不同负压持续声门下吸引家兔实验对护理实践的启示

Effects of continuous aspiration of subglottic secretion on different suction negative pressures in rabbits

目的通过动物实验探讨不同负压持续声门下吸引对实验家兔的影响,旨在寻找安全有效的持续声门下吸引方式。方法采用自身对照法,选取临床上持续声门下吸引常用的负压,将入选的40只健康家兔按随机数字表法分成A、B两组,即A组:40~60 mmHg(1 mmHg=0.133 kPa)、B组:60~80 mmHg,两组分别间歇4 h声门下冲洗1次。观察并记录两组实验家兔机械通气1周内痰液量、声门下至气囊上滞留物引流量;机械通气第4天和实验结束时,记录两组出现肉眼可见血性液体和潜血实验阳性例数。同步显微镜下观察两组试验家兔气管黏膜组织的形态学改变。结果两组试验家兔痰液量、声门下至气囊上滞留物引流量和滞留物出现肉眼可见血性液体情况相比,差异均无统计学意义(均P>0.05);滞留物潜血实验阳性情况:机械通气第4天和第7天,B组例数明显多于A组,P均<0.05。电镜下气管黏膜损伤情况:机械通气第4天和第7天,A组气管黏膜损伤为I度,B组气管黏膜损伤为IV度。结论在保持安全有效吸引的前提下,恒定40~60 mmHg负压持续声门下吸引,间歇4 h声门下冲洗1次,不仅可以保证吸引效果,而且可以减轻对气管黏膜的损伤。

Objective To explore the effects of different suction pressures on trachea mucosa of rabbits through animal experiments in order to find a safe and effective method of continuous aspiration of subglottic secretion.Methods Using self-control method,the commonly used suction pressures during clinical practice for continuous aspiration of subglottic secretion were chosen. A total of 40 healthy white rabbits were randomly divided into Group A and Group B. Group A:40~60 mmHg,Group B:60~80 mmHg. Subglottic flushing was performed in 2 groups at intervals of 4 hours. Sputum volume and subglottic-supraglottic detention volume within 1 week for 2 groups were recorded. On the fourth day of mechanical ventilation and at the end of the experiment,the amount of visible bloody fluid with naked eyes and positive cases of occult blood test in 2 groups were recorded. Meanwhile,the changes of airway mucosa were observed under microscopes in 2 groups. Results There were no significant differences in sputum volume,subglottic-supraglottic detention volume and visible bloody fluid with naked eyes between 2 groups(P >0.05). Positive occult blood tests of retained substances on the 4 th and 7 th days of mechanical ventilation,the number of cases in Group B were significantly higher than those in Group A(P<0.05).Tracheal mucosal injury under electron microscopy:4 th day,Group B(Ⅳ degree)>Group A(Ⅰ degree);7 th day,Group B(Ⅴ degree)>Group A(Ⅰ degree). In Group B,the degree of airway mucosa injury was more serious in different time periods,and it was aggravated with the extended length of mechanical ventilation. Conclusion On the premise of maintaining safe and effective suction,continuous subglottic suction with constant negative pressure of 40 ~60 mmHg and intermittent subglottic flushing for 4 hours can not only ensure the suction effect,but also reduce damage to airway mucosa.