How are IV neural blocks administered for pain management?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Answer

Answer

IV neural blockade is performed using a technique similar to that described for IV sympathetic blockade. The patient is prepared for IV infusion in the affected limb. The limb is elevated, and the tourniquet is inflated to a pressure above the patient's systolic blood pressure. Using a 50-mL disposable syringe, 30-40 mL of 0.5% lidocaine or procaine, without epinephrine or other vasoconstrictors, is injected slowly. The skin often becomes mottled as the injection proceeds, and analgesia develops rapidly. Adequate analgesia often develops within 5-10 minutes.

Tourniquet discomfort may require adjunctive systemic injections of sedatives or narcotics; however, concomitant opioid use can confound diagnostic interpretations. Usual indications for this procedure include CRPS syndromes, neuralgia, and deafferentation pain. IV lidocaine in doses of 1-1.5 mg per kilogram of body weight, or in a 0.1% solution administered over 35 minutes to 200 mg, are alternative technical approaches for this procedure.

Successful neural blockade by continuous infusion may allow the pain medicine specialist to consider oral lidocainelike derivatives such as mexiletine. To this point, neural blockade and therapeutic procedures that have been described entail the use of LAs. However, LA blockade of certain painful conditions may lead treating practitioners to consider a neurolytic agent for more permanent pain relief.

Neurolytic blockade is an important tool because it offers the potential for long-term relief from severe pain caused by conditions such as advanced cancer, certain neuralgias, and incurable conditions such as occlusive vascular disease. Neurolytic cranial nerve blocks, subarachnoid block, celiac plexus block, and lumbar sympathetic block, when properly executed, result in a high degree of success with acceptably low instances of adverse effects in patients who have not obtained satisfactory relief by other methods.

Practitioners with extensive experience, skill, and knowledge of the pharmacology and application of neurolytic agents should perform these procedures. Informed consent including potential outcomes and adverse effects should be expressed clearly through practitioner-patient communication.


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