Do endotracheal tubes prevent microaspiration?

Introduction

For decades it was assumed that cuffed endotracheal tubes prevented aspiration. However, currently used cuffed tubes do not prevent the development of post-intubation pulmonary complications caused by microaspiration [1, 2]. A new taper-shaped cuffed tube (TaperGuard (TG)) has recently been introduced. The aim of this study was to compare this tube with a traditional tube (Hi-Lo (HL)) in an aspiration pig model.

Methods

Fourteen pigs between 65 and 75 kg were studied. The pigs were randomly intubated with either TaperGuard (tapered cuff) or Hi-Lo (barrel cuff) tubes. The tube size was either 7.0 or 8.5 depending on weight. Cuff pressures were maintained between 24 and 27 cm water. After intubation, 0.3 ml/kg acidic blue dye (ph 2.5) was placed on top of the cuff. The animals were ventilated for 3 hours. The animals were then sacrificed and the tracheobronchial tree and lungs examined. Aspiration was characterized as follows: dye leak, ulceration/erosion, hemorrhagic pneumonia, bronchitis/bronchiolitis.

Results

Of the 14 pigs, one had to be excluded due to accidental cuff deflation. Tube sizes were evenly distributed amongst the groups. Cuff pressures were equal: TG 23.7, HL 25.2 - P < 0.2. As seen in Table 1, the incidence of microaspiration was significantly less for TG in the Blue Dye and bronchitis groups.

Table 1 Incidence of microaspiration

Conclusions

The TG provided significant microaspiration protection compared with the conventional tube in the dye and bronchitis categories. Although not statistically significant, the difference in the other two categories may be of clinical significance. Further clinical studies are necessary to confirm this point.