10% Lidocaine Versus 1% Diclofenac Spray in Radial Arterial Blood Gas Sampling: A Randomized, Double-Blind, Placebo-Controlled Trial using Perfusion Index.

BACKGROUND

Radial arterial blood gas (ABG) sampling is a common but painful procedure essential for assessing critically ill patients. Effective pain control is vital for patient comfort and procedural success.

OBJECTIVE

This study aimed to compare the analgesic efficacy of topical 10% lidocaine and 1% diclofenac sprays versus placebo in alleviating pain during radial ABG sampling. We also explored perfusion index (PI) as an objective pain assessment tool.

METHODS

This randomized, double-blind, placebo-controlled study was conducted in the emergency department. A total of 150 patients undergoing radial ABG sampling were randomly assigned to three groups: placebo (n = 50), 10% lidocaine (n = 50), and 1% diclofenac (n = 50). Baseline perfusion index (PI0) was recorded, sprays applied, and a 10-min waiting period followed. After ABG sampling, post-procedure measurements were obtained, including PI1 and pain intensity assessed using the Visual Analog Scale (VAS). Analgesic effects were compared based on VAS scores and changes in PI (ΔPI and %ΔPI).

RESULTS

The mean post-procedure VAS scores were 4.18 ± 2.09 (lidocaine), 4.80 ± 2.70 (diclofenac), and 4.90 ± 2.59 (placebo), with no significant differences between groups (p = 0.292). As a secondary finding, a moderate positive correlation was observed between VAS scores and %ΔPI (r = 0.379, p < 0.001). PI significantly decreased in all groups after ABG sampling, but no significant differences were observed among groups.

CONCLUSION

Topical 10% lidocaine and 1% diclofenac sprays did not provide significant pain relief compared to placebo. Although a moderate correlation between VAS and PI was observed, further research is needed to establish PI's clinical utility.

TRIAL REGISTRATION: ClinicalTrials.gov (NCT06918340).