The present recommendation for maximum doses of tumescent lidocaine in healthy, young female patients is as follows:
40 mg/kg for thin patients
45 mg/kg for average patients
50 mg/kg for overweight patients
Males, whose percentage of body fat is usually 10 to 20 % less than females, have a smaller volume of distribution for lidocaine and therefore the maximum allowable dose should be reduced by 10 to 20 percent. See List of Drugs that Interact with Lidocaine.
Serial liposuction procedures separated by at least a month are safer than a one-day mega-liposuction-session utilizing imprudent doses of lidocaine. The fundamental philosophy of tumescent liposuction is safety first and convenience second.
Maximal lidocaine doses must be reduced in certain situations. In patients who are taking drugs that interfere with lidocaine metabolism, such as the newer SSRI antidepressant sertraline (Zoloft), lidocaine doses must be reduced by at least 30 to 40 percent.
Relatively obese patients seem to tolerate higher mg/kg-dosages of lidocaine better than relatively thin patients. There is a higher incidence of lidocaine toxicity among coronary care unit patients weighing less than 70 kg. Thus, thin patients may have a smaller volume of distribution for lidocaine. In other words, given identical mg/kg dosages of lidocaine, thinner patients will have greater peak plasma lidocaine concentration than obese patients, and a greater risk of lidocaine toxicity.
Younger patients tolerate more lidocaine than older patients. This is attributed to the decrease in cardiac output, and the consequent decrease in hepatic perfusion associated with advancing age. Thus, older patients should be given smaller doses of tumescent lidocaine.
A lidocaine dose that would be safe under normal circumstances might be toxic as a result of unanticipated drug interactions. As a general rule, drugs that potentially interfere with lidocaine metabolism should be discontinued one to two weeks before using tumescent liposuction when relatively large dosages of lidocaine are anticipated. If it is not possible to simply discontinue a drug that might interfere with lidocaine metabolism, then the surgery should be limited to smaller total dosages of lidocaine.
When greater dosage is anticipated, the surgical plan ought to be re-evaluated and the surgery divided into sequential procedures separated by several weeks. In fact, the two procedures are typically one month apart to allow the resolution of most of the post-operative soreness from the initial procedure before subjecting the patient to additional surgical trauma and discomfort.