|Ahead of print publication
Effectiveness of different techniques of ethyl chloride spray for venepuncture-induced pain: A randomised controlled trial
Parnandi Bhaskar Rao1, Chitta Ranjan Mohanty2, Neha Singh1, Manisha Mund1, Anamika Patel1, Alok Kumar Sahoo1
1 Department of Anaesthesiology and Critical Care, All India Institute of Medical Science, Bhubaneswar, Odisha, India
2 Department of Trauma and Emergency (Anaesthesia), All India Institute of Medical Science, Bhubaneswar, Odisha, India
Chitta Ranjan Mohanty,
Department of Trauma and Emergency, All India Institute of Medical Sciences, Bhubaneswar - 751 019, Odisha
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Venepuncture is an essential component of anaesthesia services. However, this invites pain generating the first negative experience with anaesthesia. Hence, relief of this pain carries considerable importance. Efficacy of ethyl chloride spray although studied, there is no consensus for the best way of application. Objectives: The present study was conducted to find an effective technique/method of ethyl chloride spray application to reduce venepuncture pain. Methods: Adult patients posted for different anaesthesia procedures were randomised into three groups. Venepuncture was done either after installation of distilled water or spray of ethyl chloride either once to twice. Venepuncture pain was assessed with a 0-100 Numeric Rating Scale. Results: The analysis showed significant differences among the groups (F [2,96] = 66.27, P < 0.05). The twice sprayed group experienced the least pain ([mean ± standard deviation [SD] 16.67 ± 10.21), lower in the once spray group ([mean ± SD] 27.58 ± 13.24), and the controls had the highest pain score ([mean ± SD] 49.09 ± 11.28). Post hoc Tukey's tests showed all the three groups differed significantly. The effect size was large, and the variability of the spray on the reduction of pain scores is 58% (η2 = 57.99). Conclusion: Ethyl chloride spray effectively reduces the pain on venepuncture, especially when the vapocoolant is sprayed twice each over 5 s, and from a distance of 5 cm perpendicular to the skin.
Keywords: Cannulation, ethyl chloride, pain, venepuncture
|How to cite this URL:|
Rao PB, Mohanty CR, Singh N, Mund M, Patel A, Sahoo AK. Effectiveness of different techniques of ethyl chloride spray for venepuncture-induced pain: A randomised controlled trial. Anesth Essays Res [Epub ahead of print] [cited 2019 Aug 20]. Available from: http://www.aeronline.org/preprintarticle.asp?id=262724
| Introduction|| |
Venepuncture is one of the most commonly performed invasive procedures leading to anxiety and pain. This may be considered their first negative experience related with the hospital course. Various non-pharmacological methods such as Valsalva manoeuvre and pharmacological agents such as eutectic mixture of local anaesthetics (EMLA) and ethyl chloride were used for cannulation pain relief with inconsistent success. None of the studies looked into the best technique of administration for effective pain relief at venepuncture.
Relief of this pain carries considerable importance in making their hospital course more pleasant. Therefore, the present study was undertaken to evaluate two different techniques of ethyl chloride spray on venepuncture-induced pain in patients undergoing elective anaesthesia procedures.
| Methods|| |
After approval from the institute ethics committee (ECR/534/Inst/OD/2014/RR-17) and written informed consent, 112 patients undergoing elective surgery under anaesthesia were recruited. Inclusion criteria were patient age >18 years, of both the sex. Patients with history of asthma, skin allergy, skin infection, uncooperative patients, history of allergy to local anaesthetics, pregnancy and requiring more than one venepuncture attempt were excluded from the study. The study was registered with the National Clinical Trial Registry bearing no. CTRI/2018/05/013728.They were randomised pre-operatively into three groups by computer-generated block randomisation of six. The group allocation was concealed from both patients and the assessor by utilising sealed envelopes. The sealed envelopes were opened only by the first investigator (CM), followed by spray according to the group allocation. All the bottles were covered by an opaque sheet of paper. Following the spray, venepuncture was done by an anaesthesiologist with more than 3 years of experience on the forearm using a 20G cannula after wiping with 70% alcohol. Group A patients received a spray of distilled water for 5 s from a distance of 5 cm; patients in Group B received a spray of ethyl chloride for 5 s perpendicular to the skin from a distance of 5 cm and patients in Group C received two sprays of ethyl chloride each over 5 s perpendicular to the skin. All patients reported the procedure related pain following a 0–100 mm pain rating scale where 0 means no pain and 100 means worst pain imaginable. The investigators (PBR and NS) who were blinded to both group allocation and spray, collected the data 5 min after the end of the procedure.
Sample size calculation
Considering Numeric Rating Scale to be the primary outcome and one-way analysis of variance (ANOVA) to be used to compare the means between three groups, a sample size of 33 per group (total 99) will achieve 90% power to detect a difference of 14 among the groups using an F-test with a 0.05 significance level. The common standard deviation within a group is assumed to be 18.00.
As the pain scores were found to be normally distributed by Shapiro–Wilk test, we expressed the parameters as mean (standard deviation [SD]). One-way ANOVA was used to determine whether the severity of pain scores differed among the control, once sprayed or twice sprayed groups. In addition, we did post hoc test to assess where the difference between groups exists exactly. P < 0.05 was assumed to be statistically significant.
| Results|| |
The flow of patients into the study is being represented in [Figure 1]. We recruited 112 patients out of which 8 were excluded for refusing to participate after giving consent and requiring more than one venepuncture attempt. Therefore, here, we present the analysis of 104 patients. There was no difference in the mean age or the gender distribution as depicted in [Table 1]. The analysis showed significant differences among the groups (F (2, 96) = 66.27, P < 0.05). The average pain score in the once sprayed group was mean ± SD 27.58 ± 13.24, whereas it was 16.67 ± 10.21 in the twice sprayed group. The control group had the highest level of pain on venepuncture 49.09 ± 11.28 as compared to the other two groups. We observed the twice sprayed group experienced the least pain (mean ± SD, 16.67 ± 10.21), somewhat lower pain in the once sprayed group (mean ± SD, 27.58 ± 13.24), whereas the controls had the highest pain score (mean ± SD, 49.09 ± 11.28). Post hoc Tukey's tests showed all the three groups differed significantly with each other. The size of the effect is quite large; the variability of ethyl chloride spray on the reduction of pain scores is 58% (η2 = 57.99). While the twice sprayed group on an average had the lowest pain scores, a wide variation is observed among all the studied groups. With regard to the severity of pain, none from the ethyl chloride spray groups had severe intensity of pain, whereas only 6% individuals in the control group had mild pain [Figure 2].
|Figure 2: Pain severity among the three groups. This figure depicts the severity of pain as experienced by the patients in the three studied groups. Majority in Group C had mild pain but none experienced severe pain, whereas only 6% in Group A had mild pain and the rest moderate-to-severe pain. The patients who received spray for once only also had a greater relief of pain with none experiencing severe pain and 73% had mild pain|
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| Discussion|| |
Venepuncture pain is a common but avoidable entity. The analgesic technique to reduce this pain is less often practised due to lack of an effective, readily available, cost-effective and quick onset drug or method. We studied the effect of increasing the number of ethyl chloride spray on venepuncture induced pain and evaluated against a control group. The study resulted in a significant reduction in pain when it is sprayed either once or twice as compared to the saline spray group. The group of patients, who received the spray once, had experienced a higher degree of pain scores than those receiving it twice.
Pain relief is considered to be a human right. In addition to local anaesthetic agents, there are some topical vapocoolant sprays such as ethyl chloride, and fluorohydrocarbons which produce immediate anaesthesia on the skin applied over. A rapid drop in skin temperature due to immediate evaporation of the volatile liquid brings in temporary but reversible desensitisation of the skin, hence interrupts all sensations including pain.,
The available studies evaluating the efficacy and safety of ethyl chloride spray are limited and also have controversial results. Selby and Bowles did a comparison of the available agents on the venepuncture pain. They found EMLA cream, lignocaine and ethyl chloride spray to be effective for reducing pain, but none was found to be superior to the other. In a similar study, Armstrong et al. found ethyl chloride to be effective if sprayed for 10 s in reducing the pain on venepuncture. In contrast, an unblinded randomised controlled trial conducted by Hartstein and Barry did not find any difference in the mean pain scores among patients receiving ethyl chloride (27 mm, 95% confidence interval [CI] 19.9, 34.1 mm) against no spray group (28 mm, 95% CI 20.4, 35.6 mm; P = 0.93). This probably results from bias induced by non-blinding and lack of a standardised technique of the vapocoolant spray which further reinforces the need and results of our study. Our study results not only corroborate with the role of ethyl chloride in reducing pain at venepuncture, but also supports a two times spray each of 5 s from a distance of 5 cm perpendicular to the skin.
Local anaesthetics have been utilised repeatedly for the purpose with good results, but injection in itself can be painful. In addition, there are reports of delayed time to intervention time and a similar or surprisingly higher pain scores with injectable lignocaine opposed to vapocoolant spray. Another similar study compared the reduction in pain on venepuncture in both arms in 17 patients with lignocaine spray. However, they did not observe any significant change in the study group as opposed to placebo. Few studies found lignocaine to be superior to ethyl chloride in mitigating the pain on cannulation. Although the beneficial effect of lignocaine can never be underestimated, these results probably also reflect a lack of an optimal technique of ethyl chloride spray. EMLA is a combination of lidocaine 2.5% and prilocaine 2.5% which requires to be applied over the site for at least 45 min. Riendeau et al. did a study to evaluate the effect of EMLA cream applying it for over 60, 90 and 120 min before venepuncture. They concluded that an application time for 60 min is effective enough to reduce pain on venepuncture significantly in patients with differing skin pigmentation. Hence, although effective, it is time-consuming and requires a lot of preparation mostly unsuitable for emergency, daycare and many other elective scenarios.,
Ethyl chloride spray has also been used for purposes such as ultrasound-guided steroid injections for musculoskeletal pain with good results. In contrast, a similar placebo-controlled randomised trial by Ballesteros-Peña et al. did not result in significant pain relief with ethyl chloride spray after arterial puncture as compared to the aerosol spray of alcohol in water group. A review done by Hogan et al. on 1266 patients found no beneficial effect of vapocoolant sprays on venepuncture pain which probably reflects the need of an appropriate technique rather than questioning the drug.
Literature evidence as regard to its spray technique varies a lot. The vapocoolant spray was sprayed from a distance of 10 cm for 2 s which was allowed to evaporate for 10 s and the venepuncture was performed after 20 s by Celik et al. Another similar study by Farahmand et al. utilised the ethyl chloride spray from a distance of 20 cm followed by wiping of the site after 5 s and cannula was put within 1 min of the spray. In contrast, Page and Taylor evaluated the effect of a vapocoolant spray administered for 2 s from a distance of 12 cm. With differences in the outcome, it is highly pertinent that either the drug or the technique needs to be scrutinised. We hypothesised that as the distance of spray increases area of spread shall increase but the concentration of the drug at the venepuncture site will be lesser. Therefore, we formulated two separate techniques consisting of once or twice spray from a distance of only 5 cm rather than 12 cm or 20 cm and compared to the saline spray group. This theoretically increases the concentration of the drug at the site making it available for cannulation immediately with better conditions. We observed ethyl chloride if sprayed from a distance of 5 cm may it be once or twice, effectively reduces pain on venepuncture. Even the group which received two sprays did better with respect to the pain scores as against those receiving spray only once. This further suggests a two-time spray of ethyl chloride for a better reduction in pain just before venepuncture.
We conclude that ethyl chloride spray is effective in reducing the vene puncture pain. The best technique is to spray twice and each over 5 s from a distance of 5 cm perpendicular to the skin. Future studies may explore other possibilities on this matter to find any better combination of distance and technique.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]