Iotti G A, Braschi A, Brunner J X, Palo A, Olivei M C
Servizio di Anestesia e Rianimazione 1, I.R.C.C.S. Policlinico S. Matteo, Pavia, Italy.
Chest. 1995 Jul;108(1):208-15. doi: 10.1378/chest.108.1.208.
The measurement of esophageal pressure (Pes) is the conventional method for the evaluation of the forces applied to the respiratory system by the respiratory muscles. As an alternative to Pes measurement, we propose the calculation of the instantaneous net pressure applied by the respiratory muscles [Pmusc(t)].
Prospective, randomized study.
A general ICU of a university hospital.
Eight intubated patients submitted to pressure support ventilation for acute respiratory failure.
Four different levels of pressure support were used to unload progressively the respiratory muscles. Pmusc(t) was calculated at all levels of pressure support and compared with Pes corrected for chest wall load as a reference. Pmusc(t) was further used to calculate inspiratory work of breathing, which in turn was compared with data obtained with the conventional method.
Airway pressure, airflow, and Pes were measured. Both for amplitude and for timing, Pmusc(t) showed good agreement with reference measurements. Work of breathing as calculated from Pmusc(t) agreed well with the measurement obtained with the conventional method (mean difference, 0.057 +/- 0.157 J).
Noninvasive evaluation of Pmusc(t) allows extended monitoring of mechanical ventilation, which is particularly interesting for pressure preset ventilation modes.
测量食管压力（Pes）是评估呼吸肌作用于呼吸系统力的传统方法。作为Pes测量的替代方法，我们建议计算呼吸肌施加的瞬时净压力[Pmusc(t)]。
前瞻性随机研究。
一所大学医院的综合重症监护病房。
8例因急性呼吸衰竭接受压力支持通气的插管患者。
使用四种不同水平的压力支持来逐步减轻呼吸肌负荷。在所有压力支持水平下计算Pmusc(t)，并将其与校正胸壁负荷后的Pes作为参考进行比较。进一步使用Pmusc(t)计算吸气呼吸功，然后将其与传统方法获得的数据进行比较。
测量气道压力、气流和Pes。无论是幅度还是时间，Pmusc(t)与参考测量值均显示出良好的一致性。根据Pmusc(t)计算的呼吸功与传统方法获得的测量值吻合良好（平均差异，0.057±0.157 J）。
对Pmusc(t)进行无创评估可实现对机械通气的扩展监测，这对于压力预设通气模式尤其有意义。
