Original research WOUNDS 2012;24(11):317 322 From 1 Connecticut Clinical Nursing Associates, LLC, Plymouth, CT; 2 Federal Hill Plastic Surgery, Bristol, CT Address correspondence to: Catherine T. Milne, APRN Connecticut Clinical Nursing Associates, LLC P.O. Box 1535 Bristol, CT 06011-1535 ccna2@juno.com A Comparison of Collagenase to Hydrogel Dressings in Maintenance Debridement and Wound Closure Catherine T. Milne, APRN, MSN, CWOCN 1 ; Armann Ciccarelli, MD, FACS 2 ; Mandie Lassy, BSN 1 Abstract: The role of maintenance debridement in wound healing has been well described, yet little is known regarding comparative methods and associated outcomes with this process when using collagenase or hydrogel. Objective. Evaluation of maintenance debridement and wound closure with collagenase compared to hydrogel in institutionalized adults with pressure ulcers from time of necrotic tissue removal up to 84 days from enrollment. Methods. This second phase of a rollover evaluation enrolled only subjects who successfully completed phase 1 (previously reported) from time of necrotic tissue debridement. Subjects received daily dressing changes with either hydrogel or collagenase followed by a standard semiocclusive dressing to evaluate wound-healing parameters and wound closure from initial enrollment to day 84. Investigators blinded to randomization evaluated weekly wound photographs using a digital planimetry software package for wound-healing parameters. Additionally, Pressure Ulcer Scale for Healing (PUSH) Tool and wound bed scores (WBS) were monitored. Results. Eleven of 13 subjects from the collagenase group entered into phase 2, with 4 of the 14 subjects from the hydrogel group. One subject from each group was eliminated within the first week of phase 2. All subjects (n = 3) in the hydrogel group reached complete epithelialization with a mean of 32.6 days. Nine of 10 subjects in the collagenase group reached completed epithelialization with a mean of 45 days. An independent samples t test showed no statistical significance between the 2 groups (P = 0.121) in days to healing. A Fisher s exact test performed on the primary endpoint of complete epithelialization also demonstrated no significant difference in outcomes between the groups (P = 0.99). Mean WBS at the onset of phase 2 was 13.7 (range 12-16), and the PUSH Tool mean score was 1.0 (range 0-3). In aggregating phase 1 and phase 2 data, a difference in the closure rates at the end of the study, 69% (collagenase) vs 21% (hydrogel), was statically significant (P = 0.0213) using a Fisher s exact test. Conclusion. Facilitating maintenance debridement by either collagenase or hydrogel can be used to complete wound closure when used in conjunction with a validated predictive wound-healing tool that closely monitors therapy. This study showed statistical significance in favor of collagenase when evaluating closure rates from the onset of the pressure ulcer. Vol. 24, No. 11 November 2012 317
318 WOUNDS www.woundsresearch.com Wound bed preparation (WBP) is an established concept in chronic wound management. Addressing the relationship between necrotic tissue, exudate, and bacterial and cellular dysfunction 1 leads to optimal outcomes. Execution of WBP includes eliminating necrotic tissue, bacterial burden, biofilms, edema, and exudate, while promoting the formation of granulation tissue. Debridement is one essential step in accomplishing these goals. Concepts related to debridement have evolved with increased understanding of WBP. Initially considered the removal of visible, nonviable tissue, debridement is further elucidated into 2 distinct phases: initial debridement and maintenance debridement. Initial debridement is defined as the removal of necrotic, damaged, and/or infected tissue. 2 However, despite removal of visibly necrotic tissue, phenotypically altered senescent fibroblasts and keratinocytes, coupled with accumulating extracellular matrix materials and substrates that may contribute to bioburden, need ongoing removal from the wound bed. 2-4 Maintenance debridement offers a continuous removal of cellular burden not visible to the naked eye and frees the wound bed from these obstacles to healing. Falanga s review of in vitro studies suggest that maintenance debridement may recruit functional cells to the chronic wound. 5 Maintenance debridement can be achieved via mechanical, enzymatic, or autolytic means; though there is little literature that associates these concepts in vivo. Regardless, incorporating this key concept in clinical practice is paramount to optimizing wound outcomes. The clinical setting in which maintenance debridement occurs often influences decision-making regarding treatment, as resources, patient populations, and expertise in wound management may differ. Clinicians often change from one therapeutic modality to another when the wound appears to be free from necrotic debris upon visual assessment. A less-skilled clinician often equates the absence of necrotic tissue with wound health, 4 failing to appreciate the pathophysiological processes occurring at the cellular level. Many skilled nursing facilities have adopted predetermined wound protocols, as standardization has been shown to improve wound healing outcomes. 6,7 Many protocols provided by wound care vendors strongly encourage changing from an active debridement process, such as an enzymatic agent, to a product that provides corrective moisture balance when visible, non-viable tissue has been removed. Collagenase has not been traditionally accepted in clinical practice for use beyond the removal of necrotic tissue, though in vitro work suggests collagenase may play a role in reducing formation of biofilms and bacterial proliferation, 8,9 and enhance keratinocyte proliferation and migration. 10,11 While comparison of hydrogel dressings and enzymatic debriding agents on wound healing have been done using swine, 12 there are no reports in the clinical area, or, specifically, the long-term care setting, where these agents are extensively used. The aim of this 2-phase study was to evaluate the outcomes of both hydrogel and collagenase on initial debridement of nonviable tissue and impact on the maintenance debridement phase of wound bed preparation. The results of phase 1, examining initial debridement, have been published. 13 This manuscript reports the time from complete debridement of visible, nonviable tissue to epithelialization from phase 2. Execution of wound bed preparation includes eliminating necrotic tissue, bacterial burden, biofilms, edema, and exudate, while promoting the formation of granulation tissue. Debridement is one essential step in accomplishing these goals. Collagenase has not been traditionally accepted in clinical practice for use beyond the removal of necrotic tissue, though in vitro work suggests collagenase may play a role in reducing formation of biofilms and bacterial proliferation, 8,9 and enhance keratinocyte proliferation and migration. 10,11 While comparison of hydrogel dressings and enzymatic debriding agents on wound healing have been done using swine, 12 there are no reports in the clinical area, or, specifically, the long-term care setting, where these agents are extensively used. Methods The study protocol was approved by the local Institutional Review Boards of the long-term care facilities from which patients were recruited. Patients or their legal representatives were asked to sign a written informed consent prior to entering phase 1. Inclusion and exclusion criteria for phase 1 have been reported, 13 and salient details have been reproduced (Table 1). Subjects were rolled over to phase 2 if complete debridement of all visible, nonviable tissue was complete by day 42, with continuance of pressure redistribution or offloading recommendations, and adherence to dietary intake recommendations. The primary outcome of this evaluation was to determine the number of days needed to achieve epithelialization, capped at 84 days. Secondary outcomes in-
Table 1. Inclusion/Exclusion Criteria Inclusion Criteria Age > 18 years Presence of at least 85% necrotic nonviable tissue on a pressure ulcer between 1 cm 2 and 64 cm 2 Hydrogel or collagenase dressing naïve on study pressure ulcer No current use of parenteral or oral antibiotics except for urinary tract suppressive therapy Hemoglobin A1C (HbA1c) < 7.9% Currently receiving adequate pressure redistribution to the affected area via devices such as a group 2 or group 3 specialty bed, and a static air wheelchair cushion if out of bed, and/or an offloading device if the pressure ulcer was located on the lower extremity Compliance with nutritional interventions per registered dietician No allergies to collagenase or hydrogel No allergies to semiocclusive secondary dressing Written informed consent Exclusion Criteria Steroid use > 5 mg daily Inability to cooperate with offloading recommendations Ankle-brachial index < 0.85 if the pressure ulcer was located on the lower extremity Presence of callus requiring sharp or surgical debridement within 3 days prior to enrollment Medical instability as deemed by the investigator Pregnancy Participation in another clinical trial or wound dressing evaluation in the 30 days prior to enrollment cluded the portion of patients with complete wound closure by 84 days, and the evaluation of changes in wound measurements on a weekly basis. Randomization occurred after informed consent was obtained to reduce selection bias. Subjects were assigned to either collagenase (Santyl Ointment, Healthpoint, LTD, Fort Worth, TX) or hydrogel (SoloSite Gel, Smith & Nephew, Largo, FL). Successful completion of phase 1 was determined by visual assessment by 1 investigator, and confirmed by wound photography using calibrated digital wound measurement software (PictZar, BioVisual Technologies, Elmwood Park, NJ) by investigators blinded to randomization category. Subjects remained on the same assigned agent when rolling over into phase 2. Each dressing change consisted of the following: normal saline irrigation with a device providing 4-15 psi (Irri- Max, Weston, FL) followed by application of the assigned therapeutic agent, nickel thick, to the entire wound bed. In the presence of wound depth, after application of the assigned agent, the wound was then filled to the depth equal to that of the surrounding wound tissue with gauze dampened with normal saline, so that there was no excess moisture noted when pressure from the clinician s hand was applied. The wound was then covered with a semi-occlusive dressing (CoverSite, Smith and Nephew, Largo, FL). Dressing changes, performed by the nursing staff at the long-term care facility, occurred on a daily basis and as needed if the dressing integrity was lost due to dislodgement or incontinence. Weekly subject evaluations, including subject and wound assessment, as well as wound photographs, were conducted by the same investigator. Wound photos were evaluated for wound healing parameters using calibrated digital wound measurement software (Pictzar, Biovisual Technologies, Elmwood Park, NJ) by 2 designated investigators blinded to randomization. In addition, each weekly photograph was assigned a wound bed score (WBS) 14 or a Pressure Ulcer Scale for Healing (PUSH) Tool score, 15-17 as each of these tools has shown reliability and validity in monitoring and predicting wound healing. Nursing staff at each facility were trained by one investigator in the wound dressing procedure. Other methods of debridement were not performed during phase 2. Subjects were assigned to either collagenase or hydrogel. Successful completion of phase 1 was determined by visual assessment by 1 investigator, and confirmed by wound photography using calibrated digital wound measurement software by investigators blinded to randomization category. Subjects remained on the same assigned agent when rolling over into phase 2. Dressing changes, performed by the nursing staff at the long-term care facility, occurred on a daily basis and as needed if the dressing integrity was lost due to dislodgement or incontinence. Results Twenty-seven subjects consented to participate over an enrollment period of 1 year. Thirteen subjects were randomized to the collagenase group; 14 were randomized to the hydrogel group. Data analysis was performed by SPSS. Using Student s t test, there were no significant differences in groups for age, gender, age of wound, or percentage of nonviable tissue at the time of enrollment (P < Vol. 24, No. 11 November 2012 319
Milne et al E leven of the 13 subjects from the collagenase group, and 4 of the 14 subjects from the hydrogel group, entered the portion of the study reported in this paper. One subject from each group was eliminated within the first week of phase 2. All subjects (n=3) in the hydrogel group reached complete epithelialization with a mean of 32.6 days. Nine of the 10 subjects in the collagenase group reached completed epithelialization with a mean of 45 days. An independent samples t test showed no statistical significance between the 2 groups (P = 0.121) in days to healing. Hydrogel group N = 14 Wound Closed 3(21%) Figure 1. Intent-to-treat wound closure rates. U Wound Closed 9(69%) D O N O T D 0.03). More than half of the pressure ulcers (55.5%) were related to devices such as splints, braces, ill-fitting wheelchair arm rests, or prostheses.wound size was statistically different; overall the collagenase group presented with larger wounds (P < 0.004) when entering phase 1. Eleven of the 13 subjects from the collagenase group, and 4 of the 14 subjects from the hydrogel group, entered the portion of the study reported in this paper. One subject from each group was eliminated within the first week of phase 2: 1 collagenase subject was lost to follow-up when transferred to an acute care facility for treatment of pneumonia; and 1 hydrogel subject was discontinued from the study after developing cellulitis at the wound site. Data analysis occurred on 10 of the collagenase and 3 of the hydrogel subjects using SPSS. There were no significant differences using a Student s t test in groups for age, gender, age of wound,wbs, or PUSH Tool score.there were no differences (P = 0.26) in wound size between the 2 groups at the onset of the rollover into phase 2, despite a statistical significance between groups at the onset of the entire study showing greater wound size in the collagenase group than in the hydrogel group (P = 0.04). At the time of complete debridement, 7 patients had stage 3 pressure ulcers (4 collagenase; 3 hydrogel) with the remaining 6 patients having stage 4 pressure ulcers (6 collagenase; 0 hydrogel). Significance in wound pressure 320 WOUNDS www.woundsresearch.com ulcer stage was noted using Chi-Squared analysis, with the collagenase group having greater severity (P = 0.03). All subjects (n=3) in the hydrogel group reached complete epithelialization with a mean of 32.6 days. Nine of the 10 subjects in the collagenase group reached completed epithelialization with a mean of 45 days. An independent samples t test showed no statistical significance between the 2 groups (P = 0.121) in days to healing. A Fisher s exact test performed on the primary endpoint of complete epithelialization also demonstrated no significant difference in outcomes between the groups (P = 0.99). The WBS mean at the onset of phase 2 was 13.7 (range 12-16) and the PUSH Tool mean score was 1.0 (range 0-3). Intent-to-treat closure rates were statistically significant (P = 0.0213) at the end of the study: 69% (collagenase) vs 21% (hydrogel) using a Fisher s exact test. (Figure 1). Weekly reductions in wound sizes occurred at a greater rate in the collagenase group (P = 0.009) as compared to subjects receiving hydrogel using a Fisher s exact test. PL 84 Days IC Collagenase group N = 13 A TE Patients N = 27 Discussion Hydrogels, which are composed of hydrophilic polymers in a dimensional matrix, are frequently used after the removal of visible necrotic material to provide moisture to the wound bed. By providing an exogenous source of moisture, the body s own physiological mechanisms to achieve wound repair can occur in the optimized environment. Maintenance debridement is achieved via moisture-facilitated cell migration in the absence of dessication18 and thermal insulation.19 Intrinsic enzymes recruited by the moist wound bed environment provided by hydrogel are selective in the protein degradation. This passive method of debridement has been shown to be slow and associated with anaerobic bacteria.18 Hydrophilic components and water content of hydrogels vary,
making general comparisons between this class of topical wound treatment and other, nonhydrogel treatments difficult. However, hydrogels have been shown to be superior to moist saline gauze dressings. 20 Hydrogels have shown efficacy in wound healing 19-22 and now have replaced wet-to-dry dressings as the product category for which to compare outcomes. 21 Bale et al 23 compared 2 amorphous hydrogels and found little difference in time to debridement between them. Eisenbud et al 22 in their review of physiological interaction of hydrogels with the wound bed suggested that one particular hydrogel offered no clinical benefit over any other hydrogel. Collagenase ointment, a metalloproteinase made from the bacteria Clostridium histolyticum, has been studied extensively with regards to its ability to degrade eschar in the clinical setting, though not for maintenance debridement. Herman 10 and Shi et al 11 have shown in vitro ability of collagenase to promote fibroblast proliferation, keratinocyte migration, and growth factor preservation. Falanga first suggested the clinical utility of collagenase in performing maintenance debridement. 3 The ability of collagenase to debride eschar from the edge of the wound while simultaneously promoting angiogenesis and reepithelialization, thus allowing a smaller wound to be managed at the time of complete eschar removal, was postulated. This may be considered a beneficial edge effect of collagenase. The results of this study suggest maintenance debridement begins at the time of initial application of collagenase, lending support to the findings of Margolis et al 24 for predictive significance of wound healing with edge migration. At day 84, there was complete epithelialization in 9 of the 13 intent-to-treat subjects assigned to the collagenase group, which clinically supports previous works by Riley and Herman 12, Herman 10 and Shi et al. 11 As collagenase in vitro avoids nondenatured collagen and other protein degradation, growth factors are preserved. Accumulation of nonviable cellular debris and remaining denatured collagen in the wound bed, invisible to the naked eye, promotes the prolongation of the chronic wound state. This study suggests collagenase may impact this accumulation. Additional studies with larger subject numbers are warranted. In the intent-to-treat hydrogel group, slower closure rates suggest that no edge effect with fibroblast proliferation and keratinocyte migration occurred. As hydrogel success is related to the host s ability to mount the physiological response for wound healing, the quick epithelialization time in the study suggests this group may have improved regardless. This may have influenced the nonstatistical significance between the primary outcome comparing days to healing. Further studies with larger subject numbers should be performed to confirm these findings. The prognostic ability of both the WBS and PUSH Tool to predict complete wound closure supports the previous works in this area. 14, 16-17 Upper quartiles of the WBS favor wound closure in pressure ulcers with a score of less than 14, as do PUSH Tool scores. Until biological markers that correlate with wound health are routinely available at the bedside, the use of these instruments can provide reliable objectivity to the clinician in guiding treatment decisions. Given cost considerations in the current health care economic climate, changing therapies without objective measurements that support prognostic capability based on wound visualization may not be cost-effective. Of the patients in the rollover analysis reported here, it is important to recognize that the continuum of data from phase 1 and phase 2 provides information on the clinical management of pressure ulcers in long term care. This was addressed by assigning these patients to identical clinical pathways with the only difference being the choice of debridement, enzymatic vs autolytic. In this case, the proportions healed (9 of 13 for collagenase; 3 of 4 for hydrogel) in this intent-to-treat group, encompassing both phases of the evaluation, were assessed at 84 days after the initiation of therapy (Figure 1). In this study, there is a statistically significant difference in the healing rates of 48 percentage points between the collagenase and hydrogel groups. Limitations of this study include the small number of enrolled patients that entered into phase 2. Further exploration into the area of maintenance debridement with Falanga first suggested the clinical utility of collagenase in performing maintenance debridement. 3 The ability of collagenase to debride eschar from the edge of the wound while simultaneously promoting angiogenesis and reepithelialization thus allowing a smaller wound to be managed at the time of complete eschar removal was postulated. This may be considered a beneficial edge effect of collagenase. In the intent-to-treat hydrogel group, slower closure rates suggest that no edge effect with fibroblast proliferation and keratinocyte migration occurred. As hydrogel success is related to the host s ability to mount the physiological response for wound healing, the quick epithelialization time in the study suggests this group may have improved regardless. Vol. 24, No. 11 November 2012 321
these and other agents is required. These results cannot be generalized to all hydrogels owing to their different chemical compositions. Generalizations cannot be made in populations with wounds caused by other etiologies or outside the long-term care setting. Conclusion Pressure ulcer healing continues to be a challenging issue for clinicians in the long-term care setting. In a frail population within a financially stressed health system, this study adds to the evidence base that facilitating maintenance debridement, either by collagenase or hydrogel, can be used to complete wound closure when utilized in conjunction with a validated predictive wound healing tool that closely monitors therapy. References 322 WOUNDS www.woundsresearch.com 1. Vowden K, Vowden R. Wound bed preparation. World Wide Wounds. www.worldwidewounds.com/2002/april/ Vowden/Wound-Bed-Preparation.html. Published March 2002. Accessed February 23, 2010. 2. Falanga V, Brem H, Ennis WJ, Wolcott R, Lisa JG, Ayello EA. Maintenance debridement in the treatment of difficult-to-heal chronic wounds. Ostomy Wound Manage. 2008;54(6)(suppl-1):S1-S13. 3. Falanga V. Wound bed preparation and the role of enzymes: a case for multiple actions of therapeutic agents. WOUNDS. 2002;14(2):47-57. 4. Panuncialman J, Falanga V. The science of wound bed preparation. Clin Plast Surg. 2007;34(4):621-632. 5. Falanga V. The chronic wound: impaired healing and solutions in the context of wound bed preparation. Blood Cells Mol Dis. 2004;32(1):88-94. 6. Bolton L, McNees P, van Rijswijk L, et al. Wound healing outcomes using standardized assessment and care in clinical practice. J Wound Ostomy Continence Nurs. 2004;31(2):65-71. 7. Baier R, Gifford D, Lyder C, Schall M, Funston-Dillin D, Ordin D. Quality improvement for pressure ulcer care in the nursing home setting: the northeast pressure ulcer project. J Am Med Dir Assoc. 2003;4(6):291-301. 8. Knox KR, Dariashvili RO, Granick MS. Surgical wound bed preparation of chronic and acute wounds. Clin Plas Surg. 2007;34:4633-641. 9. Smith RG. Enzymatic debriding agents: an evaluation of the medical literature. Ostomy Wound Manage. 2008;54(8):16-34. 10. Herman IM. Stimulation of human keratinocyte migration and proliferation in vitro: insights into the cellular responses to injury and wound healing. WOUNDS. 1996;8(2):33-41. 11. Shi L, Ermis R, Garcia A, Telgenhoff D, Aust D. Degradation of human collagen isoforms by clostridium collagenase and the effects of degradation products on cell migration. Int Wound J. 2010;7(2):87-95. 12. Riley KN, Herman IM. Collagenase promotes the cellular responses to injury and wound healing in vivo. J Burns Wounds. 2005;4:e8. www.ncbi.nlm.nih.gov/pmc/articles/pmc1501117/. Epub May 17, 2005. Accessed March 3, 2008. 13. Milne CT, Ciccarelli A, Lassy M. A comparison of collagenase to hydrogel dressings in wound debridement. WOUNDS. 2010; 22(11):270-274. 14. Falanga V, Saap LJ, Ozonoff A. Wound bed score and its correlation with healing of chronic wounds. Dermatol Ther. 2006; 19(6):383-390. 15. National Pressure Ulcer Advisory Panel (NPUAP). PUSH tool 3.0. Available at: www.npuap.org/pdf/push3.pdf. Accessed February 23, 2010. 16. Gardner SE, Hillis SL, Frantz RA. A prospective study of the PUSH tool in diabetic foot ulcers. J Wound Ostomy Continence Nurs. 2011;38(4):385-393. 17. Hon J, Lagden K, McLaren AM, et al. A prospective, multicenter study to validate use of the PUSH in patients with diabetic, venous, and pressure ulcers. Ostomy Wound Manage. 2010;56(2):26-36. 18. Turner TD. The development of wound management products. In: Krasner DI, Rodeheaver GT, Sibbald RG, eds. Chronic Wound Care: A Clinical Source Book for Healthcare Professionals, 3rd ed. Wayne, PA: HMP Communications; 2001:292-310. 19. Morin RJ, Tomaselli NL. Interactive dressings and topical agents. Clin Plastic Surg. 2007; 34(4):643-658. 20. Edwards J, Stapley S. Debridement of diabetic foot ulcers. Cochrane Database of Syst Rev. 2010;1:CD003556. 21. Sussman C, Bates-Jensen B. Wound Care: A Collaborative Practice Manual for Health Professionals. 4th Ed. Philadelphia, PA: Lippincott, Williams and Wilkins; 2011. 22. Eisenbud D, Hunter H, Kessler L, Zulkowski K. Hydrogel wound dressings: where do we stand in 2003? Ostomy Wound Manage. 2003;49(10):52-57. 23. Bale S, Banks V, Haglestein S, Harding KG. A comparison of two amorphous hydrogels in the debridement of pressure sores. J Wound Care. 1998;7(2):65-68. 24. Margolis DJ, Allen-Taylor L, Hoffstad O, Berlin JA. The accuracy of venous leg ulcer prognostic models in a wound care system. Wound Repair Regen. 2004;12(2):163-168.