Effects of dyclonine mucilage and compound lidocaine cream as tracheal catheter lubricant on postoperative pharyngeal complications after general anesthesia

Abstract

Background:

The aim of this study was to observe the effects of dyclonine mucilage and compound lidocaine cream on postoperative pharyngeal complications after general anesthesia.

Methods:

Ninety patients were randomly divided into a dyclonine mucilage group (D group), a compound lidocaine cream group (L group), and a normal saline group (NS group). The primary outcomes were the incidence and severity of postoperative sore throat (POST). The secondary outcomes were postoperative cough (POC), hoarseness of voice (HOV), and the incidence of foreign body sensation (FBS) in the pharynx at 1, 6, and 24 hours after surgery.

Results:

The incidence of POST at 1 and 6 hours after surgery in the L group was significantly lower than that in the D group (P = 0.015 and 0.012, respectively). There was no difference in the incidence of POC and HOV at 1, 6, and 24 hours after surgery between the D and L groups (P_POC = 0.267, 0.236, 0.335, and P_HOV = 0.500, 0.353, and 0.306, respectively). The severity scores of POST, POC, and HOV were significantly lower in the L groups than in the NS group at 1 and 6 hours after surgery (P < 0.001, P < 0.001, P < 0.001, P = 0.001, 0.011, and 0.005, respectively). The incidence of pharyngeal FBS in the D group was significantly greater than that in the NS group at 1 hour after surgery (P = 0.012). The postoperative satisfaction scores in the L group were significantly greater than those in the D group (P = 0.007 and P = 0.009).

Conclusion:

Compared with dyclonine mucilage, compound lidocaine cream was associated with a lower incidence of early POST and higher postoperative satisfaction, with no increase in the incidence of pharyngeal FBS.

Introduction

Postoperative sore throat (POST), postoperative cough (POC), and hoarseness of voice (HOV) are common pharyngeal complications after tracheal intubation in patients who are receiving general anesthesia, and may prolong hospitalization time and increase postoperative discomfort and pain[1]. Moreover, tracheal intubation and extubation may lead to increased heart rate, elevated blood pressure, and even myocardial infarction and cerebrovascular accidents in patients[2]. To reduce the occurrence of postoperative pharyngeal complications in patients who are receiving general anesthesia, using nondrug prevention measures such as silicon material, smaller tracheal catheter, intraoperative monitoring and maintenance of tracheal catheter cuff pressure and superior laryngeal nerve block were selected. Drug prevention measures such as intravenous injection of local anesthetics, glucocorticoids, tracheal catheter application of anesthetic drugs, and atomized inhalation drugs have been applied in clinical practice[1].

HIGHLIGHTS

• Postoperative sore throat (POST), postoperative cough (POC), and hoarseness of voice (HOV) are common pharyngeal complications after tracheal intubation in patients undergoing general anesthesia.

• The use of tracheal catheter lubricant can reduce the occurrence of postoperative pharyngeal complications.

• Both dyclonine mucilage and compound lidocaine cream are clinically used to smear and lubricate tracheal tubes to reduce complications of endotracheal intubation.

• Both dyclonine mucilage and compound lidocaine creams reduced the incidence and severity of early POST, POC, and HOV in patients.

• Compound lidocaine cream had a lower incidence of early POST than dyclonine mucilage, with no increase in the incidence of pharyngeal foreign body sensation.

The use of a tracheal catheter lubricant is a common clinical method to prevent POST, which can reduce the degree of irritation caused by the tracheal catheter on the airway mucosa, thus reducing the occurrence of postoperative pharyngeal complications, and the cardiovascular response caused by tracheal catheter stimulation of the airway. Previous studies have shown that the application of tracheal catheter lubricant can effectively reduce the occurrence of POST in patients[3]. Compound lidocaine cream is a eutectic mixture of lidocaine and prilocaine 1:1, containing 25 mg of lidocaine and prilocaine per 1 g of compound lidocaine cream, which stabilizes cell membranes by blocking the ion flow required for the production and conduction of nerve impulses, resulting in a local anesthetic effect[4]. Both lidocaine and prilocaine belong to the amide class of local anesthetics, and lidocaine has a fast onset time and strong permeability. The structures of prilocaine and lidocaine are similar, but compared with those of lidocaine, the onset time of prilocaine is slower and the anesthesia time is longer. The combination of prilocaine and lidocaine improved the anesthetic effect and time[5]. The main component of dyclonine mucilage is dyclonine hydrochloride, which can reversibly bind to sodium channels on the nerve cell membrane, reduce the permeability of the nerve cell membrane to sodium ions, and thus play a role in local mucosal anesthesia. Its onset time is 2–10 minutes, and the anesthesia time is 20–30 minutes [6].

Both dyclonine mucilage and compound lidocaine cream are clinically used to smear and lubricate tracheal tubes to reduce complications of endotracheal intubation^[6,7]. However, the potential of dyclonine mucilage and compound lidocaine cream as tracheal tube lubricants to reduce postoperative pharyngeal complications is different. At present, no study has compared the effects of dyclonine mucilage and a compound lidocaine cream as tracheal catheter lubricants on postoperative pharyngeal complications in patients who are receiving general anesthesia. Therefore, this study was conducted to observe the effects of dyclonine mucilage and a compound lidocaine cream as a tracheal catheter lubricant on postoperative pharyngeal complications in patients under general anesthesia, and to provide a reference for clinical practice.

Materials and methods

Study setting

This trial was reviewed and approved by the Ethics Committee of the Affiliated Hospital of North Sichuan Medical College (approval number: 2022ER206-1, Chairperson Chunmei Hu, on 18 May 2022) and registered in the Chinese Clinical Trial Registry (www.chictr.org.cn/showproj.html?proj=175668; registration number: ChiCTR2200062260, Date of registration: 31/07/2022). All the participants signed informed consents before the trial. Adult ASA I-II patients aged between 18 and 64 years who underwent laparoscopic cholecystectomy in the Affiliated Hospital of North Sichuan Medical College from August 2022 to January 2023 were enrolled in the study. The exclusion criteria were having a body mass index (BMI) ≥30 kg/m² or <18.5 kg/m², allergy or intolerance to the above local anesthetics, history of hypertension, symptoms of upper respiratory infection within the past week, history of difficulty intubating, history of smoking and chronic pharyngitis, and history of oropharyngeal surgery. The withdrawal criteria were having tracheal intubation more than twice or failure, oropharyngeal injury during tracheal intubation, a change in surgical plan, allergy during the study, surgery time >4 hours, incomplete data collection, and voluntary withdrawal of participants. All the procedures performed in this study followed ethical standards of research and the Declaration of Helsinki, and the trial has been reported in keeping with the Consolidated Standards of Reporting Trials Guidelines[8]. No artificial intelligence was used in this study, and our manuscript is compliant with the TITAN Guidelines 2025 – governing declaration and use of AI[9].

Patients were randomly divided into the D group (dyclonine mucilage group), L group (compound lidocaine cream group), and NS group (normal saline group), with 30 patients in each group, according to the random-numbered table method. The cards containing patient grouping information were sealed in opaque envelopes. When patients entered the operating room, an anesthesia nurse who was blinded to the groups randomly selected an envelope, prepared the drugs according to the card information and used them to lubricate the tracheal tube.

Endotracheal intubation was performed by an anesthesiologist with more than 10 years of clinical experience. Owing to the appearance characteristics of the two drugs, the anesthesiologists performing the intubation could not be blinded, but the intraoperative and postoperative observation indicators were measured by another anesthesiologist who was not aware of the grouping. The surgeons, patients, operating nurses, ward nurses were blinded to the treatment allocation. The primary outcome was the incidence and severity of POST. The secondary outcomes were POC, HOV, and the incidence of postoperative foreign body sensation in the pharynx.

Ansesthesia management

The patients fasted preoperatively for 8 hours and abstained from drinking water for 4 hours, and no preoperative medication was administered. Peripheral venous channels were secured after the patient entered the operating room, and compound sodium chloride solution 8–10 ml/kg · h was intravenously infused intraoperatively. Electrocardiography, systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse oximetry (SpO₂), and the bispectral index (BIS) were routinely monitored. General anesthesia was induced by intravenous administration of 0.05 mg/kg midazolam, 0.4 μg/kg sufentanil, 1.5–2.5 mg/kg propofol, and 0.15 mg/kg cisatracurium benzoate, respectively. An ID 7.0 mm enhanced tracheal catheter was selected for male patients, and an ID 6.5 mm enhanced tracheal catheter was selected for female patients in all groups. Three milliliters of dyclonine mucilage, 3 g (approximately equal to 3 ml) compound lidocaine cream, and 3 ml normal saline were applied as lubricant from the tip of tracheal catheter to 1/3 of the front end in the D, L, and NS groups, respectively. Assisted ventilation with high flow of pure oxygen was performed after the muscle relaxant had fully taken effect and the patient’s BIS reached 40–60. Tracheal intubation was performed by an anesthesiologist with more than ten years of clinical experience using a visual laryngeal scope. After successful intubation, the catheter cuff was inflated, and the cuff pressure was monitored with a pressure measuring device every 10 minutes and maintained at 25–30 cm H₂O[5]. After each tracheal intubation, the endotracheal tube was connected to the anesthesia machine for mechanical ventilation, and the partial pressure of end-tidal carbon dioxide was maintained at 35–45 mmHg. During surgery, the concentration of sevoflurane was adjusted between 1% and 3% to maintain the BIS value between 40 and 60, and sufentanil and cisatracurium were given as needed. The administration of muscle relaxants and the inhalation of sevoflurane were stopped 40 and 5 minutes before the end of the operation, respectively. After the indication for extubation (patients were conscious, had tidal volume >6 ml/kg, SpO₂ >90% under air inspiration, a train-of-four ratio ≥0.9, BIS >80, and spontaneous respiratory rate >13 breaths per minute), the tracheal catheter was removed. All the patients were transferred to the post-anesthesia care unit for further monitoring of vital signs and nasal catheter low-flow oxygen inhalation, and returned to the surgical ward after reaching a Steward score ≥4. If the heart rate was less than 50 beats per minute, 0.5 mg of intravenous atropine was administered. The intraoperative blood pressure of the patient was maintained within the basic value of ±20%, and if the SBP fell more than 20% before anesthesia or if the SBP was <90 mmHg, 6 mg of ephedrine was administered intravenously.

The incidence and severity of throat pain at 1, 6, and 24 hours after surgery were assessed. The severity of throat pain was assessed with the four-point NRS score (0 = no throat pain after surgery; 1 = mild sore throat: only complained of sore throat when the follow-up staff asked; 2 = moderate throat pain: during follow-up, the patient actively complained of throat pain; 3 = severe sore throat: patients complained of significant sore throat after surgery, accompanied by voice changes)[10]. The incidence and severity of cough at 1, 6, and 24 hours after surgery were evaluated with the following four-point NRS score: 0 = no cough after surgery; 1 = mild cough (less severe than usual cold cough); 2 = moderate cough (similar to usual cold cough symptoms); and 3 = severe cough (more severe than usual cold cough symptoms)[11]. The incidence and severity of hoarseness at 1, 6, and 24 hours after surgery were evaluated with the four-point NRS score: 0 = no signs of hoarseness after surgery; 1 = mild hoarseness (during the follow-up, the patient complained of hoarseness, but only the patient could detect it, and the follow-up staff and the patient’s family members could not detect it); 2 = moderate hoarseness (during the follow-up, the patient complained of hoarseness, and the follow-up staff could also detect it, but it was mild); and 3 = severe hoarseness (changes in the patient’s voice were significantly noticed by the staff at follow-up)[10]. The incidence of foreign body sensation in the pharynx[12] and patient postoperative satisfaction score[13] at 1, 6, and 24 hours after surgery was recorded. The SBP, DBP, and HR values in the three groups were recorded 5 minutes before anesthesia induction (T₀), 1 minute after anesthesia induction (T₁), immediately after intubation (T₂), 3 minutes after intubation (T₃), 5 minutes after intubation (T₄), immediately after extubation (T₅), 3 minutes after extubation (T₆) and 5 minutes after extubation (T₇).

Sample size

The sample size was calculated on the base of a pilot study with 10 patients in each group. The incidence rates of POST 6 hours after surgery in the L, D, and NS groups were 20%, 40%, and 70%, respectively. The PASS software revealed that 25 patients were required in each group with a type I error of 0.05, and a power of 90%. Considering a 15% dropout rate, 30 patients were ultimately included in each group. The total sample size of this study was 90. The sample size was calculated by using the following formula:

$$n=\frac{1641.6\lambda }{{\left(si{n}^{-1}\sqrt{p_{max}-si{n}^{-1}}\sqrt{p_{min}}\right)}^2}$$

Statistical analysis

SPSS 26.0 statistical software was used to perform the statistical analysis. Normal distributed measurement data are expressed as the mean ± standard deviations, and enumeration data are presented as frequencies. The measurement data conforming to a normal distribution were statistically tested by one-way Analysis of Variance (ANOVA), and further comparisons between groups were statistically tested by using the Bonferroni correction test. The measurement data from each group at multiple time points were analyzed by repeated-measures ANOVA, and the Student-Newman-Keuls (SNK) post hoc test was performed if comparisons between groups were positive. The chi-square test or Fisher’s exact probability method and the Kruskal–Wallis test were used for statistical tests. The Bonferroni correction test was used for further statistical comparisons between groups. P < 0.05 was considered statistically significant.

Results

A total of 106 patients who underwent laparoscopic cholecystectomy were screened for eligibility, eight patients with a BMI >30 kg/m², four patients who had chronic pharyngitis and one patient with a history of difficult intubation were excluded. Ninety-three patients were subsequently allocated to three groups. One patient who had a surgery time of more than 4 hours in the L group, one patient who had a change in surgical plan in the NS group, and one patient who experienced tracheal intubation more than twice in the D group were withdrawn from the trial. A total of 90 patients completed the study (Fig. 1).

Figure 1.

Participant flow diagram.

There was no difference in the demographic data in the three groups according to their gender, height, weight, age, ASA class, surgery time, extubation time and sufentanil dosage (P = 0.731, 0.186, 0.208, 0408, 0.875, 0.520, 0.101, and 0.617, respectively), as shown in Table 1.

Table 1.

Demographic data in three groups

	D group (n = 30)	L group (n = 30)	NS group (n = 30)	F/χ2 values	P-values
Gender, n (%)
Male	16 (53.3%)	18 (60%)	15 (50%)	0.627	0.731
Female	14 (46.7%)	12 (40%)	15 (50%)
Age, mean ± SD (year)	46.8 ± 7.8	43.3 ± 10.6	44.7 ± 11.9	0.905	0.408
ASA class, n (%)
I	15	13	14	0.268	0.875
II	15	17	16
Height, mean ± SD (cm)	164.1 ± 6.0	162.8 ± 8.3	160.8 ± 5.8	1.714	0.186
Weight, mean ± SD (kg)	66.1 ± 8.7	64.7 ± 9.2	62.3 ± 7.5	1.597	0.208
Surgery time, mean ± SD (min)	48.1 ± 17.0	50.1 ± 11.5	52.4 ± 14.6	0.658	0.520
Extubation time, mean ± SD (min)	18.3 ± 2.6	17.1 ± 1.9	17.8 ± 2.1	2.354	0.101
Sufentanil dosage, mean ± SD (µg)	40.1 ± 5.5	39.4 ± 4.0	38.8 ± 5.0	0.486	0.617

Values are mean ± SD, and number of patients. Differences in age, height, weight, surgery time, extubation, and sufentanil dosage between groups were analyzed using one-way ANOVA, and in gender and ASA class between groups were analyzed using χ² tests.

D group, dyclonine mucilage group; L group, compound lidocaine cream group; NS group, normal saline group. ASA, American Society of Anesthesiologists; SD, standard deviation.

Compared with that in the NS group, the POST incidence at 6 hours after surgery in the D group was significantly lower (P = 0.010). The incidence of POST at 1, 6, and 24 hours after surgery was significantly lower in the L group than in the NS group (P < 0.001, P < 0.001 and P = 0.016, respectively). The incidence of POST at 1, 6 hours after surgery in the L group was significantly lower than that in the D group (P = 0.015 and 0.012).

The incidences of POCs at 1 and 6 hours after surgery in the L and D groups were significantly lower than those in the NS group (P < 0.001, P < 0.001, P = 0.010, and 0.007, respectively). There was no difference in the incidence of POC at 1, 6, and 24 hours after surgery between the D and L groups (P = 0.267, 0.236, and 0.335, respectively).

The incidences of HOV at 1, 6, and 24 hours after surgery in the L group were significantly lower than those in the NS group (P = 0.013, 0.003, and 0.016, respectively), and the incidences of HOV at 1 and 6 hours after surgery in the D group were significantly lower than those in the NS group (P = 0.015 and 0.010). There was no difference in the incidence of HOV between the D and L groups at 1, 6, and 24 hours after surgery (P = 0.500, 0.353, and 0.306, respectively), as shown in Figure 2.

Figure 2.

The incident of POST, POC, and HOC in three groups at different times after surgery.

The severity scores of POST, POC, and HOV in the L group were significantly lower than those in the NS group at 1 and 6 hours after surgery (P < 0.001, P < 0.001, P < 0.001, P = 0.001, 0.011, and 0.005, respectively). Twenty-four hours after surgery, there was no difference in the severity scores of POST, POC, and HOV among the three groups (P = 0.262, 0.247, and 0.178, respectively), as shown in Table 2.

Table 2.

The POST, POC, and HOV severity score at different time in the three groups

	Time points	Severity score	D group (n = 30)	L group (n = 30)	NS group (n = 30)	P-values
						Among three groups	Between D and L groups	Between L and NS groups	Between D and NS groups
POST	1 h after surgery	0	15 (50.0)	24 (80.0)	8 (26.7)	<0.001	0.097	<0.001*	0.036
		1	9 (30.0)	3 (10.0)	5 (16.7)
		2	4 (13.3)	2 (6.7)	10 (33.3)
		3	2 (6.7)	1 (3.3)	7 (23.3)
	6 h after surgery	0	19 (63.3)	27 (90)	8 (26.7)	<0.001	0.081	<0.001*	0.030
		1	6 (20.0)	1 (3.3)	8 (26.7)
		2	3 (10.0)	1 (3.3)	9 (30.0)
		3	2 (6.7)	1 (3.3)	5 (16.7)
	24 h after surgery	0	24 (80.0)	28 (93.3)	21 (70.0)	0.262	0.385	0.061	0.807
		1	4 (13.3)	1 (3.3)	6 (20.0)
		2	2 (6.7)	1 (3.3)	2 (6.7)
		3	0 (0.0)	0 (0.0)	1 (3.3)
POC	1 h after surgery	0	21 (70.0)	26 (86.7)	10 (33.3)	0.002	0.517	<0.001*	0.038
		1	5 (16.7)	2 (6.7)	8 (26.7)
		2	2 (6.7)	1 (3.3)	7 (23.3)
		3	2 (6.7)	1 (3.3)	5 (16.7)
	6 h after surgery	0	24 (80.0)	27 (90.0)	14 (46.7)	<0.001	0.706	0.001*	0.048
		1	4 (13.3)	2 (6.7)	9 (30.0)
		2	1 (3.3)	1 (3.3)	5 (16.7)
		3	1 (3.3)	0 (0.0)	2 (6.7)
	24 h after surgery	0	26 (86.7)	28 (93.3)	22 (73.3)	0.247	0.671	0.096	0.441
		1	3 (10)	2 (6.7)	5 (16.7)
		2	1 (3.3)	0 (0.0)	3 (10.0)
		3	0 (0.0)	0 (0.0)	0 (0.0)
HOV	1 h after surgery	0	24 (80.0)	25 (83.3)	15 (50.0)	0.006	1.000	0.011*	0.025
		1	4 (13.3)	3 (10.0)	7 (23.3)
		2	1 (3.3)	2 (6.7)	6 (20.0)
		3	1 (3.3)	0 (0.0)	2 (6.7)
	6 h after surgery	0	25 (83.3)	27 (90)	15 (50.0)	0.011	0.748	0.005*	0.035
		1	3 (10.0)	2 (6.7)	9 (30.0)
		2	2 (6.7)	1 (3.3)	5 (16.7)
		3	0 (0.0)	0 (0.0)	1 (3.3)
	24 h after surgery	0	27 (90.0)	29 (96.7)	23 (76.7)	0.178	0.612	0.082	0.394
		1	2 (6.7)	1 (3.3)	4 (13.3)
		2	1 (3.3)	0 (0.0)	3 (10.0)
		3	0 (0.0)	0 (0.0)	0(0.0)

Values are number of patients. Differences in the POST, POC, and HOV severity score at different time between groups were analyzed using χ² or Fisher’s exact test. Bonferroni correction test was used for further statistical comparison between groups.

POST, postoperative sore throat; POC, postoperative cough; HOV, hoarseness of voice; D group, dyclonine mucilage group; L group, compound lidocaine cream group; NS group, normal saline group.

^*P < 0.0167 vs. NS group.

The incidence of pharyngeal foreign body sensation in the D group was significantly greater than that in the NS group 1 hour after surgery (P = 0.012). There was no difference in the incidence of foreign body sensation in the pharynx among the three groups at 6 hours after surgery (P = 0.122), and none of the three groups experienced foreign body sensation in the pharynx 24 hours after surgery, as shown in Table 3.

Table 3.

The incidence of foreign body sensation in the pharynx after surgery

Time points	D group (n = 30)	L group (n = 30)	NS group (n = 30)	χ2 values	P-values
1 h after surgery, n (%)	9 (30)*	6 (20)	1 (3.3)	7.939	0.017
6 h after surgery, n (%)	4 (13.3)	1 (3.3)	0 (0)	4.473	0.122
24 h after surgery, n (%)	0 (0)	0 (0)	0 (0)	–	–

Values are number of patients.

D group, dyclonine mucilage group; L group, compound lidocaine cream group; NS group, normal saline group. Differences in the incidence of foreign body sensation in the pharynx after surgery between groups were analyzed using Fisher’s exact test.

^*P < 0.0167 vs. NS group.

There were significant differences in postoperative satisfaction scores among the three groups at 1, 6, and 24 hours after surgery (P < 0.001, P < 0.001, and P = 0.042). One and 6 hours after surgery, the postoperative satisfaction scores in the L and D groups were significantly greater than those in the NS group (P < 0.001, P < 0.001, P = 0.004 and P = 0.009), and the postoperative satisfaction scores in the L group were significantly greater than those in the D group (P = 0.007 and P = 0.009), as shown in Table 4.

Table 4.

Patient postoperative satisfaction score

Time points	Severity score	D group (n = 30)	L group (n = 30)	NS group (n = 30)	P-values
					Among three groups	Between D and L groups	Between L and NS groups	Between D and NS groups
1 h after surgery	0	14 (46.7)	24 (80.0)	7 (23.3)	<0.001	0.007**	<0.001*	0.004*
	1	9 (30.0)	4 (13.3)	8 (26.7)
	2	7 (23.3)	2 (6.7)	8 (26.7)
	3	0 (0.0)	0 (0.0)	7 (23.3)
	4	0 (0)	0 (0)	0 (0)
6 h after surgery	0	15 (50.0)	25 (83.3)	9 (26.7)	<0.001	0.009**	<0.001*	0.009 *
	1	9 (30.0)	3 (10.0)	7 (26.7)
	2	6 (20.0)	2 (6.7)	9 (30.0)
	3	0 (0.0)	0 (0.0)	5 (16.7)
	4	0 (0.0)	0 (0.0)	0 (0.0)
24 h after surgery	0	25 (83.3)	26 (86.7)	19 (63.3)	0.042	0.500	0.040	0.066
	1	4 (13.3)	3 (10.0)	8 (26.7)
	2	1 (3.3)	1 (3.3)	3 (10.0)
	3	0 (0.0)	0 (0.0)	0 (0.0)
	4	0 (0.0)	0 (0.0)	0 (0.0)

Values are number of patients. Differences in the patient postoperative satisfaction score at different time between groups were analyzed using χ² or Fisher’s exact test. Bonferroni correction test was used for further statistical comparison between groups.

D group, dyclonine mucilage group; L group, compound lidocaine cream group; NS group, normal saline group.

^*P < 0.0167 vs. NS group.

^**P < 0.0167 vs. D group.

Because the SBP, DBP and HR data violated sphericity, two-way repeated-measures ANOVA with Greenhouse–Geisser correction was used. The time effect, time * group effect, and group effect of SBP, DBP, and HR were significant in the three groups (P < 0.001, P < 0.001, and P < 0.001, respectively). There was no difference in the SBP, DBP, and HR among the groups at T₀ ~ T₂ (P > 0.05). At T₃–T₇, the SBP, DBP, and HR in the D and L groups were significantly lower than those in the NS group (P < 0.05). Compared with those at T₀, the SBP and DBP decreased more significantly at T₁, T₂, T₅, and T₆ in the three groups (P < 0.05), and at T₄ in the D and L groups (P < 0.05). The HR decreased at T₁ and T₅, and increased at T₂ (P < 0.05) in the three groups, as shown in Table 5.

Table 5.

The blood pressure and HR at different time points in three groups

	Time points	D group (n = 30)	L group (n = 30)	NS group (n = 30)	F values	P-values
SBP (mmHg)	T0	123.1 ± 6.2	121.9 ± 6.7	122.8 ± 7.0	0.252	0.778
	T1	105.8 ± 8.1**	104.1 ± 8.6**	104.9 ± 9.5**	0.271	0.764
	T2	128.9 ± 7.0**	128.5 ± 7.42**	132.1 ± 9.5**	1.809	0.170
	T3	121.4 ± 8.1*	119.7 ± 7.1*	128.9 ± 9.0	10.928	<0.001
	T4	115.4 ± 7.8***	114.4 ± 5.5***	123.2 ± 6.7	15.230	<0.001
	T5	140.0 ± 8.6***	136.8 ± 8.6***	153.5 ± 10.2**	27.947	<0.001
	T6	131.7 ± 6.5***	128.8 ± 5.2***	142.3 ± 6.2**	42.047	<0.001
	T7	127.2 ± 5.9*	124.8 ± 5.9*	131.1 ± 6.8**	8.002	0.001
F values		60.859	61.518	90.511	–	–
P-values		<0.001	<0.001	<0.001	–	–
DBP (mmHg)	T0	74.9 ± 7.0	73.3 ± 7.7	72.8 ± 5.6	0.785	0.459
	T1	63.9 ± 8.0**	62.4 ± 8.4**	61.1 ± 7.2**	0.934	0.397
	T2	81.4 ± 7.4**	80.1 ± 7.6**	82.2 ± 8.2**	0.596	0.553
	T3	71.6 ± 7.5*	70.8 ± 6.1*	79.8 ± 8.3**	13.636	<0.001
	T4	68.8 ± 4.5***	67.3 ± 6.8***	75.2 ± 7.0	14.800	<0.001
	T5	90.9 ± 7.4***	88.2 ± 7.6***	97.3 ± 8.5**	10.532	<0.001
	T6	80.8 ± 5.5***	80.2 ± 6.2***	90.0 ± 5.4**	27.691	<0.001
	T7	78.8 ± 6.2*	78.0 ± 6.0*	82.8 ± 5.4**	5.848	0.004
F values		46.554	39.976	72.021	–	–
P-values		<0.001	<0.001	<0.001	–	–
HR (beats/minute)	T0	80.3 ± 7.3	77.1 ± 7.3	77.0 ± 6.3	2.218	0.115
	T1	72.8 ± 9.0**	69.3 ± 7.6**	69.9 ± 8.8**	1.422	0.247
	T2	87.7 ± 8.8**	84.6 ± 7.8**	84.8 ± 10.0**	1.094	0.340
	T3	74.8 ± 7.3*	77.2 ± 5.3*	82.9 ± 7.4**	11.642	<0.001
	T4	71.5 ± 6.1***	73.9 ± 5.3*	78.9 ± 6.0	12.655	<0.001
	T5	87.3 ± 8.0***	83.8 ± 5.9***	97.2 ± 8.5**	25.363	<0.001
	T6	82.8 ± 6.2*	79.5 ± 6.4*	91.0 ± 6.6**	25.631	<0.001
	T7	79.2 ± 5.2*	76.2 ± 6.2*	83.3 ± 4.8**	13.072	<0.001
F values		21.415	17.791	37.861	–
P-values		<0.001	<0.001	<0.001	–

Values are mean ± SD, and number of patients. Differences in SBP, DBP, and HR between groups were analyzed using a two-way repeated measurement ANOVA with Greenhouse–Geisser correction.

D group, dyclonine mucilage group; L group, compound lidocaine cream group; NS group, normal saline group; SBP, systolic blood pressure; DBP, diastolic blood pressure; HR, heart rate.

^*P < 0.05 vs. NS group.

^**P < 0.05 vs. T₀.

Discussion

In this study, the use of dyclonine mucilage and a compound lidocaine cream as tracheal tube lubricants significantly reduced the incidence and severity of POST, POC, and HOV, and improved patient satisfaction 1 and 6 hours after surgery. Compared with dyclonine mucilage, compound lidocaine cream had a lower incidence of sore throat and higher postoperative satisfaction scores at 1 and 6 hours after surgery, without an increased incidence of foreign body sensation in the pharynx at 1 hour after surgery. Moreover, both using dyclonine mucilage and compound lidocaine cream as a tracheal tube lubricant could maintain hemodynamic stability in patients after tracheal intubation and extubation.

POST is a common postoperative pharyngeal complication after tracheal intubation. Trauma, nerve injury, and the inflammatory response caused by catheter stimulation to the airway wall may be causes of POST, which is also related to the size and type of tracheal catheter, catheter sleeve pressure, and the technique of the anesthesiologist^[14–16]. In this study, tracheal intubation was performed in all patients by an anesthesiologist with more than 10 years of clinical experience in general anesthesia using video laryngoscopy. Moreover, the pressure of the tracheal catheter cuff of all the patients was continuously monitored during surgery and maintained within the pressure range of 25–30 cmH₂O, thus avoiding the influence of the above factors on POST. Studies have shown that the incidence of POST in patients with tracheal catheters treated with placebo lubrication alone is greater than 80%^[1,5]. In our study, the incidence of POST at 1, 6, and 24 hours after surgery in the saline group was 73.3%, 70%, and 30%, respectively, which was consistent with previous clinical studies^[5,16]. Larijani et al and Sohmer et al^[4,17] used lidocaine and prilocaine cream to perform local oropharyngeal anesthesia for flexible bronchoscopy, and reported that the lidocaine and prilocaine cream provided enough local anesthesia for these procedures. Moreover, the oral administration of 10 ml of dyclonine mucilage before tracheal intubation during endoscopic submucosal dissection or peroral endoscopic myotomy under general anesthesia surgery can effectively reduce the incidence of throat pain at 24 hours after surgery[6]. In our study, both the administration of compound lidocaine cream and dyclonine mucilage as tracheal catheter lubricants significantly reduced the incidence of POST 1, 6, and 24 hours after surgery. This result may be due to the local anesthetic effect of compound lidocaine cream and dyclonine mucilage on tracheal mucosa^[6,7].

In our study, the incidence of POST was lower in the compound lidocaine cream group (20% and 10%) than in the dyclonine mucilage group (50% and 36.7%) 1 and 6 hours after surgery. These findings indicate that compound lidocaine cream is more effective than dyclonine mucilage in reducing the incidence of POST in patients with tracheal intubation under general anesthesia. This result may have occurred because the combination of lidocaine and prilocaine has a stronger local anesthetic effect, and both exist in the form of a liquid emulsion, which promotes the drugs to penetrate the mucosal layer and effectively reducing local pain and discomfort, and the action time of prilocaine is 5–6 hours, which is longer than that of dyclonine mucilage (20–30 minutes)[6]. There was no difference in the severity of POST between the dyclonine mucilage group and the compound lidocaine cream group at 1 and 6 hours after surgery in the present study, possibly because both are local anesthesia drugs, that can effectively reduce the severity of POST in patients. At 24 hours after surgery, there was no difference in the incidence and severity of POST among the groups, which may be related to the short duration of action of the two drugs and the patients’ ability to self-heal after short-term laparoscopic cholecystectomy.

Coughing normally acts as a protective mechanism for airways, by which foreign matter is expelled from the body to prevent further inhalation[18]. In patients with tracheal intubation under general anesthesia, the incidence of cough during extubation is 15%–94%, and cough can cause adverse complications, such as increased intracranial pressure and intraocular pressure, cardiovascular adverse reactions, and even severe arrhythmia[7]. Previous studies have shown that the use of lidocaine and prilocaine cream as tracheal catheter lubricants can effectively reduce the incidence and severity of POC in patients who are receiving general anesthesia[5]. Another study[19] showed that taking dyclonine mucilage before the bronchoscopy period reduced the incidence and severity of cough reactions in patients during bronchoscopy. In the present study, the incidence of cough at 1, 6, and 24 hours after surgery and the severity at 1 and 6 hours after surgery were significantly reduced in D and L groups, which was consistent with the results reported in the above studies. One and 6 hours after surgery, the incidence of POC with compound lidocaine cream (13.3% and 10%) was significantly lower than that with dyclonine mucilage (30% and 20%), indicating that the use of compound lidocaine cream as a tracheal tube lubricant can more effectively improve POC in patients undergoing general anesthesia with tracheal intubation.

Patients who are receiving general anesthesia with endotracheal intubation often suffer from hoarseness after surgery, with an incidence rate ranging from 16% to 55%[20]. A previous study showed that the use of lidocaine and prilocaine cream as a tracheal catheter lubricant significantly improved postoperative HOV[5]. The application of dyclonine mucilage to the endotracheal tube cuff and its front end can effectively reduce the incidence of postoperative hoarseness in children undergoing general anesthesia with tracheal intubation[21]. In our study, although both dyclonine mucilage and compound lidocaine cream as tracheal tube lubricants significantly reduced the incidence and severity of postoperative hoarseness, their improvement on postoperative hoarseness was consistent.

Endotracheal intubation is usually accompanied by postoperative discomfort in the throat[22]. Krantz et al[23] reported that a patient who underwent bone grafting complained of severe throat pain and foreign body sensation 48 hours after surgery, which was due to uveal necrosis following endotracheal intubation. Our study showed that compared with the use of normal saline, the use of dyclonine mucilage as a tracheal tube lubricant significantly reduced the incidence of foreign body sensation in the throat at 1 hour after surgery (30% vs. 3.3%). This finding may be related to the fact that dyclonine mucilage contains sodium carboxymethyl cellulose as a thickening agent, which is attached to the airway mucosa of patients, and the residual material remains after extubation. The incidence of foreign body sensation in the throat of patients in the compound lidocaine cream group 1 hour after surgery was 20%, which was greater than the 3.3% reported in the normal saline group, but the difference between the two groups was not statistically significant. Twenty-four hours after surgery, there was no foreign body sensation in the throat of any patient in any group, which may be due to the gradual weakening of the drug effect and self-healing ability of the patients.

Postoperative discomfort reduces patient satisfaction after surgery[24]. Although the sore throat after tracheal intubation is minor, it has an adverse effect on patient satisfaction and postoperative function[25]. In our study, 1 and 6 hours after surgery, the patient satisfaction score in the L group was significantly higher than that in the D group. This might mainly be due to the fact that the incidence of sore throat at 1 and 6 hours after surgery and the incidence of foreign body sensation in the pharynx at 6 hours after surgery in the L group were significantly lower than those in the D group. It is suggested that the use of compound lidocaine cream as a tracheal tube lubricant has more potential to improve postoperative satisfaction.

During endotracheal intubation, stimulation of various parts of the patient’s respiratory airway can cause the sympathetic adrenal system to release a large amount of catecholamines, resulting in severe hemodynamic fluctuations[26]. A previous study[27] confirmed that applying a compound lidocaine cream as a local anesthetic to the tracheal catheter can effectively reduce the hemodynamic fluctuations of patients during intubation and extubation, and stabilize the hemodynamic. In our study, both dyclonine mucilage and the compound lidocaine cream effectively attenuated the stress response of patients during intubation and extubation. The application of dyclonine mucilage and compound lidocaine cream as tracheal tube lubricants effectively inhibited the increase in blood pressure and heart rate 3, 5 minutes after intubation and extubation, and made the hemodynamics more stable. However, our study showed that, immediately after intubation, both the compound lidocaine cream and dyclonine mucilage did not reduce the increase in blood pressure and heart rate following intubation, possibly because tracheal intubation is usually completed within tens of seconds[28], and the insufficient contact time between the two drugs and the tracheal mucosa led to a failure of the anesthetic effect and the inability to inhibit the immediate stress response effectively after tracheal intubation.

There are some limitations in our study. First, previous studies[27] have shown that the commonly used dosage of compound lidocaine cream as a tracheal catheter lubricant is 1–4 g. However, whether there is an optimal dose of dyclonine mucilage as a tracheal catheter lubricant has not been studied, which needs to be further studied. Second, although the incidence of postoperative HOV in the D group (20%, 16.7%, 10%) was greater than that in the L group (16.7%, 10%, 3.3%) at 1, 6, and 24 hours after surgery, the difference between the two groups was not statistically significant, which may be due to the small sample size of this study[29]. In the future, clinical trials with large sample sizes will be conducted to determine the effects of dyclonine mucilage and compound lidocaine cream as tracheal tube lubricants on the incidence of HOV. Third, the endotracheal intubation procedure can stimulate sensory C fibers and accompany the release of nerve substances, which may be related to POST[30]. The lidocaine component in the compound lidocaine cream may inhibit the excitation of airway sensory C fibers, thus reducing the occurrence of throat pain and cough in patients[31]. Dyclonine mucilage inhibits pain perception by blocking the transmission of nerve impulses[19]. However, the mechanism by which these two drugs reduce the occurrence of POC and HOV is still unclear and needs to be further studied in the future. Fourth, the present study was conducted at a single center, which may limit the broader applicability of our findings to broader general anesthesia populations.

Conclusion

The use of dyclonine mucilage and compound lidocaine cream as tracheal catheter lubricants can reduce the incidence and severity of early POST, cough, and hoarseness in patients who are receiving general anesthesia. Patients treated with compound lidocaine cream have a lower incidence of early POST and higher postoperative satisfaction than those treated with dyclonine mucilage. Both dyclonine mucilage and compound lidocaine cream can significantly reduce the increase in heart rate and blood pressure during intubation and extubation, and can stabilize the hemodynamic of patients.

Ethical approval

The present study was approved by the Ethics Committee of the Affiliated Hospital of North Sichuan Medical College (IRB 2022ER206-1) and registered with the Chinese Clinical Trial Registry (www.chictr.org.cn/showproj.html?proj=175668; registration number: ChiCTR2200062260, Date of registration: 31/07/2022) prior to patient enrolment.

Consent

Participants received oral and written information about the clinical controlled study prior to inclusion and signed informed consent.

Sources of funding

This study was funded by the foundation of Sichuan Medical Association (EH-MN14-06).

Author contributions

X.L. helped design the study, perform the experiments, collect the data, analyze the data, and write the manuscript. X.W. helped perform the experiments, collect the data, analyze the data, and write the manuscript. Y.L. helped perform the experiments, collect the data, and write the manuscript. S.Z. helped perform the experiments, collect the data, and analyze the data. F.W. helped design the study, perform the experiments, analyze the data, and write the manuscript.

Conflicts of interest disclosure

The authors declare that they have no competing interests.

Research registration unique identifying number (UIN)

The present study was registered with the Chinese Clinical Trial Registry (www.chictr.org.cn/showproj.html?proj=175668; registration number: ChiCTR2200062260, Date of registration: July 31, 2022) prior to patient enrolment.

Guarantor

Fangjun Wang.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request. Due to ethical reasons, to protect the integrity of the participants, the study data are not publicly available.