Introduction
In 2002, 28.6 million intravenous (IV) catheters were placed in U.S. emergency departments (EDs).1 Venous cannulation for IV starts and blood draws is the most common procedure in the acute care setting, and cannulation causes moderate to severe pain in a significant number of patients.2
Multiple guidelines from national and international organizations, including the American Academy of Pediatrics, the American Pain Society, and the Society of Infusion Nurses, have been issued for minimizing the predictable pain of IV initiation. However, a survey of U.S. EDs showed that few institutions have practice protocols for decreasing the pain of cannulation.3
This article reviews recent literature on a variety of approaches to decreasing the pain associated with IV cannulation in both adult and pediatric patients.
Topical Skin Coolant for IV Insertion in Adults: No Pain Relief
Source: Harstein BH, et al. Mitigation of pain during intravenous catheter placement using topical skin coolant in the emergency department. Emerg Med J 2008;25:257-261.
The authors of this study sought to evaluate if cryoanesthesia, the use of a topical coolant to reduce pain, was an alternative to cutaneous analgesia for IV cannulation in an ED setting. The proposed mechanism for this type of anesthesia is that the rapid evaporation of the agent cools the skin and temporarily disrupts interpretation of pain signals.
The study was an unblinded, randomized, controlled study of a convenience sample of adults at two tertiary care centers. They used a skin coolant (1,1,1,3,3-pentafluropropate and 1,1,1,2-tetrafluoroethane) applied for 2-4 seconds and immediately followed by IV insertion. The outcome evaluated was decrease in pain of IV cannulation, and secondary outcomes were patient anxiety and projection of future anxiety, patient's pain during skin preparation, staff evaluation of vein visualization, and staff perception of the effect of the spray on procedural success. Outcomes were all evaluated via questionnaire responses.
The study found that the mean pain scores, using a 100 mm Visual Analogue Scale (VAS), were 27 mm (95% CI 19.9-34.1) in the study group and 28 mm (95% CI 20.4-35.6) (p=0.934) in the control group. There was no statistically significant difference between the two groups. Pain of preparation was slightly increased, anxiety regarding future IV cannulation attempts was less, and vein visualization was slightly improved in the study group. Sixty-eight percent of staff said they would use the spray again, and 72% of study participants reported that they would choose the spray prior to future cannulation attempts.
Commentary
Cryoanesthesia is typically easy to use, cost effective, and instantaneous in effect, potentially making it an ideal method for decreasing the pain of IV cannulation in an acute care setting. Unfortunately, evaluation of this method, which has been studied many times, has yielded mixed results. In this study, there is no statistical significance in pain reduction. Interestingly, however, both the patient and operator would opt to use this method for future cannulations.
Topical Skin Coolant for IV Insertion in Children: Pain Relief
Source: Farion KJ, et al. The effect of vasocoolant spray on pain due to intravenous cannulation in children. CMAJ 2008;179:31-36.
In this study, farion and colleagues evaluated the effectiveness of a vasocoolant spray to decrease the pain of IV cannulation in children.
This was a randomized, placebo-controlled, double-blind trial in 80 children age 6-12 years who were receiving IV cannulation at an academic tertiary children's hospital. A skin coolant (1,1,1,3,3-pentafluropropate and 1,1,1,2-tetrafluoroethane) was sprayed for 4-10 seconds, until skin blanching occurred; that was followed by cannulation within 60 seconds. Primary outcome was patient-reported pain. Secondary outcomes were success rate on first attempt and rating of patient's pain by parents, nurses, and child life specialists (who were present and provided distraction at every IV attempt).
This study found a significant reduction in patient-reported pain on a 100 mm VAS in the study group versus the control group (mean difference 19 mm, 95% CI 6-32 mm; p< 0.01). Evaluation of pain by parents, nurses, and child life specialists was significantly decreased with the study group, as well. Additionally, cannulation on the first attempt was 85% in the study group versus 62% in the control group, making the number needed to treat to prevent cannulation failure five.
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References
1. Pitts SR, et al.National Hospital Ambulatory Medical Care Survey : 2006 Emergency Department Summary. National Health Statistics Report. 2008 Aug; no 7. Hyattsville, MD: National Center for Health Statistics, 2008.
2. Singer AJ, et al. Comparison of patient and practitioner assessment of pain from commonly performed emergency department procedures. Ann Emerg Med 1999;33:652-658.
3. Bhargava R, et al. Procedural pain management patterns in academic pediatric emergency departments. Acad Emerg Med 2007;14:479-482. | 
