Vapocoolant Spray vs Subcutaneous Lidocaine Injection in IV Cannulation
Vapocoolant Spray vs Subcutaneous Lidocaine Injection in IV Cannulation
Background We compared the efficacy, acceptability, and safety of a topical vapocoolant alkane spray and 1% plain s.c. lidocaine in reducing pain from i.v. cannulation.
Methods This was a non-blinded, randomized, controlled trial, in a large emergency department. Adult patients requiring i.v. cannulation were enrolled. The vapocoolant was administered from a pressure pack, at a distance of 12 cm for 2 s, and cannulation was undertaken within 15 s. Alternatively, 1% plain lidocaine 0.2 ml was administered s.c. using a 27 G needle, and cannulation was undertaken after a minimum of 30 s. The primary outcomes were anaesthetic administration and cannulation pain (0–100 mm visual analogue scale). Convenience of anaesthetic use and patient satisfaction were measured using a five-point Likert scale.
Results One hundred and ten patients were enrolled in each group. The groups did not differ in age, gender, cannulation anxiety, cannulator experience, cannulation indication or site, or cannula size. Median anaesthetic administration pain scores were 0 and 11 mm in the vapocoolant and lidocaine groups, respectively (P<0.001). Median cannulation pain scores were 9 and 0 mm, respectively (P<0.001). Vapocoolant was associated with greater cannulation success (83.6% vs 67.3%, P=0.005), less time to administer (median 9.0 vs 84.5 s, P<0.001), and more staff convenience (median 5 vs 4, P<0.001). Median patient satisfaction was 4 in both groups. Unexpected events were rare and minor.
Conclusions Although vapocoolant reduces cannulation pain less than lidocaine, it has a number of important advantages. Vapocoolant offers a useful alternative in the emergency department setting.
Approximately one-half of patients undergoing i.v. cannulation report moderate pain and anxiety before the procedure. Pain scores range from 20 to 35 mm on a 100 mm visual analogue scale. Accordingly, local anaesthesia before cannulation has been investigated. S.C. or intradermal lidocaine is shown to effectively reduce cannulation pain by clinically important amounts. However, lidocaine injection itself is painful, and there is the theoretical risk of needle stick injury. Additionally, reports are divided as to whether local tissue distortion increases or has no effect on cannulation failure rates.
Topical local anaesthetic agents have also been used before cannulation. However, EMLA® (lidocaine 2.5% and prilocaine 2.5%) and Ametop® (4% tetracaine) require application times of at least 45 min. In emergency departments, such delays before cannulation may be unacceptable if immediate cannulation is required.
Topical vapocoolant sprays (e.g. ethyl chloride, fluorohydrocarbon, and alkane mixtures) can produce immediate skin anaesthesia. Rapid evaporation of the volatile liquid spray from the skin surface causes a decrease in temperature and results in temporary interruption of pain sensation, possibly through desensitization of pain receptors or activation of ion channels involved in pain transmission. Clinical trials of vapocoolant sprays before cannulation report varying results. Two studies showed ethyl chloride to be effective, whereas two others found ethyl chloride and fluorohydrocarbon to be ineffective. However, the most recent study by Hijazi and colleagues found that an alkane mixture of butane, propane, and pentane significantly reduced cannulation pain compared with a control (water) spray. Median cannulation pain scores were 12 and 36 mm in the vapocoolant and control groups, respectively.
In this study, we compared the efficacy, convenience, and acceptability of an alkane vapocoolant spray and s.c. lidocaine injection. Although lidocaine was expected to be more effective in decreasing cannulation pain, it was hypothesized that the vapocoolant would be quicker, easier to use, and be a viable alternative.
Abstract and Introduction
Abstract
Background We compared the efficacy, acceptability, and safety of a topical vapocoolant alkane spray and 1% plain s.c. lidocaine in reducing pain from i.v. cannulation.
Methods This was a non-blinded, randomized, controlled trial, in a large emergency department. Adult patients requiring i.v. cannulation were enrolled. The vapocoolant was administered from a pressure pack, at a distance of 12 cm for 2 s, and cannulation was undertaken within 15 s. Alternatively, 1% plain lidocaine 0.2 ml was administered s.c. using a 27 G needle, and cannulation was undertaken after a minimum of 30 s. The primary outcomes were anaesthetic administration and cannulation pain (0–100 mm visual analogue scale). Convenience of anaesthetic use and patient satisfaction were measured using a five-point Likert scale.
Results One hundred and ten patients were enrolled in each group. The groups did not differ in age, gender, cannulation anxiety, cannulator experience, cannulation indication or site, or cannula size. Median anaesthetic administration pain scores were 0 and 11 mm in the vapocoolant and lidocaine groups, respectively (P<0.001). Median cannulation pain scores were 9 and 0 mm, respectively (P<0.001). Vapocoolant was associated with greater cannulation success (83.6% vs 67.3%, P=0.005), less time to administer (median 9.0 vs 84.5 s, P<0.001), and more staff convenience (median 5 vs 4, P<0.001). Median patient satisfaction was 4 in both groups. Unexpected events were rare and minor.
Conclusions Although vapocoolant reduces cannulation pain less than lidocaine, it has a number of important advantages. Vapocoolant offers a useful alternative in the emergency department setting.
Introduction
Approximately one-half of patients undergoing i.v. cannulation report moderate pain and anxiety before the procedure. Pain scores range from 20 to 35 mm on a 100 mm visual analogue scale. Accordingly, local anaesthesia before cannulation has been investigated. S.C. or intradermal lidocaine is shown to effectively reduce cannulation pain by clinically important amounts. However, lidocaine injection itself is painful, and there is the theoretical risk of needle stick injury. Additionally, reports are divided as to whether local tissue distortion increases or has no effect on cannulation failure rates.
Topical local anaesthetic agents have also been used before cannulation. However, EMLA® (lidocaine 2.5% and prilocaine 2.5%) and Ametop® (4% tetracaine) require application times of at least 45 min. In emergency departments, such delays before cannulation may be unacceptable if immediate cannulation is required.
Topical vapocoolant sprays (e.g. ethyl chloride, fluorohydrocarbon, and alkane mixtures) can produce immediate skin anaesthesia. Rapid evaporation of the volatile liquid spray from the skin surface causes a decrease in temperature and results in temporary interruption of pain sensation, possibly through desensitization of pain receptors or activation of ion channels involved in pain transmission. Clinical trials of vapocoolant sprays before cannulation report varying results. Two studies showed ethyl chloride to be effective, whereas two others found ethyl chloride and fluorohydrocarbon to be ineffective. However, the most recent study by Hijazi and colleagues found that an alkane mixture of butane, propane, and pentane significantly reduced cannulation pain compared with a control (water) spray. Median cannulation pain scores were 12 and 36 mm in the vapocoolant and control groups, respectively.
In this study, we compared the efficacy, convenience, and acceptability of an alkane vapocoolant spray and s.c. lidocaine injection. Although lidocaine was expected to be more effective in decreasing cannulation pain, it was hypothesized that the vapocoolant would be quicker, easier to use, and be a viable alternative.
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