Abstract
The purpose of this research was to examine the effects of stockinets processed with deodorizing and antibacterial agents. The subjects were injured patients who received plaster cast immobilization. The following were performed: 1) sensory evaluation using an odor intensity measurement method, 2) measurement of residual odor concentrations of ammonia, acetic acid, and hydrogen sulfide, and 3) measurement of bacteriostatic activity values. Odor was significantly reduced in the processed stockinets (2.27 ± 0.93) compared to the unprocessed stockinets (2.92 ± 1.03). The odor concentrations were reduced and significant differences were observed in ammonia and hydrogen sulfide concentrations, but not for acetic acid. The bacteriostatic activity was 4.23 ± 0.70 for processed stockinets and a criterion of 2.2 or greater was satisfied. These findings demonstrated the deodorizing and antibacterial effects of the processed stockinets.
Introduction
Currently, there is great consumer demand for deodorizing products due to changes in social and living environments.1,2Thus, a wide variety of such products have been developed and sold. For example, Febreze (Proctor & Gamble, P&G) sold well in the US, Europe, and Japan during the global economic slowdown, helping it become the 24th P&G brand to reach US$1 billion in annual sales. 3
Although there has been a high demand for deodorizing products in the medical field, the problem of malodor has not been resolved. As Fleck reported, odor causes social embarrassment and fosters a destructive psychological impact on individuals. 4 In particular, malodor can become a major problem in orthopedics when plaster casts are used for long-term wear. This study examined the effects of a newly-developed stockinet processed with a deodorizing and antibacterial agent. The purpose of this study is to examine the deodorizing and antibacterial effects of a processed stockinet in comparison with an unprocessed stockinet.
Experimental
Materials
Inodore treatment 5 (Seiren Co. Ltd.), which involves a combination of antibacterial and deodorizing treatments consisting of physical deodorization using ceramics and chemical deodorization using metal ions and surfactants, was selected as the deodorizing and antibacterial process. The commonly-used stockinet in this study was commercially available (Alcare Co. Ltd). For each stockinet, one-half of its circumference was made of an inodore-processed fabric and the other half made of an unprocessed fabric, and the two halves were sewn together (Fig. 1). The stockinet was placed on a patient so that the seams would be located along the anterior and posterior midlines. This set up avoided any differences in processed and unprocessed stockinets due to variations in their location. Specifically, if the placement was on the upper limb, the seams were placed along the anterior and posterior midlines of the forearm or upper arm. If the placement was on the lower limb, the seams were placed along the anterior and posterior midlines of the thigh or lower leg (Fig. 1).
One-half of the stockinet circumference was made of processed fabric and the other half made of unprocessed fabric. The stockinet was placed on a patient so that the seams would be located along the anterior and posterior midlines.
Subjects and Stockinet Wear/Collection
The subjects were 50 patients who received plaster cast immobilization on their limbs (30 men and 20 women) due to fractures or sprains. The age range was from 2 to 83 years old (with mean age of 31.8 years). Patients were excluded if they had any skin disorder. Plaster casts were placed on the upper limbs in 25 patients and the lower limbs in 25 patients. The casts were worn between 7 to 41 days (with mean treatment time of 17.0 days). The stockinet was collected after the final cast removal, and cut in half to promptly evaluate the processed and unprocessed sides. The samples were placed in an empty 500-mL vinyl bag that could be sealed by a zipper immediately after cutoff.
Analysis
Sensory evaluations using odor intensity measurements, residual odor concentration measurements of ammonia, acetic acid, and hydrogen sulfide, and activity against Staphy-lococcus aureus were performed. Evaluations were done on the day of collection by three blindfolded evaluators—co-authors of this study who were stationary.
Sensory Evaluation
Sensory evaluation used the six grades odor intensity measurement method. 6 This measured the intensity of odor perceived by human sense of smell, where 0 = none, 1 = threshold, 2 = moderate, 3 = strong, 4 = very strong, and 5 = excessively strong odor. Sensory evaluation was performed in an odor-free laboratory room at a set temperature of 22 °C and humidity of ∼30%. The samples were divided into two equal parts, and half of the sample was used for both sensory evaluation and measurement of ammonia and acetic acid concentrations. The sample was placed in a 500-mL glass container and incubated at 40 °C for 1 h to diffuse the odor components, followed by sensory evaluation. The evaluation time was approximately 10 s with 5 min between evaluations.
Residual Odor Measurement
After sensory evaluation, the residual odor concentrations of ammonia and acetic acid were measured in the same container. Glass detector 3L and 81L tubes (Gastec Co. Ltd.) were used for the measurement of ammonia and acetic acid, respectively.
One-half of the sample was used for measuring ammonia and acetic acid concentrations and the remaining half of the sample was used for measuring the hydrogen sulfide concentration. The sample was placed in a 3000-mL vinyl bag containing 1000 mL of nitrogen and was incubated at 40 °C for 2 h. Gas, including the odor components, was injected into a concentration tube containing liquid oxygen as the cooling medium, followed by adsorption of the components. The concentration tube was then superheated and the odor components measured by gas chromatography using a Shimadzu GC-14B chromatography system (Shimadzu Co. Ltd.). The column contained 25% β, β’ oxydipropionitrile (ODPN), Uniport HP 60/80 mesh, and glass 3.1 m (GL Sciences Inc.) Nitrogen was used as the carrier gas, with the column, injection port, and detector temperatures set at 70 °C, 120 °C, and 120 °C, respectively.
A t-test was used to compare these values to the sensory evaluation results between the processed and unprocessed stockinets. The significance level was set at 5%.
Bacteriostatic Activity
Evaluations were made to determine whether the bacte-riostatic activity values of the treated stockinets satisfied the criterion of the Certification Standards of Antibacterial Finished Textile Products of the Japan Textile Evaluation Technology Council (JTETC). 7 This criterion was expressed as the bacteriostatic activity value = log (viable bacterial count for the control fabric after 18 h of culturing / viable bacterial count for the treated fabric after 18 h of culturing) > 2.2. The viable bacterial count was calculated using 0.4 g of stockinet (processed or unprocessed) which was inoculated with 0.2 mL of bacterial culture and incubated at 37 °C for 18 h. The stockinet was washed with 20 mL of saline containing 0.2% non-ionic surfactants. The bacterial count of the resulting wash fluid was calculated using the pour plate method. 7
Approval was given by the institutional review board of our university (Ethics Committee of the School of Medicine, Kanazawa University). Written informed consent was obtained from each patient. If the patient was under the age of 20, written informed consent was obtained from parent or guardian of patient.
Results
Sensory Evaluation
Odor was significantly reduced in the processed stockinets (2.27 ± 0.93) compared with the unprocessed stockinets (2.92 ± 1.03) (p < 0.05).
Residual Odor Measurement
The following were the residual odor concentrations for the processed stockinets and unprocessed stockinets: 0.93 ± 1.29 ppm and 1.57 ± 2.54 ppm (p < 0.05), respectively, for ammonia, 0.56 ± 0.90 ppm and 0.69 ± 0.98 ppm (p > 0.05) for acetic acid, and 0.0055 ± 0.0032 ppm and 0.0072 ± 0.0080 ppm (p < 0.05) for hydrogen sulfide. Significant differences were observed for ammonia and hydrogen sulfide concentrations, but not for acetic acid.
Bacteriostatic Activity
The bacteriostatic activity was 4.23 ± 0.70 for processed stockinets and 0.48 ± 1.49 for unprocessed stockinets, and the aforementioned criterion of 2.2 or greater was satisfied.
Discussion
Various osteosynthetic implants for internal fixation have been developed to date. However, external fixation by plaster cast is still an important treatment option not only for limb fractures, but also for tendon rupture and joint sprain. Plaster casts are generally worn continuously for long term, and malodor can be problematic.8,9 Especially in Japan, the climate can be very hot and humid during some parts of the year, and malodor can occur. In clinical practice, we tend to focus on treatment aspects, including fracture reduction and bone union. However, the same level of consideration should be given to address malodor that can reduce quality of life (QOL) due to anxiety, depression, and shame.4–10
Deodorization is divided into four major categories: physical deodorization, chemical deodorization, sensory deodorization, and biological deodorization. Physical deodorization uses porous materials to absorb malodor. In chemical deodorization, malodor components are broken down by chemical reactions into material of low odor level. Sensory deodorization masks malodor using a stronger odor. Biological deodorization uses microbes to break down malodor components.
It is difficult to apply the last two methods to deodorization of plaster casts. Yokoseki 11 and Furukawa12,13 have reported on a combination of physical and chemical deodorization. These reports used stockinets made from fibers which supported metal phthalocyanine derivatives developed by Shirai et al. 11 These stockinets were used on the stumps of amputated limbs—the deodorizing and antibacterial effects were objectively and subjectively evaluated. Because malodor associated with plaster casts is thought to be caused by bacterial contamination of secreted sweat, lactic acid, proteins, and lipids, 14 antibacterial effects were evaluated in their studies. Tough the results showed the effectiveness of the stockinets, these stockinets have not been made commercially available. Therefore, we began the development of stockinets that had antibacterial and deodorizing treatment with the prospect of commercialization, and we selected inodore treatment.
The advantages of inodore treatment 5 are that it is 1) effective against a wide variety of malodorous substances, 2) has antibacterial activity, and 3) can be applied to fabrics used in medical settings. Cotton fabric with inodore treatment was proven to have highly deodorizing effects for problematic odors in medical settings, such as sweaty odor (ammonia and acetic acid) and fecal odor (hydrogen sulfide) upon examination. Cotton fabric with inodore treatment had the ability to absorb nitrogen-containing organic compounds. Therefore, such fabrics demonstrated an antibacterial effect by degeneration of bacterial proteins. This effect also satisfied the aforementioned certification standards of the JTETC. 7 Inodore treatment could be performed on cotton, hemp, and rayon. Since two types of adhesive agents were used to immobilize deodorizing components onto the fibers, resistance to abrasion was increased without compromising the texture of the fiber or appearance.
The present study demonstrated the superiority of processed stockinets with inodore treatment over unprocessed stockinets. The effectiveness was determined by sensory evaluation, examination of residual odor concentration, and measurement of bacteriostatic activity even under unfavorable conditions in our study, which involved continuous, long-term wear. The processed stockinets developed in this study should be commercially available in the near future, and the QOL should improve in patients who are troubled by the malodors from wearing plaster casts.
A limitation of this study is that the effects of processed and unprocessed stockinets were examined in the same patients. Because the results of the preliminary experiment showed that there are large individual variations in malodor among patients, we selected as such a study design. Our future studies will include randomized trials to evaluate the effects of processed stockinets on malodors and QOL during cast immobilization.
Conclusion
This study demonstrated the deodorizing and antibacterial effects of the newly-developed processed stockinets. This stockinet will improve the QOL of patients who are troubled by malodors from wearing plaster casts.