4.
两组导管置管耗时的比较 （x±s，min）
| 组别 | 例数 | PICC置管耗时 |
| 对照组 | 80 | 20±4 |
| 观察组 | 80 | 16±3 |
| t值 | 7.243 | |
| P值 | < 0.001 |
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