Endotracheal tubes and fluid aspiration: an in vitro evaluation of new cuff technologies

Abstract

BackgroundAspiration of subglottic secretions past the endotracheal tube (ETT) cuff is a prerequisite for developing ventilator-associated pneumonia (VAP). Subglottic secretion drainage (SSD) ETTs reduce aspiration of subglottic secretions and have demonstrated lower VAP rates. We compared the performance of seven SSD ETTs against a non-SSD ETT in preventing aspiration below inflated cuffs.MethodsETTs were positioned vertically in 2 cm diameter cylinders. Four ml of a standard microbial suspension was added above inflated cuffs. After 1 h, aspiration was measured and ETTs demonstrating no leakage were subjected to rotational movement and evaluation over 24 h. Collected aspirated fluid was used to inoculate agar media and incubated aerobically at 37 °C for 24 h. The aspiration rate, volume and number of microorganisms that leaked past the cuff was measured. Experiments were repeated (×10) for each type of ETT, with new ETTs used for each repeat. Best performing ETTs were then tested in five different cylinder diameters (1.6, 1.8, 2.0, 2.2 and 2.4 cm). Experiments were repeated as above using sterile water. Volume and time taken for aspiration past the cuff was measured. Experiments were repeated (×10) for each type of ETT. Results were analysed using non-parametric tests for repeated measures.ResultsThe PneuX ETT prevented aspiration past the cuff in all experiments. All other ETTs allowed aspiration, with considerable variability in performance. The PneuX ETT was statistically superior in reducing aspiration compared to the SealGuard (p < 0.009), KimVent (p < 0.002), TaperGuard (p < 0.004), Lanz (p < 0.001), ISIS (p < 0.001), SACETT (p < 0.001) and Soft Seal (p < 0.001) ETTs. Of the 4 ETTs tested in differing cylinder sizes, the PneuX significantly reduced aspiration across the range of diameters compared to the SealGuard (p < 0.0001), TaperGuard (p < 0.0001) and KimVent (p < 0.0001) ETTs.ConclusionsETTs showed substantial variation in fluid aspiration, relating to cuff material and design. Variability in performance was likely due to the random manner in which involutional folds form in the inflated ETT cuff. The PneuX ETT was the only ETT able to consistently prevent aspiration past the cuff in all experiments.

Implementation of the TaperGuard™ endotracheal tube in an unselected surgical population to reduce postoperative pneumonia

“…Multiple small laboratory studies have evaluated the degree to which the TaperGuard™ ETT reduces leakage of uid around an in ated cuff in an experimental tracheal model. Most have found that in static conditions, the tapered cuff reduces the passage of uid below the cuff [8][9][10][11][12][13][14]. Experimental studies that more closely mimic the physiologic conditions of tracheal intubation and ventilation suggest less sustained effects.…”

“…Another study using microbial suspensions of Staphylococcus, Pseudomonas and Candida above the cuff revealed that the TaperGuard™ ETT failed to prevent inoculation of the space below the cuff [11].…”

“…This device has undergone multiple independent and manufacturer sponsored laboratory and clinical trials. Laboratory evaluations have demonstrated decreased passage of uid or dye around the ETT compared with conventional barrel-shaped cuffs, but not in all experimental conditions [8][9][10][11][12][13][14].…”

Endotrakealtube med subglottis-sug kan forebygge ventilatorassosiert pneumoni

“…Det er mange forskjellige produsenter som leverer endotrakealtuber, og en nyere studie viser at det er stor forskjell på kvaliteten når det aspireres fra sugekanalen (14). Dette betyr at materialet og designet på cuffen er av stor betydning for å hindre aspirasjon av orofaryngealt sekret.…”

Unintentional endotracheal tube cuff deflation during routine checks: a simulation study

“…High pressures against the trachea may impede mucosal blood flow, resulting in mucosal ischaemia and necrosis (Touat et al, ). Although microaspiration normally occurs at recommended pressures with high‐volume low‐pressure ETT cuffs (Chenelle et al, ; Mariyaselvam et al, ), if the ETT cuff pressure is too low, the seal is further broken, allowing bolus aspiration of subglottic secretions from the oropharynx into the lungs. Subglottic secretions become colonized with bacteria from the upper respiratory tract and are contaminated with gastric contents (Metheny et al, ).…”