Preemptive analgesia is an antinociceptive treatment modality that prevents the central hypersensitivity that causes postoperative pain (1). Inflation of a laryngeal mask airway (LMA) cuff reduces blood flow to the pharyngeal mucosa and causes tissue trauma (2). This results in sore throat (3,4). Benzydamine hydrochloride (BH) is a unique nonsteroidal antiinflammatory drug (NSAID) with local anesthetic properties (5). It is absorbed transdermally and is concentrated in inflamed tissue (6). BH is a pyrazole. It inhibits the synthesis of prostaglandins similar to NSAIDs (7). BH cream is very effective in relieving the pain of pressure sores (6). It has also been used both topically and systemically for inflammatory conditions (5,8). We investigated whether preemptive BH treatment can prevent the sore throat caused by a LMA cuff inflated with room air.
Methods
Ethics committee approval and informed consent were obtained. The study was designed as a double-blinded comparison of BH spray with placebo. Patients with any of the following were excluded from the study: upper airway abnormality or infection, sore throat, abdominal or neck surgery, failed first insertion attempt of LMA, full stomach, emergencies, pregnancy, smoking, drug allergy, history of taking BH during their lifetime, and lack of cooperation. Patients of either sex aged between 20 and 60 yr were selected for the study. One-hundred ASA status I–II adult patients were consecutively scheduled for general anesthesia in the supine position for operations of the lower extremity and the inguinal, perineal, and genital regions. According to a randomized sequence, patients were allocated into two groups. In the first group, four puffs of BH were applied to the posterior pharyngeal wall. Patients swallowed after each puff, 30 min before the operation, and 5 min before the induction of anesthesia. Distilled water with a similar bottle was used using the same protocol in the second group. All patients had received midazolam 0.03 mg/kg IV as premedication 20 min before the operation. Patients were taken into the operating room, and routine monitors were used. Anesthesia was induced with fentanyl 1–2 μg/kg and propofol 2.5–3.5 mg/kg. The LMA was deflated via the deflator and lubricated with saline (9). It was inserted after the patient had become unconscious and the eyelash reflex was no longer present. In both groups, the LMA cuff was inflated with appropriate volumes (Size 3 LMA for small adults with room air inflation of 20 mL, Size 4 LMA inflated with 30 mL for normal adults, and Size 5 LMA inflated with 35 mL for large adults) (10,11). Success with LMA insertion was assessed with chest expansion and capnography. Anesthesia was maintained with sevoflurane (1%–1.5% end-tidal concentration) in a 50% nitrous oxide and 50% oxygen mixture and fentanyl 50 μg every 30 min. The cuff pressures were measured after the first adjustment and at 30, 60, and 90 min. Incision regions of all patients were infiltrated with bupivacaine for analgesic effect. At the end of operation, the LMA was removed after recovery of spontaneous breathing. The patients were asked about sore throat symptoms at the first, second, and fourth hours. Sore throat was determined as scores ranging between 0 and 10 points and was evaluated by an anesthesiologist who was blinded to the type of the solution administered before application (0, no pain; 1, pain needing no analgesic [verbal numerical rating scale ≤4]; 2, pain needing an analgesic [verbal numerical rating scale >4]) (12). Because the analgesics were routinely given to the patients by the surgical departments after operation, we did not evaluate pain after 4 h. Demographic values, cuff volumes, cuff pressures, and operation times were assessed with unpaired Student’s t-tests, and sore throat and side effects were assessed with χ2 tests. P < 0.05 was accepted as significant.
Results
Demographics values, cuff volumes, cuff pressures, and operation times are displayed in Table 1. Demographically, there was no statistically significant difference between groups. There were also no significant differences between groups for cuff pressures, cuff volumes, analgesic doses, and operation times. Sore throat symptoms were significantly less severe for the BH group for both resting and swallowing at the first, second, and fourth hours (P < 0.05) (Table 2). Local numbness was seen in three cases and throat irritations in one case in the BH group 30 min before the operation, and in the control group there were no adverse effects. The patients complained of coldness and an unknown taste in their throats when the drug was administered.
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Table 1: Demographic Values, Cuff Volumes, Cuff Pressures, and Operation Times
Table 2: Sore Throat Data
Discussion
The relation between airway devices used for general anesthesia and the frequency and severity of laryngo-pharyngeal complications is well known (9,13,14). The inflated LMA cuff can produce sufficient compression to cause a reduction in pharyngeal mucosal blood flow and induce direct tissue trauma, as has also been reported for the tracheal tube (2). This may result in sore throat (3,4). In contrast, in another study, differences in LMA cuff pressures did not influence either the incidence or the severity of laryngopharyngeal complaints (dysphagia, hoarseness, and sore throat) (13). Sore throat is a common postoperative complaint (9). The incidence of postoperative sore throat with the LMA ranges from 5.8% to 34% (3,4,15,16). In our study, sore throat data correlated with the literature. The wide variation in these figures is presumably due to different skills and techniques among anesthesiologists and to differences between individual anesthesiologists and patients in the way sore throat is defined (9). BH is an NSAID with local anesthetic, analgesic, and antibacterial properties (5,17,18). The duration of the analgesic effect of BH has been reported as 1.84 hours (18). BH has been suggested for the symptomatic treatment of acute sore throat pain by McHardy and Chung (9). It is used both topically and systemically for the treatment of primary or more active types of inflammation (19–21). It has been reported that local tissue concentrations of BH are larger after topical application than after systemic administration. There may, therefore, be advantages to local application of the drug where the desired target site is accessible (19,20). Absorption of BH after systemic administration was rapid and almost complete. After local administration, the absorption was slower and peak plasma concentrations occurred at progressively later times, possibly reflecting different rates of diffusion through nonspecialized mucosa (5). Although BH is not well absorbed through the skin, peak plasma concentrations after topical application occurred later than 24 hours in five of the six female subjects, i.e., after the drug had been removed from the surface of the treatment area. It would appear possible, therefore, that BH penetrates and temporarily resides in the deeper dermal layers, from whence it is slowly absorbed. Such a property would be useful in the treatment of soft tissue injury (5). BH oral rinse was effective, safe, and well tolerated for prophylactic treatment of radiation-induced oral mucositis but was not useful for pain on swallowing. This was an expected finding, because BH is not likely to reach the esophagus in sufficient concentrations (21). The frequent incidence of local adverse events in the BH-treated patients (64%) was not surprising (18). BH has side effects such as local numbness, a local burning or stinging sensation, nausea or vomiting, throat irritation, cough, and dryness of the mouth, with thirst, drowsiness, and headache (18). In our study, local numbness was seen in three cases and throat irritation in one case in the BH group 30 minutes before the operation, and in the control group there were no adverse effects. We conclude that BH, given preemptively, reduced sore throat during resting and swallowing when compared with control.
In conclusion, preemptive topical BH may decrease the incidence of sore throat due to LMA use.
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