Heat and moisture exchangers and vaporizing humidifiers in the intensive care unit

A prospective, randomized, controlled study was undertaken to compare the Pall Ultipor breathing circuit filter (PUBCF), a heat-and-moisture exchanger, and heated hot water systems (HHWSs) in ICU patients submitted to controlled mechanical ventilation. Humidification of inspired gas and bacterial contamination of breathing circuits were evaluated. During the study, there were six episodes of tracheostomy tube (TT) occlusion in six patients included in the PUBCF group. No patient out of 42 included in the HHWS group experienced this complication (p less than 0.01). There were 4 percent of days with thick and tenacious bronchial secretions in the PUBCF group and no case in the HHWS group (p less than 0.02). In the PUBCF group, 23 percent of days with hypothermia were noted as opposed to 12 percent in the HHWS group (p less than 0.01). Fewer breathing circuits were found to be contaminated in the PUBCF group (11 percent) than in the HHWS group (54 percent, p less than 0.01). In patients with an organism growing in bronchial specimens, the same organism was found to contaminate the breathing circuit in 10 percent of cases in the PUBCF group and 77 percent of cases in the HHWS (p less than 0.01). We conclude that, in the conditions of this study, the PUBCF did not provide sufficient humidification of inspired gas in ICU patients. Protection against contamination of breathing circuits was effective, but 10 percent of patients remained at risk for this complication.