Abstract ID: A46

Abstract Title: Ultrasound-Guidance vs. Nerve Stimulation for the Infraclavicular Blockade of the Brachial Plexus: A Comparison of the Vascular Puncture Rate

Authors: Maalouf D¹, Gordon M², Paroli L³, Tong-Ngork S⁴
Hospital for Special Surgery New York NY USA¹, Hospital for Special Surgery New York NY USA², Hospital for Special Surgery New York NY USA³, Hospital for Special Surgery New York NY USA⁴
Poster Type: Either

ABSTRACT BODY

Introduction:
The infraclavicular approach for blockade of the brachial plexus for upper extremity surgery has relatively high success rate and patient satisfaction(1). This technique, however, is not without complications even when a nerve stimulator is used to locate the plexus. Such complications include pneumothorax and vascular punctures(2). The latter has an incidence between 0 and 50% depending on the study and the approach taken(2). In an effort to minimize these complications, ultrasonography has been used to aid in needle guidance. The technique allows direct visualization of the needle and of the anatomic structures along its path. As a result, the anesthesiologist can avoid the vessels and the pleura while performing this block(3). So far, no studies have demonstrated any difference in efficacy or safety of the nerve stimulator versus the ultrasound-guided technique. We compared the two techniques in a randomized prospective clinical trial, using the rate of vascular puncture as our primary outcome. Secondary outcomes were block performance time and efficacy.

Methods:
74 patients ASA I, II and III, scheduled for surgery of the elbow, or distal to it, were randomized into 2 groups. In both the Nerve Stimulator group (NSG) and the Ultrasound group (USG) a 4-inch 21G Braun Stimuplex needle was inserted, according to the technique described by Wilson, and advanced under continuous aspiration. In the NSG, a twitch at the wrist or fingers was elicited, and a current less than 0.5 mA was accepted for injection of the local anesthetic.
In the USG, a Sonosite C11/8-5MHz probe was placed just below the needle insertion point. The needle was advanced under direct visualization in the sagittal plane until its tip was tangential to the posterior cord of the brachial plexus. Patients in both groups received 45 to 60 ml, of Mepivacaine 1.5% with epinephrine 1:200,000 and bicarbonate 1 mEq/10 ml, in 5 ml increments between aspirations. An independent observer recorded the number of needle passes, blood aspirations and time to perform the block. The anesthesiologist performing the block rated its difficulty as well as sensory and motor function, every 5 minutes following completion of the injection, until skin incision. A test for anesthesia and analgesia was performed by the surgeon before commencement of surgery. The adequacy of the block was rated by the anesthesiologist as optimal or adequate, based on the need for additional administration of sedative and/or narcotics.

Results:
There was no significant difference between groups in age, sex and BMI.
No vascular punctures were reported in the ultrasound group whereas 12 patients in the nerve stimulator group sustained at least one vascular puncture (p= 0.0002).
Time to perform the block was 5.39 min in the USG and 8.43 min in the NSG, (p=0.0013). The number of needle passes was higher in the NSG: 5.59 vs 1.89 times in the USG (p <0.05). The block was rated optimal in 83.3% (n=30) and 51.3% (n=19) in the USG and NSG respectively (p<0.01).

Discussion:
We conclude that the ultrasound–guided infraclavicular block has a lower incidence of vascular puncture than the nerve stimulator technique, it is faster and easier to perform, and may have a higher success rate.

ATTACHED FILES

A46_ASRA references.doc

Reg Anesth Pain Med 2005; 30(3):A46