Background: Perineural catheters (PNCs) are increasingly being used. Few data are available on the infectious complications of PNCs. The incidence and localization of local inflammation and infection associated with PNCs were assessed. Methods: PNCs placed under sterile conditions for regional anesthesia and post-operative analgesia were evaluated prospectively. Local inflammation was defined as redness, swelling or pain on pressure at the catheter insertion site. Infection was defined as purulent material at the catheter insertion site with or without the need for surgical intervention. Results: In total, 2285 PNCs were evaluated: 600 axillary, 303 interscalene, 92 infraclavicular, 65 psoas compartment, 574 femoral, 296 sciatic and 355 popliteal. Local inflammation occurred in 4.2% and infection in 3.2%. The duration of PNC placement was a risk factor (P < 0.05). Surgical intervention was necessary in 0.9%. No late complications occurred in any patient. Interscalene catheters were associated with an increased risk of infection (4.3%; P < 0.05). Anterior proximal sciatic catheters were associated with a lower risk of local inflammation (1.7%; P < 0.05) and infection (0.4%; P < 0.05). Staphylococcus epidermidis and Staphylococcus aureus were isolated in 42% and 58% of catheter tip cultures, respectively. Conclusion: In the present study population, infection of PNCs was a rare occurrence, but the incidence increased with the duration of PNC placement, and close clinical monitoring is required.

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We show that one-dimensional (1D) nanostructures and two-dimensional (2D) supramolecular crystals of organic semiconductors can be grown on substrates under ambient conditions directly from three-dimensional (3D) organic crystals. The approach does not require dissolving, melting or evaporating of the source crystals and is based on the Organic SolidSolid Wetting Deposition (OSWD). We exemplify our approach by the pigment quinacridone (QAC). Scanning Tunnelling Microscopy (STM) investigations show that the structures of the resulting 2D crystals are similar to the chain arrangement of the alpha and beta QAC polymorphs and are independent of the 3D source crystal polymorph (gamma). Furthermore, distinct 1D chains can be produced systematically.