Botulinum toxin uses five elements: dose, dilution, dispersion, duration and principle.
First of all, the injection doctor must be familiar with the facial anatomy. Secondly, the surgeon must be clear about the secondary compensation mechanism when injecting a muscle or muscle group.
Choosing the right patient is the premise of successful injection therapy. Patients should be reminded that injection of botulinum toxin can only change dynamic wrinkles, and deep wrinkles caused by light damage or aging can not be well improved. Absolute contraindications of botulinum toxin injection include: infected people at the injection site, people who are allergic or allergic to this product. Relative contraindications include: patients with high psychological expectations; Patients (actors) who eat by their faces; Patients with neuromuscular diseases such as myasthenia gravis and Eaton-Lambert syndrome; Patients who are taking drugs that interact with this product, such as aminoglycoside antibiotics, penicillamine, quinine and calcium antagonists; Pregnant and lactating women. Only a few cases of injecting botulinum toxin before pregnancy or in the early and late pregnancy were reported, and no adverse reactions were found. Only one woman with a history of spontaneous abortion aborted after injection.
Botulinum toxin injection will interfere with the monitoring of neuromuscular block after general anesthesia, because neuromuscular block is usually achieved by monitoring the facial nerve innervating the orbicularis oculi muscle. Therefore, if patients have been injected with botulinum toxin within one month before general anesthesia, they need to inform the anesthesiologist that these patients can monitor and control the peripheral ulnar nerve replacement of adductor pollicis.
Dilution technique
Botulinum toxin is unstable, so we must pay attention to it when diluting it. Early literature advocated adding sodium chloride slowly in the dilution process to avoid foaming and shaking. We believe that the foaming process and foam will lead to the surface denaturation of botulinum toxin. In addition, some scholars believe that the foam produced by vibration and shaking does not affect the activity of botulinum toxin when diluted with saline without preservatives. This conclusion is consistent with our clinical experience, but further research is needed to confirm this conclusion. In short, at present, the slow and gentle dilution process is the best.
keep
The manufacturer recommends that the botulinum toxin be used immediately after dilution and dissolution, or it can be used up in the refrigerator at 2-8℃ for 4 hours. A recent study shows that botulinum toxin diluted with sodium chloride containing preservatives is stored in a conventional refrigerator and will not be contaminated by microorganisms after being smoked and used by many doctors. It is safe to store and reuse botulinum toxin within 7 weeks after dilution. Hexsel et al. found that botulinum toxin diluted with preservative-free saline can be used for 6 weeks and maintain its activity. But they didn't measure the microbial content. Doctors who inject botulinum toxin must be aware that the risk of bacterial contamination in the solution will increase with the extension of use time. In addition, the author observed that the activity of botulinum toxin just diluted and dissolved was stronger, but no comparative study was made.
Dilution/dispersion
The specification of botulinum toxin is that each bottle contains botulinum toxin 100 unit (U), human albumin 0.5mg and sodium chloride 0.9mg, and aseptic vacuum packaging does not contain preservatives.
The concentration and dosage of botulinum toxin are mainly determined according to the operating habits of clinicians and the number of injection points. This is a very controversial issue. Some doctors argue that using more concentrated solution can be more accurate and reduce side effects, such as the solution spreading to adjacent muscle tissues. The opposite opinion is that concentrated solution is difficult to handle and wasteful. They also think that regional dispersion like frontalis muscle is an advantage, which can reduce our injection units (injection points).
The dilution concentration ranges from 100U/ml to 10U/ml. The dilution concentration used by most dermatologists on the face is 100-33.3U/ml. Some researchers have found that when the concentration of botulinum toxin is between 100U/ml and 10U/ml, the therapeutic effect and the duration of the effect are the same. Another study found that highly diluted botulinum toxin has a wider range of effects after being injected into the forehead. It was found that the higher concentration of botulinum toxin (5U/0.05ml) was more effective than the diluted dose (5U/0.25ml), but the statistical difference was meaningless (the sample size was too small). The use of low concentration and high volume makes the pain more obvious during use.
It is suggested that the ideal strategy is to use high concentration and low volume injection for smaller muscle groups, while low concentration and high volume injection should be used for larger muscle groups like frontalis muscle. They also suggested that syringes with shorter needles should be used when injecting higher concentrations of botulinum toxin.
Although the manufacturer of botulinum toxin suggests using preservative-free saline when diluting botulinum toxin, many studies have shown that it is not necessary. A few studies have found that the treatment of dynamic lines and spontaneous eyelid contracture on the upper part of the face by diluting botulinum toxin with saline containing preservatives can alleviate the pain during use, and the safety and effect are the same as those recommended by manufacturers. It may be that benzyl alcohol contained in physiological saline containing preservatives has anesthetic effect and can relieve pain. Recently, it has been reported that 2% lidocaine diluted botulinum toxin can be used to treat axillary hyperhidrosis and effectively relieve pain.
Injection technique/dosage
Generally speaking, during the injection process, the needle should be inserted vertically and injected into the muscle. Injection should follow the individualized plan. Most patients may have slight facial asymmetry, so be sure to explain and take photos before treatment.
Injection site, quality and strength of injected muscle, etc. * * * Same as injection dose and injection unit (injection point). Generally speaking, men have more injection units (points) than women.
conclusion
Botulinum injection is the most common cosmetic method in America. With the use of botulinum toxin, our understanding of it is also growing rapidly. The usage principle can never keep up with the new usage progress. First of all, mastering facial anatomy, injection technology and appropriate dilution and preservation methods are the prerequisites for avoiding complications and correct use.