The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts


Theron Van Hooser M Ed, RRT, Tom Flood, Chris Blaes, Beverly Hyte, Ed Madsen Research and Development Department, Ballard Medical Products, Draper Utah.

Background: Recent studies have shown reduced rates of ventilator associated pneumonia (VAP) by maintaining a closed circuit beyond 24 hours. A previous study has shown that in those hospitals surveyed, the majority of patients are mechanically ventilated for 72 hours or less. Ballard TRACH CARE* 72, REF 227 (Kimberly-Clark Corp., Draper, Utah) closed suction system was designed for 72 hour use. The aim of this study was to compare the ability of REF 227 to clean the catheter tip as compared with the 24 hour Ballard TRACH CARE*, REF 2210. Methods and materials: Two hundred and forty catheters were equally divided (120 REF 2210 and 120 REF 227), then challenged with four common bacterial pathogens. Non-virulent strains of these four bacteria were chosen because they represent common respiratory pathogens which are responsible for approximately 47% of nosocomial pneumonias in the United States.

Staphylococcus aureus ATCC #6538 Pseudomonas aeruginosa ATCC #27853

Klebsiella pneumonia ATCC #23357 Escherichia coli ATCC #8739

The catheters were challenged by simulating the suction procedure over 24 to 72 hours. A simulated mucus solution was prepared in four containers. Each container of simulated mucus was inoculated with one species of organism at 1 x 107 ± 0.5 log10 CFU/ml. This level simulates the level of colonization in the respiratory secretions of a patient with pneumonia. The inoculum was stored at room temperature and new inoculum was prepared every 24 hours. An AEROS Mobl-Vac III vacuum system and a saline vial were attached to each catheter. The vacuum level was set to 120 ± 5 mm Hg [15.9 ± .6 kPa]. Each catheter was dipped into the inoculum approximately 5 centimeters. Inoculum was suctioned approximately 30 centimeters up the inside of the catheter. The catheter was then removed from the inoculum. The catheter tip was cleaned, by applying suction and retracting the catheter, as per the instructions for use. The REF 2210 catheters were cleaned with saline by the usual method of squeezing the saline vial. The REF 227 catheter design has a self closing valve or "flapper", which closes under vacuum which causes the vial to empty into the catheter-cleaning chamber. Twelve suction simulations were performed every 24 hours, using the following schedule on each day: 12:00, 13:00, 15:00, 16:00, 18:00, 19:00, 21:00, 22:00, 06:00, 07:00, 09:00, and 10:00. At 12:00 following the last suction simulation, the catheter was extended and the first 2 centimeters of the tip was aseptically removed. The bioburden was measured at 24 and 72 hour time points. Catheters were tested in groups of five replicates per catheter. Bacteria grow at an exponential rate. To improve accuracy, the data was converted into Log (CFU) before the analysis was performed. This is consistent with USP guidelines for antimicrobial effectiveness testing. Statistical analysis was performed using SAS statistical software. Results: REF 2210 had 275,000 CFU/ml at the end of 24 hours, and REF 227 had 19,800 CFU/ml. at the end of 72 hours. This represents a 1.1 log reduction in tip colonization. REF 227 has an overall significant (p < 0.001) reduction in colonization as measured by tip colonization.

The design has a significant effect on catheter tip bacterial colonization of closed suction systems.