Warmed versus room temperature saline for laceration irrigation: a randomized clinical trial. (Original Article).

Background: Patient comfort is an important part of laceration repair.

Methods: The study was a randomized single-blind cross-over trial in which each participant received 250 ml warmed and 250 ml room temperature saline irrigation in simple linear wounds after a local anesthetic was instilled. The solutions and the order of irrigation (warmed first versus second) were separately randomized with a washout period between. Investigators obtaining scores were blinded. Participants determined preferred solution, whether the solution was soothing, and which caused the most discomfort. Participants rated the pain of irrigation using separate Visual Analog Scale scores.

Results: Thirty-eight patients were enrolled in the study. Significantly more preferred warmed to room temperature solutions (difference, 34%; 95% confidence interval, 5.7--63). A Wilcoxon signedrank test for paired data showed no order effect (P = 0.49) or difference in pain measured according to the Visual Analog Scale (P = 0.082).

Conclusion: Warmed saline was more comfortable and soothing than room temperature saline as a wound irrigant among patients with linear lacerations.

Key Words: irrigation, laceration, patient comfort, temperature

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Key Points

* Patient comfort is essential in laceration repair.

* Warmed saline irrigation is more comfortable and more soothing than room temperature saline irrigation.

* We found no adverse effects of using warmed saline in this pilot study.

Wound irrigation is often the initial therapy of choice before suturing lacerations. (1) Normal saline is probably the most widely used irrigant due to its availability, safety, sterility, low cost, and few side effects. (2-5) Warmed saline has been shown to be more comfortable in ocular and aural irrigation; however, no studies have demonstrated a similar effect for wound irrigation. (6,7) The purpose of the present study was to compare warmed versus room temperature saline for wound irrigation. The hypothesis is that warmed solution would be significantly preferred to room temperature solutions for wound irrigation in anesthetized wounds.

Patients and Methods

Study Design

The study was a prospective, randomized, single-blind clinical trial. The university Institutional Review Board approved the study. Written informed consent was obtained from each participant.

Setting and Population

Study participants were patients with simple linear laceration presenting to a university emergency department (ED). No muscle was involved and the depth of the wounds were 1 cm or less.

Study Protocol

Participants were excluded if they were unable to consent due to intoxication, drug use, if they had severe injury, a contaminated wound, infection, an allergy to local anesthetics

From the Division of Emergency Medicine, University of California at Davis Medical Center, Sacramento, CA.

Presented at the annual meeting of the Society for Academic Emergency Medicine, 2001.

Reprint requests to Amy A. Emst, MD, FACEP, Division of Emergency Medicine, University of California at Davis Medical Center, 2315 Stockton Blvd., Suite 2100 PSSB, Sacramento, CA 95817. Email: [e-mail]

Copyright (C) 2003 by The Southern Medical Association 0038-4348/03/9605.0436 or a language barrier. Each participant received warmed and room temperature saline wouad irrigation in a single blind, randomized, crossover design with a 10-minute washout period in between. The study was conducted during a 6-month period. "Warmed" for the purposes of this study was defined as saline maintained at a temperature between 90[degrees]F (32.2[degrees]C) and 100[degrees]F (37.8[degrees]C), confirmed by digital thermometry. The pH of the saline solution was 7.47. The ambient room temperature was 70[degrees]F. Using sterile technique, wounds were sequentially irrigated with 250 ml room temperature normal saline at 76[degrees]F and 250 ml warmed normal saline with 10minute washout periods between irrigations of the different temperature solutions. The SPSS version 9.0 computer program (SPSS, Inc., Chicago, IL) was used to randomize the order in which the solutions were administered (ie, room temperature versus warmed first ). One physician delivered the irrigation and a different researcher collecting the data was blinded to the temperature of each solution. Although participants were not told which solution was warm or room temperature, blinding the participant was not possible because of perceived temperature differences.

After providing written informed consent, each participant lay supine on a gurney. Local anesthetic was administered before irrigation according to the protocol to render the lacerations painless for irrigation. The investigator irrigated the wound at a rate of approximately 3 ml/s with a luer tip syringe and guard. All lacerations were irrigated with the guard in the same fashion using 20-mi syringes. The distance from the wound was 3 cm. All wounds were checked for complete anesthesia before irrigating the wounds. When the first irrigation was completed, the participant was asked to rate the amount of pain experienced on a standard 100-mm Visual Analog Scale (VAS) in which one end was labeled "no pain" and the other end was "worst pain ever." Ten minutes afterward, the wound was again washed with the opposite solution in an identical fashion. The participant was again asked to rate the amount of discomfort experienced on a separate 100-mm VAS.

Participants were asked four questions:

1. Which was the preferred solution?

2. Which solution was more soothing?

3. Which caused the most discomfort of the solutions?

4. Was there irritation (ie, pain) noted?

Next, each wound was examined for signs of bleeding and rated according to a 5-point Likert scale. Any complications were listed.

Measurements and Main Results

The main end points determined a priori were preferred solution, soothing effect, and solution with most discomfort. Secondary end points were amount of bleeding. This was measured by a 5-point Likert scale (not previously validated).

Statistical Analysis

The statistical analysis software program used was SPSS version 9.0. Differences in discomfort between the two irrigation solutions were expressed using 95% confidence intervals (Cis). Paired 95% CIs were used for paired data and proportions involving the total of 38. The influence of order on patient preference was determined by comparing scores of the groups receiving warmed first versus room temperature first. A Wilcoxon signed-rank test was used to analyze nonparametric VAS data. With 35 lacerations, the study was powered at 0.8 with [alpha] = 0.05 and [beta] 0.2 to detect a 60 to 40% difference in preference between the two solutions.

Results

Forty patients participated in the study during an 18month study period in 2000 and 2001 (Fig. 1). Two were excluded due to protocol violation (irrigation before anesthetizing the wound). Three patients refused because they stated that this procedure would prolong their care in the ED. Twenty-four patients were male. The patients' mean age was 38 [+ or -] 15. The mean time until treatment after injury was 3 [+ or -] 1.8 hours. The mean length of laceration was 2.79 [+ or -] 1.3 cm with a mean depth of 0.54 [+ or -] 0.36 cm. Twenty patients were administered plain lidocaine local anesthesia, nine were administered lidocaine with epinephrine, and nine were administered bupivacaine. Twenty-one of the wounds were to the upper extremities, 2 were to the lower extremities, and 11 were to the face or the scalp. Ten patients were administered bupivacaine, and 28 were administered lidocaine. All wounds were anesthetic before irrigation, and all patients noted a difference in the temperatures of the two solutions.

Twenty-four patients (63%) preferred the warmed solution, 11 (29%) preferred the room temperature solution, and 3 (8%) preferred neither solution (difference, 34%; 95% CI, 6-63). Eighteen (47%) found the warmed solution soothing, 6 (16%) found the room temperature solution soothing, 2 (5%) found both soothing, and 12 (32%) found neither soothing (paired difference, 32%; 95% CI, 8-55). Nine patients (24%) found the warmed solutions caused more discomfort, 20 (53%) found that the cold solutions caused more discomfort, and 9 (24%) found both solutions to be approximately the same (difference, 29%; 95% CI, 3-55).

When asked about pain, 7 found the room temperature solution irritating, 1 found the warmed solution irritating, 2 found both irritating, and the remaining 28 found neither irritating (P > 0.05). There was no significant difference between the two solutions with regard to VAS scores for pain. The results are summarized in Table 1. There was no order effect found on the basis of nonparametric analysis (Mann-Whitney U test). These results are summarized in Table 1. A small amount of bleeding was noted in relation to the use of warmed irrigation (mean 0.9 on 5-point Likert scale). No other side effects were noted.

Discussion

In this study, we found that warmed saline was more comfortable for wound irrigation in participants with acute lacerations undergoing repair. A small amount of bleeding was noted in relation to use of warmed irrigation, which appeared to be minimal. No other side effects or complications were noted. Wound irrigation with warmed normal saline was independently more soothing and preferred by patients than was irrigation with normal saline at room temperature.

Previous studies have considered the difference in comfort and side effects when warmed solutions were used for local anesthetic use, (8) IV fluid administration, (9) ocular irrigation, (6) and ear irrigation. (7) It was found that local anesthetic injection, instilling LV fluid, ocular, and ear irrigation are more comfortable when warmed fluids were used. Until the present study actual comparisons between warmed and room temperature saline for wound irrigation have not been addressed.

This study differs from previous studies in that local anesthesia was applied before the study, so that the painful part of the procedure was not included as part of the study. Adequate anesthesia is verified by finding no difference in pain of irrigation as pain fibers are affected by local anesthesia. All patients were able to detect a difference in the two solutions, however, leading to differences in patient comfort levels from the different temperature solutions.

We continuously measured temperatures to be sure they were within the specified range for the irrigations. When necessary, we rewarmed some of the solutions as needed using a microwave oven. This has been demonstrated to be safe and effective for irrigation solutions. (10) Checking the solution's temperature may be useful to prevent administration of a solution that is too hot.

Previous studies have found an order effect in ocular irrigation (11) and in injection of local anesthetics in wound repair. (12, 13) In the present study, there was no order effect of the solution, confirming the success of randomization. This study showed that warmed solutions were preferred to room temperature for irrigation. Irrigation is important in cleansing traumatic wounds, which may have an implication in wound healing. (5,14) A previous study of intraoperative surgical wounds showed that wound hypothermia caused by the use of room temperature irrigation before closure may delay healing and thus predispose patients to wound infections. (15) Whether this has an implication for simple or more complex lacerations in the ED is yet to be determined. Further study of wound healing after the use of warmed solutions in patients with simple lacerations is needed.

This study has several limitations. The findings would not apply to situations in which larger amounts of solution are needed to irrigate larger wounds. Anesthetic use was not standardized for this study; however, the study was begun after administration of total wound anesthesia. Wound location was not standardized; however, all had clean simple lacerations needing irrigation and repair. Contaminated wounds have not been addressed either. This may not be standard practice in all cases but does represent a reasonable approach to wound management. The study was too small to determine if location of laceration affected the response to warm versus room temperature irrigants. It may be possible that some of what is being measured is response to solutions in unanesthetized areas; however, anesthetics do not block temperature fibers. The confidence interval results show wide ranges and may indicate results that need further testing.

Conclusion

We recommend administering warm solutions for wound irrigation. Related bleeding with the use of warmed solutions seems to be minimal.

Table 1

Results (a)

Variable (paired wound            Room
irrigation)                    temperature    Warmed         Neither

No. of participants             38             38
Preferred solution, N (%)       11 (29)        24 (63)        3 (8)
More soothing solution, N (%)    6 (16)        18 (47)       12 (32)
Worse solution, N (%)           20 (53)         9 (24)        9 (24)
Irritation, N (%) (b)            7 (18)         1 (3)        18 (47)
VAS order preference, N (%)     14 (37)        19 (50)        5 (13)
VAS pain scores, median (IQR)  0.9 (0.3-3.8)  0.5 (0-1.65)

Variable (paired wound                 Difference (%),
irrigation)                    Both   95% CI or P Value

No. of participants
Preferred solution, N (%)                 34%, 6-63
More soothing solution, N (%)  2 (5)      32%, 8-55
Worse solution, N (%)                     29%, 3-55
Irritation, N (%) (b)          2 (5)
VAS order preference, N (%)               P = 0.49
VAS pain scores, median (IQR)             P = 0.082

(a)Visual analog scale (VAS) readings for pain: 2-tailed P = 0.082.

(b)Not significantly different (P > 0.05).

(c)IQR, interquartile range; CI, Confidence interval.

Accepted August 2, 2002.

References

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(2.) Edlich RF, Thacker JG. Wound irrigation. Ann Emerg Med 1994;24:88-90 (editorial).

(3.) Howell JM, Stair TO, Howell AW, Mundt DJ, Falcone A, Peters SR. The effect of scrubbing and irrigation with normal saline, povidone iodine, and cefazolin on wound bacterial counts in a guinea pig model. Am J Emerg Med 1993;1l:134-138.

(4.) Dire DJ, Welsh AP. A comparison of wound irrigation solutions used in the emergency department. Ann Emerg Med 1990;19:704-708.

(5.) Moscati RM, Reardon RF, Lerner EB, Mayrose J. Wound irrigation with tap water. Acad Emerg Med 1998;5:1076-1080.

(6.) Ernst AA, Weiss SJ, Thomson T, Haynes ML. Warmed versus room temperature saline for ocular irrigation. Ann Emerg Med 1998;32:676-9.

(7.) Ernst AA, Takakuwa KM, Letner C, Weiss SJ. Warmed versus room temperature saline solution for ear irrigation: A randomized clinical trial. Ann Emerg Med 1999;34:347-350.

(8.) Bainbridge LC. Comparison of room temperature and body temperature local anaesthetic solutions. Br J Plast Surg 1991;44:147-148.

(9.) White SJ, Slovis CM, Stephens S, Jones S. Effect of fluid temperature on patient comfort during intravenous rehydration. Ann Emerg Med 1996;27:144 (abstr).

(10.) Werwath DL, Schwab CW, Scholten JR. Robinett W. Microwave ovens: A safe new method of warming crystalloids. Am Surg 1984;50:656-659.

(11.) McGary WB, Ernst AA, Nick TG, Walker LA III. Normal saline vs lactated Ringer's solution for ocular irrigation. Acad Emerg Med 1998;5:371-372 (letter).

(12.) Bartfield JM, Gennis P, Barbera J, Breuer B, Gallagher EJ. Buffered versus plain lidocaine as a local anesthetic for simple laceration repair. Ann Emerg Med 1990;19:1387-1389.

(13.) Orlinsky M, Hudson C, Chan L, Deslauriers R. Pain comparison of unbuffered versus buffered lidocaine in local wound infiltration. J Emerg Med 1992;10:411-415.

(14.) Anglen J, Apostoles PS, Christensen G, Gainor B, Lane J. Removal of surface bacteria by irrigation. J Orthop Res 1996;14:251-254.

(15.) Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization: Study of Wound Infection and Temperature Group. N Engl J Med 1996;334:1209-1215.

(16.) Moher D, Schulz, Altman D. The CONSORT statement: Revised recommendations for improving the quality of reports of parallel-group randomized trials. JAMA 2001;285:1987-1991.

From the Division of Emergency Medicine, University of California at Davis Medical Center, Sacramento, CA.

Presented at the annual meeting of the Society for Academic Emergency Medicine, 2001.

Reprint requests to Amy A. Ernst, MD, FACEP, Division of Emergency Medicine, University of California at Davis Medical Center, 2315 Stockton Blvd., Suite 2100 PSSB, Sacramento, CA 95817. Email: [e-mail]