The only anatomic detail necessary for clinical use of the IV regional block is identification of a peripheral vein, as one must be cannulated in the involved extremity. The patient should be resting supine on the operating table with an IV tube already established in the nonsurgical arm. The involved arm should be extended on an arm board near available supplies, as illustrated in
The only anatomic detail necessary for clinical use of the IV regional block is identification of a peripheral vein, as one must be cannulated in the involved extremity.Position.
The patient should be resting supine on the operating table with an IV tube already established in the nonsurgical arm. The involved arm should be extended on an arm board near available supplies, as illustrated in Figure 9-2 .
Before placing the IV catheter in the operative extremity, a tourniquet, either double or single, should be placed around the upper arm of the patient. An IV cannula is then inserted in the operative extremity as distally as possible, most commonly in the dorsum of the hand ( Fig. 9-3 ). There are two methods for exsanguinating venous blood from the operative extremity. The traditional technique requires wrapping an Esmarch bandage from distal to proximal ( Fig. 9-4 ). When the Esmarch bandage is not available or the patient is in too much pain to allow its placement, another method is to raise the arm for 3 to 4 minutes to allow gravity to exsanguinate it ( Fig. 9-5 ). After the blood has been exsanguinated from the upper extremity, the tourniquet is inflated. If a single tourniquet is used, it is inflated; if a double tourniquet is used, the upper tourniquet is inflated at this point.
Recommendations for tourniquet inflation pressures range from 50 mm Hg above systolic blood pressure with a wide cuff to a cuff pressure double the systolic blood pressure to 300 mm Hg regardless of blood pressure. Until more information is available, I caution against using pressures higher than 300 mm Hg during upper extremity block.
If an Esmarch bandage has been used, the elastic bandage is then unwrapped, and in the average adult 50 mL of 0.5% lidocaine without a vasoconstrictor is injected. Onset of the block usually occurs within 5 minutes, and the block is effective for procedures lasting as long as 90 to 120 minutes. The time limit is due to tourniquet time constraints rather than to diminution of the local anesthetic effect. The IV cannula is removed before preparation for the operation. The block persists as long as the cuff is inflated and disappears shortly after deflation.Potential Problems.
The principal disadvantage of IV regional anesthesia is that physicians unfamiliar with treating local anesthetic toxicity may use the technique when appropriate resuscitation measures are not available. Although some workers report successful use of IV regional anesthesia for lower extremity surgery, especially if a calf tourniquet is employed for foot surgery, its use is not widespread. During upper extremity use, a considerable number of patients complain about tourniquet pressure even when a double tourniquet is used, and this is often the clinical limiting feature of this technique. Appropriate use of IV sedatives is important for patient comfort.