Local application of EMLA and glyceryl trinitrate ointment before venepuncture

First do no harm: pain relief for the peripheral venous cannulation of adults, a systematic review and network meta-analysis

BACKGROUND

Peripheral venous cannulation is an everyday practice in hospitals, which many adults find painful. However, anaesthesia for cannulation is usually only offered to children. Inadequate pain relief is not only unpleasant for patients but may cause anxiety about further treatment and deter patients from seeking medical care in the future. The aim of this study is to discover the most effective local anaesthetic for adult peripheral venous cannulation and to find out how the pain of local anaesthetic application compares with that of unattenuated cannulation.

METHODS

These aims are addressed through a systematic review, network meta-analysis and random-effects meta-analysis. Searching covered 12 databases including MEDLINE and EMBASE from 1990 to August 2015. The main included study design was RCTs. The primary outcome measure is self-reported pain, measured on a 100 mm visual analogue scale.

RESULTS

The systematic review found 37 includable studies, 27 of which were suitable for network meta-analysis and two for random-effects meta-analysis. The results of the network meta-analysis indicate that none of the 17 anaesthetic considered had a very high probability of being the most effective when compared to each other; 2 % lidocaine had the highest probability (44 %). When the anaesthetics were compared to no treatment, the network meta-analysis showed that again 2 % lidocaine was estimated to be the most effective (mean difference -25.42 (95 % CI -32.25, -18.57). Other members of the 'caine' family were also estimated to be more effective than no treatment as were Ametop®, EMLA® and Rapydan® patch. The meta-analysis compared the pain of anaesthetic application with the unattenuated pain of cannulation. This found that all applications of local anaesthetic were less painful than cannulation without local anaesthetic. In particular a 1 % lidocaine injection was estimated to be -12.97 (95 % CI -15.71, -10.24) points (100 mm VAS) less painful than unattenuated cannulation.

CONCLUSIONS

The pain of peripheral venous cannulation in adults can be successfully treated. The pain of application of any local anaesthetic is less than that of unattenuated cannulation. Local anaesthetic prior to cannulation should become normal practice and a marker of high quality care.

PROTOCOL REGISTRATION

The protocol for the larger study was registered with PROSPERO no. CRD42012002093 .

The use of glyceryl trinitrate ointment with EMLA cream for i.v. cannulation in children undergoing routine surgery

This prospective randomized controlled double-blind trial was performed to investigate whether glyceryl trinitrate (GTN) ointment, applied ten minutes after the removal of a eutectic mixture of local anaesthetic cream, lignocaine/ prilocaine (EMLA), influences site selection for intravenous cannulation in children. Eighty children aged between five and 15 years, having general surgery as day patients, received EMLA cream on both hands for 90 minutes prior to transfer to the theatre suite. Acting as their own controls, the children received GTN on one hand, and placebo on the other, after removal of the EMLA cream and ten minutes prior to the insertion of an intravenous cannula. The application of GTN or placebo to left or right hand was blinded and randomized. At induction, the hand with the visually best quality veins was selected and cannulated. The primary outcome was selection between the EMLA/GTN hand and EMLA/placebo hand. The selection having been made, the number of attempts at cannulation, ease of insertion and pain scores (VAS) for cannulation were also recorded. The choice of hand was positively influenced by the use of GTN, with the GTN hand chosen in 51 of 72 (70%) children who completed the protocol (P = 0.001). The findings of this study suggest that the application of GTN after EMLA removal may be clinically useful in aiding cannulation in children.

Topical amethocaine (Ametop) is superior to EMLA for intravenous cannulation. Eutectic mixture of local anesthetics

PURPOSE

A eutectic mixture of local anesthetics (EMLA) is commonly used to provide topical anesthesia for intravenous (i.v.) cannulation. One of its side effects is vasoconstriction, which may render cannulation more difficult. A gel formulation of amethocaine (Ametop) is now commercially available. The aim of this study was to compare EMLA and Ametop with regard to the degree of topical anesthesia afforded, the incidence of vasoconstriction and the ease of i.v. cannulation.

METHODS

Thirty two ASA I adult volunteers had a #16 gauge i.v. cannula inserted on two separate occasions using EMLA and Ametop applied in a double blind fashion for topical anesthesia. Parameters that were recorded after each cannulation included visual analogue pain scores (VAPS), the presence of vasoconstriction and the ease of cannulation, graded as: 1 = easy, 2 = moderately difficult, 3 = difficult and 4 = failed.

RESULTS

The mean VAPS +/- SD after cannulation with Ametop M was 12+/-9.9 and with EMLA was 25.3+/-16.6 (P = 0.002). Vasoconstriction occurred after EMLA application on 17 occasions and twice after Ametop (P = 0.001). The grade of difficulty of cannulation was 1.44+/-0.88 following EMLA and 1.06+/-0.25 with Ametop (P = 0.023).

CONCLUSIONS

Intravenous cannulation was less painful following application of Ametop than EMLA. In addition, Ametop caused less vasoconstriction and facilitated easier cannulation. Its use as a topical anesthetic agent is recommended, especially when i.v. access may be problematic.

A comparison of the vasodilatation produced by two topical anaesthetics

The vasoactive properties of EMLA (eutectic mixture of local anaesthetic) and amethocaine were compared using Doppler colour ultrasound to measure vein diameter in 20 male volunteers. EMLA or amethocaine cream were applied over veins on the dorsum of the hand and vein diameter was measured prior to application of the preparations and at 1, 1.5 and 2 h after removal. Visual analogue scores for skin colour and vasodilatation were performed at 1 h. The results showed no significant difference in vein diameter between the EMLA and amethocaine groups. However, the amethocaine-treated hands were significantly more erythematous at 1 h (p < 0.00002).

Reducing the pain of venipuncture

Patient satisfaction with nursing care is the strongest predictor of overall satisfaction. Reducing discomfort of routine procedures, such as venipuncture for an intravenous insertion, can contribute to perceived satisfaction. This article reviews three common pharmacological interventions that can be used by perianesthesia nurses to reduce the pain of venipuncture.

EMLA patch for intravenous cannulation in adult surgical outpatients

PURPOSE

The purpose of this study was to evaluate the effectiveness of a single-unit-dose package of the EMLA Patch for dermal analgesia during intravenous cannulation in adult, outpatients and in preventing vaso-vagal side effects.

METHODS

After giving consent, 51 ASA I-III adult outpatients participated in a randomized, double-blind, placebo-controlled, parallel-group trial to receive either an EMLA or placebo patch applied to the intravenous cannula site for 60 to 90 min. Following cannula insertion, patients and investigators rated the pain using a 100 mm VAS ruler. The incidence and severity of vaso-vagal responses, local skin reactions, and willingness to pay for the patch were also evaluated.

RESULTS

The median VAS pain score by patient assessment in the EMLA patch group was lower (8 mm; range: 0-92) than in the placebo group (25 mm; range: 0-98, P < 0.05). The median VAS pain score by investigator assessment was also lower in the EMLA patch group (15 mm; range 1-79) than in the placebo group (23 mm; range 3-81, P < 0.05). There was a notable difference in the number of vaso-vagal reactions (17 placebo vs 4 EMLA, P < 0.05). Eighty-eight percent of patients who received the EMLA patch would be willing to pay for the patch in the future compared with 69% of the placebo patch patients.

CONCLUSION

This study showed that the EMLA patch, applied for 60-90 min before venous cannulation reduced the pain of venepuncture and vaso-vagal side effects in adult outpatients.

The application of EMLA and glyceryl trinitrate ointment prior to venepuncture

The efficacy of EMLA cream combined with glyceryl trinitrate (GTN) ointment was assessed by a double-blind prospective study. Adult female patients were randomly allocated to receive either EMLA 1 ml or 2 ml combined with GTN 2 mg, or EMLA 2 ml only. The difference in pain scores between the three groups was not statistically significant. When GTN was used with EMLA, the quality of the veins was superior and aided intravenous cannulation. There were no significant side-effects. It is concluded that if GTN is used with EMLA, the dose of EMLA can be reduced and intravenous cannulation is technically easier compared with EMLA alone.

Onset time of topical analgesia with EMLA 5%: no reduction with glyceryl trinitrate

Many adults are distressed by painful investigations or treatment, including venepuncture. The early effects of Eutectic Mixture of Local Anaesthetics (EMLA) 5%, on relief of pinprick pain in the antecubital area was investigated and compared with EMLA plus glyceryl trinitrate and with a placebo cream in 100 patients. Topical analgesia after application of EMLA developed within 5 min in 69% and within 10 min in 83% of those tested, significantly different from placebo, (P = 0.01).

Eutectic lidocaine/prilocaine cream. A review of the topical anaesthetic/analgesic efficacy of a eutectic mixture of local anaesthetics (EMLA)

Eutectic lidocaine/prilocaine cream 5% is a eutectic mixture of the local anaesthetics lidocaine (lignocaine) 25 mg/g and prilocaine 25 mg/g that provides dermal anaesthesia/analgesia following topical application. The principal indication in which eutectic lidocaine/prilocaine cream has been studied is the management of pain associated with venipuncture or intravenous cannulation, where significantly greater pain relief than placebo, with equivalent efficacy to ethyl chloride spray and lidocaine infiltration, has been demonstrated. In dermatological surgery, eutectic lidocaine/prilocaine cream offers effective pain relief in children undergoing curettage of molluscum contagiosum lesions, and in adults undergoing split-skin graft harvesting. Particular benefit has also been shown with use of eutectic lidocaine/prilocaine cream in association with treatment of condylomata acuminata in both men and women, and it appears to provide a useful alternative to lidocaine infiltration in this context. Further research in such indications as paediatric lumbar puncture, minor otological surgery, and minor gynaecological, urological and andrological procedures is likely to further broaden the profile of clinical use for eutectic lidocaine/prilocaine cream. Eutectic lidocaine/prilocaine cream has a very favourable tolerability profile, transient and mild skin blanching and erythema being the most frequent adverse events to occur in association with its application to skin. The potential for inducing methaemoglobinaemia, attributed to a metabolite of the prilocaine component of the formulation, prohibits its use in infants younger than 6 months. In summary, eutectic lidocaine/prilocaine cream is a novel formulation of local anaesthetics that has proven to be effective and well-tolerated in the relief of pain associated with various minor interventions in adults and children.

Topical glyceryl trinitrate and eutectic mixture of local anaesthetics in children. A randomised controlled trial on choice of site and ease of venous cannulation

One hundred and four children aged between 1 and 11 years were studied in a double-blind randomised controlled trial of glyceryl trinitrate ointment versus placebo, when used in addition to standard eutectic mixture of local anaesthetics cream. Each child received glyceryl trinitrate ointment on one hand and placebo on the other, and thus acted as his/her own control. A group of 30 children who received only the eutectic mixture on both hands (60 measurements) was also studied. The choice of site and ease of cannulation was scored. Skin colour and venous dilatation under the eutectic mixture were scored on a visual analogue scale. The addition of topical glyceryl trinitrate ointment to the standard eutectic mixture positively affected venous dilatation (p less than 0.01), choice of cannulation site (p less than 0.001), and ease of cannulation (p less than 0.001) of topical anaesthetic-treated skin.