Wound Literature Review 2010

Abstract

General Concepts in Wound Management W1. Older Adults and Ulcers: Chronic Wounds in the Geriatric Population Cheung C. Advances in Skin and Wound Care. 2010;23(1):39–43. Article Type: Integrative review (CE) Description/Results: Provides overview of common problems affecting prevalence and management of wounds in the elderly, including relationship between chronic pain and increased fall risk, and between falls and diabetic foot ulcers. Addresses medication issues unique to the elderly, such as the need to reduce warfarin dosage by 50% during antibiotic administration (especially trimethoprim/sulfamethoxazole). Provides table addressing dosing and adverse effects of analgesic medications. What does this mean to me and my practice? This is a helpful resource for clinicians managing wounds in geriatric patients, and especially for those who are prescribing meds or counseling patients re: meds. W2. An evaluation of Cost and Effects of a Nutrition-Based Skin Care Program as a Component of Prevention of Skin Tears in an Extended Convalescent Center Groom, M, Shannon R, Chakravarthy D, Fleck C. Journal of Wound, Ostomy and Continence Nursing. 2010;37(1):46–51. Article Type: Research Study Description/Results: Skin treatment with a nutrient-based skin care (NBSC) formulation was compared to a non–nutrient-based skin care (non-NBSC) formulation. The number of skin-tear-free days was the primary outcome measure. 100 residents were followed for 12 months, 6 months on each protocol. There was a statistically significant difference (P = 0.000) in the incidence of skin tears: 180 skin tears in 6 months with the non-NBSC formulation, as compared to 2 skin tears in 6 months with the NBSC formulation. The number of expected skin-tear-free days using NBSC was 179.7 days as compared to 154.8 days with non-NBSC days. What does this mean for me and my practice? These data suggest that NBSC, along with a comprehensive skin tear prevention program (staff education, proper positioning, protective clothing, and appropriate repositioning and transfer techniques), may significantly reduce the incidence of skin tears. (Note authors received financial support for manuscript development.) W3. A Comparison of Collagenase to Hydrogel Dressings in Wound Debridement Milne C, Coccarelli A, Lassy M. Wounds. 22(11):270–274. Article Type: Research study Description/Results: Phase I of a 2-phase trial evaluating time to complete wound debridement using collagenase or an amorphous hydrogel. Over 1 year, 27 participants of long-term care facilities with necrotic pressure ulcers were randomized to collagenase (n = 13) or hydrogel (n = 14). The same investigator performed the initial and weekly assessments. Participants remained in the study until day 42 or complete debridement. In the collagenase group, 85% achieved full debridement within the 42 days as compared to 29% of the hydrogel group (P < 0.002). A decrease in wound size occurred more quickly in the collagenase group (P < 0.009). What does this mean to me and my practice? In situations where conservative sharp debridement is not possible due to the limitations of the staff performing wound care, collagenase may provide more rapid debridement than plain hydrogel. Limitations of the study include small sample size and commercial sponsorship. W4. The Effect of Various Wound Dressings on the Activity of Debriding Enzymes Shi L, Ermis R, Kiedaisch B, Carson D. Advances in Skin and Wound Care. 2010;23(10):456–462. Article Type: Research study Description/Results: This in vitro study compared the effects of cadexomer iodine, nanocrystalline silver, and a foam dressing impregnated with methylene blue and gentian violet on the enzymatic activity of collagenase and of papain. Results: Cadexomer iodine almost totally inhibited the activity of collagenase, and nanocrystalline silver produced a 52% reduction in enzymatic activity, while the methylene blue/gentian violet dressing produced no inhibitory effects. What does this mean to me and my practice? This study provides further evidence that enzymatic agents and antimicrobial dressings should be used together only if there are data demonstrating compatibility. W5. The Use of Dakin's Solution in Chronic Wounds Corwell, P, Arnold-Long M, Bernahl Brass S, Varnado M. Journal of Wound, Ostomy and Continence Nursing. 2010;37(1):94–103. Article Type: Case study/series Description/Results: Provides review of literature related to the antimicrobial effect of various strengths of Dakin's solution. Includes review of five case studies demonstrating that dilute Dakin's solution can be effective in selected situations. Addresses factors that must be considered when contemplating the use of Dakin's: goals of treatment; dilution (concentration), frequency of dressing change; duration of treatment; protection of periwound skin; and patient condition and tolerance of treatment. What does this mean for me and my practice? These case studies provide limited data supporting the use of dilute Dakin's (eg, 0.0125%) for selected wounds (wounds in the inflammatory phase of repair that would benefit from removal of necrotic tissue and/or reduction in bacterial loads). W6. Topical Cream or Inhaled Nitrous Oxide for Debridement Pain Bolton L. Wounds. 22(8):A10–A11. Article Type: Research study Description/Results: Multicenter open-label RCT pilot study compared the analgesic efficacy of a topical cream and an inhaled short-term anesthetic agent with oxygen in 41 patients prior to debridement. Curette debridement of venous and/or arterial leg ulcers was preceded by the administration of nitrous oxide with oxygen (NOO) at 9–12 L/min for 3 minutes (n = 20) or topical application of up to 10 g of lidocaine-prilocaine (LP) cream covered with occlusive plastic film dressing for 30 minutes (n = 21). Pain postdebridement was lower for the LP cream group (P < 0.001). Requests to interrupt debridement due to pain was more frequent with NOO (P < 0.002). What does this mean to me and my practice? These data demonstrate the efficacy of LP cream in reducing pain associated with debridement. W7. Validity of Diagnosis of Superficial Infection of Laparotomy Wounds Using Digital Photography: Inter- and Intra-observer Agreement Among Surgeons Von Ramshorst G, Vrijland V, Van der Harst E, et al. Wounds. 22(2):38–43. Article Type: Research study Description/Results: In a prospective observational study involving abdominal surgical wounds, 4 GI surgeons independently assessed photos of 100 wounds; 50 of the wounds had been opened due to clinical indicators of infection. Surgeons were asked to determine presence or absence of infection based on CDC criteria for superficial SSI (surgical site infection). In addition to the photos, surgeons were provided information regarding current and previous day wound pain scores, morning temperature, and postop day. Surgeons agreed on treatment for 76 of the 100 wounds (conservative management versus surgical drainage), but agreed on the diagnosis of infection for only 12 of the wounds that had been previously opened due to apparent infection. What does this mean to me and my practice? This study provides additional evidence that digital photography is not a stand-alone assessment tool, and that accurate assessment and diagnosis must involve physical assessment and relevant clinical data. W8. When and How to Perform a Biopsy on a Chronic Wound Alavi A, Niakosari F, Sibbald G. Advances in Skin and Wound Care. 2010;23(3):132–139. Article Type: Integrative review Description/Results: Comprehensive review of wound biopsies, to include indications, considerations, selection of biopsy site (which is determined by reason for biopsy), supplies, technique for performing various types (shave, punch, and elliptical deep excisional biopsy), and processing guidelines. What does this mean to me and my practice? This review is geared primarily toward midlevel providers or MDs performing biopsies; it provides clear clinical guidance in regards to when and how to perform wound biopsies. W9. Insights Into Acinetobacter War-Wound Infections, Biofilms, and Control Dallo S, Weitao T. Advances in Skin and Wound Care. 2010;23(4):169–174. Article Type: Integrative review Description/Results: Provides summary of findings from recent studies regarding infected wounds among military personnel with Acinetobacter infections. Includes discussion of antibiotic resistance and an overview of the process and time frame for biofilm formation associated with Acinetobacter infections. Suggests that immunization may be used in the future to protect against pathogens such as Acinetobacter. What does this mean to me and my practice? Review provides further insight into the problems associated with biofilm development and management. W10. A Cross-sectional Study to Validate Wound Care Algorithms for Use by Registered Nurses Beitz JM, van Rijswijk L. Ostomy Wound Management. 2010;56(4):46–57. Article Type: Research study Description/Results: Goal of study was to evaluate the use of wound care algorithms by acute care nurses; algorithms had been previously validated by wound care nurses. Nurses using the algorithm made appropriate dressing decisions 75–91% of the time. What does this mean to me and my practice? Study demonstrates that clinically validated algorithms can promote appropriate wound care by clinicians who lack expertise in wound care. W11. Hyperbaric Oxygen Therapy for Chronic Wounds Hunter S, Langemo D, Anderson J, Hanson D, Thompson P. Advances in Skin and Wound Care. 2010;23(3):116–119. Article Type: Integrative review Description/Results: Presents prognostic indicators for successful use of HBOT: TcPO2 at wound edge of <40 mm Hg that increases by at least 10 mm Hg in response to 100% oxygen via mask; and TcPO2 >200 mm Hg after HBOT. Addresses contraindications and risks associated with HBOT. Provides current criteria for CMS reimbursement (diabetic ulcers Wagner grade 3 or higher that do not respond to 30 days of conservative therapy). What does this mean to me and my practice? This review provides updated guidelines for appropriate use of HBOT. W12. Scale: Skin Changes at Life's End: Final Consensus Statement: October 1, 2009 Sibbald RG, Krasner D, Lutz J. Advances in Skin and Wound Care. 2010;23(5):225–238. Article Type: Integrative review (CE) Description/Results: Provides summary of recommendations generated by consensus panel convened to discuss skin changes at end of life (including Kennedy Terminal Ulcers). Recommendations emphasize the importance of thorough assessment of both skin status and patient's care goals, and development of an individualized management plan based on these data. Panel members also address lack of research regarding normal changes in skin and tissue status at end of life and identify specific research priorities. What does this mean to me and my practice? Concisely summarizes current guidelines for skin assessment and skin care for terminally ill patients. W13. Chronic Wounds Treated With a Physiologically Relevant Concentration of Platelet-Rich Plasma Gel: A Prospective Case Series Frykberg R, Driver V, Carman D, et al. Ostomy Wound Management. 2010;56(6):36–44. Article Type: Case series Description/Results: Series included 49 patients in several long-term acute care (LTAC) hospitals and outpatient clinics with 65 chronic wounds who were selected for treatment with PRP gel. Average wound duration was 47.8 weeks; article provides no discussion of previous treatment. 97% of patients showed progress toward healing as demonstrated by reduced area, volume, undermining, and sinus tracts/tunneling. What does this mean to me and my practice? Study results suggest that PRP gel may be a viable treatment option for chronic wounds that are poorly responsive to standard therapy. Findings are limited by the fact that this was a convenience sample with no control group. W14. The Lived Experience of Diverse Elders With Chronic Wounds Goldberg E, Beitz J. Ostomy Wound Management. 2010;56(11):36–46. Article Type: Research study Description/Results: Study was extension of previous study of 16 financially stable Caucasian elders; this study included 11 non-Caucasian elders with chronic wounds of >8 weeks' duration. Taped interviews and analyses were used to identify common themes in their lived experience: themes common to original group and this group included tolerating pain, limited mobility, and living with chronic illness. Concerns of this group that were different included cost considerations and impact on social roles; the previous group had identified distrust of caregivers and altered sleeping and eating habits. What does this mean to me and my practice? Provides helpful insight into potential concerns of various groups of elders with wounds. W15. Diagnosis and Management of Foreign Bodies in the Skin Winland-Brown J, Allen S. Advances in Skin and Wound Care. 2010;23(10):471–476. Article Type: Integrative review (CE) Description/Results: Provides review of assessment, diagnostic workup, and management of wounds associated with foreign bodies. What does this mean to me and my practice? Would be helpful for clinicians working in urgent care centers, emergency departments, and outpatient wound centers. W16. A Prospective Comparison of Clinical Outcomes and Medicare Expenditures in Skilled Nursing Facility Residents With Chronic Wounds DaVanzo J, El-Gamil A, Dobson A, Sen N. Ostomy Wound Management. 2010;56(9):44–54. Article Type: Research study Description/Results: Study involved 683 residents of long-term care facilities who had a chronic lower extremity wound documented by ICD-9 codes and the MDS. The study group included 372 residents, and the control group included 311 residents; groups were matched for severity of wounds, age, gender, diabetes, and other comorbidities. The study group was managed according to a comprehensive wound protocol under the direction of a consulting wound care specialist, and the control group was managed with usual care. Outcomes measures included wound-related hospitalizations and total cost of wound care to the point of closure. The study group had statistically fewer hospital days and days to healing. The total Medicare costs for the control group were almost double the costs for the study group ($21,449.64 vs $40,678.83). What does this mean to me and my practice? Provides support for the use of standardized guidelines for care and the role of wound care specialists. Data from this study would be helpful to a wound care nurse who is trying to prove his/her value in objective terms. Nutrition W17. Immunonutrition for High Risk Surgical Patients: A Systematic Review and Analysis of the Literature Marik PE, Zaloga GP. Journal of Parenteral and Enteral Nutrition. 2010;34(4):378–386. Article Type: Systematic review Description/Results: Provides a summary analysis of 21 studies with a total of 1918 patients treated with Immunonutrition Modulating Diets (IMD) containing arginine and fish oil. Formulas studied included Impact, Stresson, arginine alone, and fish oil alone. Patients on IMDs had significantly reduced incidence of postoperative infections (P < .0001), wound complications (P < .02), and length of stay (P < .0001), but no reduction in mortality. What does this mean to me and my practice? This study provides evidence of the effect of nutrition on surgical wound healing, especially its effect on the immune system. W18. Nutrition: A Critical Component of Wound Healing Posthauer ME, Dorner B, Collins N. Advances in Skin and Wound Care. 2010;23(12):560–572. Article Type: Integrative review (CE) Description/Results: Provides comprehensive review of nutrition as related to wound healing. Specific information includes tools and guidelines for nutritional assessment; review of reasons why lab data cannot be utilized as “sole indicator” of nutritional status; indicators of specific vitamin and mineral deficiencies; and recommendations for dietary interventions. Includes summary of nutritional support recommendations from NPUAP Guidelines (30–35 cal/kg body weight per day, 1.25–1.5 g protein/kg body weight per day, and vitamin/mineral supplements if dietary intake poor and vitamin-mineral deficiencies suspected). What does this mean to me and my practice? Provides thorough review of current guidelines for nutritional assessment and management of patients with wounds. W19. Sarcopenia, Cachexia, and Starvation Collins N. Ostomy Wound Management. 2010;56(2):14–17. Article Type: Integrative review Description/Results: Article addresses three causes of weight loss: sarcopenia, cachexia, and starvation. Provides guidance for selection of nutritional interventions based on etiology of weight loss: food, nutritional supplements, vitamins, selected amino acids, appetite stimulants, and/or anabolic agents. What does this mean to me and my practice? Provides in-depth review of the various types/causes of weight loss, with implications for management. This review is particularly valuable for wound care providers who do not have ready access to a dietitian. W20. Using Laboratory Data to Evaluate Nutritional Status Collins N, Friedrich L. Ostomy Wound Management. 2010;56(3):14–16. Article Type: Integrative review Description/Results: Provides thorough review of the various lab studies typically used in evaluation of nutritional status: albumin, prealbumin, C-reactive protein, retinol binding protein, transferrin, total lymphocyte count, and cholesterol. Addresses factors other than nutritional status that affect values and focuses attention on the fact that laboratory values should not be used as sole indicators of nutritional status. What does this mean to me and my practice? Provides clear explanations of factors affecting commonly used lab values, such as prealbumin, and implications for practice: laboratory values are only one element of a comprehensive nutritional assessment and cannot function as sole indicators. W21. Dealing With Patients Who Disregard Nutritional Advice Collins N. Ostomy Wound Management. 2010;56(6):16–20. Article Type: Integrative review Description/Results: Discusses concepts and types of nutritional nonadherence: nonadherence related to demographic characteristics, psychological variables, and social variables. Includes table of “tips” for dealing with patients who are nonadherent to nutritional advice. What does this mean to me and my practice? Provides very practical guidance to wound care nurses in assessing and assisting patients who are initially nonadherent to the nutritional treatment plan. W22. Nutrition Advice for Patients Living at Home Collins N. Ostomy Wound Management. 2010;56(10):18–21. Article Type: Integrative review Description/Results: Provides overview of nutritional needs of wound patients in the home setting, where there is typically lack of or very limited nutritional education. Provides practical tips for boosting calorie and protein intake and for managing blood glucose and kidney health. Includes extensive list of “healthy snacks” provided as a helpful alternative to nonspecific advice to “eat healthy” or “increase your protein.” What does this mean to me and my practice? Provides guidelines that could be used by wound care nurse to provide meaningful and practical patient education, especially in situations when a registered dietitian is not readily available. W23. The Physical Assessment Revisited: Inclusion of the Nutrition-Focused Physical Exam Collins N, Harris C. Ostomy Wound Management. 2010;56(11):25–29. Article Type: Integrative review Description/Results: Discusses the fact that lab studies such as albumin and prealbumin may not be the best indicators of nutritional status, since these values are significantly impacted by other factors, such as inflammation. Includes review of factors to be included in a comprehensive nutritional evaluation, such as height and weight, recent weight changes, and physical findings (status of skin and oral cavity, head and neck, abdomen, bones, and joints). What does this mean to me and my practice? Provides additional information regarding limitations of albumin and prealbumin in nutritional evaluation, and other factors that need to be included in nutritional assessment. Pressure Ulcers W24. Clarification From the ANA on the Nurse's Role in Pressure Ulcer Staging Lyder C, Krasner D, Ayello E. Adv Skin Wound Care. 2010;23(1):8–10. Article Type: Regulatory update Description/Results: In response to establishment of ICD-9 (diagnosis) codes for various pressure ulcer stages, there have been numerous questions as to whether or not nurses can classify wounds as pressure ulcers and stage them. The authors therefore wrote a letter to ANA Board of Directors, posing this question. ANA responded that skin assessment including identification and staging of pressure ulcers is within the nursing scope of practice, if the nurse has the educational preparation and experience to carry out this level of differential assessment. ANA also noted that WOC nurses are the experts. ANA Board of Directors further stated that this does not take the place of the physician's documentation of pressure ulcer stage. What does this mean to me and my practice? Provides support for role of wound care nurse in differential assessment and staging of pressure ulcers. W25. An Overview of the Tissue Types in Pressure Ulcers: A Consensus Panel Recommendation Black J, Baharestani M, Black S, et al. Ostomy Wound Management. 2010;56(4):28–42. Article Type: Integrative review Description/Results: Goal of consensus panel was to develop a common language with anatomically accurate and practical terms that can be used to describe and stage pressure ulcers. The goal is to implement this terminology in all care settings. Provides description of all pressure ulcer stages and types of tissue associated with wounds. What does this mean to me and my practice? Provides current guidelines for staging and for description of wound status; promotes standardization of wound-related terms. This would be a beneficial resource for a wound care nurse when in-servicing staff and new orientees regarding wound assessment. W26. Friction and Shear Considerations in Pressure Ulcer Development Hanson D, Langemo D, Anderson J, Thompson P, Hunter S. Advances in Skin and Wound Care. 2010;23(1):21–24. Article Type: Integrative review Description/Results: Provides review of current information regarding relationships between friction, shear, and pressure. Friction is described as “resistance to motion in a parallel direction” that can cause surface abrasions; authors state that friction can contribute to pressure ulcers by reducing the amount of pressure needed to create an ulcer, and can also contribute to shear damage by causing the superficial skin layers to adhere to the linens while the deeper tissue layers move downward. Includes discussion of mechanisms by which shear force causes ischemic injury (by causing tissue distortion) and discusses implications for practice, including a review of studies indicating that dressings with a low-friction outer layer can reduce shear force. What does this mean to me and my practice? Provides definitions and clarification of roles played by friction and shear in development of superficial and deep tissue injuries. Includes a review of data suggesting that clinicians can reduce shear force through selection of dressings with a low-friction outer surface. W27. Heel Ulcer Incidence Following Orthopedic Surgery: A Prospective, Observational Study Campbell K, Woodbury M, Labate T, LeMesurier A, Houghton P. Ostomy Wound Management. 2010;56(8):32–39. Article Type: Research study Description/Results: Incidence of heel ulcers in orthopedic patients is reported as being as high as 17%. In this study 72 patients were followed from acute care through rehab or home health. 12 of the 72 patients developed ulcers; all ulcers developed in the acute care setting. 42% of the wounds were Stage II, 33% were sDTI, 16% were Stage 1, and 8% were unstageable. What does this mean to me and my practice? Provides clear evidence that prevention of pressure ulcers in the orthopedic population must begin in the acute care setting, with a focus on prevention through offloading (heel elevation) and close monitoring/early detection. W28. Pressure Ulcers in Individuals Receiving Palliative Care: A National Pressure Ulcer Advisory Panel White Paper Langemo D, Black J; National Pressure Ulcer Advisory Panel. Advances in Skin and Wound Care. 2010;23(2):59–72. Article Type: Integrative review Description/Results: Comprehensive review of the current literature related to prevention and management of pressure ulcers in palliative care setting, with levels of evidence for each recommendation. Major topics include risk assessment, prevention measures (pressure reducing surfaces, turning and positioning, nutrition and hydration, and skin care), goal-setting related to skin and wound care, and guidelines for wound management (pain management, control of infection and odor, indications for debridement, exudate management, and dressing selection). Includes discussion of concept of skin failure. What does this mean to me and my practice? This would be a valuable resource for anyone developing policies, procedures, or care guidelines for prevention and management of pressure ulcers in the palliative care population. W29. The Demographics of Suspected Deep Tissue Injury in the US: An Analysis of the International Pressure Ulcer Prevalence Survey 2006–2009 VanGilder C, MacFarlane G, Harrison P, Lachenbruch C, Meyer S. Advances in Skin and Wound Care. 2010;23(6):254–261. Article Type: Research study Description/Results: Provides a summary of findings from Hill Rom's P&I studies from 2006–2009, with particular attention to the percentage of ulcers classified as sDTI (suspected deep tissue injury), and characteristics of patients with sDTI as compared to those with ulcers of different stages. Authors relate characteristics of patients with sDTI to a theory advanced by Gefen that sDTI formation is more likely in patients and anatomical sites characterized by angular bony prominences and inadequate tissue padding. In this report sDTIs represented 9% of all ulcers and 41% occurred on the heels (19% on the sacrum and 13% on the buttocks). Extreme obesity was associated with a lower incidence of sDTIs. The authors point out that these data appear to support Gefen's hypothesis, though further study is needed. What does this mean to me and my practice? These data reinforce the importance of heel elevation and attention to sites with limited fat padding in pressure ulcer prevention and suggest that these sites may be at greater risk for sDTI formation. W30. Pressure Ulcer Prevention in Long-term Care Facilities: A Pilot Study Implementing Standardized Nurse Aide Documentation and Feedback Reports Horn S, Sharkey S, Hudak S, Gassaway J, James R, Spector W. Advances in Skin and Wound Care. 2010;23(3):120–131. Article Type: Research study Description/Results: Summarizes results of pilot trial to determine effects of increased involvement of CNAs in tracking, documenting, and reporting on resident factors affecting risk for pressure ulcer development in LTC. Multicenter initiative involved development of one simple form for tracking resident's weight, nutritional intake, hygienic care, skin status, bowel and bladder management, mobility, and negative behaviors; these data were used to generate reports that identified early changes in resident status that increased their risk of pressure ulcer development. CNAs were active participants in the study. Pressure ulcer incidence decreased by 62%. Authors conclude that this approach is feasible and that centralizing reports on resident status and empowering CNAs are critical success factors, as is DON involvement. What does this mean to me and my practice? Provides specific guidelines for increasing staff awareness of changes in resident status and using this enhanced awareness to adjust the care plan in a timely manner. This study also provides objective data that CNAs play a critical role in pressure ulcer prevention. W31. Factors Associated With Pressure Ulcers in Patients in a Surgical Intensive Care Unit Slowikowski G, Funk M. Journal of Wound, Ostomy and Continence Nursing. 2010;37(6):619–626. Article Type: Research study Description/Results: Study was designed to identify factors associated with the development of pressure ulcers in an intensive care unit (ICU) population as a first step in the development of a pressure ulcer risk assessment tool for this population (Surgical ICU Pressure Ulcer Risk Assessment Scale, SUPRA). In Phase 1, investigators utilized literature review to identify comorbidities associated with PrUs in the critical care setting, and constructed the initial scale based upon this review; they then conducted a chart review of 230 ICU patients with hospital acquired pressure ulcers and modified the initial scale based upon this review. In Phase 2, investigators used the modified scale to assess risk in 139 additional patients. Results: In this ICU population, age >70 and diabetes were found to be additional relevant risk factors (in addition to a low Braden Score). What does this mean to me and my practice? Data from this study suggest that age and diabetes may represent risk factors for pressure ulcer development in ICU patients (in addition to low Braden Scale); however, further study is needed. Study limitations included convenience sample, one care setting, incomplete data on selected variables, and definition of inadequate nutrition limited to present nutritional intake. W32. WOCN Update on Evidence-Based Guidelines for Pressure Ulcers Ratliff C, Tomaselli N; Guidelines Task Force. Journal of Wound, Ostomy and Continence Nursing. 2