Sutures, dissolving

In addition to glycolic and lactic acids (Section 30.6B), dissolving sutures can also be prepared from each of the following lactone monomers. Draw the structure of the polymer formed from each monomer. 

The BPB has a dissolvable suture attached to the return electrode. The BPBs stimulation electrode end is inserted into the sheath and gently pushed by the ejection tool to the sheath tip, so that only the BPB stimulation electrode end protrudes. From the ejection tool tip, saline is infused into the sheath to allow the anodal end of the BPB to have electrical connection to the tissues through small holes in the distal sheath. The BPB is activated to test and confirm its optimal position relative to the target nerve/motor-point. By withdrawing the sheath over the ejection tool, the BPB is deposited into the tissues (Figure 34.11). The sheath and the ejection tool are then removed. 

Dissolving sutures, such as dexon and poly(dioxanone) (PDS), are S3mthetic polymers that are now routinely used in surgery. The many ester groups they contain are slowly hydrolyzed to small molecules that are then metabolized to compounds easily excreted by the body. Patients no longer have to undergo a second medical procedure to remove the sutures that was required when traditional suture materials were used. 

One of the two polymers used for sutures shown in the box on Dissolving Sutures loses 50% of its strength in two weeks, and the other loses that much strength in three weeks. Which suture material lasts longer ... 

Sei f-Tfst 19.4A (a) Write the formula for the monomer of the polymer sold as Teflon, — (CF2CF2),—. (b) The polymer of lactic acid (16) is a biodegradable polymer made from renewable resources. It is used in surgical sutures that dissolve in the body. Write the formula for a repeating unit of this polymer. 

Lactic acid is an important chemical that has wide applications in food, pharmaceutical, cosmetic, and chemical industries. There are increasing interests in production of lactate esters and biodegradable polylactic acid (PLA) from lactic acid. Lactate esters are a relatively new family of solvents with specific properties. They are considered safe and are biodegradable (1). In many situations they can replace toxic solvents. Their functions vary from that of intermediates in chemical reactions to solvents in ink formulations and cleaning applications (2). PLA has been widely used in medical implants, sutures, and drug-delivery systems because of its capacity to dissolve over time (3-5). PLA also can be used in products such as plant pots, disposable diapers, and textile fabrics. 

The implant consists of a tablet-shaped ganciclovir reservoir. The drag is initially completely coated with poly(vinyl alcohol) (PVA) and then coated with a discontinuous film of hydrophobic, dense poly (ethylene-co-vinyl acetate) (EVA). Both polymers are nonerodible and hydrophobic (the PVA used in the implant is cross-linked and/or high molecular weight, to ensure it does not dissolve when exposed to water). The entire assembly is coated again with PVA to which a suture tab made of PVA is attached (Figure 4.5). 

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