Nasogastric tubes: hard to swallow☆☆☆

1.1. Randomized clinical trial #1 

In 1995, Nott and Hughes3 randomly allocated 63 adult patients requiring nasogastric tubes to 3 equal groups of 21 patients. The experimental group received 0.5 to 1.0 mL of lidocaine 4% (20 to 40 mg of lidocaine) applied as a spray by means of atomizer to the nose only. The placebo group received normal saline solution nasal spray. The control group received no spray. Vasoconstrictors were not used. Although blinding was attempted, it was probably unsuccessful. Practitioners of varying skill and experience (71% physicians, 29% nurses) inserted nasogastric tubes (size not reported) using plain gel lubricant. Ninety percent of the experimental group reported none to moderate discomfort versus 60% of the combined placebo and control groups, for a difference of 30% (95% confidence interval [CI] 12% to 50%). No difference between the groups in the difficulty of tube insertion was found, and no complications were reported.

Conclusion: Lidocaine nasal spray decreases the discomfort of nasogastric tube insertion. This difference appears to be both clinically and statistically significant.3

1.2. Randomized clinical trial #2 

In 1999, Singer and Konia2 randomly allocated 40 adult ED patients requiring nasogastric tubes into 2 equal groups of 20 patients. The experimental group received a vasoconstrictor (phenylephrine 0.5% nasal spray) plus 2 topical anesthetics: (1) 5 mL of intranasal lidocaine jelly 2% (100 mg of lidocaine) and (2) Cetacaine spray (combination of tetracaine 2% and benzocaine 14%) applied to the pharynx. The control group received no topical anesthetics or vasoconstrictors. Physicians, whose technique was standardized before beginning the study, inserted 16F nasogastric tubes using plain gel lubricant. Blinding was deemed impractical, and no placebo spray was used. The primary endpoint of mean difference in overall pain score as measured on a visual analog scale was 29 mm (95% CI 12 to 45 mm), favoring the group that received topical anesthesia. No between-group differences in the difficulty of tube insertion or other complications were found. Epistaxis was not reported in either group.

Conclusion: Lidocaine intranasal jelly, combined with Cetacaine (tetracaine plus benzocaine) pharyngeal spray and a nasal vasoconstrictor, decreases the discomfort of nasogastric tube insertion. This difference appears to be both clinically8., 9. and statistically significant.2

1.3. Randomized clinical trial #3 

In 2000, Spektor et al4 reported findings from a randomized crossover study in which 10 healthy adult volunteers had nasogastric tubes inserted after receiving each of the following regimens on 3 separate occasions at least 24 hours apart: (1) 2.5 mL of nebulized lidocaine 4% to the nose and pharynx (100 mg of lidocaine) plus normal saline solution nasal spray plus normal saline solution pharyngeal spray; (2) nasal lidocaine 10% spray plus pharyngeal lidocaine 10% spray (100 mg of lidocaine total) plus nebulized normal saline solution; and (3) normal saline solution nasal spray plus normal saline solution pharyngeal spray plus normal saline solution via nebulizer.4 On all occasions, subjects received 5 mL of intranasal lidocaine 2% jelly (100 mg of lidocaine) plus 0.5% phenylephrine nasal spray. All nasogastric tubes were 16F and were passed by a single operator. The primary endpoint of mean within-subject difference in visual analog scale pain scores was 15 mm (95% CI 8 to 22 mm), favoring nebulized lidocaine over sprayed lidocaine. Complications (defined as epistaxis, gagging, coughing, choking, or vomiting) occurred less frequently in the nebulized lidocaine arm than in the lidocaine spray arm (difference in incidence of complications 43% [95% CI 22% to 65%]).

Conclusion: Among healthy volunteers, all of whom received intranasal lidocaine jelly and a nasal vasoconstrictor, those randomized to nebulized lidocaine delivered to the nose and pharynx had less discomfort and fewer complications from nasogastric tube insertion than those randomized to nasal and pharyngeal lidocaine spray. The difference in discomfort and complications appears to be both clinically8., 9. and statistically significant.4

1.4. Randomized clinical trial #4 

In 2000, Wolfe et al5 randomly allocated 40 adult ED patients requiring nasogastric tubes into 2 equal groups of 20 patients. The experimental group received 5 mL of intranasal lidocaine 2% jelly plus 1.5 mL of nasal lidocaine 4% spray plus 3 mL of pharyngeal lidocaine 4% spray, for a total dose of 280 mg of lidocaine. The control group received 5 mL of intranasal lidocaine 2% jelly plus normal saline solution nasal and pharyngeal spray, for a total dose of 100 mg of lidocaine. Lidocaine spray was delivered by means of a disposable mucosal atomization device. Lidocaine jelly was used in both groups to promote blinding. No vasoconstrictors were used. Experienced ED nurses inserted 16F nasogastric tubes. The primary endpoint of mean difference in overall pain score as measured on a visual analog scale was 27 mm (95% CI 15 to 39 mm), favoring the group receiving topical nasal and pharyngeal lidocaine spray. There were no inadvertent tracheal intubations. Other complications were not reported.

Conclusion: Addition of nasal and pharyngeal lidocaine spray to intranasal lidocaine jelly decreases the pain of nasogastric tube insertion compared with lidocaine jelly alone. This difference appears to be both clinically8., 9. and statistically significant.5

1.5. Randomized clinical trial #5 

In 2003, Ducharme and Matheson6 reported findings from a randomized crossover study in which 30 healthy adult volunteers had 3 nasogastric tubes inserted after receiving each of the following 3 regimens an hour apart: (1) 5 mL of intranasal lidocaine 2% jelly (100 mg of lidocaine) plus normal saline solution nasal spray; (2) 1.5 mL of atomized nasal lidocaine 4% spray (60 mg of lidocaine) plus 5 mL of intranasal placebo gel; and (3) 1.5 mL of atomized nasal cocaine 4% spray (60 mg of cocaine) plus 5 mL of intranasal placebo gel. In all 3 arms of the study, participants received 2 sprays of topical lidocaine to the pharynx to preserve blinding. All sprays were delivered by means of a disposable mucosal atomization device. No vasoconstrictors were used. All nasogastric tubes were 16F and were passed by a research assistant. The primary endpoint of mean within-subject difference in overall discomfort as measured on a visual analog pain scale found a trend favoring lidocaine gel.

Conclusion: In subjects receiving pharyngeal lidocaine spray, there was a trend favoring intranasal lidocaine gel over atomized cocaine nasal spray, and to a lesser extent, over atomized lidocaine nasal spray. However, this trend was not clinically or statistically of sufficient magnitude to support any firm conclusions.6., 8., 9.

1.6. Randomized clinical trial #6 

In this month's issue of Annals, Cullen et al7 randomized 50 adult ED patients requiring nasogastric tubes into 2 unequal groups. The experimental group (N=29) received 4 mL of lidocaine 10% (400 mg of lidocaine) delivered to the nose and pharynx by means of face mask nebulizer. The placebo group (N=21) received nebulized normal saline solution. Vasoconstrictors were not used. ED nurses passed 18F nasogastric tubes using plain gel lubricant. The primary endpoint of mean between-group difference in overall discomfort as measured on a visual analog scale was 22 mm (95% CI 5 to 38 mm), favoring the group that received nebulized lidocaine. There was no detectable difference in difficulty of insertion. However, epistaxis occurred more frequently in the lidocaine group (17% versus 0%, 95% CI for difference of 17% [4% to 31%]).

Conclusion: Nebulized lidocaine delivered to the nose and pharynx by means of nebulizer decreases the discomfort of nasogastric tube insertion. This difference appears to be both clinically and statistically significant.8., 9. Whether the increased incidence of epistaxis in the experimental group is caused by injury of insensate nasal mucosa, and if so, whether this may be reduced with vasoconstrictors remain unanswered.7

An additional interesting question raised by Cullen et al7 is whether lidocaine delivered by nebulizer is superior to sprayed lidocaine delivered by atomizer. The main difference between the 2 methods of delivery is that a nebulizer provides continuous delivery of medication and has baffles, which are designed to remove large droplets from the outgoing mist.10

Recently, concerns have surfaced about cross-contamination of patients by means of multi-use atomizers,11., 12. leading to a recommendation that single-use disposable atomizers be used.13 Indeed, 2 of the clinical trials discussed in this editorial used single-use, disposable atomization devices to deliver anesthetic sprays.5., 6. Until this question is resolved, it seems wise to avoid multi-use atomizers and use either disposable atomizers or (disposable) nebulizers. On the basis of a single small study, nebulizers may have a slight edge over atomized spray delivery.4

The theoretical concern that nasogastric anesthesia might place patients at increased risk of inadvertent tracheal intubation due to depression of protective airway reflexes has thus far not been substantiated. Among studies that examined this complication, either no difference was found between groups2., 5., 7. or there were fewer tracheal placements of nasogastric tubes among subjects receiving pharyngeal anesthesia than among those given placebo (difference of 22% [95% CI 4% to 40%]).4 This finding is consistent with the observation that coughing is associated with nasogastric tube misplacement.3 Although coughing may simply be a physiologic response to a nasogastric tube mistakenly passed into the larynx, it is also possible that it may sometimes be the cause rather than the effect of inadvertent tracheal intubation. This is at least plausible because the initial inspiratory phase of a cough entails a deep inspiration through a widely opened glottis, thus providing an opportunity for a nasogastric tube to slip into the trachea rather than the esophagus. The probability of tube misplacement into the airway might therefore be diminished if coughing is suppressed by application of local anesthesia, thus maintaining a closed glottis.14., 15.