Journal: Anaesthesia 62(12):1257-1261, 2007. 16 References
Reprint: Dept of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary of Edinburgh, Little France Drive, Edinburgh EH16 4SA, UK (JK Baillie, MD) RK.01 JU0816/166 ©2008
Faculty Disclosure: Abstracted by R. Klotz, who has nothing to disclose.
Hospital-acquired infections are commonly resistant to antibiotics and may cause substantial morbidity and mortality in susceptible patients. Asymptomatic colonization with potentially pathogenic bacteria confers an increased risk of infection. Patients undergoing surgery have a variety of risk factors for serious nosocomial infections, including the catabolic response to major surgery, intravascular lines, prolonged tracheal intubation, in addition to pre-existing risk factors such as sepsis, diabetes mellitus, renal failure, and old age. During induction of anesthesia the anesthetist’s gloved hands are held around the patient’s mouth and nose and are commonly inserted into the patient’s mouth. There is frequent contact with upper airway secretions and blood. During initial airway management it is also necessary to manipulate the controls on the anesthetic machine, ventilator, and the monitoring and suction apparatus. Current infection control procedures in anesthesia do not protect the patient from indirect contact with contaminated anesthetic equipment. The infection control guidelines of the Association of Anaesthetists of Great Britain and Ireland (AAGBI) recommend that all surfaces of anesthetic machines and monitors should be cleaned daily or immediately if visibly contaminated. The authors aimed to identify whether viable pathogenic bacteria are present on anesthetic equipment during normal cases, and whether a simple and practical change to departmental policy would reduce the overall burden of pathogenic bacteria on anesthetic equipment. This study was conducted in a single UK district general hospital with 8 operating rooms and 8 induction rooms utilized for a wide range of surgical specialties. Before the study, AAGBI guidelines for cleaning of equipment were followed. Two cross-sectional studies were performed, before and after intervention. Cultures were taken from the surfaces of the anesthetic and monitoring equipment that are routinely touched by the anesthetist but do not come into direct contact with the patient: oxygen, nitrous oxide and air flow control knobs; vaporizer dials; breathing system bag; adjustable pressure-limiting valve; and monitoring control buttons. Replicate Organism Detection and Counting (RODAC) blood agar plates were applied directly to the surfaces of anesthetic equipment by two investigators using the same technique for all samples. Within 5 hours the plates were placed in an incubator set at 37º C. After 48 hours the plates were removed from the incubator and the colonies counted. Results from the first data collection were collated to determine the overall prevalence of pathogenic bacteria on anesthetic equipment, and to identify patterns of contamination on specific items of equipment. It was agreed that each machine should be wiped once with a detergent wipe between cases. Following the presentation of evidence of contamination with pathogenic organisms, this new protocol was accepted with some enthusiasm. Both before and after the intervention, the items of equipment most likely to be contaminated with organisms were the flow control knobs, vaporizer dials and breathing system bags. Potentially pathogenic bacteria such as Staphylococcus aureus and gram-negative bacilli were found in 14/78 cultures (18%) from the initial study. No multidrug-resistant bacteria were identified. Six weeks after the interventions, S. aureus and gram-negative bacilli were present in 5/77 cultures (6%). The specific sites showing the most contamination were the surfaces most commonly touched by the anesthetist during induction of anesthesia: the ventilator bag, vaporizer dials, and flow control knobs. Also, most of the organisms isolated commonly colonize the upper respiratory tract. This is consistent with the hypothesis that the anesthetist’s hands are the main route of transmission of contaminants, and that the patient’s oropharynx is the most likely source. The concern about the use of a contaminated anesthetic machine is that it is obligatory for the anesthetist’s hands to go from the patient’s airway to the anesthesia machine and back again without time to change gloves or wash hands. Therefore, handwashing and gloves cannot protect a patient from pathogens present on the anesthesia machine. Since there is a clear route for transmission of potentially pathogenic bacteria between patients through indirect contact with anesthetic equipment, cleaning the anesthetic equipment between cases should become routine practice. |
