Arterial blood gas: local anaesthetic reduced pain.

Clinical bottom line (level 1b)

Patients who had local anaesthetic before arterial blood gas sampling felt less pain than those given placebo.
The procedure took around 30 seconds longer to perform, but multiple attempts were not clearly more likely.

Giner et al: Chest 1996; 110 (6): 1443-1445

Expires November 2002

The study

Double-blinded concealed randomised trial with intention-to-treat
Setting: university hospital, Spain

140 patients (aged mean 61 years, 67% male) undergoing lung function tests which required arterial blood gases from the radial artery
Control Group: (n = 70, 70 analysed): placebo
Experimental Group: (n = 70, 70 analysed): local anaesthetic used: mepivacaine 1% 0.2 ml sc

100% followed for ?

The evidence

Outcome	Time to outcome	CER	EER	RRR (95% CI)	ARR (95% CI)	NNT (95% CI)
multiple attempts required	unknown	5 (7.14%)	6 (8.57%)	-20% (-275% to 62%)	-1.43% (-10.3% to 7.48%)	-70 (NNT = 13 to infinity; NNH = 10 to infinity)

Outcome	Control Group (SD)	Experimental Group (SD)	Mean Difference (95% CI)
pain: visual analogue pain scale (0 to 10)	3.06 (2.15)	1.50 (1.54)	1.6 (0.94 to 2.2)
time taken to obtain sample (sec)	134 (15)	171 (13)	-37 (-41 to -32)

Thirty other patients had both venous and arterial punctures within a few minutes and they ranked the pain of each. Arterial puncture was more painful: mean difference 1.9 (95% CI: 1.5 to 2.3).

Comments

Note the technicians had an excellent first time success rate at 91%, suggesting expertise.
The benefits of anaesthetic may have been underestimated due to the technicians skill.
It would be interesting to see a similar study using topical anaesthetic.

Citation

Giner J, Pere C, Jose B, et al: Pain during arterial puncture. Chest 1996; 110 (6): 1443-1445

_{Clinical Question.}

_Patient	_{undergoing lung function tests}
_{Intervention or Exposure}	_{local anaesthetic before arterial blood gas sampling}
_Outcome	_pain