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Three Part Question

In [patients requiring nasogastric tube insertion] is [nebulised lidocaine better than alternative anaesthetic techniques or no anaesthetic] at [reducing pain and discomfort during the procedure and preventing complications]?

Clinical Scenario

A 52 year old man who has been diagnosed with gastrointestinal obstruction requires a NGT to be inserted. Is nebulised lidocaine the most clinically efficacious and safe agent to reduce pain and discomfort associated with the procedure?

Search Strategy

A computer generated search was conducted using MEDLINE (PubMed interface; 1966 to the present). No language limits were applied. The following terms were used :( lidocaine) AND (((nebulis* OR nebuliz*) OR ("Nebulizers and Vaporizers"[Mesh: noexp])) OR ((NASOGASTRIC TUBES) OR (NASOGASTRIC TUBE) OR (NASOGASTRIC INTUBAT*) OR (NASOGASTRIC INTUBATIONS)))
This strategy was adapted for the following databases:
1. Cochrane Central Register of Controlled Trials
2. Cochrane Database of Systematic Reviews. Keywords which were searched were: nasogastric, nebulised and lidocaine.
3. EMBASE
4. CINAHL
Additional efforts to locate potential randomized controlled trials were identified from the following data source: WHO, International Clinical Trials Registry Platform. Keyword search: nasogastric, lidocaine.
A bibliographical search of those papers identified by the above searches was done. A hand search of relevant emergency medicine journals was performed for the past three years.

Search Outcome

RESULTS
MEDLINE
149 citations were identified. Of these, 2 fulfilled the inclusion criteria (table 1). No additional completed trials were identified through any other means.
The Cochrane database was searched for relevant studies. The registered title "Topical anaesthesia for nasogastric tube insertion in adults" was found. There was no completed Cochrane protocol or review of relevance. Personal communication was made with the authors of the registered Cochrane review article. The authors of this ongoing review were unaware of any other studies concerning the adult population.
The WHO, International Clinical Trials Registry Platform revealed a single relevant trial which is currently at the open to recruitment stage. The title is: Randomised Controlled Trial of Nebulised Lignocaine Versus Placebo for Relief of Pain of Nasogastric Tube Insertion in Children; Date of registration 06/03/07. The age group of participants is however beyond the scope of this review.
The trials were then assessed, in terms of methodological quality, using accepted criteria. [10] [11]Both papers were of sufficient standard to be considered for inclusion in this review. See Table 2.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Spektor 2000 USA	10 healthy volunteers between 20 and 40 years of age.	blinded, placebo controlled crossover study	Difference in VAS scores between NL and SL. Comparison of VAS scores between NL and P, and comparisons of incidences of	Mean within-subject difference in VAS pain scores was 15 mm (95% CI 8 to 21 mm), favoring nebulised lidocaine over sprayed lidocaine. Incorrect tube placements were less common with the NL protocol (n = 1) than with SL (n = 4, p > 0.33) or P (n = 9, p < 0.05). Complications were also less common with the NL protocol (n = 13) than with either SL (n = 26, p = 0.008) or P (n = 24, p = 0.02).	Small sample size, healthy volunteers, subjects not fully blinded, nebulised saline may have diluted lidocaine spray thus reducing its efficacy.
Cullen 2004 Australia	50 patients requiring NGT insertion, 29 received lidocaine, 21 received saline	Double-blind, placebo-controlled, randomized clinical trial	Mean VAS score for patients' discomfort during nasogastric tube insertion	Mean VAS was 37.7mm	Patients were non-consecutively enrolled. Unequal numbers of patients enrolled at study locations. Different operators for NGT insertions – details not recorded.

Comment(s)

In a survey of emergency physicians' practices and attitudes regarding procedural anaesthesia for nasogastric tube insertion it was found that "91% would change their practice if new literature were to show a convenient way to effectively reduce this pain".[12] This clinical topic review evaluated the highest level evidence relating to the efficacy and safety of nebulised lidocaine at reducing the pain of NGT insertion. 2 RCTs of sufficient methodological quality were identified by the stated search strategy which directly examined the effect of nebulised lidocaine at reducing the pain of NGT insertion. Neither of these trials compared the same interventions, therefore the results could not be pooled to produce a scientifically valid meta-analysis. These studies revealed that nebulised lidocaine is better than placebo and lidocaine spray at reducing pain of NGT insertion when assessed using a VAS score. Incorrect tube placement and complications are fewer but a higher rate of epistaxis may occur when using nebulised lidocaine. This is not seen when nebulised lidocaine is combined with nasal lidocaine gel and a topical vasoconstrictor. The most important limitation of Spektor's study is that it was performed on a small number of healthy volunteers, all of whom received intranasal lidocaine jelly and a nasal vasoconstrictor. Spektor stated that although blinded, some subjects were able to perceive the effect of lidocaine spray on their mucosa. However it is unclear why a volunteer would assume that the lidocaine and not the saline would have that effect. A theoretically limitation of the study was that nebulised lidocaine may have diluted the lidocaine spray and hence reduced its efficacy. Cullen's study revealed a higher frequency of epistaxis in the nebulised lidocaine group. However a significant limitation was that different operators inserted the NGTs, the details of which were not recorded. It is thus unclear whether the epistaxis complication rate was attributable to the intervention or the individual operator. Patients were non consecutively enrolled however randomisation after enrollment reduced selection bias. Nasogastric tube insertion continues to be performed without adequate analgesia. A questionnaire survey of all emergency medicine SpRs in the Irish Republic revealed that 62.5% provide no form of analgesia for the procedure bar lubricant gel. Juhl, found that although 93% of those he surveyed took some measure to reduce the pain of the NGT insertion, only 28% believed they provided adequate pain relief. [12] From the available evidence and personal research it appears that there are two issues of concern. Firstly and most importantly practitioners still either do not believe NGT insertion is painful or they do not actually use the measures they believe are most effective at reducing pain.[12] Secondly practitioners may be unaware that sufficient analgesia may be achieved adequately and safely by nebulisation of lidocaine. This is unlikely as 67% of those Irish emergency SpRs who use an anaesthetic agent use nebulised lidocaine with or without another agent. Nebulised lidocaine is convenient and preferred by patients to lidocaine spray for other invasive procedures. [13] It is unclear if this is because a better degree of analgesia is provided by a fine mist delivered to the entire oro-nasopharynx than occur for example with sprays. Six randomised controlled trials have been published looking at various formulations of analgesia for NGT insertion. [14] Lidocaine spray has been compared with placebo, and lidocaine jelly plus phenylephrine plus Cetacaine [tetracaine plus benzocaine has been compared with placebo. [7, 8] Placebo was inferior to analgesia in reducing pain in both cases. In another randomised trial lidocaine spray plus lidocaine 2% jelly was superior to lidocaine jelly alone. [5] Ducharme's results suggested that lidocaine jelly was superior to lidocaine spray and cocaine spray in a trial of 30 healthy volunteers although results were not statistically significant. [3] The combination of nebulised lidocaine, lidocaine jelly and phenylephrine as used by Spektor may well prove to be the ideal analgesic cocktail to aid NGT insertion.[6]

Clinical Bottom Line

Nebulised lidocaine is an effective anaesthetic agent for the insertion of nasogastric tubes. In terms of safety there may be an increased risk of epistaxis but a reduction in nasotracheal intubations and other complications.

References

1. Spektor M, Kaplan J, Kelley J, Wheary J, Dalsey W. Nebulized or sprayed lidocaine as anesthesia for nasogastric intubations. Acad Emerg Med. 2000 Apr;7(4):406-8.
2. Cullen L, Taylor D, Taylor S, Chu K. Nebulized lidocaine decreases the discomfort of nasogastric tube insertion: a randomized, double-blind trial. Annals of emergency medicine 2004 Aug;44(2):131-7.