BULLETIN OF THE NEW YORK ACADEMY OF MEDICINE

VOL. 54, No. 5

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MAY 1978

THE CONTROL OF OPERATING ROOM INFECTION: DISCIPLINE, DEFENSE MECHANISMS, DRUGS, DESIGN, AND DEVICES* HAROLD LAUFMAN , M.D., Ph.D. Professor of Surgery Albert Einstein College of Medicine of Yeshiva University Director, Institute for Surgical Studies Department of Surgery Montefiore Hospital and Medical Center Bronx, New York

T HE prevention of infection in patients undergoing surgical operation is complex, and the number of facets in this effort has increased with the complexity of modern surgery. This report will attempt to collate various aspects of the problem, conveniently called the five Ds of surgical infection control: discipline, defense mechanisms, drugs, design, and devices.

CURRENT STATUS

Despite significant recent advances in all aspects of infection control, *Presented in part before the Section on Orthopedic Surgery of the New York Academy of Medicine December 1, 1975. Address for reprint requests: Montefiore Hospital, I 1I E. 210 St., Bronx, N.Y. 10467.

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especially during the past two decades, overall rates of surgical infection have not decreased proportionately. Reasons for this apparent stalemate appear to lie in the following interrelated facts: 1) Surgical operations have become increasingly complex and timeconsuming; extensive surgical procedures, regardless of the time they require, disrupt physiologic systems which, in turn, influence the incidence of infection.' Lengthy, complicated operations increase the risks of contaminating the wound, not only because of long exposure of open tissue to the manipulations of surgery, but because of greater demands on natural body defenses. Longer periods of anesthesia in themselves carry more risks, not only for respiratory tract infection, but for such complications of infection as pulmonary embolism and remote organ failure. Lengthy surgical operations, during which surgical drapes and gowns are subjected to the stresses of stretch, shear, pressure, and contact with blood and other fluids, have greater risk of moist strike-through contamination of these materials than shorter, less extensive procedures.2 2) Surgical operations now are performed on an increasing proportion of patients whose resistance to infection is low and who have anergic responses to disease or injury, such as patients receiving cytotoxic or steroid drugs, those with longstanding debilitating or highly toxic diseases, and those with numerous severe traumatic wounds. 3) An ever-increasing number of patients undergoes operations during which large and intricate foreign bodies are implanted, including cardiac valves, synthetic vascular prostheses, and mechanical articulation devices to replace joints of the hip, shoulder, knee, elbow, and digits. Foreignbody implantations stimulate infection in wounds which otherwise would heal uneventfully.3 4) The nature of hospital infections has changed during the last two decades, with an absolute increase in Gram-negative infections; they now outnumber Gram-positive hospital infection by almost two to one. Other types of infections which also have increased are those caused by anaerobic bacteria, Mycoplasma, L-forms, and viruses.4 Reasons for these changes in microbiologic predominance vary from improvements in culturing techniques to the excessive use of antibiotics.' 5) Although antimicrobial and antibiotic drugs continue to be useful in the prevention and treatment of surgical infections, their use has resulted in the emergence of resistant strains of bacteria and mutational types. Moreover, many strains of bacteria, which had been previously thought to Bull. N.Y. Acad. Med.

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be harmless saprophytes, now are proving to be pathogenic organisms.4 Surgical infections commonly are understood as infections of surgical wounds, but other types of clinical infections in surgical patients must be recognized as surgical infections. These include respiratory infections, local or remote cellulitis and abscesses, infected body cavities (such as peritonitis or pleuritis), deep-wound infections, bone and joint infections, myocarditis, mediastinitis, inflammatory disease of such remote organs as kidneys, liver, or lungs, exacerbation or continuation of such primary disease as hepatitis, nephritis, septic thrombi, mycotic emboli, toxemias, and septicemias. Different operations result in different infection rates under the best of circumstances. A widely accepted classification' considers four categories: Class I (clean-clean): no inflammation encountered; no break in technique; and no invasion of gastrointestinal, biliary, genitourinary, or respiratory tracts. Class II (clean-contaminated): gastrointestinal or other visceral lumina entered but without significant spillage, minor breaks in technique, biliary or genitourinary tracts entered in presence of infected bile or urine. Class III (contaminated): major break in technique, acute bacterial inflammation without pus, gastrointestinal spillage, recent trauma with relatively clean source. Class IV (dirty): pus encountered, perforated viscus, old traumatic wound or recent trauma with dirty source. Since the advent of operations on extremely poor risk patients or those with immunologic suppression and operations in which large foreign bodies are implanted, a new category has been proposed for which the term ultra clean has been suggested (Class V, or better, a new Class I in the above list). DISCIPLINE

Regardless of whether effort to control surgical infection is technical, educational, supportive, or environmental, it must be accompanied by a set of disciplines; without these it cannot succeed. At the vanguard of the people who must adhere to technical disciplines are the surgeon and his team. Of course, they must know of and how to execute aseptic and hygienic maneuvers, including preparation of the patient, hand-scrubbing, proper wearing of surgical apparel (masks, gloves, and shoe covers) as well as actual surgical techniques. The basic science portion of a surgeon's education includes several fields which bear upon the control of infection: physiology, microbiology, pathology, anat-

omy, chemistry, and related disciplines. Education in clinical medicine Vol. 54, No. 5, May 1978

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provides a background for controlling infection through courses in infectious disease, epidemiology, immunology, and clinical pathology. Surgical technique itself is important in preventing infections, from avoiding contact contamination to preventing tissue necrosis caused by tight stitches or pressure. The surgeon learns to prevent dead tissue accumulations in spaces by accurate apposition of tissues and drainage procedures. The surgeon's actions demand a level of disciplined conduct, efficiency, and strict enforcement of basic principles unparalleled in the nonsurgical medical specialties. Discipline also must guide all nonsurgical personnel in the surgical suite and support services-nurses, technicians, orderlies, housekeeping and janitorial personnel, laundry workers, and supply people. This discipline involves a highly motivated work ethic and integrity which must be depended upon without the least doubt. One nurse consultant recently emphasized this point:8 "...if, for example, personnel, including physicians, do not wash their hands between dressing changes or fail to practice aseptic techniques.. .it really doesn't matter if the dressing tray has been sterilized, stamped with an expiration date, or protected in storage." Sterilizing and clean-up techniques must be tested repeatedly for their efficacy. Inherent in sterilizing surgical instruments and packs is proving the efficacy of wrapping and packaging, with special reference to shelf-life sterility. Laundry methods must be examined carefully, whether done in the hospital, in a central area laundry, or by a commercial service. Bed linens may disseminate infection before, during, and after laundering. Such linens ordinarily are not sterilized before use, and therefore, special attention must be given to collection, separation, laundering, and distribution, especially in situations of known infection. Methods of handling, processing, and storing materials directly affect the dissemination of infection in a hospital. Discipline in these areas is important, and involves careful instruction and enforcement in all aspects of personal hygiene, appropriate dress, and personal behavior with respect to everybody working in these areas. Bedside nursing, especially in intensive care areas, is important in preventing infection, and a well-disciplined nursing staff will have had appropriate instruction in such isolation techniques as hand-washing,

gowning, glove-wearing, hair-covering, etc. Education of and communication among hospital personnel have beBull. N.Y. Acad. Med.

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SUGGESTED MEMBERSHIP OF A SURGICAL INFECTION-CONTROL COMMITTEE IN A LARGE HOSPITAL

Representatives from Department of surgery Laundry Operating room (supervisor and Housekeeping manager or administrator) Department of microbiology Infection control (nurse or officer) Department of engineering Intensive care (nurse) House staff (resident) Recovery room (nurse) Purchasing In-house nursing education Central supply Department of anesthesiology As required Animal-care unit Unit management Nutrition Department of pediatrics Chemotherapy Department of obstetrics Department of internal medicine

come increasingly important in controlling surgical infections. The Joint Commission on Accreditation of Hospitals (JCAH) now requires the designation of an infection-control nurse or officer whose duties include education, communication, acquisition of data, and related responsibilities. In large hospitals one such nurse is assigned to about 400 patients. A well-functioning hospital infections committee is absolutely necessary to enforce disciplinary measures relative to infection control. In hospitals in the United States such a committee now is required by the JCAH. Among its responsibilities are constant review of methods and systems of controlling infection throughout the hospital, overseeing effective reportage of offenses, reviewing tutorials for all professional and technical personnel, and encouraging the general education behind such control, not only in operating rooms and special care areas but in all parts of the hospital. Repetitive instruction in isolation and clean-up techniques should be under scheduled review. An important responsibility of the infections committee is maintenance and regular review of accurate prospective records of all surgical and nonsurgical infections in the hospital. Strict self-assessment is valid only when it is based on accurate statistical data. In a large hospital, suggested membership in the infections committee is exemplified in the table.

DEFENSE MECHANISMS It has long been known that people are not equally susceptible to infection, but only recently have the defense mechanisms of surgical Vol. 54, No. 5, May 1978

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patients been defined in more than general terms. Because more patients with poor or suppressed defense mechanisms undergo major surgical operations, this work has taken on added significance. Some bacteria can be found in the exposed tissues of virtually every surgical wound. Fortunately, these bacteria usually are killed effectively and removed from contaminated tissues by the early or late phases of inflammation involving relations between specific antibody, complement, and phagocytic cells.9 Alexander divides abnormalities of the antibacterial immune mechanisms into three categories: those affecting inflammatory responses, those affecting phagocytic function, and those affecting opsonins (humoral immunity).9 Each may be critical in protecting a patient against invasive bacterial infection. Many endogenous and exogenous pathophysiologic factors alter natural defense mechanisms. MacLean"' and others11 measured alterations in such natural immunity factors as inhibition of T-lymphocyte function and anergic responses of patients who develop wound infections. Patients whose immune mechanisms are affected by corticosteroid or cytotoxic drugs were found to have the greatest risk of infection. Less but still significantly at risk of surgical infections are patients with severe anemia, hypoproteinemia, or specific protein-fraction deficiencies. When a foreign substance is implanted, patients with any of these pathophysiologic alterations tend to react more severely than those with unaltered immune mechanisms. It has been known since the work of Elek3 that, up to a certain limited number, bacterial contamination does not impair clean healing of a surgical wound, but if a sterile foreign body is implanted at the same time as the bacteria, infection results. Alexander12 and Edlich"3 later showed that size and other physical characteristics of a biologically inert foreign material had a quantifiable influence on the incidence of wound infection. So-called "sterile" accumulations of pus often are ascribed to noninfectious initiation by foreign bodies. Chemical and physical properties of foreign substances unrelated to bacteria may play a role in the development of such accumulations, and infections, with or without pus, are known to self-sterilize and to fail to yield bacteria after long latent periods. In such cases it is difficult to determine whether the pus results from sterile tissue necrosis (tight sutures, tension, tissue-space accumulations, foreign body reactions, etc.), or from burned-out bacterial infections. Bull. N.Y. Acad. Med.

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Beck14 proposed the term "xenogenic" for infections resulting from imbalance between the amount or virulence of bacterial inoculum and the type and size of implant or the host's defense mechanisms. Xenogenic infections usually are deep; a superficial infection would not fit Beck's definition unless a significant foreign body was present. DRUGS A number of investigators have contributed to a large literature on the prophylactic value of antibiotic drugs to prevent wound infection. Polk15 and Davidson"6 independently have shown a correlation between the incidence of wound infection and the density of organisms in the open wound at the time of closure. In addition to the prevention of wound infection, the prophylactic concept includes the prevention of such intracavitary infections as peritonitis and intraperitoneal abscess. Burke17 suggested separate terms to denote initiation of antibiotics before operation and during or shortly after. He prefers the term "preventive" when antibiotics are administered to a poor-risk patient or in anticipation of implanting a large foreign body, and "prophylactic" for the intraoperative or early postoperative initiation of the drug, that is, either during the period of contamination prior to colonization or, if colonization has taken place, before invasive infection begins. Burke17 and Miles and Burke,11 among others, demonstrated that development of infection following the lodgment of contaminating organisms could not be influenced after a critical period, and that effective prophylaxis depends upon an appropriate antibacterial agent being present in adequate concentration at the time of contamination or shortly thereafter. The following recommendations represent a crystallization of the existing literature, and appeared in the recent Manual on Control of Infection in Surgical Patients, published by the Committee on Control of Surgical Infections of the American College of Surgeons.18 Clean category. Prophylactic antimicrobial drugs are not recommended unless the consequences of infection would be grave or permanent implants are inserted. Prophylactic administration of drugs also is recommended when operations must be performed on patients who are known carriers of pathogenic microorganisms, who harbor even remote infection, or who have a history of rheumatic valvular disease or a valvular implant. Clean-contaminated category. Many procedures in this category carry a minimal risk of contamination and probability of infection insufficient to Vol. 54, No. 5, May 1978

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justify the risks of antimicrobial prophylaxis. However, antibiotic prophylaxis is recommended in the following surgical operations and procedures: 1) Operations in which the lumen of the colon or ileum is entered, or on the small or large intestine in which blood supply is compromised 2) Gastric resection for carcinoma 3) Amputation of an extremity with poor blood supply, especially if an open ulcer is present or has been present recently 4) Operations on or instrumentation (including cystoscopy) of the urinary tract in the presence of infected urine or obstructive uropathy and operations on the lower genital tract such as vaginal hysterectomy 5) Operations that enter the extrahepatic biliary tract in the presence of infected bile or when the tract is obstructed 6) Operations that enter the oropharyngeal cavity in continuity with neck dissection 7) Operations on known carriers of pathogenic microorganisms or on patients who have anatomically remote infection 8) When the consequences of infection would be grave Contaminated and infected (or dirty) categories. Prophylactic antibiotics are recommended in both these categories and when wounds are heavily contaminated, even if not frankly infected. The term "prophylaxis" is used here rather than therapy in the sense that clean tissue traversed during the operation may be protected against bacterial invasion from the grossly infected or inflamed area. Although the preferred antibiotic for preventive or prophylactic administration varies from decade to decade and from one group of investigators to another, certain patterns have emerged. For clean orthopedic operations, cephaloridine, penicillin G, or nafcillin most commonly are used. For cardiac operations, penicillin G or methicillin and streptomycin in combination have been used. For gastrointestinal procedures and bum and trauma patients, penicillin G, cephaloridine, methicillin, and chloramphenicol alone or in various combinations have been advocated. Dosages and time schedules can be found in individual reports."9 DESIGN

Contrary to popular belief and a number of design concepts directed at controlling surgical infections, no correlation ever has been made between Bull. N.Y. Acad. Med.

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the design of surgical suites and the incidence of surgical infection. To those who have studied the surgical environment closely, acceptable evidence suggests that people rather than things are the chief problem in controlling wound infection. However, inevitably a relation between design, efficiency, methods, economy, and the effective deployment and discipline of people exists, and, thus, the architectural configuration and interior design of the surgical suite may be reflected in the incidence of surgical infection. Proof of the effects of operating-room architecture on infection is almost impossible to obtain, but the surgeon's working environment cannot be ignored. A number of design principles have emerged over the years, some valid and others unproved, relating to traffic patterns, materials handling, and special requirements. It is accepted that a surgical suite should be isolated from most common corridor traffic in a hospital. It may be on any floor of a hospital, provided that it is readily accessible to service and supply departments, patients' rooms, and related special-care facilities. Every effort is made to separate "clean" from "dirty" surgical areas and to designate "mixed" or "gray" areas, yet such designations are abused daily in the best surgical suites. Unfortunately, in recent years a stereotyped design of surgical suites has developed to which many architects adhere blindly: the "peripheral corridor" and "clean central core." Originally, this concept was suggested in the belief that preoperative patient traffic had to be separated from postoperative patient traffic. The clean central core is an empty area in the center of the suite where instrument packs are prepared and from which distribution of materials to the rooms is made.20 All traffic in this area is intended to be in the direction of the operating rooms and all traffic out of the operating rooms is supposed to be in the direction of the peripheral corridor. Blueprints designating this area as clean do not make it so. Our tests of the environment in such an area find it to be the dirtiest in the surgical suite. In practice, personnel working in the clean core move about in short sleeves with masks down. Skin squames, lint, and dust constantly are shed and circulated. People who work in this area constantly leave and reenter it. This unavoidable activity and other abuses which contaminate the environment make one question the validity of the entire architectural con-

cept.21 Similarly, the peripheral corridor is intended to separate "clean" from "dirty" traffic within the surgical suite. Here, too, the concept is unrealisVol. 54, No. 5, May 1978

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tic and assumes that a patient should be taken along one route before surgery and another route after surgery within the suite. Thus, the patient might be brought into an operating room from the central core, but taken out of the room by the peripheral corridor. He also could be brought into and taken from the room by the peripheral corridor, but enter through one operating room entrance and come out another. This latter idea has been augmented in some British and continental hospitals by having two ancillary rooms connected to every operating room, an induction room where the patient is given anesthesia before he enters the operating room, and an extubation room where he is taken after surgery, ostensibly to have the endotracheal tube removed, but in practice to provide a separate exit path from the operating room. Our studies show that neither the peripheral corridor nor the central core affect rates of infection.22 The supernumerary equipment, additional square footage, and additional personnel required for these plans are all drawbacks, and a recent tour of European hospitals revealed that the extubation room almost never is used for the purpose intended. Once the patient is inside the surgical suite, traffic patterns are unimportant provided the area is kept clean.23 More realistic, perhaps, is the principle that the vehicle carrying the patient from his hospital room to the surgical suite, called the "outside cart," not enter the inner surgical suite, but that the patient be transferred to an "inside cart" in an area in the vestibular space inside the entrance to the surgical suite. Although this practice has no demonstrable effect on rates of surgical infection, it is carried out to some extent on doctrinaire grounds in many hospitals. A well-proportioned vestibular space or "gray area" with inside-outside access to the common corridor and surgical suite, appropriately isolated by doors, serves a number of purposes in the control of contamination. The area itself is a sort of airlock between the common corridor and surgical suite proper and demarcates a well-designed transfer area, including storage space for clean carts. Opening on this vestibular space would be the control office, scheduling desk, various offices, surgeons' lockers, and other areas requiring outside-inside access. By such an arrangement these spaces need not open directly onto a common hospital corridor. The number and sizes of operating rooms can directly affect the control of contamination hazards. If there are too few rooms to accommodate a heavy surgical load, additional cases assigned to a room conceivably may Bull. N.Y. Acad. Med.

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add to the hazard of contamination. This possibility is more theoretical than practical since more stringent cleanup routines and more efficient air-handling systems have become widely employed. If operating rooms are too small, personnel wearing sterile gowns have a greater risk of contamination than in rooms of adequate size. This risk is especially great during draping procedures and operations requiring much equipment and movement of people in the room, for example, open heart or transplant operations, and some orthopedic procedures such as those using x-ray equipment and other large devices. Hence, in new construction special procedure rooms are somewhat larger than conventional rooms, perhaps 500 to 600 square feet compared with about 400 square feet for the average 20-feet-by-20-feet operating room. Other design features which may have some bearing on the control of contamination include floors, ceilings, walls, cabinets, and other surfaces; and locations of family waiting rooms, the instrument-cycling operation, cart-wash installations, preoperative holding areas, and postoperative recovery areas. In general, the harder and less porous surfaces are, the more bacteria-resistant and easy to clean they are. Ceramic tile has been criticized because the rough surface of grouting may entrap bacteria, but new grouting materials are suitable for operating room use because of their smoothness. Other suitable surface materials include laminated polyesters with an epoxy finish and hard vinyl coverings which can be heat-sealed leaving no seams. Floors also should be as nonporous as possible. Terrazzo floors have stood the test of time as an easy-to-clean, relatively nonporous surface, but plastic terrazzo tends to dry with small holes after being laid. A variety of hard, seamless plastics are less expensive than terrazzo and withstand heavy traffic for many years. Wet vacuuming between operations is the most desirable method to clean floors. The relative merits of electrically conductive versus nonconductive flooring will not be discussed here, although new surgical suites are built without conductive flooring after obtaining variances from appropriate local or state agencies. If conductive flooring is used, it must be remembered that the electrical resistance of some materials changes with age and repeated cleaning. Our studies indicate that all shelving in the surgical suite and support areas should be of wire.2" Solid shelving readily accumulates dust, while wire shelving permits air circulation and negligible dust accumulation. Cultures from surgical-suite shelfing show rapid growth of bacteria on Vol. 54, No. 5, May 1978

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solid shelves despite cleaning but persistence of "no growth" cultures for days on wire shelves. Conventional closed cabinets in operating rooms have to be stocked and used from the inside, and readily accumulate dust on shelves. Because the nature of these cabinets requires that they be opened during both septic and clean surgical operations, a contradiction exists between requirements and performance. To overcome these difficulties, we have developed a new pass-through cabinet and provided for delivery of clean air into all cabinets in the surgical suite.21 The new pass-through cabinet is stocked from the outside and used from the inside. A truck on wheels serves as a bank of shelves, and inside and outside doors cannot be opened simultaneously without release of a latch. Doors may be fire-rated if required. The cabinet has a clean-air plenum derived from the nearest clean-air duct, and clean air is emitted through a multivent panel in the ceiling of the cabinet. A family waiting room near the surgical suite, although useful for surgeon-family communication, may threaten good hygiene. Surgeons wearing operating costume and leaving the surgical suite to talk to the family often do not change into fresh surgical garb when they return to the operating room. If the waiting room were more remote, the surgeon would have to change his clothes or talk with the family through telephone or video communciation.24 Where surgical instruments are processed may be important for efficient operation of the surgical suite, and, therefore, may have some effect on contamination control. In designing smaller hospitals many architects have concluded that it is economical to sterilize and cycle all instruments for the entire hospital in one central sterile supply department. Transposed to a large hospital with more than eight operating rooms, this plan runs into difficulties. The central sterile supply department usually is remote from the surgical suite and requires some form of automatic delivery system. The most elaborate tote systems have not overcome loss or damage to expensive and delicate instruments, maldistribution of instruments, errors in makeup of surgical instrument trays, pilferage, and delays in obtaining emergency instruments. Often installed under the guise of economy, remote instrument processing has proved extremely costly in practice, necessitating the purchase of several times the number of surgical instruments ordinarily required in addition to the great installation cost of the tote system, additional area, and architectural accommodations. Hence, many surgical suites of hospitals with such installations sterilize and process all Bull. N.Y. Acad. Med.

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instruments in spaces not suitable for these activities, e.g., flash sterilizers, hand sinks, and makeshift counterspace. The "clean" central core, thus, becomes an instrument-processing plant which threatens the aseptic environment. Cart-wash installations are provided in some new surgical suites, but not in others. Their necessity is questionable, and for all intents and purposes a conscientious wipe-down of metal parts with 70% ethyl alcohol and phenolic detergent wipe of the plastic mattress covers should suffice, if done often enough.25 We have never traced a surgical infection to a patient cart. A preoperative holding area for patients awaiting entry into an operating room is more necessary in large surgical suites than in smaller ones. To be useful, a preoperative holding area should provide patients with privacy and a quiet, undisturbed environment- and supply necessary illumination for such procedures as starting intravenous lines and inserting catheters and gastric tubes. If the holding area is too small, carts tend to be placed too closely for hygienic good. These considerations suggest individual cubicles rather than curtains between carts. The same dilemma faces designers of postoperative recovery areas. Most recovery rooms and surgical intensive-care units in the United States contribute to cross-infection.26 Beds are often as close as two feet apart, sometimes separated by cloth curtains, sometimes not. Air often is circulated poorly, and, in some instances, may be stagnant and foul. Attendants and nurses are prone to go from patient to patient without washing their hands. Many recovery rooms close late in the afternoon, whereupon emergency patients and others operated upon late in the day go directly to an intensive-care unit. This unit usually is distant from the operating room, and, like the recovery room, usually is designed with virtually no isolation between patients, thus exposing vulnerable postoperative patients to crossinfection. One or two isolation rooms usually are located in a distant, almost inaccessible part of the unit. For these reasons and others, recovery rooms now are designed as an important component of the clean surgical suite with individual cublicles for each bed.27 Adequate space permits enclosure of each bed in a unit with glass and metal walls and a foldaway front. Hand-washing sinks are located between beds, and air-handling and ventilation are as good as in operating rooms. Cubicles permit forward or backward isolation precautions for any patient. None is deprived of special care. Vol. 54, No. 5, May 1978

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DEVICES

Devices with important bearing on the control of surgical infection include hundreds of items, ranging from surgical instruments to the engineering installation of the surgical suite itself. This review will discuss only two types of devices: air handling systems and surgical apparel. Air-handling systems. Most conventional operating rooms should be ventilated by efficient, well-maintained systems with bag or highefficiency particulate air (HEPA) filtering. The environment of such operating rooms suffers by abuse, but otherwise has been found effectively as clean as that of costly special chambers.28 Defective air systems are hazardous under some circumstances. The role of airborne contamination in wound infection has gone through several cycles of argument.29 Today's consensus holds that airborne organisms are important in causing wound infection only when an airhandling system is grossly contaminated, when an otherwise effective air-handling system is abused, or during highly specialized procedures in which a large foreign body is implanted. Neither the cleanliness of operating room air nor the direction in which it is blown has any effect upon contact or vector contamination from the patient or surgical team. Abuses of the operating room environment include such practices as leaving a corridor door open during operative procedures;30 permitting unrestricted opening and closing of operating room doors as people come and go;31 failure to cover long hair, sideburns, or beards;32 and allowing technical, nursing, and anesthesia personnel to circulate in and out of operating rooms wearing short-sleeved shirts.32 No matter how particulate-free the air blown into a room is, the quantity of bioparticulate matter circulated around the room inevitably is directly proportionate to the number of people in the room and the area of hair and skin exposed.33 Shed particles mount exponentially with excessive numbers of improperly covered visitors and unnecessary activity such as the flapping of drapes, towels, and gowns and other maneuvers that may unsettle previously shed particles from horizontal surfaces.34 Existing Public Health Service and National Fire Protection Association requirements35 call for a minimum of 12 changes of operating room air per hour in existing facilities and a minimum of 25 changes per hour in new facilities, positive pressure compared to corridors, relative humidity between 50 and 55%, temperatures between 650 and 75TF., and, depending Bull. N.Y. Acad. Med.

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on the locality, up to 80% recirculation with effective filtering. Some states still require 100% outside air with no recirculation. Engineers suggest upgrading requirements for new hospitals in which high-risk surgery is to be performed, and specify that air be supplied to the operating room at 60 ft./min. face velocity through ceiling panels approximately 10 x 10 feet located directly over the operating table. This high-flow system delivers 6,000 cu. ft./min. of air and would result in 1.5 air changes per minute (90 per hour) in a room 20 x 20 x 10 feet.21 Adequate exhaust, to be located on the walls above the baseboard, is important to maintain directionality and prevent great turbulence with so much air flow. If inflow is reduced to 30 ft./min. face velocity, there are 45 air changes per hour, which many authorities consider satisfactory.36 Our own investigations in collaboration with engineers and microbiologists indicate that corridor air in a surgical suite should be as clean as air in the operating room; indeed, we believe that air in the entire surgical suite-including closets, storage areas, personnel areas, and recovery rooms-should be as well filtered and ventilated as air in the operating room.28 Several questions remain unanswered with respect to laminar flow in the operating room, namely, whether this method of diffusing air affects the control of infection and, indeed, whether it is relevant to hospital use at all. The term "laminar" is applied or misapplied to many unidirectional air-blowing systems, ranging from virtually any ceiling or wall diffuser to a variety of air systems producing a curtain effect. So-called laminar flow can be delivered in a horizontal or a vertical direction. While each has proponents, neither has been shown to be superior to the other or, indeed, to nonlaminar flow. The British surgeon Charnley37 promoted laminar flow chambers by attributing to them his reduction in wound infections from 9% to 1% following hip-replacement operations. Charnley's critics point out that the improvement could have been the cumulative result of several changes in technique that he employed, including a coverall surgical gown and a number of technical maneuvers. The diameter of most bacteria is 0.5 to 5.0g. Thus, with HEPA filtering, the first air downstream from the filter is virtually bacteria-free. This filtering often is confused with laminar air flow; one is a filtering capability, the other is a method of diffusing air into a space in a somewhat unidirectional manner. Laminar flow may be imparted to either filtered or unfiltered air, and air exposed to HEPA filtering can be delivered by any Vol. 54, No. 5, May 1978

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type or size of diffusing method, laminar or nonlaminar, high speed or low speed. Filtering merely produces air that is almost particle-free as it first leaves the diffuser and enters the room; particles produced in the room will not be removed until the air is filtered again. Although large-volume, unidirectional airflow can reduce ambient bacterial counts, no evidence suggests that this flow alone affects the incidence of surgical wound infections or that unidirectional flow is superior to a well-functioning, properly installed, unabused conventional nonlaminar system. A number of American orthopedic surgeons have performed thousands of hip-replacement operations in conventional operating rooms without laminar flow chambers and report a combined two-year infection rate of 0.45%, a rate equivalent to or lower than that reported by surgeons who performed comparable numbers of operations in laminar flow chambers.21 Moreover, the bacteria cultured from wound infections following hipreplacement surgery differ from those found in the air of the room or

chamber.38'39 Operating room apparel. This clothing primarily bars contamination from personnel to patient and vice versa. Traditional garb consists of gowns, caps, masks, and shoe covers of woven, launderable material or nonwoven, disposable material. Impermeability to moisture is important in any barrier material because a wicklike effect tends to transmit bacteria. Surgical gowns reinforced on the front and sleeves with a tightly woven material treated with waterproofing (Barbac or Liquishield) have demonstrated impermeability at reinforced areas through up to 100 launderings.2 However, very few nonwoven materials, unless they are reinforced with plastic film, will withstand the stresses of stretch, pressure, and friction common to operating room use without becoming permeable to moist contaminants.2 To prevent bioparticulate shedding at its source, namely, the skin or hair of personnel, a variety of coverall hoods and gowns are available for use with plastic masks or helmets which cover the entire head and body.40 These systems virtually eliminate shedding, but because of the discomfort of heat retained by such outfits, vacuum exhaust of the space between the wearer and the uniform is necessary to keep the wearer comfortable. Such precautions may be superfluous for everyday surgery other than procedures in which the risk of infection is exceptionally great, e.g., in the implantation of large devices such as joint replacements. Bull. N.Y. Acad. Med.

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Hoods rather than caps now are recommended for all operating room personnel, and, because hair acquires and sheds bacterial particles,32 all hair must be covered in the operating room. Fresh, nonwoven shoe covers are disposable, easy to put on, and equipped with a conductive strip and should be put on every time a person enters the surgical suite from the outside. Shoe covers are recommended because the usual white shoes with dried secretions on the leather are unsanitary for a number of reasons, including the tendency for flakes to come off with motion and to enter the general ambience. The search goes on for ideal disposable and reusable materials for operating room garb. Ideal materials would be impervious to bacteria and moisture; resistant to the stresses of stretch, pressure, and friction; relatively economical. No material now in use fulfills all these requirements.2

SUMMARY Because of its complexity, an enormous literature exists on control of surgical infection and, inevitably, most papers examine only one or a few facets of the problem. Although the incidence of infection following certain operations has fallen in recent years, overall statistics appear unchanged despite great advances in aseptic techniques and drug therapy. This situation appears related to extended indications for surgery, advances in surgical techniques, and changes in the predominant microbiologic flora affecting surgical patients in recent years. Surgical teams cannot eradicate contamination despite adherence to basic principles of asepsis, but extreme discipline in surgery and support activities goes a long way toward controlling the causes of surgical contamination. Patients whose defense mechanisms may be attenuated by drugs, disease, or trauma must be protected by augmenting all precautionary measures during operation and in the perisurgical period. Under specific circumstances with well-defined indications, preventive or prophylactic use of drugs undoubtedly is important in controlling infections, but drugs should not be relied upon to the exclusion of other basic practices of prophylaxis. Architects and engineers cannot design away surgical infection by manipulating the operating room environment, but sound architecture and engineering may contribute to the control of contamination by appropriate control of traffic and hazards. Vol. 54, No. 5, May 1978

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Many surgical devices contribute to the control of contamination, including air-handling equipment, surgical drapes and apparel, hundreds of disposable and reusable items, and surgical furniture and equipment. No device or combination of devices can entirely contain surgical contamination hazards because most devices depend upon human manipulation and judgment in use. The prevention of mounting rates of surgical infection as surgery becomes increasingly complex will require efforts in all these areas. REFERENCES 1. Eiseman, B., Beart, R., and Norton, L.: 10. MacLean, L. D., Meakins, J. C., Toguchik, K., et al: Host resistance in sepMultiple organ failure Surg. Gynecol. sis and trauma. Ann. Surg. /82:207, Obstet. 144:323, 1977. 1975. 2. Laufman, H., Eudy, W. W., Vandernoot, A. M., et al: Strike-through of 11. Miles, A. A., Miles, E. M., and Burke, J.: The value and duration of defense moist contamination by woven and nonreactions of the skin to the primary woven surgical materials. Ann. Surg. lodgement of bacteria. Br. J. Exp. 181:857, 1975. Pathol. 38:79, 1957. 3. Elek, S. D. and Conen, P. E.: The virulence of Staphyloccoccus pyogenes for 12. Alexander, J. W., Kaplan, L. Z., and Altemeier, W. A.: The role of suture man. A study in the problems of wound materials in the development of wound infection. Br. J. Exp. Pathol. 38:573, infections. Ann. Surg. 165:192, 1967. 1957. 4. Altemeier, W. A., Hummel, R. P., 13. Edlich, R. F., Panek, B. H., Rodeheaver, G. T., et al: Physical and Hill, E. D., and Lewis, S.: Changing chemical configuration of sutures in depatterns in surgical infections. Ann. velopment of surgical infection. Ann. Surg. 171:436, 1971. Surg. 177:680, 1973. 5. Finland, M., Jones, W. F., and Barnes, M. W.: Occurrence of serious bacterial 14. Beck, W. C.: Xenogenic infection. Guthrie Bull. 45:79, 1975. infections since introduction of antibacterial agents. J.A.M.A. 170:2188, 15. Polk, H. C., Jr., and Lopez-Mayor, J. F.: Postoperative wound infection: A 1969. prospective study of determinant factors 6. American College of Surgeons: Manual and prevention. Surgery 66:97, 1969. on Control of Infection in Surgical Patients. Philadelphia, Lippincott, 1976, 16. Davidson, A. I. G., Clark, C., and Smith G.: Postoperative wound infecpp. 29-30. tion: A computer analysis. Br. J. Surg. 7. Laufman, H.: The role of discipline in 58:333, 1971. prevention of surgical infection. Exerpta Medica Series No. 377. General 17. Burke, J. F.: The effective period of preventive antibiotic action in experimental Surgery, Orthopedics, Plastic Surgery. incisions and dermal lesions. Surgery Controversial Opinions, 1976. 50:161, 1961. 8. Ryan, P.: The package. Proc. Hosp. Inf. Control Med. Instrumentation 18. American College of Surgeons, op. cit., pp. 177-78. Series AAMI-102, 1977, p. 21. 9. Alexander, J. W. and Meakins, J. L.: A 19. Bernard, H. R. and Cole, W. R.: The prophylaxis of surgical infection. physiological basis for the development Surgery 56:151, 1964; Boyd, R. J., of opportunistic infections Ann. Surg. Burke, J. F., and Colton, T.: A double176:273, 1972. Bull. N.Y. Acad. Med.

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20. 21.

22. 23. 24.

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blind clinical trial of prophylactic antibiotics in hip fractures. J. Bone Joint Surg. 55A:1251, 1973; Campbell, P. C.: Large doses of penicillin in the prevention of surgical wound infection. Lancet 2:805, 1965; Fekety, F. R., Cluff, L. E., Sabiston, D. C., et al.: A study of antibiotic prophylaxis in cardiac surgery. J. Thorac. Cardiovasc. Surg. 157:757, 1969: Feltis, J. M. and Harnit, H. F.: Use of prophylactic antimicrobial drugs to prevent postoperative wound infections. Am. J. Surg. 114:867, 1967; Fogelberg, E. V., Zitzman, E. K., and Stinchfield, F. E.: Prophylactic penicillin in orthopedic surgery. J. Bone Joint Surg. 52A:95, 1970; Goodman, J. S., Schaffner, W., Collins, A. A., et al.: Infection after cardiovascular surgery. N. Engl. J. Med. 278:117, 1968; Karl, R. C., Mertz, J. J., Veith, F. J., and Dineen, P.: Prophylactic antimicrobial drugs in surgery. N. Engl. J. Med. 275:305, 1966; Ledger, W. J., Sweet, R. L., and Headington, J. T.: Prophylactic cephaloridine in the prevention of postoperative pelvic infections in premenopausal women undergoing vaginal hysterectomy. Am. J. Obstet. Gynecol. 115:766, 1973; Pavel, A., Smith, R. L., Ballard, A., and Larson, I. J.: Prophylactic antibiotics in clean orthopedic surgery. J. Bone Joint Surg. 56A: 777, 1974; and Polk, H. C., Jr. and Lopez-Mayor, J. F.: Postoperative wound infection: A prospective study of determinant factors and prevention. Surgery 66:97, 1969. Putsep, E. P.: Planning of Surgical Centres. London, Lloyd-Duke, 1969. Laufman, H.: Surgical hazard control: Effect of architecture and engineering. Arch. Surg. 107:562, 1973. Laufman, H.: Unpublished data. Laufman, H.: What's wrong with our operating rooms? Am. J. Surg. 122:332, 1971. Laufman, H. and Rosenberg, N.: Television in the operating room. Surgery 78:273, 1975. Peers, J.: Cleanup techniques in the operating room. Arch. Surg. 107:596, 1973.

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26. Northey, D., Adess, M. L., Hartsuck, J. M., and Rhoades, E. R.: Microbial surveillance in a surgical intensive care unit. Surg. Gynecol. Obstet. 139:321, 1974. 27. Laufman, H.: Infection hazard of intensive care. Surg. Gynecol. Obstet. 139:413, 1974. 28. Laufman, H.: Current status of special air-handling systems in operating rooms. Med. Instrum. 7:7, 1973. 29. Laufman, H.: Confusion in application of clean air systems to operating rooms. Cleve. Clin. Q. 40:203, 1974. 30. Beck, W. C. and Frank, F.: The open door in the operating room. Am. J. Surg. 125:592, 1973. 31. Wolf, H. W., Harris, M. H., and Hall, L. B.:Open operating room doors and Staphylococcus aureus. Hospitals 35:57,1961. 32. Dineen, P. and Drusin, L.: Epidemics of postoperative wound infections associated with hair carriers. Lancet 2:1157, 1973 33. Goodrich, E. O., Jr., and Whitfield, W. W.: Air environment in the operating room. Bull. Am. Coll. Surg. 50:7, 1970. 34. Walter, C. W. and Kundsin, R. B.: The airborne component of wound contamination and infection. Arch. Surg. 107: 588, 1973. 35. National Fire Protection Association Code 56A, Boston, 1972. 36. Credle, K. C.: HEW-Architecture and Engineering Office. Personal Communication, 1973. 37. Charnley, J.: A clean air operating enclosure. Br. J. Surg. 51:202, 1964. 38. Irvine, R., Johnson, B. L., Jr., and Amstutz, H.: The relationship of genitourinary tract procedures to deep sepsis in total hip replacement. Surg. Gynecol. Obstet. 139:701, 1974. 39. McLauchlin, J., Logia, J. R. C., Smylie, H. G., and Smith, G.: The role of clean air in wound infection acquired during operation. Surg. Gynecol. Obstet. 143:6, 1976. 40. Charnley, J. and Eftekhar, N.: Penetration of gown material by organisms from surgeon's body. Lancet 1:172, 1969.