Experimental contamination of a closed endotracheal suction system: 24 h vs 72 h

To ascertain the desirability of replacing closed suction systems after 72 h rather than after 24 h (manufacturer's recommendations) because it is possible that a reduction in the frequency of manipulations might reduce the risk of exogenous nosocomial pneumonia. We investigated the presence of time-dependent differences (after 24 h and 72 h) in pathogen survival/growth in artificially contaminated closed suction catheters (OptiFlo).

The trial simulated bacterial contamination of the airways using a suspension of 2 x 10(3) CFU/ml of Staphylococcus aureus or Pseudomonas aeruginosa. Contamination was performed on a total of 80 catheters. Forty were contaminated a total of eight times every 45-60 min. Another 40 catheters underwent the same procedure 24 times over three consecutive days. Microbiological analysis of the catheters took place after 24 h and 72 h, respectively.

The mean S. aureus load was 9.4 CFU/catheter after eight suction procedures and 6.2 CFU/catheter after 24 suction procedures (3 days). Mean growth of P. aeruginosa was 5.3 CFU/catheter, and 8.2 CFU/catheter after 3 days. There was no statistically significant difference between day 1 and 3 for S. aureus (p = 0.474), but there was for P. aeruginosa (p = 0.004).

Our findings show that, from an experimental point of view, it remains controversial whether routine change of closed suction catheters can be extended from 24 h to 72 h. However, clinical evidence suggests that prolonged use of a closed suctioning system is safe.