The Effects Of Endotracheal Tube On The Tracheal Mucosa In Rabbits Of Hemodynamic Instability

Objective:Tracheal intubation is a security important measures in the surgery patients and critically ill patients with assisted respiration in clinical. Many studies had shown that different sets of intra-cuff pressure were different on the trachea mucosa. Damage of tracheal mucosa mainly depended on the tracheal mucosal pressure and tracheal mucosal perfusion pressure. Mucosal pressure′s monitoring is very difficult, and it cannot be directly measured in clinical, but its numerical mucosa pressure and intra-cuff pressure of tracheal intubation are closely related. Therefore, after tracheal intubation, there are two factors leading to trachea mucosa injury: the endotracheal tube sets of intra-cuff pressure and tracheal mucosal perfusion pressure.Above results in circulation system at stably, there were lots of hemodynamic instability of the patients needing tracheal intubation. Tracheal mucosal perfusion pressure is different, such as the patients in uncontrolled hemorrhagic shock, in infection with toxic, even in toxic shock of cardiopulmonary resuscitation (CPR). The MAP is bellowing the normal based value. In this case, nothing shows the influence of trachea mucosa. This study established rabbit models of uncontrolled hemorrhagic shock in different levels (observing the blood pressure) and in different intra-cuff pressure on tracheal mucosa for providing theoretical basis to the hemodynamic instability of the patients in clinical.Methods:Eighty rabbits (no limit male and female) weighing 2.5～3.5 Kg and aging 3～3.5 months. We did general anesthesia in rabbit, did endotracheal tube, retained spontaneous breathing, and then bloodletted (through femoral artery) until mean arterial pressure (MAP) below the base value of 0%, 20%, 30%, 40% ( j = 1, 2, 3, 4 ) .In supra-cricoid 0.5 cm cutting tracheal intubation, cuff pressure were kept in 0cmH₂O, 10cmH₂O, 20cmH₂O, 30cmH₂O (about 2 hours, i = 1, 2, 3, 4 ), equipped breathing, and observing the shape and structure of rabbits′tracheal mucosa in different blood pressure and different sets of cuff pressure.According to the sets of sac pressure (C_i) and MAP (Mj) two processing factors had four levels respectively (C_i i = 1, 2, 3, 4. Mj = 1, 2, 3, 4), we divide -d the 80 rabbits into 16 groups ( n = 5 ). The rabbits'larynxes were harvested following exsanguination via theabdominal aorta. Serial sections of the larynx were cut every 50μm beginning at the inferior margin of the cricoid cartilage until a complete or nearly complete cricoid cartilage ring was identified. Four sections 7μm thick were then cut from each larynx and stained with hematoxylin-eosin. Sections were cut by one of my friends, then coded and submitted for interpretation by a professor who was unaware of the treatment group.Results:1 There were no differences in age, weight, gender, and MAP, HR, RR (pretreatment) among in the 16 groups.2 Pathology organization form of observations:Group C₁M₁, There were not significant pathological changes, and morphological structure was integrity.Group C₂M₁, Epithelium hierarchical was clear and an occasional ciliated cells lack of plaque-forming cilia.Group C₃M₁, Part of missing cilia, columnar epithelium cells mild edemaGroup C₄M₁, Parts of Epithelium fall off, Lamina propria exposure, inflamm-ation and submucosal hemorrhage.Group C₁M₂, There were no injured.Group C₂M₂, The epithelium was hierarchical clear and occasional ciliated cells lack of plaque-forming cilia. There was no obvious difference between the C₂M₂ and the C₂M₁.Group C₃M₂, There were inflammation, the lack of cilia slightly increased comparing with the C₃M₁.Group C₄M₂, Epithelium was multifocal fall off, inflammatory cells increased, submucosal vascular dilatation and congestion compared with C4M1.Group C₁M₃: Epithelium hierarchical clear, damaged slightly more than C₁M₁ and C₂M₁ groups.Group C₂M₃: Increased of lacking cilia, the injury was more serious than C2M2and C₂M₁ groups.Group C₃M₃: The injury was more serious than C₂M₃ group.Group C₄M₃: Epithelium appeared multifocal injury, inflammatory cells increased and necrosis appeared in the mucosal and submucosal.Group C₁M₄: Macroscopic observation visible mucosal pale, Appeared local epithelium necrosis and fallen off under Light microscopy.Group C₂M₄: Mucous epithelium multifocal, parts of columnar cells necrosis and fallen off, lack of base cells and inflammatory cells invasived in the submucosal.Group C₃M₄: Mucous epithelium multifocal, exfoliation of epithelium and infiltration of many inflammatory cells. Compared with C₃M₃ group, the structure had obvious difference.Group C₄M₄: Mucous epithelium diffuse injury, large necrotic cells were wrapped by inflammatory exudate. The mucosa and the submucosa were visible bleeding.3 The two factors made multiple comparisons between groups by S-N-K method. There were statistical differences between four of the capsule pressure levels and MAP.Set of intracuff pressure alone effect: The differences of injrue on trac- heal mucosa had a statistical significance in the different sets of sac pressure ( P<0.05);Set of MAP alone effect: The differences of injrue on tracheal mucosa had a statistical significance in the different sets of MAP( P<0.05); Set of sac pressure and MAP interaction effects:F=2.034,P=0.0495<0.05.Conclusion:The important findings of this study are that (1) When the MAP control in a certain level, damage of the mucous membrane of trachea become heavier by capsule pressure increasing; and (2) When the endotracheal tube cuff fixed in a certain level, damage of the trachea mucosa become heavier by MAP declining; and (3) The sets of sac pressure and MAP two factors exists interaction by Statistics test, that is, when the two factors existing at the same time, the extent of trachea mucosa injury become more serious than the sum of individual factors cause trachea mucosa injury .