Ropivacaine vs Lidocaine in the Endotracheal Tube Cuff on Post-Operative Sore Throat

We plan a randomized clinical trial comparing postoperative sore throat between three groups: 1) ETT cuff inflated with ropivacaine, 2) ETT cuff inflated with lidocaine, and 3) ETT cuff inflated with air (standard care).

The Saskatoon Health Region has on average 24 elective operating rooms in use every weekday, with tracheal intubation being a common intervention in patients coming for surgery. To aid with homogeneity, only ASA 1-3 gynecology and general surgery patients who require endotracheal intubation with major surgery criteria will be recruited. The criteria for major surgery will be defined as those that require hospitalization for more than one day.(1) Patients under the age of 18 and those with pre-operative sore throat will be excluded. In the pre-operative holding area, the anesthesia provider will explain the risk of anesthesia. Oral and written consent will be obtained after the anesthesia provider (staff or resident) has explained the risk and benefits of the research project. After informed consent has been received the patients will be randomized to one of the two intervention groups or to the control using computer-generalized random sequence. The anesthetic provided will be chosen based on clinical grounds as per the anesthesiologist's discretion. The following will be documented by the anesthesiologist: if an oral airway was used at any time, size of endotracheal tube, number of intubation attempts, the Cormack-Lehane intubation grade, the number of intubation attempts required to be successful, and if a stylet was required to secure the ETT. The ETT cuff will be inflated with either lidocaine 2%, ropivacaine 0.5%, or air. To inflate the cuff, the stethoscope guided inflation technique will be used.(2) For all groups, the anesthetist will document the volume in milliliters instilled into the cuff. Nitrous oxide will not be used at any time during the anesthetic, as nitrous oxide is associated with an increase of the ETT cuff pressure and thus potential for mucosal damage.(3) The anesthesia provider will not be blinded to the interventions. All patients will be anesthetized when the medium is placed in the ETT, thus patients will be blinded. Gentle suctioning of the oropharynx may be administered at the end of the surgery.

Documentation will be made if patients are smokers or have hyperactive airway disease (ex. asthma, COPD, or URTI in the last 4 weeks). In addition, age, sex, ASA status, duration of intubation and type of surgery will be documented. The anesthesia provider will make note of the incidence of coughing prior to extubation as mild (<5 coughs), moderate (5-10 coughs), or severe (>10 coughs); with cough defined as the sudden expelling of air from the lungs with a loud noise. Prior to discharge from the post anesthetic care unit (PACU), the resident researcher who is blinded to patient allocation will assess for the presence of sore throat (defined as pain in the throat) with a "yes" or "no" evaluation. If patients report yes, then they will be report the severity using the Numerical Rating Scale (NRS) of 0-10.(4) Surgical site pain will be assessed using the NRS of 0-10. The following will also be noted in PACU: the presence of dysphagia (defined as difficulty in swallowing), and hoarseness or dysphonia (defined as a rough or harsh voice pattern) by a "yes" or "no" evaluation. The time spent in PACU will also be recorded.

The resident researcher will perform bed side evaluation of all participants on post-op day one for the presence of sore throat with a "yes" or "no" evaluation. If patients indicate "yes", then the severity will be reported using the NRS. To ensure surgical pain is not distracting patients, the research will also assess surgical pain using the NRS. The presence of dysphagia and hoarseness or dysphonia will be assessed by a "yes" or "no" evaluation. Finally, patient satisfaction with their anesthesia will be assessed on post-operative day 1 with a 5-point Likert scale with the following categories: very satisfied, satisfied, neither, dissatisfied, or very dissatisfied. If a patient is discharged home on post-op day one prior to the resident researcher performing the bed side evaluation, the patient will be contacted by phone using the phone number proved at the time of hospital registration.

The sample size for the study is based on studies included in the meta-analysis by Lam et al. (5) The sample size required to provide a 80% power for a 0.05 significance level between the three groups is 14 per group, but 20 per group will be recruitment to account for patient drop-out.

The data will be collected by the resident researcher. Statistical analysis will be completed by a statistician within the anesthesia department. The outcomes of POST, surgery pain, dysphagia and hoarseness in the PACU and POD1, as well as the outcomes cough and cuff-pressure, will be analyzed using Pearson chi-square. Fisher's Exact test will be used where cell count of a variable is less than five. Effect size for the categorical primary and secondary outcomes will be calculated using Cramer's V and the effect size for the continuous secondary outcomes will be calculated using Eta squared (ƞ2) for Kruskal Wallis-H. If continuous variable score do not follow normal distributions we will compare the continuous variables for treatment groups (air, ropivacaine and lidocaine) using the Kruskal-Wallis test.