First-pass success of anatomical snuffbox versus distal forearm approaches for arterial blood gas sampling in the emergency department: a randomized controlled trial

Abstract

Background:

Arterial blood gas (ABG) analysis is essential in the emergency department (ED) for the rapid assessment of acid-base status, oxygenation, and metabolic disturbances in critically ill patients. The distal forearm (DF) is the conventional site for radial arterial puncture. Recent studies in interventional cardiology have explored the anatomical snuffbox (ASB) approach as an alternative vascular access site; however, its utility for ABG sampling in the ED remains unclear.

Methods:

In this single-center, randomized controlled non-inferiority trial conducted from May 2022 to October 2023, 356 adult patients requiring ABG analysis in the ED were randomized in a 1:1 ratio to undergo sampling via either the ASB or DF approach. Eligible patients had a palpable radial pulse at both access sites, while those with hypotension, local site abnormalities, or a positive Allen’s test were excluded. The primary outcome was the first-pass success rate; secondary outcomes included the number of attempts, failure rates (defined as failure to obtain a sample after three attempts), and procedure-related complications observed during a 12-h ED stay.

Results:

The DF approach demonstrated a significantly higher first-pass success rate (74.7%) compared with the ASB approach (60.7%; p = 0.006). The failure rate was lower in the DF group (5.1%) relative to the ASB group (21.3%; p < 0.001). Although minor complications such as hematoma, arterial spasm, and bleeding were noted in both groups, there were no statistically significant differences in overall complication rates.

Conclusions:

Although the anatomical snuffbox (ASB) approach has been proposed as an alternative access site based on potential benefits in other procedural settings, this trial found that it did not meet non-inferiority compared with the conventional distal forearm (DF) method for ABG sampling in the ED. Given the higher failure rate with the ASB approach, the DF method remains the preferred sampling site in this setting.

Trial registration:

The Clinical Trials Registry – India (CTRI/2022/07/044216).