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Local anaesthetic infiltration reduces the pain of arterial blood sampling

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 OR arterial blood gas$.mp OR blood gas$.mp} OR ({exp arteries OR OR AND {exp punctures OR puncture$.mp OR exp catheterisation OR OR}) AND {exp anesthesia, local OR anesthetics, local OR local anesthesi$.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,
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 needlePCTPain of arterial puncture using a scale 0 to 10.Lower mean pain score with LA 2.0 vs 7.0 without LADid 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 samplingCapillary sampling less painful
Comparability of results from arterial and capillary samplesMean 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,
270 pts attending pulmonary function lab for abg. Arterial puncture with 22g needle after infiltration with 1% mepivacaine, placebo or nothingPRCTPain using 10 cm visual analogue scaleLess 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 performLess time without LA (134 seconds vs 171 seconds with infiltration, p<0.05)
Success at first passFirst pass success 93% with LA, 91% with placebo and 90 % without infiltration, significance not tested.
Lightowler JV and Elliott MW,
101 pts requiring abg. Arterial puncture with 29G needle after infiltration with 2% lignocaine, placebo or nothing. PRCTPain, using a 4 point scaleArterial 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


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.


  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.