The word "tumescent" means swollen and firm. By injecting a large volume of very dilute lidocaine (local anesthetic) and epinephrine (capillary constrictor) into subcutaneous fat, the targeted tissue becomes swollen and firm, or tumescent. The tumescent liposuction technique is a method that provides local anesthesia to large volumes of subcutaneous fat and thus permits liposuction totally by local anesthesia. The tumescent liposuction technique eliminates both the need for general anesthesia and need for IV narcotics and sedatives. The tumescent technique for liposuction 1) provides local anesthesia, 2) constricts capillaries and prevents surgical blood loss 3) provides fluid to the body by subcutaneous injection so that no IV fluids are needed.
Depending upon the clinical requirements, a tumescent anesthetic solution may contain a 5 to 40 fold dilution of lidocaine found in commercially available formulations of local anesthesia. Commercial solutions of lidocaine used by dentists and anesthesiologists typically contain 1 gram of lidocaine and 1 milligram of epinephrine per 50 milliliters of saline. In contrast, tumescent solutions of local anesthesia contain approximately 1 gram of lidocaine and 1 milligram of epinephrine in 1,000 milliliters of saline. This is a 20 fold dilution of the commercial version of lidocaine and epinephrine.
Dilution & Vasoconstriction Produce Safety
Tumescent liposuction totally by local anesthesia has proven to be extremely safe despite the use of unprecedented large doses of lidocaine and epinephrine. The explanation for this remarkable safety is the extreme dilution of the tumescent local anesthetic solution. Large volumes of dilute epinephrine produce intense constriction of capillaries in the targeted fat, which in turn greatly delays the rate of absorption of lidocaine and epinephrine. Undiluted lidocaine and epinephrine is absorbed into the bloodstream in less than an hour. Tumescent dilution causes widespread capillary constriction which causes the absorption process to be spread over 24 to 36 hours. This reduces peak concentration of lidocaine in the blood, which in turn reduces the potential toxicity of a given dose of lidocaine. Dentists typically use concentrated epinephrine which may cause a rapid heart rate if the epinephrine is rapidly absorbed. When very dilute tumescent epinephrine is used, the wide spread vasoconstriction slows the rate of epinephrine absorption, which in turn prevents an increase in heart rate.
Vasoconstriction Prevents Blood Loss
Profound vasoconstriction (shrinkage of capillary blood vessels) results from the tumescent infiltration of a large volume of dilute epinephrine into subcutaneous fat. Tumescent vasoconstriction is so complete that liposuction can be done with virtually no blood loss. In contrast, the older forms of liposuction used before the invention of the tumescent technique were associated with so much surgical blood loss that autologous blood transfusions were often routine.
Vasoconstriction Prolongs Local Anesthesia
Because the vasoconstriction delays lidocaine absorption, the local anesthetic remains in place in the fat for many hours. This prolonged anesthesia permits surgery for up to 10 hours after infiltration, and provides 24 to 36 hours of significant postoperative analgesia.
Recommended Lidocaine Dosage
Maximum recommended lidocaine dosage is 40 mg/kg to 50 mg/kg for tumescent liposuction when lidocaine is greatly diluted. This is a relatively large dosage compared to the 7 mg/kg which is widely accepted as the "safe maximum dose for lidocaine with epinephrine" that anesthesiologists use. They use non-diluted lidocaine for nerve blocks such as epidural blocks.
A liposuction cannula is a stainless steel tube which is inserted into subcutaneous fat through a small opening or incision in the skin. A microcannula has an outside diameter of less than 3 millimeters (mm). The diameter of microcannulas range from 1 mm to 3 mm. With special designs, microcannulas can remove fat very efficiently. The use of larger cannulas, for example those having an outside diameter ranging from 3 mm to 6 mm require larger incisions which usually leave visible scars.
Adits are small holes in the skin made with round, skin-biopsy punches. Adits are used as access sites, in which the liposuction cannula is passed in and out of during the liposuction process. Adits also facilitate the drainage of blood-tinged anesthetic solution after liposuction. Because of the skin's ability to stretch, microcannulas can usually fit through a 1.0 mm, 1.5 mm, or 2 mm round hole made in the skin with a skin biopsy punch. Such tiny holes usually disappear without scars after liposuction. Adits are so small that it is not necessary to close them with sutures. Because adits are not closed with sutures, they promote copious postoperative drainage of blood-tinged tumescent anesthesia, which in turn reduces post-operative bruising, tenderness and swelling. Larger cannulas require larger incisions. When larger incisions are closed with sutures, there is delayed drainage, and prolonged swelling, bruising and pain after liposuction.
Smoother Liposuction Results
Smoother liposuction results can be achieved by using microcannulas which allow a more gradual and controlled removal of fat. This improves the ability of the surgeon to achieve smoother results. Larger cannulas are associated with an increased risk of liposuction producing skin depressions and irregularities. Larger cannulas may remove fat so quickly that there is a risk of removing too much fat. It is also more difficult to precisely control the direction of a large cannula. With any attempt to make a small incremental change in the direction of a large cannula there is tendency to re-enter a pre-existing tunnel within the fat. This lack of precise control contributes to the risk of skin irregularities associated with liposuction when using large cannulas.
Other Advantages of Tumescent Anesthesia
Because tumescent local anesthesia lasts so long, tumescent liposuction is less painful and more pleasant than liposuction under general anesthesia or IV sedation. With tumescent local anesthesia, patients are able to avoid the post-operative nausea and vomiting associated with general anesthesia. Tumescent anesthesia is so efficient at providing fluid to the body that it is unnecessary to use IV fluids. There is a risk of dangerous fluid overload if excessive IV fluids are given to a tumescent liposuction patient.