Effect of 5% EMLA Cream on Postoperative Sore Throat in Adults Following General Endotracheal Anesthesia: A Randomized Placebo-Controlled Study

Abstract

BACKGROUND: Postoperative sore throat (POST) is a distressing complaint in adults after endotracheal intubation. This study aimed to evaluate the effect of topical application of a eutectic mixture of local anesthetics (EMLA) cream over the endotracheal tube (ETT) cuff on the incidence and severity of POST, cough, and hoarseness of voice in adults after surgery. METHODS: In this randomized, placebo-controlled study, adult patients 18 to 65 years old, in American Society of Anesthesiologists (ASA) physical status I and II, and of either sex were scheduled to receive 5% EMLA cream (intervention arm) or lubricant gel (placebo-controlled arm) applied over the ETT cuff. POST was graded as none (0), mild (1), moderate (2), or severe (3). A score of ≥2 was considered as significant POST. The incidence of POST at the sixth postoperative hour was the primary outcome. Secondary outcomes included the incidence of POST at 0, second, and 24 hours, and the incidence of significant POST (score ≥2). The incidence and severity of postoperative cough and hoarseness of voice were recorded simultaneously. RESULTS: Two hundred and four patients completed the study. The incidence of POST was significantly lower in the EMLA group versus placebo at the sixth postoperative hour (4.9% vs 40.1%; relative risk [RR], 0.12; 95% confidence interval [CI], 0.05-0.29; P < .001); and at 0 hour (74.5% vs 93.1%; RR, 0.8; 95% CI, 0.7-0.9; P < .001) and second hour (51.9% vs 84.3%; RR, 0.61; 95% CI, 0.5-0.75; P < .001) but comparable at 24 hours (1.9% vs 3.9%; RR, 0.5; 95% CI, 0.09-2.67; P = .4). The number needed to treat to prevent POST with EMLA cream application was 5 at 0 hour and 3 at the second and sixth hour. The proportion of patients with significant POST over 24 hours were less in the EMLA group (9.8% vs 43.1%; P < .001). The incidence of postoperative cough and hoarseness of voice was significantly less at the 0, second, and sixth hours in the EMLA group, but comparable at 24 hours. The incidence of severe cough (8.8% vs 31.4%; P < .001) and hoarseness of voice (2% vs 7.4%; P < .001) over 24 hours was less in the EMLA group. CONCLUSIONS: The application of EMLA cream over ETT cuff reduces the incidence and severity of POST, cough, and hoarseness of voice in adults after general anesthesia in the early postoperative period compared to lubricant gel.

In Response

“…Finally, we agree with Sun and Yang 1 that the paracetamol (acetaminophen) and tramadol, which were used for postoperative analgesia in our study 2 may have reduced the incidence of POST. However, the use of these medications was uniform and comparable in both groups and unlikely to impact the results.…”

“…3 We included both laparoscopic and open surgeries which were evenly distributed in the 2 groups. 2 The increase in the incidence of POST in the study by Geng et al 3 cited by Sun and Yang 1 was primarily due to increased cuff pressures (maximum 35.2 ± 3.4 mm Hg ≈ 47.85 cm H 2 O) in the laparoscopy group. The study’s authors did not mention any steps to reduce the tracheal cuff pressures during surgery.…”

“…We did mention in the limitations of our study that coughing on extubation may have influenced POST, which could not be avoided entirely. 2 However, gentle suctioning was practiced to reduce the extubation response. 2 We used fentanyl as a bolus dose of 2 μg·kg −1 during induction with additional bolus doses administered intraoperatively; additional doses were guided by the hemodynamic response.…”

“…We thank Sun and Yang 1 for their interest in our study. They have raised 3 methodological questions regarding our study, 2 and we would like to respond to each of them. First, they state that we did not specify the procedures in our study, that is, laparoscopic versus open; there is evidence that laparoscopic surgeries may aggravate the postoperative sore throat (POST) due to increases in the airway and tracheal tube cuff pressures.…”

Effectiveness of Eutectic Mixture of Local Anesthetics in Preventing Postoperative Sore Throat

“…By a recent randomized placebo-controlled study, Abishek et al 1 observed that eutectic mixture of local anesthetics (EMLA) cream could effectively reduce the incidence and severity of postoperative sore throat (POST) in adults after general anesthesia when compared to lubricant gel. Aside from the limitations mentioned in the article, we ask if the authors might clarify several methodological questions.…”