Portable lung ventilators: the potential risk from bacterial colonisation.

Seven portable lung ventilators were investigated to assess the risk of bacterial colonization of the ventilator valve. One valve was deliberately contaminated with Serratia marcescens and the survival of organisms within the valve studied. Periods of colonization by Acinetobacter were found in all the hospital ventilators studied but none of those from the ambulance service. The potential risk to the patient from this organism is discussed and the importance of adequate storage and regular cleaning of the ventilator valve emphasised. Since humidification of the patients inspired gas during transfer is desirable, the use of a combined heat and moisture exchanger and microbiological filter would appear advisable.