转诊儿科中心。
十名囊性纤维化（CF）患者。
在体内研究期间，将备用频率逐渐增加到患者能够耐受的最大值（Fmax），并比较两种通气模式下的呼吸做功，呼吸做功通过膈肌压力/时间乘积（PTPdi/min）来判断。
七台呼吸机在触发压力、触发时间延迟、触发压力/时间乘积以及流量与压力之间的斜率方面存在差异。PS通气和AC/VT通气均与呼吸做功减少有关（自发呼吸、PS通气和AC/VT通气时的PTPdi/min分别为518±172、271±119和291±138 cmH₂O·s⁻¹·min⁻¹，p = 0.05）。在两种模式下，将备用频率增加到Fmax会导致PTPdi/min进一步降低（p = 0.001），在AC/VT通气期间这种降低更为明显，这是由于吸气/呼气时间比的自动调整。
在PS通气和AC/VT通气期间增加备用频率可降低CF年轻患者的呼吸做功，但在AC/VT通气时这种效果更为显著。
