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Three Part Question

In [a patient requiring blood gases or arterial puncture] does [an injection of local anaesthetic][reduce pain without affecting success]?

Clinical Scenario

A 67 year old man attends with increasing shortness of breath. He is known to have obstructive airways disease. You want to perform arterial puncture for blood gases. He tells you that last time it was very painful.You wonder if an injection of local anaesthetic would help?

Search Strategy

Medline 1966-07/2001 using the Ovid interface.
[{exp blood gas analysis OR abg.mp OR arterial blood gas$.mp OR blood gas$.mp} OR ({exp arteries OR artery.mp OR arterial.mp AND {exp punctures OR puncture$.mp OR exp catheterisation OR cannulation.mp OR cannula.mp}) AND {exp anesthesia, local OR anesthetics, local OR local anesthesi$.mp OR local anaesthesi$.mp} AND {exp pain OR pain$.mp}] LIMIT to human AND english

Search Outcome

88 papers were identified of which 3 were relevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Dar K et al, 1995, England	55 acute medical admissions requiring blood gas measurement. Capillary samples from all patients, plus arterial sample after infiltration of 1% lignocaine or no infiltration using 22G needle	PCT	Pain of arterial puncture using a scale 0 to 10.	Lower mean pain score with LA 2.0 vs 7.0 without LA	Did not assess significance of difference between LA or not. Pain scores for capillary sampling are different for the two groups
			Preference of capillary or arterial sampling	Capillary sampling less painful
			Comparability of results from arterial and capillary samples	Mean differences for pO2 and pCO2 were not significant. Mean differences for pH and standard bicarbonate reported to be significant but clinically unimportant
Giner J et al, 1996, Spain	270 pts attending pulmonary function lab for abg. Arterial puncture with 22g needle after infiltration with 1% mepivacaine, placebo or nothing	PRCT	Pain using 10 cm visual analogue scale	Less pain with LA (1.5 cm vs 3.06 cm with placebo, p=0.00001) (1.5 vs 2.8 cm with nothing, p=0.0002)	Not emergency patients
			Time to prepare and perform	Less time without LA (134 seconds vs 171 seconds with infiltration, p<0.05)
			Success at first pass	First pass success 93% with LA, 91% with placebo and 90 % without infiltration, significance not tested.
Lightowler JV and Elliott MW, 1997, England	101 pts requiring abg. Arterial puncture with 29G needle after infiltration with 2% lignocaine, placebo or nothing.	PRCT	Pain, using a 4 point scale	Arterial puncture less painful with LA (1.5 vs 2.2 with placebo p=0.0008, 1.5 vs 2.1 with nothing p=0.0005)	Separates pain of infiltration from arterial puncture in scoring
			Difficulty of procedure as number of times skin broken, number of passes made and doctor rating.	No difference in difficulty, doctor rating 1.2 with LA vs 1.1 placebo vs 1.1 nothing

Comment(s)

Lightowler and Elliott surveyed junior doctors prior to their study and found that 84% never used local anaesthetic prior to arterial puncture citing that it made the procedure both more difficult and more painful. Dar et al cite two papers which showed delay in presentation to be an important contributor to deaths from asthma and suggest that a previous painful experience could lead to such a delay.

Clinical Bottom Line

Local anaesthetic infiltration prior to arterial puncture significantly reduces the pain of the procedure without affecting success rates.

References

1. Dar K, Williams T, Aitken R, et al. Arterial versus capillary sampling for analysing blood gas pressures. BMJ 1995;310:24-5.
2. Giner J, Casan P, Belda J, et al. Pain during arterial puncture Chest 1996;110:1443-5.
3. Lightowler JV, Elliott MW. Local anaesthetic infiltration prior to arterial puncture for blood gas analysis: a survey of current practice and a randomised double blind placebo controlled trial. J R Coll Physicians Lond 1997;31:645-6.