Humidification method that decreases condensate contamination in ventilator tubing

Objective: To demonstrate combining unheated bubble-through humidifier with a heat-moisture exchanger filter for the purpose of decreasing condensate contamination in mechanical ventilator tubing. Design: Single-case, pretest and posttest. Setting: University-affiliated and nonprofit hospital. Patient: A 32-year-old man with Pickwickian syndrome and pneumonia caused by Pseudomonas aeruginosa received mechanical ventilation for 14 days. Methods: Ventilator tubing was cultured in two 24-hour trials, using a pretest and posttest design, to assess tubing bacterial contamination during use of 2 humidification methods. In the first trial, a traditional heated bubble-through humidifier (HBH) was used for 24 hours. Before the start of the second trial, the “wet” tubing and the heated bubble-through humidifier were removed and replaced with clean equipment through the use of aseptic technique. The bubble-through humidifier was placed on the “cold,” or unheated mode, and a heat-moisture exchanger filter was attached to the Y-connector of the ventilator tubing. Results: The heated bubble-through humidifier method revealed contamination of the ventilator tubing in 3 places with the patient’s strain of P aeruginosa in addition to copious water condensate. The unheated bubble-through humidifier/heat moisture exchanger filter method demonstrated no bacterial contamination or condensate in the tubing. Conclusion: It can be inferred that the humidification method using the combination of an unheated bubble-through humidifier and a heat moisture exchanger filter has the potential benefit of preventing “reseeding” of the patient’s airway with contaminated condensate. (Heart Lung® 2000;29:56-59)