Tracheal tubes lubricated with water to reduce sore throat after intubation: A randomized non-inferiority trial

Abstract

Background: Sore throat is common after tracheal intubation. Water can be used to lubricate tracheal tubes, but its benefit has not been validated. We thus did a randomised non-inferiority trial to test the hypothesis that a tube lubricated with water does not reduce sore throat after tracheal intubation.

Methods: We randomized female or male patients (n = 296) undergoing surgery in the ears or eyes to receive either a tube lubricated with water or a tube without lubrication for intubation. We assessed sore throat at 0, 2, 4, and 24 h after surgery; pharyngeal injury at 2 and 24 h after surgery; and respiratory infections within 7 days after surgery. For the incidence of sore throat within 24 h after surgery (primary outcome), the two-sided 90% confidence interval of the risk difference was compared with the prespecified non-inferiority margin of 15%. Other outcomes were analyzed with two-sided superiority tests.

Results: The incidence of sore throat within 24 h after surgery was 80/147 (54.4%) in the non-lubricated tube group and 83/149 (55.7%) in the water-lubricated tube group (risk difference -1.3%, 90% confidence interval -10.9% to 8.3%). Because the confidence interval was below the non-inferiority margin, the incidence of sore throat was not higher in the non-lubricated tube group than in the water-lubricated tube group. There was no significant association between groups in the sore throat, pharyngeal injury, and respiratory infection at each assessment time.

Conclusions: The tube lubricated with water did not reduce sore throat and pharyngeal injury after tracheal intubation compared to the tube without lubrication.

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1. CONSORT flow diagram.

At seven days after surgery, patients were asked by phone call whether they had respiratory infection since the surgery.

Fig 2. The risk difference (square) with 90% confidence interval (bar) for the incidence of sore throat within 24 h after surgery.

The upper limit of the confidence interval is less than the pre-specified non-inferiority margin. This means that the incidence of sore throat is not higher in the non-lubricated tube group than in the water-lubricated tube group.

Fig 3. The incidence and severity of sore throat at 0, 2, 4, and 24 h after surgery in the water-lubricated and non-lubricated tube groups.

P values are 0.851, 0.922, 0.741, and 0.957 at 0, 2, 4, and 24 h after surgery, respectively, by chi-squared tests.

Fig 4. The site and type of pharyngeal injury at 2 (A) and 24 h (B) after surgery in the water-lubricated and non-lubricated tube groups.

At 2 h after surgery (A), P values are 0.059, 0.565, 0.467, 0.634, and 0.979 in the uvula, pharyngeal wall, tonsillar pillar, tonsillar fossa, and vallecula, respectively, by chi-squared tests. At 24 h after surgery (B), P values are 0.083, 0.769, 0.962, 0.645, and 0.4000 in the same order as the fig A.