Is there an easy, effective, efficient, and inexpensive technique to reduce pain of arterial punctures?

This issue of RESPIRATORY CARE features a well-written paper by Haynes1 on the use of cryoanalgesia, specifically by application of an ice bag, to reduce pain associated with arterial puncture. Arterial puncture for blood gas (ABG) analysis is a common procedure in a variety of clinical settings, and although it is often performed in sedated patients on mechanical ventilation, it is also frequently performed on patients who are awake, and it can cause significant pain and discomfort.2 Perhaps due to the often time-sensitive nature of ABG analysis, the use of effective analgesic techniques for this procedure are not routinely employed in many settings.3 However, the lack of adequate analgesia can lead to unnecessary anxiety and morbidity and may also complicate successful completion of the procedure. Therefore, further study of effective and efficient means of providing adequate pain reduction for arterial puncture is clearly warranted. This was a randomized controlled trial of adult outpatients presenting to a pulmonary function laboratory for ABG collection. All blood draws were from the radial artery. The treatment group had ice bags applied to their wrists for 3 min before the puncture, whereas the control group had no ice bags. Pain was measured by a 100-mm visual analog scale. Haynes found a reduction in reported pain in the treatment group (mean visual analog scale score of 13.8 16.9 vs 25 23 mm). Subjects were also stratified as either naive (unable to recall a previous arterial puncture procedure) or experienced, and the analysis showed a significant reduction in reported pain in the naive group (mean visual analog scale score of 11 14.3 vs 26.5 25 mm) and a trend toward reduction in reported pain in the experienced group (mean visual analog scale score of 15.9 18.9 vs 25.1 22 mm). As noted by the author, the lack of statistical significance in the experienced group likely represents inadequate power of the study to detect a clinically important difference in the subgroups. A power analysis was conducted before the study, but only for the total group analysis. However, apprehension regarding the procedure or memory of previous pain associated with an arterial puncture may have also affected the scores of the experienced group. Haynes also found no difference in procedure success rate between groups: 85% of the treatment group successfully completed the procedure on the first attempt versus 82.5% of the control group. In addition, only 3 of 42 subjects in the treatment group could not tolerate the 3-min ice application. Although this topic has not been extensively studied, published studies provide useful comparisons. France et al4 conducted a randomized controlled trial of local anesthesia for arterial puncture with subcutaneous lidocaine, with ethyl chloride cooling spray (which has demonstrated efficacy for reduction of pain in venipuncture and peripheral venous cannulation5,6), or without anesthesia on 54 adult