Reduced Resistance to Air Flow from Nanomodified Endotracheal Tubes
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Reduced Resistance to Air Flow from Nanomodified Endotracheal Tubes Mary C. Machado1, Keiko M. Tarquinio2, and Thomas J. Webster3 1 School of Engineering, Brown University; 2 School of Pediatric Critical Care Medicine, Rhode Island Hospital; 3 Division of Engineering and Department of Orthopedics; Providence RI 02917
Abstract Ventilator associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation over 24 hours increases the risk of VAP and is associated with high morbidity, mortality and medical costs. Cost effective endotracheal tubes (ETTs) that are resistant to bacterial infection would help to prevent this problem. The objective of this study was to determine differences in bacterial growth on nanomodified and unmodified ETTs under dynamic airway conditions, a bench top model based upon the general design of Hartmann et al. (1999) was constructed to test of the effectiveness of nanomodified ETTs under the airflow conditions present in the airway. Twenty-four hour studies performed in a dynamic flow chamber showed a marked difference in the biofilm formation on different areas of unmodified tubes. Areas where tubes were curved, such as at the entrance to the mouth and the connection between the oropharynx and the larynx, seemed to collect the largest amount of biofilm. On the nanomodified tubes biofilm formation was markedly different occurring on smaller pieces. The biofilm formation on ETTs in the airflow system after 24 hours showed a large difference depending upon where tubes were oriented within the apparatus. This illustrates the importance of dynamic flow on biofilm formation in pediatric ETTs. It is of particular interest that increased biofilm density on both unmodified and nanomodified tubes appeared to occur at curves in the tube where changes in flow pattern occured. This emphasizes the need for more accurate models of airflow within pediatric ETTs, suggesting that not only does flow affect pressure gradients along the tube, but in fact, determines the composition of the film itself. More testing is needed to determine the effects of biofilm formation on the efficiency of ETT under airflow, however this study provides significant evidence for nanomodification alone (without the use of antibiotics) to decrease bacteria function.
Introduction Ventilator associated pneumonia (VAP) is one of the most common causes of hospital associated infection in children and adults. Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus ) are two common strains associated with VAP. However, multi-drug resistant strains of bacteria such as Methicillin-resistant Staphylococcus aureus (MRSA), are of particular concern to clinicians because of their increasing prevalence within hospitals. Eight to 28% of all patients receiving mechanical ventilation will develop VAP. Depending on the pathogen involved, the patient’s underlying condition, and the length of intubation, VAP can have a high mortality rate, ranging between 38% and 76%. VAP can also
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