Visible and occult blood contamination of laryngeal mask airways and tracheal tubes used in adult anaesthesia

The purpose of this study was to compare visible and occult blood contamination of 50 laryngeal mask airways and 50 tracheal tubes following routine anaesthesia for procedures not involving the oropharyngeal or nasal cavities. All airway devices were examined visually for the presence of blood before washing in 100 ml of water. A semiquantitative dipstick was used to test for the presence of blood in the washings. Laryngeal mask airways were examined visually by both authors to test agreement. The results show that occult blood contamination occurred in 78% of tracheal tubes and 76% of laryngeal mask airways, while visible blood contamination was 16% and 12%, respectively. Other studies reporting visible blood contamination of airway devices probably underestimate the true incidence of blood contamination. Oral secretions following the use of these devices should be considered as high risk for transmission of blood-born viruses. Anaesthetic and recovery staff should be protected against the risks of occupational exposure to oral secretions following the use of airway devices.