使用呼吸器最主要的原因是為了幫助氣體交換、減少呼吸功。然而，臨床醫師對於呼吸功大都只有些籠統的概念。本篇文章主要介紹：使用呼吸器病人的做功，不但可以從呼吸速率、每分鐘換氣量、呼吸型態及動脈血液氣體分析概略地來評估；更可以由坎貝爾圖(Campbell’s diagram)、壓力時間乘積(pressure time product)、呼吸氧耗(oxygen cost ofbreathing) 等生理方法來測量。此外，本文也回顧相關文獻，統整了臨床上、呼吸器設定上減少病人做功的方法，期能幫忙臨床醫師給予病人最適切的呼吸器治療。

The main goal of mechanical ventilation is to restore the gas exchange and to reduce the work of breathing (WOB). However, most clinicians have only some general concepts for WOB. The WOB in mechanically ventilated
patients can not only be evaluated from clinical presentations, but also from physiological methods such as the Campbell’s diagram, the pressure time product, and the oxygen cost of breathing. In addition, we also review the literatures and integrate ways to reduce the WOB in order to help clinicians providing the most effective use of mechanical ventilation. (