Vết thương trong chấn thương cơ xương pps

Vol 9, No 4, July/August 2001 219 According to hospital discharge data, there are approximately 6 mil- lion fractures in the United States annually and 7.5 million open wounds. 1 On the basis of statistics from European studies, it has been estimated that 4% of fractures are open, suggesting that there are nearly 250,000 open fractures annu- ally in this country. 2 Compared with closed fractures, open fractures have a higher incidence of infection, nonunion, and other adverse out- comes that lead to increased cost of treatment and result in less satisfac- tory recovery for the patient. Many of the factors that increase the risk of infection in open frac- tures are beyond the control of the surgeon, such as the severity of the injury, delay in initiation of medical care, and the health status of the patient. However, some treatment decisions are strongly believed to make a difference in the incidence of infection. These include timing of surgical treatment, use of systemic and local antibiotics, adequacy of surgical wound care, fracture stabil- ity, and early wound closure or flap coverage. The adequacy of initial surgical wound care may be the most impor- tant single factor under the surgeon’s control. This element consists of adequate sharp debridement, with removal of all debris and devitalized tissue, and thorough irrigation. De- velopment of a wound infection is a multistage process that occurs over time. It requires contamination with sufficient numbers of viable bacteria, adhesion of the bacteria to wound surfaces, proliferation of bacterial colonies on the surface, and exten- sion of the colonies beyond the origi- nal locations. The goal of initial wound care is to decrease the bacter- ial load, eliminate the devitalized tis- sue that serves as a medium for bac- terial growth, and prevent further contamination, thereby facilitating the action of host defense systems. Wound irrigation is universally recommended as an essential part of open fracture treatment, although there is relatively little information available defining the details of variables such as volume, delivery method, and optimal irrigation solution additives (Table 1). How- ever, on the basis of the current knowledge about this topic, there are some widely accepted guide- lines. Volume Most texts recommend “copious,” “ample,” or “adequate” amounts of irrigation, without giving specific Dr. Anglen is Associate Professor of Orthopae- dic Surgery, University of Missouri-Columbia, Columbia. Reprint requests: Dr. Anglen, University of Missouri-Columbia, One Hospital Drive, MC213, Columbia, MO 65212. Copyright 2001 by the American Academy of Orthopaedic Surgeons. Abstract Wound irrigation to remove debris and lessen bacterial contamination is an essen- tial component of open fracture care. However, considerable practice variation exists in the details of technique. Volume is an important factor; increased volume improves wound cleansing to a point, but the optimal volume is unknown. High- pressure flow has been shown to remove more bacteria and debris and to lower the rate of wound infection compared with low-pressure irrigation, although recent in vitro and animal studies suggest that it may also damage bone. Pulsatile flow has not been demonstrated to increase efficacy. Antiseptic additives can kill bacteria in the wound, but host-tissue toxicities limit their use. Animal and clinical studies of the use of antiseptics in contaminated wounds have yielded conflicting outcomes. Antibiotic irrigation has been effective in experimental studies in some types of animal wounds, but human clinical data are unconvincing due to poor study design. There are few animal or clinical studies of musculoskeletal wounds. Detergent irrigation aims to remove, rather than kill, bacteria and has shown promise in animal models of the complex contaminated musculoskeletal wound. J Am Acad Orthop Surg 2001;9:219-226 Wound Irrigation in Musculoskeletal Injury Jeffrey O. Anglen, MD Perspectives on Modern Orthopaedics volume recommendations. Some authors have suggested amounts ranging from 7 to 15 L per wound without reference to any data. Others have described the figure as “arbitrary.” 3 In a study examining the removal of clay particles from guinea pig wounds by irrigation, Rodeheaver et al 4 found that volume was not im- portant over a range from 100 to 400 mL. In a study of removal of bacte- ria adherent to bovine muscle by irrigation with benzalkonium chlo- ride or saline, Gainor et al 5 found that increasing volume from 0.1 L to 1.0 L increased bacterial removal with both solutions. Increasing to 10 L had no effect on removal with saline but dramatically improved bacterial removal by benzalkonium. Using a model of contaminated dorsal soft-tissue wounds in dogs, Peterson 6 found that increasing saline irrigation volume from 0 to 1,000 mL in 250-mL increments re- sulted in a steady decrease in the clinical wound infection score (with ratings for erythema, induration, exudate, healing rate, and abscess formation). There have been no reported human clinical studies related to the volume of irrigation. Nonethe- less, it appears clear that increasing volume improves removal of dirt and bacteria to a point, subject to some variability between solutions. Given the availability of 3-L irriga- tion bags, a reasonable protocol is 3 L for grade 1 fractures, 6 L for grade 2 fractures, and 9 L for grade 3 fractures. However, there are no outcome data to support these rec- ommendations. Delivery Method Many irrigation systems can pro- vide a pulsatile flow of fluid, al- though there is little evidence that pulsatile flow per se, separate from the issue of the benefit of increased pressure, provides any advantage. In one study involving quantitative culture of rabbit wounds contami- nated with Staphylococcus aureus, 7 pulsatile flow was found to be less effective than continuous flow in bacterial removal at a variety of pressures (0.5, 10, and 25 psi). The authors used a device that delivered 300 mL of saline at varying pres- sures. It could also be adjusted to provide pulsatile flow at 8 cycles per second, with delivery of fluid through a 1.5-mm-diameter outlet for 1/16 of a second in each cycle. In another study using guinea pig dor- sal wounds contaminated with soil, 4 pulsatile flow of saline was com- pared with continuous flow at pres- sures of both 1 and 10 psi. There was no difference in the amount of soil removal between the two types of flow at the same pressure. High-pressure irrigation (jet lavage) has been shown to be more effective in removing particulate matter, necrotic tissue, and bacteria than low-pressure irrigation meth- ods, such as use of a bulb syringe, in both in vitro 8,9 and in vivo 4,7,10,11 studies. This seems to be particularly true when there has been a delay in treatment and when the wound has been contaminated with foreign material. Madden et al 7 created dor- sal soft-tissue wounds in rabbits and contaminated them with S aureus or Escherichia coli. The wounds were then irrigated with 300 mL of saline after a delay of 5 minutes, 2 hours, or 4 hours at pressures of 0.5, 10, or 25 psi. Increasing pressure in- creased bacterial removal at all times, but with the 2- and 4-hour delays, only irrigation at 25 psi sig- nificantly (P<0.01) decreased the incidence of gross infection. Brown et al 11 studied rat wounds contam- inated with E coli both with and without the addition of sterile gar- den soil and crushed tissue. Jet Wound Irrigation Journal of the American Academy of Orthopaedic Surgeons 220 Table 1 Irrigation Variables Variable Effect Recommendation Volume In animal studies, increasing volume removes more Grade 1 fractures, 3 L; grade 2 fractures, 6 L; particulate matter and bacteria, but the effect plateaus grade 3 fractures, 9 L at a level dependent on the system Pressure Increased pressure removes more debris and bacteria; Use a power irrigation system that however, the highest pressure settings damage bone, provides a variety of settings; select a delay fracture healing, and may increase risk of low or middle-range setting infection by damaging soft tissue Pulsation In theory, improves removal of surface debris by means Not established of tissue elasticity; limited studies have not confirmed the effect or have suggested decreased efficacy lavage at 50 psi was more effective in removing bacteria than gravity or bulb-syringe lavage with the same saline volume in both types of wound, and only the jet lavage sig- nificantly (P<0.05) lowered contami- nation in devitalized wounds with foreign material present. There is some evidence that high- pressure irrigation may have delete- rious effects as well. One animal study involved irrigating a wound and then inoculating it with a nor- mally subinfective dose of staphylo- cocci. Those wounds that had un- dergone both high-pressure (70-psi) and low-pressure (8-psi) irrigation showed a higher infection rate than nonirrigated control wounds, sug- gesting impairment of infection- fighting ability. 12 The same study demonstrated that irrigation fluid (but not bacteria) was driven into the tissues around the wound by the high-pressure irrigation. An in vitro study showed more gross damage and microscopic fissures in cortical bone that had undergone high-pressure (70-psi) irrigation compared with bone subjected to lower-pressure (14-psi) irrigation. 8 In a rabbit articular fracture model, Dirschl et al 13 showed a decrease in new bone formation around articu- lar osteotomies in the first week after high-pressure (70-psi) irriga- tion, compared with control sites treated with low-pressure (bulb) irrigation. Using highly contaminated (1× 10 8 bacterial suspension) sections from human tibiae, Bhandari et al 14 demonstrated that pulsatile lavage with a nozzle pressure of 70 psi resulted in more positive cultures at 1 to 4 cm from the contaminated sur- face than were found in nonirrigated control specimens. The irrigation procedure removed more than 99% of the bacteria from the contam- inated surface, but did result in some propagation of bacteria down the medullary canal. However, the number of colony-forming units re- covered from specimens contami- nated with S aureus was quite low (range, 1 to 11), which is probably below the infection-causing thresh- old. The use of E coli appeared to result in higher counts, but the differ- ence was not statistically significant. The authors also quantitated macro- scopic structural damage to the bone and found it to be maximal at the irri- gated surface. The clinical signifi- cance of these findings is unclear. A new delivery strategy being investigated involves the use of an irrigation tip that provides fluid flow parallel to the surface rather than perpendicular to it. 15 The goal is to generate high rates of fluid flow, which may be less damaging to the bone surface and yet will maintain effectiveness in removal of debris, but this has yet to be verified. The nozzle pressure of the irriga- tion system has generally been reported in studies of irrigation pressure and its effects on bone. However, the actual impact pressure at the bone surface may be signifi- cantly less. Impact pressure varies with nozzle-tip design, as well as the distance from the surface of the bone and the degree of inclination. For example, surface-impact pressures measured with an electronic pres- sure transducer and oscilloscope for the Pulsavac system (Zimmer, Warsaw, Ind) at a distance of 1.5 inches vary from 0.12 to 8.8 psi depending on setting and tip design (Timothy Donaldson, written com- munication, December 2000). These are markedly lower than the nozzle and tubing pressure values that are typically reported. It is important for future studies to standardize the measurement variables and to at- tempt to develop a “dose-response” curve relating pressure to bacterial removal and bone damage while controlling for time of fluid expo- sure. Similarly, the clinical signifi- cance of both macroscopic and microscopic changes needs to be clarified. Some lavage systems allow the operator to adjust the pressure and flow rate of the irrigator. For now, it seems prudent to utilize higher pressure settings in severely contam- inated wounds and delayed treat- ment situations when bacterial removal is the most important issue, and lower pressure settings or bulb- syringe irrigation when the level of contamination is less and treatment is prompt. Irrigation Additives Since prehistoric times, wounds have been washed with a variety of fluids, including water, wine, milk, vinegar, turpentine, oils, and even urine. In the biblical story of the Good Samar- itan, wounds were treated by pour- ing in wine and oil (Luke 10:33-34). In modern times, wounds are usually irrigated with sterile saline, either alone or with additives. For conve- nience, the various additives can be divided into three categories: anti- septics, antibiotics, and surfactants (Table 2). Chelating agents were also used in irrigation in one animal study, but were shown to be of no benefit or possibly even to have been detrimental. 4 Antiseptics It is well known that decreasing the bacterial load of the inoculum will lessen the rate of clinical infec- tion. The purpose of antiseptic ad- ditives is to kill bacteria in the wound and thus lessen the patho- gen load that must be handled by the host immune system. A partial list of antiseptics that have been used either clinically or experimen- tally includes hydrogen peroxide, povidone-iodine (Betadine) solu- tion, povidone-iodine scrub, chlor- hexidine gluconate (Hibitane), hexa- chlorophene (pHisoHex), sodium hypochlorite (Dakin’s solution), benz- alkonium chloride (Zephiran), and various alcohol-containing solutions. Jeffrey O. Anglen, MD Vol 9, No 4, July/August 2001 221 All antiseptics function similarly, by damaging the cell wall or cell membrane of the pathogen, leading to changes in permeability. Each has a broad but slightly different spectrum of activity, and all are toxic to some bacteria, spores, fungi, and viruses. Antiseptics are also toxic to host cells, such as leukocytes, eryth- rocytes, fibroblasts, keratinocytes, and osteocytes. Cell and tissue culture studies uniformly show that antisep- tics have concentration-dependent detrimental effects on the viability and function of host cells. 16,17 Some antiseptics can be diluted enough to be nontoxic to cells in culture while retaining some bactericidal activ- ity (e.g., povidone-iodine solution, Dakin’s solution). The dilutions uti- lized in the cell culture experiments have been below the strengths gener- ally utilized in clinical practice. 16 Other antiseptics lose their bacteri- cidal activity before they lose their tissue toxicity during dilution (e.g., hydrogen peroxide, acetic acid). 16 However, the relevance of deleteri- ous effects on cells in culture as com- pared with cells within a functioning organ is at best tenuous. In evaluating animal studies of antiseptic irrigation, two issues are important: interference with wound healing (toxicity to host tissues) and efficacy in preventing infection. All antiseptics—and indeed, all irriga- tion fluids other than saline (includ- ing water)—have been shown to have some negative effects on micro- vascular flow and endothelial integ- rity in live animal studies. 18 Benzalkonium chloride exposure has been shown to decrease the ten- sile strength of skin in dorsal rat incisions 7 days after suture repair. 19 Hypochlorite solutions (such as chloramine) have been shown to be particularly injurious to microvascu- lar circulation. 18 Chlorhexidine has been shown to delay early skin healing and to decrease the tensile strength of healing skin wounds in animal models. 20 Povidone-iodine solution has been evaluated in various animal models. Unfortunately, the results from the studies are contradictory, even when the same species and the same concentrations were used. Several studies have shown that povidone-iodine scrub and other combinations of antiseptic and de- tergent are particularly damaging to wounds, although either alone may be less toxic. 20 The data with regard to infection prevention are equally unconvincing; of four studies in- volving contaminated guinea pig wounds and povidone-iodine irri- gation, two showed a decreased infection rate, 21 and two showed no effect. 21-23 Differences in type and quantity of inoculum, irrigation method, time from inoculation to irrigation, and bacterial recovery techniques prevent direct compar- isons. In many of these studies, low-pressure, low-volume irrigation or soaking methods were used. In human studies, most informa- tion is related to the use of povidone- iodine. The results have been mixed. Data on efficacy have been derived primarily from general surgical stud- ies evaluating the use of povidone- iodine spray in abdominal wounds. Some studies have shown a de- creased infection rate 24 ; others have shown no difference 25 or an in- creased rate of infection. 26 Similarly, chlorhexidine use in general surgical operations has been examined with Wound Irrigation Journal of the American Academy of Orthopaedic Surgeons 222 Table 2 Irrigation Additives Class Examples Advantages Disadvantages Recommendation Antiseptics Povidone-iodine, Broad spectrum of Toxic to host cells, may Findings from both animal chlorhexidine, activity against bacteria, impair immune cell and clinical studies are con- hydrogen peroxide fungi, viruses; kills function and delay or tradictory; toxicity is more pathogens in the wound weaken wound healing clearly established than benefits; should not be used Antibiotics Bacitracin, Bactericidal or bacterio- Cost, rare toxicity or Clinical efficacy in pre- polymyxin, static activity in the allergic reaction, pro- venting infection not neomycin wound, if in adequate motion of bacterial proved; should not be concentration and resistance used routinely duration Surfactants Castile soap, Interfere with bacterial Mild host-cell toxicities Clinical efficacy not green soap, adhesion to surfaces; proved; consider use benzalkonium emulsify and remove in highly contaminated chloride debris wounds, first irrigations mixed results and is not widely uti- lized. 21 The use of 0.2% chlorhexi- dine during arthroscopic reconstruc- tion of the anterior cruciate ligament has been shown to cause marked chondrolysis in articular cartilage. 27 Taken together, the evidence that the use of antiseptics in surgical wounds lowers the infection rate is not convincing, and there is little information regarding their use in musculoskeletal wounds. On the contrary, substantial evidence sug- gests that wounds can be damaged by antiseptic use. Therefore, anti- septic irrigation should not be used, as it offers risks without demon- strated benefit. Antibiotics Antibiotics differ from antiseptics in their mechanism of action as well as in their origin. Many antibiotics function through interference with some aspect of bacterial cell physiol- ogy; these agents affect only cells in the actively growing phase of the cell cycle. Other antibiotics are di- rectly damaging to cell membranes on contact. However, overall, the spectrum of activity of antibiotics is usually narrower and more specific than that of antiseptics. Historically, the use of sulfanil- amide powder in open wounds resulted in increased wound prob- lems due to local toxicity. Penicillins, cephalosporins, and aminoglyco- sides have been added to irrigation fluid in the past, but currently the most widely used additives are baci- tracin (which interferes with cell wall synthesis), polymyxin (which directly alters cell-membrane per- meability), and neomycin (which, although an aminoglycoside, acts topically through a mechanism that is unknown). Combinations of these agents in varying concentrations are also used. The effectiveness of topical anti- biotics has been suggested by the results of in vitro studies of bacterial growth in suspension or on agar. Benjamin and Volz 28 showed that a combination of bacitracin and neo- mycin applied with a plastic spray bottle would kill bacterial colonies growing on sheep’s blood agar. The results of these studies are not surprising, but may not be relevant to the clinical situation. Animal studies have been per- formed on several different species, including guinea pigs, dogs, goats, pigs, rabbits, and rats, using a vari- ety of antibiotic agents. 29-31 Wound contaminants have included S au- reus, Staphylococcus epidermidis, E coli, P aeruginosa, Proteus mirabilis, and human feces. In most animal stud- ies, antibiotic irrigation has been more effective than saline irrigation in reducing the infection rate, and has caused little or no tissue toxicity. Two studies involved a skeletal injury. Rosenstein et al 31 showed that instillation of 50 mL of bacitracin solution into the intramedullary canal of canine femora inoculated with staphylococci decreased the number of positive cultures 7 days later. Conroy et al 29 found that baci- tracin irrigation was no better than saline irrigation at reducing positive cultures in a complex musculoskel- etal wound in the rat contaminated with either S aureus or P aeruginosa. The human studies are primarily from the general surgery, obstetrics, and urology literature. They involve wound sprays, powders, and low- volume drug solutions introduced or instilled into body cavities or surgi- cal wounds either during a surgical procedure or at closure. The agent was left in place or aspirated from the wound after a specific period. In a review of the literature, Roth et al 32 found that most studies had major design defects, and those that had only minor defects were, in their opinion, inconclusive and uncon- vincing. Golightly and Branigan 33 reviewed eight recent randomized, controlled, prospective trials and found that antibiotic irrigation did not seem to add anything to systemic prophylaxis; that effective dosages were not established; and that sys- temic absorption and toxicity do occur, especially with neomycin. Evaluating the literature from an orthopaedic perspective, Dirschl and Wilson 30 found a paucity of informa- tion defining either the efficacy in musculoskeletal wounds or the dif- ferences between its use in soft-tissue incisional wounds and in skeletal injuries. They nonetheless recom- mended “strong consideration” of the practice of antibiotic irrigation for such wounds, on the basis of infor- mation extrapolated from the general surgery literature. There are two studies in the orthopaedic literature regarding the use of topical antibiotics in elec- tive orthopaedic surgery cases. Maguire 34 reported on a series of 1,200 patients who underwent clean elective procedures and were randomized to receive systemic antibiotics (penicillin or tetracy- cline), topical antibiotics (bacitracin or neomycin wound spray at clo- sure), or neither. Only the topical antibiotic wound spray decreased the infection rate. Nachamie et al 35 evaluated the data on 216 cases in which 100 mL of 1% neomycin was instilled into the wound at the con- clusion of an elective procedure and 247 cases in which it was not. They found no difference in infec- tion rate. There are no studies on antibiotic irrigation in human open fracture wounds. Many surgeons who use antibiot- ic irrigation are aware of the lack of proven efficacy but believe that at least it does no harm. However, there are three important drawbacks to the use of topical antibiotic for irrigation. The first issue is patient safety. There are reported cases of anaphylaxis following bacitracin irrigation, 36 as well as major compli- cations due to other antibiotics. The second concern in this era of cost containment is the expense of un- necessary antibiotics. The cost of Jeffrey O. Anglen, MD Vol 9, No 4, July/August 2001 223 100,000 U of bacitracin (the dose commonly used per liter of irriga- tion fluid) is over $50; if 10 L is used, the cost is more than $500 per wound per irrigation procedure. The third concern is that the indis- criminate or inadequate use of anti- biotics may contribute to the develop- ment of resistant strains of bacteria, or at least a selection pressure to- ward more resistant strains in the wound. In summary, antibiotic irri- gation is of no proven value in the care of open fracture wounds and does entail some risk, albeit small. Surfactants Before the antibiotic era, the use of soap to cleanse open wounds was recommended frequently. Koch wrote in 1941 that “In our judge- ment there is no method so effective and none which carries so little risk of injury . . . as the use of plain white soap applied with soft cotton and gloved hands.” 37 However, with the advent of antibiotics, that practice seems to have fallen by the wayside and is not widely used today. Soaps belong to that category of substances called surfactants. The surface-active molecules of surfac- tants consist of two domains: a hy- drophilic portion and a hydropho- bic (or lipophilic) portion, which are usually on opposite ends of the molecule. The hydrophilic portion may be charged: in amphoteric sur- factants, both charges are present; in cationic surfactants (invert soaps), there is only a positive charge; and in anionic surfactants (e.g., soaps), there is only a negative charge. Neither charge is present in nonionic surfactants. Surfactants function by disrupt- ing the hydrophobic or electrostatic forces that drive the initial stages of bacterial surface adhesion. They lower the surface tensions that cause bacteria to clump together on a surface, and they surround the organisms in micelles, allowing them to be rinsed from the wound. The purpose of detergent irrigation is to lower the bacterial load in the wound by removing the bacteria, rather than by killing them. Some surfactants are also antiseptics. In vitro studies have revealed detrimental effects of surfactants on living cells. Above a certain concen- tration, they are toxic to white and red blood cells. Anionic surfactants can denature proteins and damage cell membranes. Cationic surfac- tants inhibit clotting and hemolyze red blood cells. Both anionic and cationic surfactants inhibit phagocy- tosis. Nonionic detergents have been described as being gentler on tissues, but also have some tissue toxicity, which varies with the size of the hydrophilic portion. Both anionic and cationic surfactants are skin irritants; the intensity of the irritation potential varies with indi- vidual compounds. 38 In one rat study, cationic surfactants de- creased the tensile strength of skin strips from healing wounds in a concentration-dependent manner. 19 In another study, rat spinal wounds treated with benzalkonium chloride (a cationic surfactant with antiseptic properties) showed no histologic differences from those treated with normal saline. 39 In vivo studies have shown some wound irritation with soaps and detergents, primarily when they have been injected into tissues or have been allowed to soak into a wound without rinsing, which is a different manner of usage than clinically intended. In vitro studies of efficacy have shown surfactants to be better at removing surface-adherent bacteria than other types of irrigation solu- tions. Castile soap (made with a potassium salt of coconut oil) was compared with saline and antibiotic solutions with regard to the ability to remove glycocalyx-producing adherent bacteria from stainless steel screws. The soap solution was more effective by several orders of magnitude, and that effect was increased by the use of jet lavage. 40 This greater efficacy of soap solu- tion has been confirmed in studies involving various bacterial species and surfaces. 39 The castile soap solution was as good as or better than antibiotic in removing two species of staphylococci from steel, titanium, and bone and in removing Pseudomonas organisms from both metallic surfaces. A systematic evaluation of differ- ent types of surfactants using a vari- ety of microbiologic assays in vitro showed oleic acid (the primary con- stituent of castile soap), sodium dodecyl sulfate, and benzalkonium chloride to be better than saline in removing various bacterial species from steel surfaces. 9 Of the three, only benzalkonium chloride was active against a preformed bacterial film. When the effectiveness of ben- zalkonium chloride in removing bacteria from contaminated bovine muscle was tested, it was found to perform significantly better (P≤0.001) than saline irrigation. 5 With ade- quate volume (10 L) delivered via jet lavage, the recoverable residual bacterial count could be driven to 0, while irrigation with saline never resulted in counts less than 1×10 5 . In 1945, Peterson 6 studied the use of soaps in a canine soft-tissue wound model and found that while soaking a wound with soap made little difference in wound healing or inflammation, it did increase the in- fection rate in contaminated wounds. Scrubbing with soap decreased the infection rate over soaking alone. However, in this very early study, none of the data were subjected to statistical analysis. In a guinea-pig study, Singleton et al 41 found that use of soaps decreased the infection rate in soft-tissue wounds contami- nated with human fecal material, and that scrubbing augmented that effect. Falconer et al 42 found that guinea pig wounds contaminated with staphylococci had a lower infec- tion rate when irrigated with soap Wound Irrigation Journal of the American Academy of Orthopaedic Surgeons 224 and water than those irrigated with saline in experiments with a 2- to 4- hour delay between inoculation and irrigation. The effect did not hold true for groups with a 0.5- to 1-hour delay or a 10- to 12-hour delay. In a rat model of a complex mus- culoskeletal wound with bone and soft-tissue injury, the presence of hardware, and staphylococcal inocu- lation, benzalkonium chloride was significantly (P<0.001) better than normal saline at reducing the num- ber of positive wound cultures. 39 When the authors attempted to extend those findings to other bacte- rial species, they found that al- though benzalkonium chloride was better than saline or castile soap at decreasing positive cultures in wounds inoculated with staphylo- cocci, it was significantly worse (P<0.05) when tested against Pseu- domonas organisms. 29 In fact, wounds inoculated with Pseudomonas organ- isms and irrigated with benzalko- nium chloride had a 75% incidence of wound breakdown. This finding suggests that there are interactions between host tissue, pathogen, and treating agent that are specific and vary with each factor. There may be specific wound-cleansing agents that are more effective in certain types of wounds or with certain types of pathogen contamination—similar to the situation with antibiotics, in which sensitivity testing of bacterial cultures guides therapy. Based on the premise that break- down of Gram-negative bacteria by benzalkonium chloride causes the release of endotoxin into the wound, resulting in wound inflammation and dehiscence, a sequential irriga- tion strategy using different irrigants was tried. 30 Sequential irrigation with benzalkonium chloride, castile soap, and normal saline reduced the rate of infection compared with saline alone in wounds contami- nated with P aeruginosa, without the wound breakdown observed with benzalkonium chloride alone. 29 Subsequent studies involving this complex wound model showed that sequential irrigation strategies can reduce the rate of infection com- pared with saline alone in wounds inoculated with combinations of Gram-negative and Gram-positive organisms. 43 Although there are no studies of the use of soap or surfactant irri- gation for human open fracture wounds, the animal data suggest that surfactant irrigation may prove to be a useful adjunct to wound cleansing. It carries a low risk and should be considered in the heavily contaminated or very dirty wound. Summary Irrigation of open fractures has been and remains an important compo- nent of wound treatment, with the goal of reducing the amount of for- eign material and necrotic debris and the bacterial load on the host immune system, thereby reducing the incidence of infection. It is an adjunct to surgical debridement but cannot compensate for an inade- quate surgical procedure. Despite the near unanimous consensus on the importance of irrigation, specific practices concerning volume, deliv- ery method, and fluid additives vary considerably. Animal studies have convincingly shown that high-volume, high- pressure irrigation is more effective at removing bacteria and particulate debris than low-volume, low-pressure (e.g., bulb-syringe) irrigation. Al- though the threshold volume is un- known, most would agree that 6 to 10 L of fluid is a reasonable range for irrigation of grade 2 or 3 open fractures. Several types of power- irrigator and jet-lavage systems are available and have made it much simpler to deliver high volumes of fluid to a wound. Concerns about damage to bone and other tissues dictate avoiding the highest pres- sure settings and selecting a middle range setting on the irrigator. Although a variety of irrigation additives have been advocated, the scientific literature offers no conclu- sive evidence of their efficacy. Antiseptic irrigation is potentially damaging and without proven bene- fit and should, therefore, be avoided. Antibiotic usage in irrigation fluid for open fractures, although wide- spread and of generally low risk, is likewise unproved and expensive. Soap irrigation improves removal of dirt and interferes with bacterial adhesion at a low cost with low risk, but its clinical efficacy has yet to be established. Jeffrey O. Anglen, MD Vol 9, No 4, July/August 2001 225 References 1. Praemer A, Furner S, Rice DP: Muscu- loskeletal Conditions in the United States. Park Ridge, Ill: American Academy of Orthopaedic Surgeons, 1992. 2. Court-Brown CM, McQueen MM, Quaba AA: Management of Open Frac- tures. London: Martin Dunitz, 1996. 3. Wilkins J, Patzakis M: Choice and duration of antibiotics in open fractures. Orthop Clin North Am 1991;22:433-437. 4. Rodeheaver GT, Pettry D, Thacker JG, Edgerton MT, Edlich RF: Wound cleansing by high pressure irrigation. Surg Gynecol Obstet 1975;141:357-362. 5. Gainor BJ, Hockman DE, Anglen JO, Christensen G, Simpson WA: Benzal- konium chloride: A potential disinfect- ing irrigation solution. J Orthop Trauma 1997;11:121-125. 6. 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Falconer B, Liljedahl SO, Olovson T: On the effect of treatment of traumatic wounds with soap solution: An exper- imental study. Acta Chir Scand 1952; 103:222-235. 43. Burd T, Christensen GD, Anglen JO, Gainor BJ, Conroy BP, Simpson WA: Sequential irrigation with common detergents: A promising new method for decontaminating orthopedic wounds. Am J Orthop 1999;28:156-160. Wound Irrigation Journal of the American Academy of Orthopaedic Surgeons 226 . initiation of medical care, and the health status of the patient. However, some treatment decisions are strongly believed to make a difference in the incidence of infection. These include timing of surgical. use in soft-tissue incisional wounds and in skeletal injuries. They nonetheless recom- mended “strong consideration” of the practice of antibiotic irrigation for such wounds, on the basis of infor- mation