目的探讨呼吸过滤器(BF)的最佳更换时间。方法将40例机械通气患者随机分为亲水型BF组每组各20例与复合型BF组每组各20例。在患者机械通气开始时,将BF连接在气管导管与呼吸机螺纹管Y形管接头之间;在患者机械通气后的第1~5 d,每天对两组患者BF滤过膜的呼吸机侧采样并进行细菌培养。结果亲水型BF组细菌培养阳性率第1 d均为0,第2、3、4、5 d细菌培养阳性率为60%、75%、100%和100%,复合型BF组细菌培养阳性率第1、2 d均为0,第3、4、5 d细菌培养阳性率为25%、70%和100%,两组不同采样时间细菌培养阳性率比较,第2、3、4 d比较有统计学意义(P<0.05);两组细菌鉴定种类比较无差异,无统计学意义(P>0.05)。结论亲水型BF的更换时间以1次/d适宜,复合型BF的更换时间以1次/2 d适宜,复合型过滤器滤菌效应较亲水型好,不同型号BF的更换与细菌的种类无关。 Objective To explore the best replacement time of respiratory filter (BF). Methods Forty patients with mechanical ventilation were randomly divided into two groups: 20 patients in each group and 20 patients in each group. At the beginning of the patient’s mechanical ventilation, the BF was connected between the endotracheal tube and the ventilator threaded tube Y-tube fitting. On the 1st to 5th day after mechanical ventilation, Sampling and bacterial culture. Results The positive rate of bacterial culture in the group of hydrophilic BF was 0 on the 1st day, and the positive rates of bacterial culture on the 2nd, 3rd, 4th and 5th day were 60%, 75%, 100% and 100% The first and second day were 0, the positive rates of bacteria culture on the 3rd, 4th, 5th day were 25%, 70% and 100% respectively. The positive rates of bacterial culture in two groups at different sampling time were compared, (P <0.05). There was no difference between the two groups in bacterial identification (P> 0.05). Conclusion The replacement time of hydrophilic BF is 1 time / d, the replacement time of composite BF is 1 time / 2 days, the filter effect of compound filter is better than that of hydrophilic one. The replacement of BF Category has nothing to do.