Local and Topical Anesthetic Complications

CHAPTER 5 Local and Topical Anesthetic Complications



Many in-office surgical procedures require the use of local or topical anesthetics. Topical anesthetics are used more frequently in children for dermatologic procedures and in persons having nasopharyngoscopy and esophagogastroduodenoscopy (EGD). Various mixtures of potent topical medications are also being used more frequently, often under occlusion, to cover large surface areas for many aesthetic procedures. This markedly increases the risk for toxic levels to accumulate.


The primary care physician must have an understanding of the types of complications that may be encountered when using these anesthetics and must be equipped to diagnose and deal with them. For maximum recommended dosages, see Chapter 4, Local Anesthesia.





Effects of Epinephrine in Local Anesthetics


It has long been an admonition to students, residents, and practicing clinicians that epinephrine should never be used in areas of the body supplied by the fine terminal end arterioles such as the fingers and toes, penis, and nose. Theoretically, the epinephrine could cause prolonged spasm leading to ischemia and even necrosis of the tissue. This effect would be potentially magnified if the vessels were already diseased and narrowed, as occurs in smokers and patients with diabetes, peripheral vascular disease, and similar conditions. Hence, in the past, it was literally seen as substandard care to use epinephrine in these areas, especially when there was potential vascular disease or diminished blood supply.


In 2000, a series of articles began appearing in the literature to refute this “theoretical” adverse effect (see Bibliography). A paper by Denkler published in 2001 reviewed the literature from 1880 through 2000. The conclusion was: “An extensive literature review failed to provide consistent evidence that our current preparations of local anesthesia with epinephrine cause digital necrosis, although not all complications are necessarily reported. However, as with all techniques, caution is necessary to balance the risks of this technique.…”


Digits can withstand prolonged periods of ischemia. Successful reimplantations have been reported 42 hours after traumatic amputations.


The usual concentration of epinephrine in local anesthetics is 1 : 100,000. Studies have been conducted using concentrations of 1 : 1000 with virtually no adverse consequences.


A multicenter prospective study of 3110 consecutive cases of elective epinephrine use in the fingers and hands (concentration ≤1 : 100,000) found that “the true incidence of finger infarction in elective low-dose-epinephrine injection into the hand and finger is likely to be remote, particularly with the possible rescue with phentolamine. Phentolamine was not required to reverse the vasoconstriction in any patients” (Lalonde et al, 2005).


“Phentolamine rescue” or reversal of epinephrine is not discussed in this text. Nitroglycerin ointment has also been suggested to reverse any apparent ischemia, however rare (or even possible) this event is.


It would seem acceptable then to use local anesthetics with epinephrine to control bleeding for optimal wound repair and also to prolong needed anesthesia in areas supplied by end arteries. It would appear that an age-old caveat has been disproven. The prudent physician would still observe at-risk patients closely and use epinephrine sparingly.



Overdose Reactions



Central Nervous System Toxicity


Local anesthetics reach the central nervous system after slow absorption or by direct intravenous (IV) injection. An inadvertent direct IV injection may create a transient high local central nervous system level of anesthetic, which can cause seizures. Most seizures created in this way terminate within minutes, provided the administration of the drug has stopped.


A warning of less serious central nervous system effects may include circumoral numbness, lightheadedness, tinnitus, visual disturbance, muscular twitching, and irrational behavior.


If high serum levels persist, grand mal seizures, apnea, unconsciousness, and death may occur. An alert patient, in most cases, tells the physician before a seizure develops. This would be absent in the case of rapid inadvertent IV injection.


Acidosis and hypercarbia increase the likelihood of central nervous system toxicity. Pulse oximetry monitoring during the procedure may be an invaluable tool to alert the clinician to some of the effects of toxicity.


With serious central nervous system toxicity, stop the offending agent and begin oxygen and support ventilation if needed. Alert patients can be asked to hyperventilate, which lowers the PCO2 level and raises the seizure threshold. This may temporarily alleviate twitching. Seizures can usually be stopped with IV midazolam (Versed), diazepam (Valium), or lorazepam (Ativan). Lorazepam and diazepam are inconsistently absorbed by the intramuscular (IM) route. Midazolam may be used IM if an IV line is not available. Flumazenil (Romazicon) should be available as an antagonist for benzodiazepines in case of respiratory depression from the drugs.

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May 14, 2017 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Local and Topical Anesthetic Complications

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