Interscalene Nerve Blocks With Ropivacaine Alone, With Dexamethasone, Plus Systemic Dexamethasone

Duration of Interscalene Nerve Blocks With Ropivacaine Alone, Ropivacaine Mixed With Dexamethasone, and Ropivacaine Alone Combined With Systemic Dexamethasone

This study will test the hypothesis that ropivacaine in combination with either systemic or local steroid provides comparably longer-lasting analgesia tha ropivacaine alone.

This study proposes to recruit 120 patients who are undergoing open shoulder surgery. Patients will be identified preoperatively by means of the surgical schedule at each participating location. Randomization will be generated by a web-based system and stratified by hospital. The attending physician will be blinded to the contents of the supplied syringes. Treatment assignments consist of three groups:

• Ropivacaine: 30 ml 0.5% ropivacaine plus 2 ml 0.9% saline (local placebo) for interscalene block and 0.9% saline 2 ml (systemic placebo) for intravenous injection with sedation for the block;
• Ropivacaine and local steroid: 30 ml 0.5% ropivacaine plus dexamethasone 8 mg (2 ml) mixed with the local anesthetic and 0.9% saline 2ml (systemic placebo) for intravenous injection with sedation for the block;
• bupivacaine and systemic steroid: 30 ml 0.5% ropivacaine plus 2 ml 0.9% saline (local placebo) for interscalene block plus dexamethasone 8 mg (2 ml) administered intravenously with sedation administered for the block.
• bupivacaine and local steroid: 30 ml 0.5% ropivacaine plus dexamethasone 8 mg (2 ml) mixed with the local anesthetic and 0.9% saline 2ml (systemic placebo) for intravenous injection with sedation for the block;

All solutions for interscalene block will contain epinephrine 1:400,000 as a marker for intravascular injection. Insulated needles with nerve stimulation will be used. Motor response in the surgical limb at a current of < 0.4 mA at 0.1 msec duration will be considered evidence of adequate needle position.

Patients will be evaluated at 5-minute intervals for 15 minutes for development of sensory and motor block. Sensory block will be assessed by loss of sensation to pinprick over the deltoid muscle. Motor block will be assessed by evaluation of ability to abduct the shoulder, the so-called "deltoid sign". During surgery, patients will receive either general anesthesia or sedation at the discretion of the attending anesthesiologist.

Demographic variables, morphometric measurements, and the specific type of procedure will be recorded. The intraoperative management strategy (i.e. general anesthesia versus sedation) and the total doses of fentanyl, midazolam, morphine, and propofol administered perioperatively will be recorded. Finger-stick blood glucose will be measured upon arrival in the postanesthesia care unit (PACU). The primary outcome will be the duration of the interscalene nerve block, which will be measured by time from onset of sensory block until first administration of analgesic medication.

The severity of postoperative pain will be assessed by a blinded observer using a verbal response score (VRS) at 10-minute intervals for 30 minutes in the PACU. Patients reporting pain scores greater than 2 will be given intravenous morphine (1-2 mg) every 5 minutes until they are comfortable. After discharge from the PACU pain unrelieved by oral medication (VRS persistently greater than 4) will be treated with intravenous morphine. Outpatients will receive a prescription for oral acetaminophen with oxycodone.

A blinded observer will interview patients each morning for three days postoperatively. Data collected will include time of block duration,the primary outcome; defined as time from onset of sensory blockade to first administration of supplemental analgesic medication after PACU discharge, as well as secondary outcomes: time to a significant increase in shoulder discomfort, time to a noticeable decrease in numbness and/or weakness, maximum VRS with rest and movement, and total opioid consumption.

The times and VRS scores for secondary outcomes will be based on patient reporting of the corresponding events daily. A member of the study staff will contact patients at 14 days postoperatively to assess for any late or persistent complications such as residual sensory or motor block.

Inclusion Criteria:

• Patients undergoing open shoulder procedures such as rotator cuff repair, capsular shift, subacromial decompression
• Age between 18 and 70 years

Exclusion Criteria:

• Contradictions for interscalene block
• Coagulopathy
• Infection at the needle insertion site
• Moderate to severe chronic obstructive pulmonary disease (COPD)
• Contralateral pneumothorax of diaphragmatic paralysis
• Pregnancy
• Preexisting neuropathy involving the surgical limb
• Systemic glucocorticoid treatment within the last six months of surgery
• Routine opioid use