In vitro comparison of bacterial permeability of different epidural catheter filters

The rate of infection occurrence is approximately 5.4 % during epidural analgesia/anesthesia administration. Requirement for bacteria filters to reduce the infection risk is one of the most debated topics. Conflicting results have been reported for the effectiveness of different filters for short and long term use with the epidural catheters.In this study; we aimed to compare the effectiveness of different filters (Portex ? , Rusch ? ) in filtering bacteria Staphylococcus aureus and Pseudomonas aureginosa using Patient Controlled Analgesia (PCA) pump in an in vitro model. And Scanning Electron Microscope (SEM) was used to prove filtration of bacteria.Bacteria suspensions (0.5 McF of Staphylococcus aureus and Pseudomonas aureginosa) are prepared in 250 mL isotonic NaCl. Two different bacteria suspensions and control groups (sterile 250 mL isotonic NaCl) are filtered using 2 different types of filters (n=60) for 48 hours at a infusion rate of 5 mL/h by using PCA pump and collected in a sterile bottle. Bacterial colonies were counted from the samples taken from the bottles (n=60) and filters (n=60). The results were compared with Mann-Whitney U test. .A p value of <0.05 is accepted significant.Structures of the membranes in the filters and bacterial adherence were investigated using SEM and recorded. We observed that the structure of Rusch ? filters were fibrous and scattered, Portex ? filters were granular and compact. According to colony numbers counted from the bottles that represents the epidural space in clinics we established that Portex ? filters are 18 times more effective than Rusch ? filters (p=0.0001). The presence of some bacteria in the solutions in the bottles shows that neither of them were 100 % safe.As a conclusion; although they are not completely confidential the filters can be used as a barrier to prevent occurrence of infection. We think that all the filters should be compared with a similar methodology before they are used in routine clinical practice.Key Words: Epidural Analgesia/Anesthesia, Bacteria filter, Staphyloccus aureus and Pseudomonas aeruginosa, Scanning Electron Microscobe (SEM)