These garments alternate layers of materials with high and low acoustic impedance (the product of a materials density and a waves velocity through it) in order to "decouple" the blast wave, preventing its propagation into the tissues. Treatment
No treatment is known to speed the healing of a pulmonary contusion; the main care is supportive. Attempts are made to discover injuries accompanying the contusion, to prevent additional injury, and to provide supportive care while waiting for the contusion to heal. Monitoring, including keeping track of fluid balance, respiratory function, and oxygen saturation using pulse oximetry is also required as the patients condition may progressively worsen. Monitoring for complications such as pneumonia and acute respiratory distress syndrome is of critical importance. Treatment aims to prevent respiratory failure and to ensure adequate blood oxygenation. Supplemental oxygen can be given and it may be warmed and humidified. When the contusion does not respond to other treatments, extracorporeal membranous oxygenation may be used, pumping blood from the body into a machine that oxygenates it and removes carbon dioxide prior to pumping it back in. Ventilation
Positive pressure ventilation, in which air is forced into the lungs, is needed when oxygenation is significantly impaired. Noninvasive positive pressure ventilation including continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP), may be used to improve oxygenation and treat atelectasis: air is blown into the airways at a prescribed pressure via a face mask.
Mechanism of action
Alters bacterial outer membrane permeability by binding to a negatively charged site in the lipopolysaccharide layer, which has an electrostatic attraction for the positively charged amino groups in the cyclic peptide portion  (this site normally is a binding site for calcium and magnesium counter ions); the result is a destabilized outer membrane
Fatty acid portion dissolves in hydrophobic region of cytoplasmic membrane and disrupts membrane integrity
Leakage of cellular molecules, inhibition of cellular respiration
Binds and inactivates endotoxin
Relative absence of selective toxicity: nonspecific for cell membranes of any type, highly toxic.Removal of the hydrophobic tail of polymyxin B yields polymyxin nonapeptide (PMBN), which still binds to LPS, but no longer kills the bacterial cell. However, it still detectably increases the permeability of the bacterial cell wall to other antibiotics, indicating that it still causes some degree of membrane disorganization. Mixture composition
Polymyxin B is composed of polymyxins B1, B1-I, B2, B3, and B6. Polymyxins B1 and B2 are considered major components. These related components are structurally identical with the exception of a variable fatty acid group on each fraction. Results from in vitro studies have shown marginal differences in MIC data when comparing the fractions. Research application
Polymyxin B is also used to induce envelope stress in order to study the organisms response to such stress. Polymyxin envelope stress assays such as this have been used for the study of small RNA (sRNA) responses in Salmonella enterica. See also
Polymyxin

References
External links
"Polymyxin B". Drug Information Portal. U.S. National Library of Medicine.