A PROSPECTIVE, RANDOMIZED COMPARISON OF AN IN-LINE HEAT MOISTURE EXCHANGE FILTER AND HEATED WIRE HUMIDIFIERS - RATES OF VENTILATOR-ASSOCIATED EARLY-ONSET (COMMUNITY-ACQUIRED) OR LATE-ONSET (HOSPITAL-ACQUIRED) PNEUMONIA AND INCIDENCE OF ENDOTRACHEAL-TUBE OCCLUSION

Purpose: To compare the performance of an in-line heat moisture exchan ging filter (HMEF) (Pall BB-100; Pall Corporation; East Hills, NY) to a conventional heated wire humidifier (H-wH) (Marquest Medical Product s Inc., Englewood, Cole) in the mechanical ventilator circuit on the i ncidence of ventilator-associated pneumonia (VAP) and the rate of endo tracheal tube occlusion. Methods: This report describes a prospective, randomized trial of 280 consecutive trauma patients in a 20-bed traum a ICU (TICU). All intubated patients not ventilated elsewhere in the m edical center prior to their TICU admission were randomized to either an in-line HMEF or a H-wH in the breathing circuit. Ventilator circuit s were changed routinely every 7 days, and closed system suction cathe ters were changed every 3 days. HMEFs were changed every 24 h, or more frequently if necessary. A specific endotracheal tube suction and lav age protocol was not employed. Patients were dropped from the HMEF gro up if the filter was changed more than three times a day or the patien t was placed on a regimen of ultra high-frequency ventilation. The Cen ters for Disease Control and Prevention (CDC) critt ria for diagnosis of pneumonia were used; early-onset, community-acquired pneumonia was defined if CDC criteria were met in less than or equal to 3 days, and late-onset, hospital-acquired pneumonia was defined if criteria were m et in >3 days. Laboratory and chest radiograph interpretation were bli nded. Results: The patient ages ranged from 15 to 95 years in the HMEF group and 16 to 87 years in the H-wH group (p=not significant), with a mean age of 46 years and 48 years, respectively. The male to female ratio ranged between 78 to 82%/22 to 18%, respectively, and 55% of all admissions were related to blunt trauma, 40% secondary to penetrating trauma, and 5% to major burns. There was no difference in Injury Seve rity Score (ISS) between the two groups. Moreover, there was no signif icant difference in mean ISS among those who did not develop pneumonia and those patients who developed either early-onset, community-acquir ed or late-onset, hospital-acquired pneumonia. The HMEF nosocomial VAP rate was 6% compared to 16% for the H-wH group (p<0.05), and total ve ntilator circuit costs (per group) were reduced, There were no differe nces in duration of ventilation (mean+/-SD) if the patient did not dev elop pneumonia or if the patient developed an early-onset, community-a cquired or a late-onset, hospital-acquired pneumonia. Moreover, total TICU days were reduced in the HMEF group. In addition, tile incidence of partial endotracheal tube occlusion was not significantly different between the H-wH and the HMEF groups. Conclusions: The HMEF used in t his study reduced the incidence of late-onset, hospital-acquired VAP, but not early-onset, community-acquired VAP, compared to the conventio nal H-wH circuit. This was associated with a significant reduction in total ICU stay. Disposable ventilator circuit costs in the HMEF group were reduced compared to the H-wH group in whom circuit changes occurr ed at 7-day intervals. Clinical implications: The use of the HMEF is a cost-effective clinical practice associated with fewer late-onset, ho spital-acquired VAPs, and should result in improved resource allocatio n and utilization.