Continuous interscalene block has been known to improve postoperative analgesia after arthroscopic shoulder surgery. This was a prospective study investigating the ultrasound-guided posterior approach for placement of an interscalene catheter, clinical efficacy and complications after placement of the catheter.

Forty-two patients undergoing elective arthroscopic shoulder surgery were included in this study and an interscalene catheter was inserted under the guidance of ultrasound with posterior approach. With the inplane approach, the 17 G Tuohy needle was advanced until the tip was placed between the C5 and C6 nerve roots. After a bolus injection of 20 ml of 0.2% ropivacaine, a catheter was threaded and secured. A continuous infusion of ropivacaine 0.2% 4 ml/hr with patient-controlled 5 ml boluses every hour was used over 2 days. Difficulties in placement of the catheter, clinical efficacy of analgesia and complications were recorded. All patients were monitored for 48 hours and examined by the surgeon for complications within 2 weeks of hospital discharge.

Easy placement of the catheter was achieved in 100% of the patients and the success rate of catheter placement during the 48 hr period was 92.9%. Postoperative analgesia was effective in 88.1% of the patients in the post anesthetic care unit. The major complications included nausea (7.1%), vomiting (4.8%), dyspnea (4.8%) and unintended vascular punctures (2.4%). Other complications such as neurologic deficits and local infection around the puncture site did not occur.

The ultrasound-guided interscalene block with a posterior approach is associated with a success high rate in placement of the interscalene catheter and a low rate of complications. However, the small sample size limits us to draw definite conclusions. Therefore, a well-designed randomized controlled trial is required to confirm our preliminary study.