[A comparison of different endotracheal tubes. Tracheal cuff seal, peak centering and the incidence of postoperative sore throat]

Abstract

The study objective was to evaluate cuff seal, tube tip position and incidence of postoperative sore throat in three different endotracheal tubes: the reusable Rüsch "red rubber" tube (low-volume, high-pressure cuff) and the disposable Rüsch "Super Safety Clear" and Mallinckrodt "lo-pro" tubes (both high-volume, low-pressure cuffs).

Methods: In a prospective randomized trial, 150 consecutive patients scheduled for minor orthopaedic surgery under standardized general anaesthesia, including standardized cuff pressure control, were allocated to one of the three types of endotracheal tube. Leakage and intratracheal tube tip position were investigated by means of fiberoptic tracheoscopy via the endotracheal tube, preceded by pharyngeal instillation of indigocarmine. The semi-standardized interviews for the recording of postoperative sore throat were performed once a day under double-blind conditions from the day of operation to postoperative day 3. Statistical independence testing was based on the chi 2-test, significance was assumed at P < 0.05.

Main results: A past-cuff leakage of the pharyngeally instilled dye was found in three patients with "red rubber" tubes. In all of these cases the tracheal cross section deviated markedly from circular. The tips of the "Super Safety Clear" tubes tended to be better centred (P = 0.099). Bad tip position, however, had little influence on postoperative throat complaints (P = 0.394). The differences in incidence of postoperative throat complaints between the "red rubber" (48.9%), "Super Safety Clear" (35.6%) and "lo-pro" tubes (34.1%) did not reach the 5% level (P = 0.288). Such complaints, however, were significantly more frequent in females and in obese patients who exceeded their Broca weights by more than 25%. By contrast, postoperative throat complaints did not vary statistically significantly by age group, tracheal cross-sectional shape, use of atropine or duration of intubation.

Conclusion: Despite the economic (usable up to 100 times) and ecological (less PVC waste) advantages of the rubber tube, the disposable tubes with high-volume, low-pressure cuffs tended to be superior regarding cuff seal, tube tip position and incidence of postoperative throat complaints. Nevertheless, the continued use of "red rubber" type reusable tubes may be justified in cases where the tube has to stay in place for only a short time.