Application of topical pharyngeal anesthesia to reduce adverse reactions during painless gastroscopy: A prospective randomized study

Abstract

BACKGROUND:

Studies have reported that certain adverse reactions can occur during painless gastroscopy examination. Knowing how to decrease the risks and incidence of adverse reactions is of great importance.

OBJECTIVE:

To investigate whether topical pharyngeal anesthesia combined with intravenous anesthesia is superior to intravenous anesthesia alone in patients undergoing painless gastroscopy and to determine whether this combined approach had any additional benefits.

METHODS:

Three hundred patients undergoing painless gastroscopy were randomly assigned to either the control group or the experimental group. In the control group, patients were anesthetized with propofol, while patients in the experimental group received propofol combined with 2% lidocaine spray for topical pharyngeal anesthesia. Hemodynamic parameters before and after the procedure, including the heart rate (HR), mean arterial pressure (MAP), and pulse oxygen saturation (SPO ${}_{2}$ ) were recorded. Any adverse reactions experienced by the patient, including choking and respiratory depression, and the total dosage of propofol required during each procedure were also documented.

RESULTS:

Compared with pre-anesthetic data, the HR, MAP, and SPO ${}_{2}$ were reduced after the completion of the painless gastroscopy procedure in both groups. However, the HR, MAP, and SPO ${}_{2}$ measurements taken after the gastroscopy were significantly lower in the control group than those of the experimental group ( $P<$ 0.05); thus, the hemodynamic parameters of the experimental group were more stable. Compared with the control group, there was significant reduction in the total amount of propofol administered in the experimental group ( $P<$ 0.05). The incidence of adverse reactions, including choking and respiratory depression, was significantly lower in the experimental group ( $P<$ 0.05).

CONCLUSION:

The results demonstrated that the application of topical pharyngeal anesthesia in painless gastroscopy can significantly reduce the incidence of adverse reactions. Thus, the combination of topical pharyngeal and intravenous anesthesia is worthy of clinical application and promotion.

Keywords

Topical pharyngeal anesthesia adverse reactions painless gastroscopy intravenous anesthesia

1. Introduction

Gastroscopy is an important diagnostic procedure, performed worldwide, that is vital for diagnosing and treating upper gastrointestinal diseases [1]. As some patients experience discomfort while undergoing gastroscopy, the use of sedation, which can suppress the gag reflex and increase patient tolerance, has become widespread, with propofol being commonly utilized for this purpose. Studies have reported that certain adverse reactions can occur during painless gastroscopy examination, such as nausea, vomiting, choking, respiratory depression, and decreased pulse oxygen saturation (SPO ${}_{2}$ ), and increased amounts of propofol administration [2, 3]. Knowing how to decrease the risks and incidence of adverse reactions during painless gastroscopy is of great importance. The application of topical pharyngeal anesthesia in painless gastroscopy has advantages, such as high satisfaction, low discomfort, and simple administration, and several studies have found that pharyngeal anesthesia with 2% lidocaine spray may be beneficial in reducing the incidence of adverse reactions [4, 5, 6].

The present study aims to investigate whether topical pharyngeal anesthesia benefitted patients who underwent gastroscopy under propofol sedation and to discover the optimal mode of anesthesia that could improve the safety of this examination.

2. Materials and methods

2.1 Materials

A total of 300 patients (aged 20–80 years) who were due to undergo a gastroscopy between August 2020 and November 2021 at Wenzhou People’s Hospital (Zhejiang, China) were recruited to participate in the study. The physical status of all patients was classified according to the American society of anesthesiology (ASA) system as ASA I or ASA II. All patients had their medical histories checked and underwent a clinical examination. Patients with the following conditions were excluded: serious disease of the heart, brain, lung, and other vital organs; uncontrolled hypertension, diabetes, patients taking drugs $\beta$ Receptor blockers, coagulation disorders, current pregnancy; and intolerance to lidocaine or propofol. The study was approved by the ethics committee of the Wenzhou People’s Hospital. Details of the study, including the risks, were fully explained to all patients, and written informed consent was obtained.

2.2 Methods

The patients were divided randomly into two groups: a control group ( $n=$ 150) and an experimental group ( $n=$ 150). Each patient fasted prior to the procedure and did not have any food intake for the preceding eight hours and no water for the preceding four hours. After entering the gastrointestinal endoscopy room, each patient had an intravenous line inserted and was positioned in the left lateral position. Their heart rate (HR), blood pressure, and SPO ${}_{2}$ were checked, and oxygen was administered via a nasal cannula (3–5 L/min). In the experimental group, topical pharyngeal anesthesia with 2% lidocaine spray (two sprays) was administered by an endoscopy nurse five minutes prior to the patient receiving propofol sedation [5]. The total volume of the spray administered to each patient in this group was approximately 5 ml. In the control group, lidocaine was not administered. Both groups received an intravenous injection of propofol (2 mg/kg), which was repeated as needed to maintain adequate sedation. Gastroscopy examination began when the patient had lost consciousness, their eyelash reflex disappeared, and their muscles relaxed.

2.3 Observation indicators

We recorded the general characteristics of the patients in both groups (Table 1). Mean arterial pressure (MAP), HR, and SPO ${}_{2}$ were recorded and compared before anesthesia (T1) and at the end of the gastroscopy examination (T2). The incidence of adverse reactions, including choking and respiratory depression, and the total amount of propofol administered were recorded and compared.

2.4 Statistical analysis

IBM SPSS Statistics version 22.0 software was used for data analysis. The measurement data were expressed as a mean $\pm$ the standard deviation, and comparisons between the groups were performed using the Student’s $t$ -test. Enumeration data were compared using the chi-squared test. Statistical significance was set at $P<$ 0.05.

3. Results

3.1 Patient characteristics and demographics

The study included 300 patients who underwent painless gastroscopy. There was no statistically significant difference between the two groups in relation to the patients’ characteristics, such as gender, age, height, and weight ( $P>$ 0.05) (see Table 1).

Table 1
Patient characteristics

Items	Control group ( $n=$ 150)	Experimental group ( $n=$ 150)	$P$ value
Gender (M/F)	74/76	66/84	0.355
Mean age, yr (SD)	54.63 $\pm$ 10.90	54.28 $\pm$ 10.95	0.784
Height (cm)	163.94 $\pm$ 7.78	164.92 $\pm$ 7.40	0.263
Weight (kg)	65.52 $\pm$ 11.40	65.32 $\pm$ 10.51	0.875
Smoking (yes/no)	27/123	33/117	0.386
Alcohol (yes/no)	31/119	34/116	0.674

3.2 Comparison of mean arterial pressure, heart rate, and pulse oxygen saturation measurements between the two groups

Compared with T1, the MAP, HR, and SPO ${}_{2}$ measurements were lower at T2 in both groups. The MAP, HR, and SPO ${}_{2}$ measurements of patients in the control group were significantly lower than those of patients in the experimental group at T2 ( $P<$ 0.05) (see Table 2).

Table 2
Comparison of MAP, HR, SPO ${}_{2}$ between the two groups

Items	Groups	Case number	T1	T2
HR (times/minutes)	Control group	150	72.21 $\pm$ 11.04	70.10 $\pm$ 9.70
	Experimental group	150	73.09 $\pm$ 9.11	67.64 $\pm$ 10.36 ${}^{*}$
MAP (mm Hg)	Control group	150	93.96 $\pm$ 10.70	79.08 $\pm$ 10.60
	Experimental group	150	93.80 $\pm$ 10.93	81.89 $\pm$ 9.70 ${}^{*}$
SPO ${}_{2}$ (%)	Control group	150	98.14 $\pm$ 1.29	94.17 $\pm$ 5.39
	Experimental group	150	98.17 $\pm$ 1.51	96.23 $\pm$ 3.31 ${}^{*}$

Note: ${}^{*}$ Compared with control group, $P<$ 0.05.

Table 3

The adverse reactions and total propofol consumption of patients

Items	Control group	Experimental group	$P$ value
Choking (%)	39/111	15/135	0.000
Respiratory depression (%)	32/118	12/138	0.001
Total propofol consumption (ml)	144.55 $\pm$ 35.63	135.84 $\pm$ 24.43	0.014

3.3 Comparison of the incidence of adverse reactions and the total amount of propofol administered between the two groups

The incidence of adverse reactions, including choking and respiratory depression, was significantly lower in the experimental group ( $P<$ 0.05). Compared with the control group, the total amount of propofol administered in the experimental group was significantly lower ( $P<$ 0.05) (see Table 3).

4. Discussion

Gastroscopies are crucial for diagnosing upper gastrointestinal diseases, such as hemorrhages and peptic ulcers, and for early cancer detection. Due to its invasive nature, gastroscopy can be painful for patients, and elderly patients with a history of heart, lung, and brain disease, in particular, have a low tolerance for this procedure. Previous findings have shown that gastroscopy may cause a series of complications in patients with hypertension, such as myocardial infarction and cardiac arrest. As a result, patients with hypertension may refuse gastroscopy, which could lead to a decrease in the rate of early gastric cancer diagnosis.

Techniques and methods that allow gastroscopy to be a painless procedure are likely to increase its acceptability to patients and lead to an increase in patients undergoing the examination. Previous studies have shown that intravenous sedation increases the tolerability and ease of the procedure [7], and that patients undergoing painless gastroscopy were more comfortable, had higher tolerance levels, and experienced overall satisfaction with the procedure [12], although there was a lack of data relating to its safety. In addition, painless gastroscopy is safer than regular gastroscopy and has higher disease detection rates due to an improvement in patient tolerance and a reduction in gastrointestinal peristalsis, which make it easier to locate minor lesions [8].

Anesthetics have a long history of development, from analgesic drugs, such as pethidine and morphine, to sedatives, such as diazepam, midazolam, and propofol. Painless gastroscopy is often conducted using propofol – an established intravenous anesthetic that has a rapid onset, a short duration, and a quick recovery. Propofol also strongly inhibits the contraction of gastrointestinal smooth muscle, antagonizes the vomiting reflex, and reduces coughing [16, 17, 18, 19].

The risks and adverse reactions associated with gastroscopy are well documented and include an increase in HR, blood pressure fluctuations, choking, dyspnea, and decreased oxygen saturation [9, 10, 11]. Research has confirmed that adverse reactions can also occur during painless gastroscopy, including respiratory depression, hemodynamic changes, and HR fluctuations [13]. These inhibitory effects can be further complicated by the need to increase the dose of the anesthetic during the procedure. To correct them, the anesthetist may need to increase the oxygen flow rate, use mask-assisted ventilation and vasopressors, and perform tracheal intubation. Such interventions can increase the probability of complications, including throat injury and respiratory infections.

The reduction of the incidence of adverse reactions during gastroscopy has been the focus of several studies [14, 15]. Adverse reactions in painless gastroscopy commonly occurred in elderly patients with underlying diseases, such as cardiopulmonary insufficiency. To address this, researchers have designed an endoscopic nasal mask to help control hypoxia during painless gastroscopy, shorten examination times, and reduce the risk of serious complications during the examination [20].

One factor that contributes to the risk of adverse reaction during gastroscopy, is the abundance of sensory fibers in the throat, which is supplied by a branch of the superior laryngeal nerve, that makes it sensitive to stimulation. The gastroscope passing through the throat can activate the gag reflex and lead to choking, breath holding, and other adverse reactions. To address this issue, some studies [21] have explored optimal topical anesthesia regimens and dosages as a way of reducing the risk of serious complications during painless gastroscopy. The application of topical pharyngeal anesthesia before gastroscopy can suppress the gag reflex, anesthetize local sensory nerves, inhibit the secretion of catecholamines, and dilate local capillaries, thus improving blood circulation and reducing tissue hypoxia. It may also play a role in reducing post-procedure swelling and pain.

Lidocaine, which was developed in 1948, is a short-acting amide local anesthetic with analgesic and anti-inflammatory properties [22, 23, 24]. It reduces the stimulation of the superior laryngeal nerve by the endoscopic tube, potentially improving throat patency, and reduces the incidence of nausea, pain, choking, and other reactions. Topical pharyngeal anesthesia with 2% lidocaine spray, as a routine pretreatment for esophagogastroduodenoscopy, may facilitate the intubation process during endoscopy and reduce injury to the pharyngeal mucosa [25]. It has the advantages of rapid onset, short duration of action, and rapid recovery. A previous study demonstrated that when lidocaine is sprayed on the pharyngeal area, it effectively suppresses the gag reflex, significantly increases the patient’s tolerance of the procedure, improves the endoscopist’s satisfaction with the procedure, and decreases the need for intravenous sedation [26]. A high proportion of elderly patients undergo gastroscopy, and several studies have revealed that lidocaine for topical pharyngeal anesthesia combined with intravenous anesthesia can reduce the stress response in elderly patients during this procedure. Topical pharyngeal anesthesia may also ameliorate the increased risk of adverse reactions occurring in elderly patients with cardiopulmonary disease; the use of 2% lidocaine spray, administered to elderly patients with chronic obstructive pulmonary disease undergoing gastroscopy as part of this study, appeared to help maintain their hemodynamic stability, blood oxygen saturation, and may have reduced the number of complications. In this study, we observed two groups of patients (i.e., a control group and an experimental group) during painless gastroscopy and compared the incidence of adverse reactions between the two groups. We found that combining intravenous sedation with 2% lidocaine spray for topical pharyngeal anesthesia decreased the incidence of adverse reactions, thus increasing the level of safety.

Topical pharyngeal anesthesia can also reduce the number of adverse reactions, such as hypoxemia, hypotension, and coughing, in patients with obesity. However, some studies have concluded that the use of lidocaine for topical anesthesia has little clinical significance [27]. Therefore, the impact of topical pharyngeal anesthesia on hemodynamic status, oxygenation, and aspiration risk has not been fully confirmed [28].

5. Conclusion

The results of this study support the use of topical pharyngeal anesthesia in painless gastroscopy and provide a strong basis for further developments that can improve the safety of this procedure. The development of minimally invasive, safe, and painless techniques for the diagnosis and treatment of upper gastrointestinal disease continues to be important, and ways to decrease the incidence of adverse reactions during painless gastroscopy should be further explored.

Ethics statement

This study was approved by the Ethics Committee of Wenzhou Peopleâ€™s Hospital (No. 2020-182) and was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants.

Funding

This study was funded by the Scientific Research Project of Wenzhou Municipal Health Commission (No. Y2020295).

Footnotes

Conflict of interest

The authors declare that they have no competing interests.

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Application of topical pharyngeal anesthesia to reduce adverse reactions during painless gastroscopy: A prospective randomized study

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Introduction

2. Materials and methods

2.1 Materials

2.2 Methods

2.3 Observation indicators

2.4 Statistical analysis

3. Results

3.1 Patient characteristics and demographics

Table 1 Patient characteristics

Table 2 Comparison of MAP, HR, SPO 2 between the two groups

4. Discussion

5. Conclusion

Ethics statement

Funding

Footnotes

Conflict of interest

References

Table 1
Patient characteristics

Table 2
Comparison of MAP, HR, SPO ${}_{2}$ between the two groups