Laboratory Study On The Safety And Efficacy Of Subglottic Secretion Drainage

Objective: Investigating the the safety and efficacy of subglottic secretions drainage through the animal experiments,to find the most safe and effective suction pressure and intermittent suction time of it,in order to provide theoretical basis for future clinical use the technology.Methods: 32 healthy rabbits were randomly divided into two groups: continuous subglottic drainage(group A)and intermittent subglottic drainage(group B).The experimental group A and the experimental group B under different suction pressure and intermittent suction time were then randomly divided into: group A1: constant 40-60 mmHg negative pressure subglottic suction combined with intermittent subglottic irrigation;group A2: 60-80 mmHg constant negative pressure subglottic suction combined with intermittent subglottic irrigation;group B1: intermittent 2h,60-80 mmHg negative pressure suction combined with intermittent subglottic irrigation;group B2: intermittent 4h,60-80 mmHg negative pressure suction combined with intermittent subglottic irrigation;group B3: intermittent 6h,60-80 mmHg negative pressure suction combined with intermittent subglottic irrigation;group B4: intermittent 2h,80-100 mmHg negative pressure suction combined with intermittent subglottic irrigation;group B5: intermittent 4h,80-100 mmHg negative pressure suction combined with intermittent subglottic irrigation;group B1: intermittent 6h,80-100 mmHg negative pressure suction combined with intermittent subglottic irrigation.Each attraction time is 1h.There were 4 animals in each group.Effect indictors: observed and recorded within 1 weeks of subglottic secretion drainage and sputum volume;mechanical ventilation for 4d and after the end of the experiment respectively to observe and record the drainage of color(with no visible blood);No visible blood liquid groups were respectively taking 2ml drainage to be detected,for the secretion of occult blood test,4d later and at the end of the experiment.After 4 days of mechanical ventilation and at the end of the experiment,the rabbits were sacrificed in each group,and the specimens were taken for pathological examination.Conventional HE staining was performed to observe the morphological changes of airway mucosa under the electron microscope.All statistics using SPSS17.0 statistical software,enumeration data were described by frequency and composition ration,and tested by X2 method,continuous measurement data which accord with normal distribution using single factor analysis of variance(One-way ANOVA),using mean±standard deviation;According to the homogeneity of variance,the differences between groups were compared by S-N-K(q)test,P < 0.05 for the difference have statistical significance.Results:(1)The volume of sputum: there was no significant difference among all the groups within 1 weeks(P > 0.05);(2)The volume of subglottic secretions of group A1,group A2,group B4,group B5 and group B6 were respectively 13.94±1.82?14.02±1.34?13.52±0.61?13.09±1.88 and 12.98±1.29 ml/d,there were no significant difference among them(p=0.601);The volume of subglottic secretions of group B1,group B2 and group B3 were respectively 10.89±0.54?10.40±1.39 and 10.69±1.43 ml/d,there were also no significant difference among them(p=0.765);However,there was significant difference between them(P<0.05);(3)visible bloody fluid results: 4d later,visible blood were not seen in all experimental groups;after 7d,except for 1 cases of visible bloody fluid occurs in group A2,the other groups did not appear.However,the injury of A2 group increased with the prolongation of mechanical ventilation time,and there was a risk of airway mucosal bleeding;(4)The results of OB test: after 4 days of mechanical ventilation,except for A2 group with 1 positive cases,the other groups were all negative;7d later,group A2 > group B4 >group B1=group B2 = group B5> group B3= group B6 =group A1;4d : group A2 compared with other groups,p=0.429,no significant difference;7d: group A2 compared with group A1,group B3 and group B6,p=0.033,have statistical significant difference;group A2 and group B1,group B2 and group B5,p=0.371,no significant difference.Group A2 and group B4,p=0.143,no significant difference.That there is no significant differences in OB test positive situation in the process of experiment;(5)The pathological results of tracheal mucosal tissue: each group of experimental animal,s airway mucosa injury were classified and compared after that;4d:the level of airway mucosal damage in each group was as follows: group A2 > group B4 > group B1 > group B2 = group B5 = group A1 > group B3.7d: group A2> group B4 > group B1 > group B2 = group B5> group B3 = group B6 = group A1.In addition to group A1 and group B6,the other groups showed that the longer the mechanical ventilation time,the more serious the degree of airway mucosal injury.Conclusion: The subglottic secretion drainage options have no unified standard clinically,and the clinical difference of the specific practice scheme is larger.In this study,the effectiveness and safety are compared and analyzed,and the results are as follows: 1.aspects of effectiveness:(1)continuous aspiration of subglottic secretion combined with intermittent subglottic irrigation,constant 40-60 mmHg negative pressure and 60-80 mmHg negative pressure,the suction effect is similar;(2)intermittent aspiration of subglottic secretion combined with intermittent subglottic irrigation,and the suction effect under the suction of 80-100 mmHg was better than that of the suction 60-80mmHg;(3)intermittent aspiration of subglottic secretion combined with intermittent subglottic irrigation,under the same negative pressure,intermittent 2h,4h,6h subglottic suction,no significant difference in suction effect;(4)the suction effect of continuous suction under different suction pressures(40-60 mmHg and 60-80mmHg)were better than that of suction negative 60-80 mmHg intermittent subglottic aspiration;(5)the continuous aspiration of subglottic attracts different negative pressure(40-60 mmHg and 60-80mmHg),compared with suction negative pressure 80-100 mmHg and intermittent subglottic suction,the suction effect was similar,and the maximum drainage can be guaranteed.2.aspects of safety :(1)continuous aspiration of subglottic secretion with intermittent subglottic irrigation,constant 40-60 mmHg and 60-80 mmHg negative pressure suction,similar to visible blood and retentate occult blood test positive,However,the morphological changes of airway mucosa were observed under electron microscope,the constant 40-60 mmHg negative pressure suction has a mild degree of injury and better tolerance in rabbits;(2)the intermittent subglottic suction combined with intermittent subglottic,with a negative pressure,2h,4h,6h,intermittent subglottic secretion,similar to visible blood and retentate occult blood test positive,However,intermittent 6h subglottic aspiration once,the degree of injury to the airway mucosa was the lightest,and the whole process of the experiment,the degree of airway mucosal injury did not increase with the prolonged mechanical ventilation time;(3)the intermittent subglottic suction combined with intermittent subglottic,at the same time,if the interval time is short(2h),the pressure is proportional to the damage,and if the interval is long(4h or 6h),the magnitude of the pressure is not associated with airway damage;(4)Compared constant 40-60 mmHg negative pressure continuous subglottic aspiration with suction pressure 80-100 mm Hg,intermittent 6h suctionunderglottis once,no difference was showed between visible and positive cases of bloody fluid secretion appeared occult blood test results of the two groups,and the damage of airway mucosa damage were similar,the lightest.In summary,a short period of time(1 weeks),continuous aspiration of subglottic secretion in the research range of negative pressure,the negative pressure does not affect the attraction effect;but when the negative pressure is 40-60 mmHg on airway injury minimum recommended for clinical use.Intermittent subglottic secretion,in the case of the same negative pressure,the intermittent time is not related to the attraction effect;Among them,6h intermittent subglottic suction at one time had the lowest degree of damage to the airway mucosa;Under the same time,the greater the pressure,the better the effect.When the intermittent time is greater than 4h,the suction negative pressure has no effect on the airway damage.Therefore,intermittent 6h,under the negative pressure 80-100 mmHg subglottic suction,both to ensure patient safety,but also to ensure that the attraction to maximize,it is recommended.Under the same pressure,continuous suction and intermittent suction compared,although continued to attract better than intermittent attraction,but the damage of airway is more serious,so in the future clinical application in the treatment of conditions allow,recommend the use of intermittent subglottic suction.