The Hemostatic and Wound Healing Effect of Chitosan Following Debridement of Chronic Ulcers

Chitin (poly-N-acetylglucosamine) is found in the shells of crustaceans and the exoskeletons of insects.¹ Chitin is the second most abundant biopolymer in nature, with cellulose being the most abundant.² In the late 1970s, there was a growing interest in chitin as an abundant source of chitosan because of its unique cationic properties.³ The polysaccharide chitosan is a by-product of the alkaline deacetylation of chitin that occurs during seafood processing.⁴ Chitosan and chitin have shown promise as wound dressing materials largely owing to their hemostatic properties and antimicrobial effects.^5-7

Chitosan provides a nonprotein 3-dimensional extracellular matrix that stimulates fibroblast proliferation, natural hyaluronic acid synthesis, and tissue regeneration at the wound site.^8,9 In biopolymer gel form, chitosan offers hydrogel properties that are beneficial for keratinocyte delivery, which promotes skin healing and regulates burn wound exudate.¹⁰ Chitosan-based hydrogels promote wound healing by providing a moist wound environment, protecting against infections, removing wound exudate, promoting wound reepithelization, and accelerating angiogenesis.¹¹ In addition, the hydrogel provides a biocompatible delivery system for growth factors, drug delivery, antibacterial agents, and mesenchymal stem cells. The antimicrobial and antifungal properties of chitosan make it a favorable option for accelerating wound healing.¹²

Use of a biocompatible hydrogel and biodegradable antibiotic delivery system to inhibit the growth of bacteria can improve patient outcomes following traumatic injury or surgery.¹³  The antibiotic properties of chitosan and silver have been well-documented for use in wound healing.^14,15 In a pilot study of 10 children with partial-thickness burns, a chitosan-silver dressing was found to be optimal for moist wound management and wound healing without infections.¹⁶ In 19 patients with donor site split-thickness skin graft (STSG), the effective use of a chitosan-based gelling fiber dressing with silver was demonstrated.¹⁷ Use of the chitosan-based silver wound dressing resulted in markedly decreased pain between 1 and 14 days postoperatively at the STSG donor site. There were no donor site infections or adverse events, and acceptable quality of healing was achieved at the STSG donor site.

In a randomized, placebo-controlled, double-blind clinical trial, a 10% chitosan gel with isosorbide dinitrate spray combination therapy was used to treat 68 patients with diabetic foot ulcers.¹⁸ Isosorbide dinitrate is a vasodilator, and the 10% chitosan gel provides hemostatic properties. Of 61 patients who completed the study, the mean wound closure percentage was 71% ± 30 for patients who received the combination therapy compared with a mean of 50% ± 16 for patients who received the placebo (P <.001). Combination therapy was not better than chitosan or isosorbide dinitrate alone, however.¹⁸ In a study of 16 patients with venous leg ulcers, there was a mean 89% reduction in ulcer area (1.8 cm² weekly) following treatment with chitosan and compression bandage.¹⁹

Vorbeck²⁰ discussed the use of chitosan or carboxymethylcellulose dressing to treat 10 patients with venous ulcers. Chitosan was shown to be superior to carboxymethylcellulose in reduced wound size, improved dressing integrity, improved periwound skin quality, and reduced dressing shrinkage. In a pilot study of 4 patients, the combination of autologous platelet-rich plasma with chitosan-alginate membranes was used in the management of chronic venous ulcers.²¹ The ulcers were completely healed by an average of 5.4 months (range, 2–9 months) and accompanied by reduced pain, reduced exudate, and decreased bad smell for all 4 patients after the first treatment. In a different study, platelet adhesion to chitosan was enhanced in the presence of plasma and extracellular matrix proteins that resulted in activated platelets, indicating possible downstream effects on wound healing.¹

Uncontrolled hemorrhage results in 30% of trauma-related deaths, more than half of which occur before emergency care is administered.²² Since 2003, hemostatic dressings made of chitosan have been used to manage injuries in military and civilian emergency response settings, with promising results.^23,24 In an emergency medical services setting, a chitosan dressing controlled hemorrhage within 3 minutes of application in 27 of 34 cases (79%).²³ The failure rate of 21% (7 of 34 cases) was attributed to user error that was correctable with proper training and improved product design. 

Chitosan has been found to reduce blood clotting time in vitro by 40% compared with blood alone.¹ Chitosan induces clotting, which also depends on the positive charge of the amino groups on the molecule; the positive charge interacts with the membranes of red blood cells, which have a negative charge.²⁵ A higher degree of deacetylation results in a higher positive charge, which positively influences coagulation.^26,27 The form of chitosan used, whether as a solid or as a solution, has also been shown to influence the level of coagulation. To investigate if a dose-related response exists between chitosan concentration and coagulation, chitosan samples of varying concentrations were incubated with heparinized human blood for 30 minutes.²⁸ A dose-related clotting response was found, with higher concentrations of chitosan leading to greater coagulation. Mechanistically, the adhesion of platelets to chitosan seems to be mediated primarily by α_IIbβ₃ integrins and P-selectin following platelet activation.¹

Before autografting, adequate debridement, hemostasis, and infection control are critical to prepare the wound bed and prevent graft failure.²⁹ Significant blood loss can occur during debridement and excision, however.²⁹ In a study by Stone et al,²⁹ chitosan was shown to facilitate more rapid reepithelialization and nerve regeneration within the vascular dermis compared with conventional dressing. During wound debridement, excessive and prolonged bleeding may interfere with the wound healing process.³⁰ Compared with the use of gauze alone, the topical application of a chitosan-based dressing better controlled blood loss following wound debridement in a heparin-treated animal model.³⁰ For the current study of 20 patients with chronic wounds, the authors wanted to test if the same chitosan dressing would reduce bleeding in humans following wound debridement, with the subsequent result of decreased size of the wound area. In addition, the authors evaluated improvement in wound assessment scores, reduction in wound pain, and patient and provider satisfaction.  

Twenty patients between the ages of 52 years and 88 years were recruited from an outpatient chronic wound management clinic (Parkwood Institute Research, St. Joseph’s Health Care Wound Clinic, Southwestern Ontario, Canada) based on an institutional review board–approved study on the hemostatic properties of a chitosan-based gelling fiber dressing (Opticell; Medline Industries, Inc). The purpose of the study was to assess for patent acceptance and performance of the novel chitosan-based dressing in achieving hemostasis following wound debridement. The following inclusion criteria were used to select patients for this case series study: patient with skin wound requiring debridement, patient age greater than 18 years, patient capable of consent, and wound managed using best practice care as outlined in the Wounds Canada Best Practice Recommendations.³¹ The exclusion criterion was known sensitivity to any components of the chitosan dressing.  

Patient etiology included diabetic neuropathy (45%), lymphedema (15%), pressure ulcers (5%), and other etiologies (35%), as shown in Table 1. Wound size and area were determined during the first visit (prior to treatment) and 1 week after treatment. The Photographic Wound Assessment Tool (PWAT) was used to assess the degree of wound healing between visits.³² The revised PWAT is divided into 8 categories,³³ 5 of which are size, depth, necrotic tissue, granulation, and skin viability. The PWAT scores range from 1 to 4 per section (8 sections total), and total sum values range from 0 to 32, with a decrease in score an indication of wound healing. 

During the first visit (week 1), all ulcers and wounds were sharply debrided by curettage, electrocautery, scalpel, forceps, or a combination of methods. The chitosan-based gelling fiber dressing was then applied to the freshly debrided wound. The level of bleeding was rated as mild, moderate, or severe based on the judgment of the independent researcher. The time to hemostasis was measured in seconds from the time of application of the chitosan dressing to when hemostasis occurred, as assessed by the progression of bleeding on the chitosan dressing. Digital photographs of the wound sites were obtained at the time of debridement before applying the chitosan dressing and at 1 week after debridement and application of the chitosan dressing treatment (week 2). 

For pain caused by the debridement procedure, lidocaine (1%–4%) analgesia was administered as required. The pain score for each patient was assessed using an adapted Verbal Numerical Rating Scale consisting of no pain (0), mild pain (1–3), moderate pain (4–6), and severe pain (7–10).³⁴ Other outcomes measured patient and provider satisfaction with the dressing using a Patient Reported Acceptance Questionnaire (PRAQ) and Provider Acceptance Questionnaire (PAQ) measured on an analytical numeric scale. The PRAQ and PAQ were developed by the authors' research group and were accepted as an outcome measure by the ethics review board at the authors' institution. The scores on the questionnaires ranged from 1 to 5, with 1 being very dissatisfied; 2, dissatisfied; 3, neither satisfied nor dissatisfied; 4, somewhat satisfied; and 5, very satisfied. The maximum total possible PRAQ score for 7 questions is 35 (7 questions × 5 points maximum per question), and the maximum possible PAQ score is 15 (3 questions × 5 points maximum per question).

Statistical analysis was performed using a paired t test to determine if the mean change in PWAT score was significantly different from week 1 to week 2. A Wilcoxon signed rank test was used to determine if the wound area was significantly different from week 1 to week 2; this test was used because the data for wound area were not normally distributed. 

As shown in Table 1, there were 14 male patients and 6 female patients with a variety of etiologies, ulcer locations, and ulcer durations. All patients were evaluated as outpatients. The mean ulcer size was 6.8 cm² (range, 0.35 cm²–32.5 cm²), with an ulcer duration ranging from 3 weeks to 288 weeks. Of the 20 patients, 12 underwent ulcer debridement by curette, 2 by electrocautery alone, 3 by scalpel, 1 by scalpel and forceps, 1 by curette and electrocautery, and 1 by scalpel and curette. Following debridement, the chitosan dressing was applied to the freshly debrided wound site. The level of bleeding was rated as mild in 9 patients, moderate in 9, and severe in 2. The overall mean time to hemostasis was 75 seconds ± 41 SD, with mean bleeding time for mild, moderate, and severe bleeds of 73 seconds ± 23 (n=9), 58 seconds ± 15 (n=9), and 168 seconds ± 76 (n=2), respectively. One patient in the mild bleed group was considered an outlier because the patient was on a factor Xa inhibitor. However, there was a wide range of time to hemostasis (28 seconds–221 seconds), with the most bleeding at 114 and 221 seconds in the 2 patients with severe bleeds.

Figure 1 shows a representative wound site before debridement, after debridement, and 1 week following chitosan dressing application. This patient had a PWAT score of 25 at the first visit and 17 at the second visit, demonstrating an 8-point decrease by 1 week following debridement.

Patient pain score following debridement (week 1) at the time of debridement and 1 week after debridement following treatment with the chitosan dressing (week 2) is shown in Table 2. Nine patients required lidocaine 1% to 4% for pain during debridement, and 11 patients required no analgesic. Twelve of the 20 patients (60%) experienced no pain following debridement treatment at week 1. The remaining patients had pain scores ranging from 1 to 7. Of the 7 patients who reported experiencing pain at week 1, 2 patients reported a 100% decrease in pain at week 2, 2 reported a 50% to 68% decrease, 2 reported a 25% decrease, and 1 reported a 0% decrease. Given the number of patients who reported no pain and the variance in analgesic administered, statistical analysis was not conducted on the change in pain score. Table 2 provides the patient pain scores at weeks 1 and 2 with additional detail regarding the decrease in pain and relationship to analgesic.  

The patient PWAT score and wound area following debridement at the time of debridement (week 1) and 1 week after debridement following chitosan dressing treatment (week 2) are shown in Table 3. For the 18 patients whose wound areas were evaluated at week 1, 50% (n = 9) had a decrease in the wound area and 50% (n = 9) had no change in wound area. As shown in Table 3, the mean wound area decreased from 6.91 cm² ± 7.81 (week 1) to 6.23 cm² ± 7.88 (week 2), representing a 0.67 cm² ± 1.1 decrease in the wound area, which was statistically significant (P =.004). Size of decreased wound area was a range of 0.0 cm² to 3.7 cm² (mean, 18% decrease). Two patients did not return for wound area assessment at week 2.  

In addition, the mean PWAT score was 17.70 ± 4.93 at week 1 and 11.42 ± 4.99 at week 2, representing a 6.42 ± 3.13 decrease in wound area from week 1 to week 2 (Table 3), which was also statistically significant (P <.0001). The PWAT scores at week 1 ranged from 9 to 28; scores were higher in patients with more complex wounds. The PWAT scores at week 2 ranged from 5 to 22, with 1 patient unavailable for evaluation. As shown in Figure 2, PWAT scores improved for all patients from week 1 to week 2. For all patients, the PWAT scores showed that wound healing had occurred after only 1 week of treatment, with scores decreasing by an average of 35% ± 18.

Seventeen of 20 patients completed the PRAQ. As shown in Table 4, there was a favorable response from those patients, with 3 questions receiving a mean response of 4.7 to 4.9 out of 5 and 4 questions receiving a mean response of 3.9 to 4.3 out of 5. The highest PRAQ score was for overall ease of wear (4.9 ± 0.2), and the lowest score was for overall improvement in your wound (3.9 ± 1.1). The mean total PRAQ score was 30.5 ± 3.9 out of 35, or 87%, with 35 being the highest possible satisfaction score. The provider highly rated the chitosan dressing, with a PAQ score of 15 (15 being the highest possible satisfaction score) for 19 patients, with 1 patient receiving a score of 13. 

During wound debridement, excessive and prolonged bleeding may interfere with the wound healing process.³⁰ Following initial wound debridement and 1 week of treatment, a chitosan dressing was shown to control bleeding and reduce wound size. For this study, the overall mean time to hemostasis was 75 seconds ± 41 (n = 20), with mean bleeding time for 2 patients with severe bleeds of 168 seconds ± 76. Routine treatment of chronic wounds begins with mechanical debridement to cleanse the wound of necrotic tissue, fibrin, or dressing remnants.³⁵ Chitosan has been applied after adequate debridement to control bleeding and promote wound healing. Chitosan is a natural hemostatic agent owing to its cationic alkaline polysaccharide and electrostatic interaction with anions on the surface of red blood cells.^35,36 In a study of STSG donor site blood loss, the hemostatic properties of a chitosan dressing and standard (petrolatum gauze) dressing were compared.³⁷ Blood loss in the chitosan group (n = 10) was 15.4 gm, compared with 26.3 gm in the standard group (n = 10), resulting in a 40% reduction in blood loss using chitosan. Other studies have shown that skin graft donor sites treated with chitosan showed better vascularization, connective tissue repair, epithelization, and epidermis maturation when compared to standard treatment.³⁸ 

Using the PWAT, significant improvement in PWAT scores and decrease in wound area was shown between week 1 and week 2 for 19 of 20 patients with chronic ulcers treated with the chitosan dressing. It was observed that 100% of evaluated patients responded favorably to treatment with the chitosan dressing, with an average decrease in PWAT score of 35% ± 18 at week 2. The study data align with previously published literature suggesting that chitosan dressings demonstrate excellent hemostasis and overall wound area reduction. In a pilot study of 20 patients with pressure ulcers, wound area reduction and patient satisfaction were evaluated following treatment with a chitosan gel.³⁹ Overall, 90% of patients responded, and 20% of the wounds were completely healed by 30 days of treatment. The wound area following treatment significantly improved compared with pretreatment (P =.0002). Patient satisfaction with the treatment was assessed by visual analog scale (VAS), with scores ranging from not satisfied (0) to fully satisfied (100). At day 14, the VAS scores ranged from 15 to 75. At day 30, the scores ranged from 21 to 100.³⁹ Based on the PRAQ results at week 2, the mean total PRAQ score was 30.5 ± 3.9 out of a possible 35, or 87%, indicating that patients in the current study were satisfied with the wound healing results. In addition, the PAQ scores were the highest possible as provided by the attending physicians.

Following debridement and application of chitosan dressing, 60% of the patients in the current study experienced no pain, and 35% experienced decreased pain from week 1 to week 2. Only 1 patient, who reported the highest pain assessment score of 7, experienced no change in pain level. In an open multicenter randomized clinical study of patients with chronic wounds, the primary endpoint was wound reduction, and the secondary endpoint was pain reduction.⁴⁰ A total of 90 patients were treated with either a chitosan wound dressing (45 test patients) or petrolatum gauze (45 control patients). After 4 weeks of treatment, there was significant wound area reduction in the test group (mean, 65.97% ± 4.48) compared with the control group (mean, 39.95% ± 4.48). The average pain level was 1.12 ± 0.23 in the test group and 2.30 ± 0.23 in the control group.

Even though the methodology indicates that healing occurred with the chitosan dressing, this study lacks a comparison group to assess outcomes for similar wounds. The type of ulceration wounds included in the patient sample was similar but quite diverse and without comparison. Therefore, it is difficult to know for certain if these changes are truly significant. Another limitation is time to complete wound healing. This study was abbreviated to a duration of only 1 week. As a result, complete wound healing was not observed for most patients in the study. 

Adequate debridement, hemostasis, and infection control is critical to prepare the wound bed for treatment.⁴¹ Significant blood loss can occur during debridement and excision, however. Herein, the successful use of a chitosan dressing to control blood loss and decrease wound area is reported, along with PWAT scores following debridement of various wound etiologies and ulcer types. Overall, the results in 20 patients indicate that a chitosan dressing is an effective hemostatic agent that is able to control bleeding, reduce wound area, minimize pain, and promote healing of the wound site. Further study using this treatment approach in larger patient studies with longer duration and other wound types is warranted. 

This research was funded by a restricted research grant provided by Medline Industries, Inc., through the St. Joseph’s Health Care Foundation. Medline Industries provided medical writing support from Stephen Smith, PhD, for this manuscript.

Authors: David H Keast, BSc, MSc, MD, FCFP(LM); and Ashrafunissa Janmohammad, MBBS, MSc, MPH, CCRP

Affiliation: Lawson Health Research Institute, London, Ontario, Canada

Correspondence: David Keast, BSc, MSc, MD, FCFP(LM), Associate Scientist, Lawson Health Research Institute, Parkwood Institute Research, 550 Wellington Road, Suite B3-187, PO Box 5777 Stn B, London, Ontario N6A4V2 Canada; david.keast45@outlook.com

Disclosure: The authors disclose no financial or other conflicts of interest.