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

Date Published: October 4, 2018

Publisher: Public Library of Science

Author(s): Eugene Kim, Seong Mi Yang, Sang Gyu Kwak, Seoyeong Park, Jae-Hyon Bahk, Jeong-Hwa Seo, Iratxe Puebla.


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.

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.

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.

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

Partial Text

Sore throat is common after tracheal intubation [1–21]. Various drugs [7,9,12,13,15,16,19] or lubricants [5,10,14,17,18] have been introduced to reduce the sore throat although some methods seem to be applied without evidence. Moreover, these pharmacological interventions may not only affect the sore throat but also cause side effects.

After screening 300 patients, 296 patients were randomized to the water-lubricated (n = 149) or non-lubricated (n = 147) tube groups (Fig 1). There was no significant association in patient characteristics (Table 1) and preoperative airway evaluation (Table 2).

Water can reduce the friction between the tracheal tube and airway tissues during intubation because of its lubricating effect [22–25]. In our study, the water-lubricated tube passed the glottis with lower resistance than the non-lubricated tube although the resistance was assessed subjectively by the unblinded investigator. However, no significant association was found in the time or number of attempts for intubation and hemodynamic changes during intubation. Therefore, the water-lubricated tube may neither improve performance nor reduce noxious stimuli during tracheal intubation.




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