Continuous And Automatic Control Of Tracheal Cuff Pressure And Subglottic Secretion Drainage For Prevention Of Ventilator-associated Pneumonia: Clinical Trial And Experiment Study

Part one: Continuous and automatic control of tracheal cuff pressure and subglottic secretion drainage for prevention of ventilator-associatedpneumoniaObjective: To investigate the effect of continuous automated cuff pressure regulation and subglottic secretion drainage on ventilator-associated pneumonia(VAP) in critically ill patients with intubation. Methods: 90 patients with intubation admitted to ICU from October 2013 to December 2014 were enrolled for a prospective study. All the patients were randomly(random number) divided into continuous automated cuff pressure regulation group(n=48) and controlgroup(n=42). Subglottic secretions,ventilatorasso- ciated pneumonia, days of mechanical ventilation, Length of dayin ICU,mortality of 28 days were measured in two groups. Results: The results of study showed:Compared with control group, the control rates of cuff pressure were more constant(100% vs. 59.5%,P<0.05), the volume of subglottic secretions were significantly increased(50±5 m L vs. 31±3 m L, 60±8 m L vs. 42±5m L, 45±7 m L vs. 32±64 m L;P<0.05), morbidity of ventilator- associated pneumonia, days of mechanical ventilation and ICU were significantly decreased(22.9% vs. 47.6%;7.3±3.2 d vs. 12.3±4.0 d;10.3±2.2 d vs. 15.1±3.0 d;P<0. 05). In ICU hospital mortality or 28-day mortality was similar between two groups(P>0.05). Compared to the control group, the percentage of gram-positive cocci from the lower respiratory tracts was significantly decreases(P<0.05). Multivariate logistic regression analysis showed that monitoring method of cuff pressure was the risk factor of VAP. Conclusions: Continuous control of tracheal cuff pressureand subglottic secretion drainage for preventing microaspiration of gastric contents can decrease the incidence of VAP, days of mechanical ventilation and ICU, but the mortality was unchanged.Part two: Continuous and automatic control of tracheal cuff pressureand Subglottic secretion drainage for preventing aspiration of gastriccontentsObjective: To study effect for preventing aspiration of continuous automated cuff pressure regulation and subglottic secretion drainage. Methods: Ninety patients with tracheal intubation were recruited. They received monitoring pepsin detection in nasal and respiratory tract by enzyme-linked immunosorbent assay cavity(ELISA). Results: Compared with control group, pepsin concentration and positive rate in secretions of lower respiratory tract were significantly decreased(20.1±4.2 ng/m L vs.28.1±3.1 ng/m L; 23.8% vs. 50.0%, P<0.05), pepsin in the secretion of the lower respiratory tracts were related to morbidity of ventilator-associated pneumonia(VAP); Multiple logistic regression analysis showed that automatic monitoring method of cuff pressure were risk factors of aspiration in patients with tracheal intubation, adjusted ORs confidence intervals was 1.078(1.016~1.144, P=0.0120. Conclusions: The incidence of aspiration was high in critically ill patients with tracheal intubation; the frequency of aspiration events was decreased by Continuous and automatic control of tracheal cuff pressure and Subglottic secretion drainage, which was related to VAP.Part three: Study of variables affecting leakage pastendotracheal tubecuffs and tube cuff pressureObjective: To studyinfluencing factors affecting leakage pastendotracheal tube cuffs in vitro and cuff pressure of endotracheal tubes in critically ill patients treated with mechanical ventilation. Methods: Endotracheal tubewitha subglottic aspiration port andhigh-volume low-pressure cuffs made of polyvinylchloride, plastic syringes, pressure transducer with standardlock were studiedwithin a tracheal modelto assess leakage of oropharyngeal secretions in vitro leak test. Theeffect of a variety of changes onthe endotracheal tube cuff pressure in patients treated with mechanical ventilation was investigated. Results: Cuffs of 7.5 mm and 8.0 mm internal diameter(ID) ETT types were tested, the liquid leakage rate around endotracheal tube cuffs inflated in the 8.0 mm mock trachawere higher than 7.5 mm mock tracha because of different longitudinal folds that formed in the cuff membrane(P<0.05), It showed increased leakage around the cuffs with decreased cuffs outside diameter(OD) relative to tracheal internal diameter. Methylene blue below entrance of subglottic aspiration port unable to be drainedwhen the tracheal model was oriented 30°~45° above horizontal.Endotracheal tube cuff pressure waveform changed with the respiratory cycleduring mechanical ventilation. Cuff pressure was increased by cough, tracheal suctioning and PEEP.Cuff pressure waveformcould induce adequate sealing of the extra-luminal airway. Conclusions: Leak can result from discrepancy between ETT and Tracheal Diameters. Fluidleakage occurs through longitudinal folds that form in the cuffmembrane even when it is fully inflated.Fluid below entrance of subglottic aspiration port should be drained. Cuff pressure could be increased because of breath, cough, tracheal suctioning and PEEP and regulated by pressure waveform.