Remifentanil is one kind of opiates with strong analgesic effect,which has the rapid onset
and short lasting duration. Remifentanil usually is used to help reducing the pain of
patients with mechanical ventilation in ICU. Maybe it can also be used to ease the pain in
ICU small short time operation.The purpose of this study is to determine (1) whether
remifentanil is effective in small short time operations in ICU or not, (2) the save range of
remifentanil in small short time operations in ICU, (3) and the adverse reaction that happens
in these operations.