An index of patient care was created composed of factors related to the frequencies of cleaning laryngoscope blades, anesthetic machine surfaces, changing breathing circuits, use of aseptic technique, disinfecting multidose vial septums, and reuse of syringes. Using a hierarchal regression analysis which controlled for years in practice and practice type, anesthesiologists who had read the CDC guidelines for prevention of occupational transmission of infection were shown to have a significant (P < 0.01) increase in recommended patient care behaviors.
Practice type was associated with certain behaviors. Twenty-eight percent of anesthesiologists in private practice reported frequently or always reusing syringes for more than one patient compared with 7.3% in university practice (P < 0.01). In addition, private practioners were more likely to change the breathing circuit after each patient than those in university practice (94% vs 77.5%; P < 0.01).
Ninety-six percent of anesthesiologists surveyed admitted giving anesthesia while harboring a respiratory tract infection, 60.1% with a gastrointestinal infection, 22% with herpes simplex exacerbations, and 15.4% with psoriasis or dermatitis. On a scale of 0-10 (10 = high) anesthesiologists perceived their role of transmitting infection to the patient as 4.7 +/- 0.12 (mean +/- SE).
Although transmission of infection to a healthy patient is difficult, there are certain patient populations that are readily predisposed to infection. For example, burn patients, patients who are obese, elderly, or diabetic, or those having poor nutritional status (e.g., alcoholics and drug abusers) are all at risk. Patients who smoke may also have an increased incidence of pulmonary infections [7-9]. In addition, the anesthesiologist today may be faced with an increasing number of patients with acquired or congenitally immunosuppressive diseases or who are receiving immunosuppressive treatments for transplantation or malignancy. Many of these patients may also present with unusual infections which have become opportunistic in the face of a compromised immune system. Indeed, infection is one of the leading causes of morbidity and mortality in these patients. Pneumonia, for example accounts for up to 40% of deaths among children and adults with cancer [3,4] and it has been estimated that 35% of renal transplant recipients develop pneumonia in the first year after transplantation .
The practice of anesthesiology has the potential for transmitting a number of infectious agents to the patient, since it often requires violation of the body's mechanical barriers. Placement of intravenous and intraarterial catheters, instrumentation of the airway, and mechanical ventilation all provide potential vehicles for transmission of infection . However, although the potential for nosocomial transmission of infection in anesthesiology practice is real, there is very little data to support a cause and effect relationship. The contamination of anesthesia equipment and the potential for nosocomial transmission has long been a cause for concern. Indeed, as long ago as 1873, Skinner  decried the use of the same inhaler on successive patients without cleaning. However, the role of contaminated anesthesia equipment in the development of postoperative infections is controversial. Although outbreaks of Pseudomonas aeruginosa infections have been described in patients ventilated using a contaminated anesthesia machine, the use of disposable anesthestic circuits with bacterial filters has not been shown to improve the incidence of postoperative pulmonary infections [12,13]. In addition, the administration of anesthesia to patients with documented Gram-negative infections does not result in significant colonization of the anesthesia machine . Blood and body fluid contamination of stopcocks, anesthesia machine working surfaces, monitor cables, drawer handles, oximeter probes, and patient anesthesia records have all been described, although their role in transmission of infection has not been established [15-17].
Although direct evidence of anesthesia-related transmission of infection is difficult to substantiate, certain anesthetic practices described in this study have been associated with infectious transmission. Use of a common syringe for the administration of drugs to more than one patient, for example, is a risky practice, even if a new sterile needle is used for each individual patient use . Froggatt et al.  reported six patients who contracted acute HBV infections from a reused syringe that had come in contact with a contaminated stopcock from a hepatitis B carrier. More recently, a case of multiple patient-to-patient transmission of HIV in a private surgery clinic in Australia was described wherein the practice of reusing syringes from a potentially contaminated multidose local anesthetic vial was implicated [20,21]. Chant et al.  also reported on an investigation of possible patient-to-patient transmission of hepatitis C. In this case, transmission from the source patient to four other cases implicated either a reused syringe or contaminated anesthetic circuitry. It should be noted, however, that these modes of transmission have not been substantiated.
Recently, surveys from the CDC have implicated extrinsic contamination of propofol with cases of postoperative infection . It is recommended that infusion solutions should be used on a one-time, one-patient basis. Studies show that contaminated infusions have resulted in bacterial and fungal infections when used on more than one patient . The potential for transmission of nosocomial infection is further enhanced in the patient who is immunocompromised by disease or immunosuppressed by drugs. Indeed, many commonly used anesthetics are immunosuppressive and may compound the likelihood of pathogenic transmission [24-26]. Multidose vials generally contain preservatives and, therefore, can be used on more than one patient. However, care should be taken to clean the rubber septum with alcohol prior to each use. Vials that have obvious contamination should be discarded. Although transmission of infection by this route is uncommon, there have been reports of viral and bacterial infections linked to contaminated multidose vials [27,28].
Despite these examples, adherence to simple hygienic practices may be the best approach. For example, simple handwashing or the use of disposable gloves can prevent transmission of a number of pathogens . Gwaltney et al.  showed that during experimental rhinovirus infections, transmission of the virus occurs in 73% of cases via the hands and only 8% via sneezing and coughing. In our study, although handwashing was fairly routine after high-risk exposure, only half of the respondents stated that they washed their hands after a low-risk patient.
The observation that 90% of anesthesiologists administer anesthesia while harboring an infection of the respiratory tract is perhaps not surprising, and although this does not imply that the practice results in transmission of the infection to the patient, it suggests an interesting area for future study. Similarly, anesthesiologists with active herpes simplex lesions should be reminded to wear a mask and gloves to prevent transmission to the patient during manipulation of the airway . Anesthesiologists with herpetic whitlow on their hands should take care to cover the lesion with a dressing and gloves or avoid direct patient contact during exacerbations .
The potential biases in this study relate to self-report bias, sample representativeness, and nonresponse bias. In order to diminish the effect of a self-report bias, the questionnaire was designed to be completed anonymously, thus reducing the potential for respondents to intentionally report untrue behaviors. The demographics of the sample were very similar to those of the membership of the ASA suggesting that it was representative of anesthesiologists throughout the United States. Finally, despite the moderate response rate, analysis of a sample of the nonrespondents suggested that they were similar demographically to the respondents and had similar attitudes and behaviors. Comparisons between the demographics of the sample, the ASA, and the nonrespondents, together with tests of question reliability, are described in more detail elsewhere .
Although a cause-effect relationship between anesthesia practice, equipment contamination, and postoperative infection is not easy to establish, this survey suggests that there are several potentially hazardous practices that continue. However, in the absence of evidence to support anesthesiology-related transmission of infection, it may be inappropriate to label these breeches in recommended protocols as contributory or anesthesiology practice as necessarily "bad." It would seem, however, that the best approach would be to follow approved infection control guidelines where possible until evidence to the contrary is available. Certainly, it is not the purpose of this study to define the role of anesthesiology practice in the transmission of perioperative infection, but rather to describe the degree to which anesthesiologists adhere to recommended infection control guidelines. The fact that there are few documented cases of anesthesiology-related transmissions of infection should not be a cause for complacency, and every effort should be made to ensure that anesthesia personnel receive appropriate training and education regarding the implementation of universal precautions and other hygienic protocols in their clinical practice.
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© 1995 International Anesthesia Research Society
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