Original Contribution

Lidocaine gel as an anesthetic protocol for nasogastric tube insertion in the ED

Ofir Uri MD?, Lior Yosefov MD, Amir Haim MD, Eyal Behrbalk MD, Pinchas Halpern MD

Department of Emergency Medicine, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 64239, Israel

Received 12 September 2009; revised 21 October 2009; accepted 24 October 2009

Abstract

Objective: The aim of the study was to evaluate the efficacy of topical 2% lidocaine gel in reducing pain and discomfort associated with nasogastric tube insertion (NGTI) and compare lidocaine to ordinary lubricant gel in the ease in carrying out the procedure.

Methods: This prospective, randomized, double-blind, placebo-controlled, convenience sample trial was conducted in the emergency department of our tertiary care university-affiliated hospital. Five milliliters of 2% lidocaine gel or placebo lubricant gel were administered nasally to alert hemodynamically stable adult patients 5 minutes before undergoing a required NGTI. The main outcome measures were overall pain, nasal pain, discomfort (eg, choking, gagging, nausea, vomiting), and difficulty in performing the procedure. Standard comparative statistical analyses were used.

Results: The study cohort included 62 patients (65% males). Thirty-one patients were randomized to either lidocaine or placebo groups. Patients who received lidocaine reported significantly less intense overall pain associated with NGTI compared to those who received placebo (37 +- 28 mm vs 51 +- 26 mm on 100-mm visual analog scale; P b .05). The patients receiving lidocaine also had significantly reduced nasal pain (33 +- 29 mm vs 48 +- 27 mm; P b .05) and significantly reduced sensation of gagging (25 +- 30 mm vs 39 +- 24 mm; P b .05). However, conducting the procedure was significantly more difficult in the lidocaine group (2.1 +- 0.9 vs 1.4 +- 0.7 on 5-point Likert scale; P b .05).

Conclusion: Lidocaine gel administered nasally 5 minutes before NGTI significantly reduces pain and gagging sensations associated with the procedure but is associated with more difficult tube insertion compared to the use of lubricant gel.

(C) 2011

Introduction

Nasogastric tube insertion (NGTI) has been used routinely in emergency medicine for more than a century and is one of the most commonly performed procedures in the emergency department (ED). The pain and discomfort associated with the procedure has only recently been

* Corresponding author. Tel.: +972 52 4262285; fax: +972 3 6974775.

E-mail address: [email protected] (O. Uri).

recognized and investigated. Singer et al [1] found NGTI to be the single most painful routine ED procedure. A survey among ED physicians conducted recently by Juhl and Conners [2] found that more than 90% of responders were aware of the pain and discomfort associated with NGTI and used measures to reduce it, but fewer than 30% of them believed that the available measures were adequate. Most of the physicians who participated in the survey were willing to change their usual practices based on new evidence on effective analgesic measures for NGTI.

0735-6757/$ – see front matter (C) 2011 doi:10.1016/j.ajem.2009.10.011

A number of studies evaluated the efficacy of several anesthetic regimens (eg, lubricants, topical vasoconstrictors, and Topical anesthetics applied by gel/spray/nebulizer/atom- izer) for the alleviation of pain and discomfort associated with NGTI. Spektor et al [3] instilled topical 0.5% phenylephrine and 5 mL of 2% lidocaine gel to 10 young healthy volunteers and then administered 3 anesthetic combinations of nebulized lidocaine, oral lidocaine spray, and placebo spray. They found that the addition of nebulized lidocaine to topical phenyleph- rine and lidocaine gel resulted in less pain and discomfort during NGTI. Ducharme and Matheson [4] evaluated the effectiveness of 3 topical anesthetics (1.5 mL of 4% atomized lidocaine, 1.5 mL of 4% atomized cocaine, and 5 mL of 2% lidocaine gel) in 30 healthy volunteers. Their results showed that the level of discomfort was lower when 2% lidocaine gel was used compared to the other anesthetics. Singer and Konia

[5] prospectively assessed pain reduction in 40 alert adults requiring NGTI in the ED setting. They found that topical 2% lidocaine gel with 0.5% phenylephrine for the nose and 2% tetracaine with 14% benzocaine spray for the throat resulted in significantly less pain and discomfort than a nasal lubricant gel alone.

Some of the anesthetic protocols suggested in these and other studies may be too complicated for routine use in the ED and include medications that are not always available in the ED. The objective of this study was to evaluate the effectiveness of a simple and readily available anesthetic protocol, nasally instilled 5 mg of 2% lidocaine gel, compared to placebo, for the alleviation of pain and discomfort associated with NGTI.

Materials and methods

Study setting and sign

This prospective randomized double-blind placebo-con- trolled study was approved by the institutional ethics committee. It was conducted in the adult ED of our tertiary care university-affiliated hospital. The ED has approximately 160 000 adult patient visits per year. The study patients were enrolled from October 2007 to March 2008 on a convenience sample based on the authors’ availability. Inclusion criteria were (1) patients requiring NGTI as decided by the treating physician according to the common indications for NGTI [6], (2) age older than 18 years, (3) willingness and mental ability to provide informed consent and to complete the study questionnaire, and (4) stable hemodynamic status. Pregnant women and patients receiving anticoagulation therapy and those with lidocaine hypersensitivity or who sustained acute trauma were excluded from the study.

Study protocol

Patients requiring NGTI in the ED were informed about the medical indication and importance of NGTI and about the

purpose of this study. After obtaining their written informed consent, the enrolled patients were randomized to nasally receive either 5 mL of 2% lidocaine gel or 5 mL of nonanesthetic water-based lubricant gel (K-Y gel, Johnson & Johnson, New Brunswick, NJ). Randomization was achieved by opening sealed coded envelopes, each containing an identical 5-mL syringe with lidocaine or placebo gel. The envelopes were prepared in advance in sets of 10 with equal numbers of lidocaine and placebo assignments and kept in the ED refrigerator. Patients, nurses, and physicians involved in the study remained blinded to the intervention assignments. All procedures were performed by 1 of 8 registered nurses involved in the study, using the same method. All nurses involved in the study were experienced ED nurses, specialty- trained, and government-certified in emergency nursing, who had performed more than 100 NGTIs before this study. The patients were positioned in a semiseated position and asked to inhale through the nose, so that the more patent nostril could be identified. Five milliliters of lidocaine or placebo gel were instilled to the more patent nostril, and the patients were instructed to inhale the gel and to swallow it when it reached the pharynx. A 16F NGT was inserted 5 minutes after gel application in both groups to enable the anesthetic effect of lidocaine on the mucous membrane of the nose and pharynx to reach its peak [7]. The tip of the tube was lubricated with a small amount of placebo gel before insertion for additional lubrication. The tube was gently advanced parallel to the nasal floor until reaching the nasopharynx. At this point, the patient was asked to sip 50 mL of water given by a syringe to induce swallowing and assist tube progression. In case of resistance or difficulty, the tube was withdrawn and insertion was reattempted. The NGT placement was confirmed by auscultation and

aspiration of gastric contents.

Outcome measures

Immediately after insertion and securing the NGT, the patient were asked to rate their pain levels and the selected discomfort measures (eg, overall pain, nasal pain, choking, gagging, nausea) on a 100-mm Visual analog scale . The registered nurse performing the procedure rated the difficulty in carrying it out by using a 5-point Likert scale (eg, minimal, less difficult than usual, usual amount of difficulty, more difficult than usual, extremely difficult) and noted the number of attempts and the incidence of discomfort. The patients’ Demographic and clinical data were obtained directly from the medical records.

Statistical analysis

Continuous parameters were summarized by means and SD with 95% confidence intervals (CIs). Proportions with 95% CI are presented for categorical parameters. A comparison between the groups with regard to age and

outcome measures was performed using the Mann-Whitney nonparametric test. Categorical parameters, such as sex, indications for NGTI, and vomiting rate, were compared between groups using the ?2 or Fisher exact tests. Multiple Linear regression models were applied to evaluate the effect of demographic and clinical parameters on overall pain score. The statistical analysis was performed using the SPSS software for Windows, version 14.0 (SPSS Inc, Chicago, IL).

Results

Sixty-two patients were enrolled for this study between October 2007 and March 2008, of whom 40 (65%) were males. The mean age of the study population (+-SD) was 66 +-

19 years. Sixty-one patients (98.4%) were Israeli Jews. Indications for NGTI included Small bowel obstruction and diagnosis of gastrointestinal bleeding (eg, hematemesis and melena). Half of the 62 participants were randomized to the treatment group (5 mL of 2% lidocaine gel) and the other half to the control group (5 mL of K-Y gel). There were no significant differences between the groups in age, sex, and indication for NGTI. The mean age of the study group was 68 +- 19 years compared to 64 +- 17 for the control group (difference, 4 years; 95% CI, 1.8-6.2 years; P = not significant [NS]). Sex distribution was 61% males in the study group and 68% males in the control group (difference, 7%; 95% CI, -17% to 28%; P = NS). Small bowel obstruction was the indication for NGTI in 35% of the patients in the study group and 48% in the control group (difference, 13%; 95% CI, -11% to 35%; P = NS). Hematemesis was the indication for NGTI in 29% of patients in the study group and 16% in the control group (difference, 13%; 95% CI, -8% to 32%; P = NS), and melena in 35% for both groups (difference, 0%; 95% CI,

-23% to 23%; P = NS). Demographic and clinical data for

each group are summarized in Table 1.

Patients in the study group reported experiencing less intense overall pain associated with the procedure compared

Table 1 Patient characteristics

Study group (n = 31)		Control group (n = 31)		P
Age (y)	68 +- 19	64	+- 17	NS
(mean +- SD)
Sex (n [%])
Males	19 (61.3)	21	(67.7)	NS
Females	12 (38.7)	10	(32.3)
Indication for NGTI (n [%])
Small bowel	11 (35.5)	15	(48.4)	NS
obstruction
Hematemesis	9 (29.0)	5	(16.1)
Melena	11 (35.5)	11	(35.5)

Study Control Difference group group (95%CI) n = 31 n = 31		P
Overall pain	37 +- 28 51 +- 26 14 (11 to 17)	b.05
and discomfort a
Nasal pain a	33 +- 29 48 +- 27 15 (12 to 18)	b.05
Choking	27 +- 26 42 +- 32 15 (12 to 17)	NS
sensation a
Gagging	25 +- 30 39 +- 24 14 (11 to 17)	b.05
sensation a
Nausea a	25 +- 29 40 +- 38 15 (12 to 18)	NS
Vomiting	3 (9.7) 3 (9.7) 0 (-16% to 16%)	NS
(n [%])
Difficulty of	2.1 +- 0.9 1.4 +- 0.7 0.7 (0.25 to 1.15)	b.05
NGTI b
NGTI attempts	1.4 +- 0.7 1.2 +- 0.6 0.2 (-0.2 to 0.6)	NS
(n) (mean +- SD)
a Visual analog scale of 100 mm. b 5-point Likert scale.

to patients in the control group (37 +- 28 mm vs 51 +- 26 mm on 100-mm VAS, respectively, difference, 14 mm; 95% CI, 11-17 mm; P b .05). Nasal pain was also less intense among the patients in the study group (33 +- 29 mm vs 48 +- 27 mm; difference, 15 mm; 95% CI, 12-18 mm; P b .05), as was the

sensation of gagging (25 +- 30 mm vs 39 +- 24 mm;

Table 2 Outcome measures

difference, 14 mm; 95% CI, 11-17 mm; P b .05). The Choking sensation, nausea, and vomiting rates were similar for both groups. Nasogastric tube insertion was successful in all patients, but the difficulty in performing the procedures as scored by the registered nurses who carried them out was significantly greater in the study group compared to the control group (2.1 +- 0.9 vs 1.4 +- 0.7 on 5-point Likert scale;

difference, 0.7; 95% CI, 0.25-1.15; P b .05). The average number of attempts needed for completing the procedure was also higher in the study group but not significant (1.4 +- 0.7 vs 1.2 +- 0.6; difference, 0.2; 95% CI, -0.2 to 0.6; P = NS).

Outcome measures are summarized in Table 2.

We applied multiple linear regression models to evaluate the effect of demographic and clinical parameters (eg, sex, age, prior NGTI, difficulty of the current NGTI) on the outcome measures. Difficulty in performing the index procedure was the only parameter that significantly influ- enced the outcomes. Specifically, patients who underwent a difficult NGTI (scoring >= 4 on the 5-point Likert scale) were likely to have a higher overall pain level compared to patients who underwent an easy NGTI (difference, 24 mm; 95% CI, 19-26 mm; P b .05). Female sex and having undergone a previous NGTI showed a tendency (although not significant) to influence the overall pain score related to NGTI. Specifically, females were likely to have a higher overall pain compared to males (difference, 12 mm; 95% CI, 9-14 mm; P = NS), and patients who had undergone a previous NGTI were likely to have a lower overall pain compared to patients for whom this was their first NGTI (difference,

8 mm; 95% CI, 5-11 mm; P = NS). Patient age did not influence the outcome measures.

Discussion

Nasogastric tube insertion is one of the most painful procedures performed routinely in the ED. The considerable pain and discomfort associated with the procedure mandates the use of anesthetic measures. Several protocols of topical anesthetics have been evaluated for that purpose; however, none of them has gained wide acceptance. Although they are effective, some proposed protocols may be too cumbersome for routine use in the busy environment of the ED [3,5]. There is still no simple, effective, and acceptable protocol for the relief of pain and discomfort associated with NGTI. Our study results demonstrated that 5 mL of 2% lidocaine gel instilled nasally 5 minutes before NGTI significantly reduced the overall pain associated with the procedure. Todd et al [8] reported that pain relief of 13 mm (on a standard 100-mm VAS) was the minimum mean change that should be considered clinically significant. Thus, our finding of a 14- mm reduction in overall pain and 15-mm reduction in nasal pain associated with NGTI are not only statistically significant but also Clinically meaningful. However, it should be pointed out that the study by Todd et al [8] dealt with traumatic injuries and not ED procedures. Wolfe et al [9] demonstrated a reduction of 27 mm in the overall pain associated with NGTI, when an NGT was inserted immediately after administration of atomized lidocaine to the nasopharynx and oropharynx (lidocaine gel was also used as a lubricant, without waiting for its anesthetic effect) compared to placebo (64 mm vs 37 mm; difference, 27 mm). Similarly, Cullen et al [10] showed a reduction of 21 mm in the overall pain score when an NGT was inserted immediately after administration of nebulized lidocaine (K- Y gel was used as a lubricant) compared to placebo (59 mm vs 38 mm; difference, 21 mm). The pain relief reported in both these studies was greater than the levels reported by our patients (51 mm vs 37 mm; difference, 14 mm); however, the level of the overall pain after anesthetics administration in the studies done by Wolfe, Cullen, and that of the authors was similar (around 37 mm). Atomized and nebulized lidocaine deliveries have a very rapid anesthetic onset that enables immediate NGTI–a feature that represents an advantage in the busy ED environment compared to the 4- to 5-minute intervals required for lidocaine gel to produce its anesthetic effect. However, atomization and nebulization require special devices, which are not always available in the ED, and the required preparation is time consuming as well. Ducharme and Matheson [4] reported that the overall discomfort associated with NGTI was lower after adminis- tration of lidocaine gel compared to other anesthetic protocols (eg, atomized lidocaine or cocaine). Because “overall discomfort” can be difficult to define, we measured discomfort in this study by using several specific adverse

symptoms commonly experienced during NGTI (eg, choking, gagging, nausea, and vomiting). We found that gagging was significantly reduced in the study group, probably due to the anesthetic effect of lidocaine on the pharynx and elimination of the gag reflex. This effect of local anesthesia on the gag reflex is reported to reduce the rate of successful NGTI in placement and to increase the rate of inadvertent tracheal instead of nasogastric intubation [11,12]. This can explain the greater difficulty in the performance of the NGTI procedure that was encountered in our current study. Similar to our findings, Singer and Konia

[5] found that local anesthesia reduced gagging during NGTI, although reduced gagging was not associated with increased difficulty in carrying out the procedure. We found no between-group differences in the other 3 discomfort measures that were evaluated.

Our multiple linear regression models revealed that patients who underwent difficult NGTIs were likely to have more overall pain associated with the procedure. These findings are contrary to those of Singer and Konia [5] who found no correlation between the procedural difficulty and pain scores. The mean overall pain intensity in our study group was significantly lower compared to the placebo group, despite the higher rate of NGTI difficulty recorded for the former group. This finding emphasizes the clinical benefit of lidocaine gel in reducing pain associated with NGTI.

Our study has several limitations. First, the population in the study was quite homogenous, having been made up of Jewish Israeli patients at one facility, and this serves to limit the external validity. Second, we found that the use of lidocaine gel resulted in greater difficulty in carrying out the procedure, but we failed to document adverse reactions associated with difficult NGTIs (eg, nasal bleeding, esophageal abrasions, pulmonary aspiration, and others). The occurrence of such adverse reactions might have influenced our conclusions. Third, patient selection for this study was made on a convenience sample based on the authors’ availability, which can potentially cause a selection bias. Finally, multiple registered nurses performed the procedures in this study. Because placement of a NGT is operator related, this fact might have been a confounding factor. We did not document which Nurse performed each of the procedures and therefore could not analyze the influence of the procedure operator on the outcomes. However, all nurses involved were trained emergency nurses, highly experienced in performing the procedure (had performed N100 NGTIs before the study) and used the same method should restrict this potentially bias.

In conclusion, this study demonstrates the benefit of lidocaine gel in reducing pain associated with NGTI in the ED setting and offers a simple and readily available anesthetic protocol for that purpose. It should be born in mind that lidocaine gel requires 4 to 5 minutes to achieve its maximal anesthetic effect and that this time interval between lidocaine administration and NGTI should be observed; otherwise, the anesthetic would serve merely as a lubricant

with no anesthetic properties. Nasogastric tube insertion was more difficult after lidocaine administration; however, the overall pain intensity and gagging sensation were still significantly relieved.

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