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Three Part Question

In [conscious adults receiving drugs or fluids via the intraosseous route] is [an initial flush with local anaesthetic or with saline] more effective at [reducing pain]?

Clinical Scenario

Having been unable to obtain intravenous access you have just placed an intraosseous needle in a 30-year-old intravenous drug user who has attended the emergency department with a Glasgow coma scale score of 6, pinpoint pupils and respiratory rate of 3 following an opiate overdose. You are about to inject lidocaine to reduce the pain of the infusion when a passing colleague suggests that it is a waste of time as it will not be effective (as the pain is caused by pressure effects distant to the injection site). You wonder if there is any evidence to support your practice?

Search Strategy

Medline 1950–Week 46 2012 via NHS Evidence EMBASE 1980–Week 46 2012 via NHS Evidence [exp INFUSIONS, INTRAOSSEOUS/OR intraosseous.ti,ab OR IO.ti,ab] AND [exp PAIN/ or pain.ti,ab] Limit to: English language
A further search was performed using:

[exp Lidocaine/ or exp Tetracaine/ or exp Anesthetics, Local/ or exp

Bupivacaine/ or exp Anesthesia, Local/ or local anaesthetic.mp or

lignocaine.mp or exp Prilocaine/] AND [exp Infusions, Intraosseous/]

This did not reveal any more evidence.

Search Outcome

A total of 379 papers was identified by the stated search in Medline and 566 in EMBASE. Of these, two papers provided the best evidence to answer the question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Philbeck et al, 2009, USA	10 Healthy volunteers undergoing IO infusion into proximal humerus Incremental doses of 20 mg lidocaine injected via IO needle before flushing. Flush followed by further 40 mg lidocaine before commencing infusion. Pain scores recorded during infusion	Open-label trial	Pain on IO insertion (10-point VAS)	Mean 3.9 (±1.5)	Conference abstract only; small numbers; healthy volunteers; sponsored by device manufacturer
			Pain during infusion (10-point VAS)	Mean 2.0 (±1.2) after 20 mg initial bolus; no pain after 40 mg initial bolus
Philbeck et al, 2010 USA	Part 1: 10 healthy volunteers undergoing bilateral tibial IO access. Left tibial IO had 40 mg 2% lidocaine injected, followed by 10 ml saline flush and a further 20 mg lidocaine. The right tibial IO had 80 mg 2% lidocaine injected, followed by 10 ml saline flush and 20 mg lidocaine Part 2: 5 of the volunteers, plus an additional 6 had a proximal right humerus IO needle then 40 mg 2% lidocaine injected, followed by 10 ml saline flush and 20 mg lidocaine and then saline infusion at increasing pressures	Open-label trial	Mean pain during IO insertion	Tibia 4.4 (±2.6) left; 3.6 (±2.3) right Humerus 3.0 (±1.5)	Healthy volunteers; 5 took part in both parts, so may have become ‘habituated’ to IO access. 1 new volunteer to part 2 withdrew after IO insertion because of excess pain; sponsored by manufacturer
			Mean pain score during initial flush	Tibia 6.8 (±2.9) left; 7.9 (±2.8) right Humerus 4.6 (±2.9)
			Peak pain during infusion	Tibia 2.9, humerus 1.4 (also 8/10 in tibia study needed an additional lidocaine injection to the right tibia to keep infusion pain below 5)

Comment(s)

Injecting lidocaine to reduce the pain of fluid infusion via the intraosseous route is widely advocated but little studied. The two papers quoted are simple open-label trials with healthy volunteers comparing different doses of lidocaine rather than lidocaine against placebo. The fact that higher doses appear to be more effective in reducing pain (in the 2009 study) does suggest that local anaesthetic has some effect. The 2010 study suggests that proximal humerus intraosseous access is less painful than tibial. As there is some evidence of efficacy, further placebo-controlled trials in patients may be unethical. Further research to determine the optimum doses and rate of injection would still be beneficial.

Editor Comment

IO, intraosseous; VAS visual analogue scale.

Clinical Bottom Line

Injecting lidocaine both before and after flushing an intraosseous needle is an effective method of reducing the pain of fluid infusion via this route.

References

1. Philbeck TE, Miller L, Montez D. Pain management during intraosseous infusion through the proximal humerus. Ann Emerg Med 2009;54:S128.
2. Philbeck TE, Miller LJ, Montez D, et al. Hurts so good. Easing IO pain and pressure. J Emerg Med Serv 2010;35:58–62.