Diaphragmatic Dysfunction After Ultrasound-guided Supraclavicular Block With Single or Double Injection Technique

Diaphragmatic Dysfunction After Ultrasound-guided Supraclavicular Brachial Plexus Block With Single or Double Injection Technique

The investigators plan to determine the incidence of hemi-diaphragmatic paresis (HDP) with two commonly used techniques of supraclavicular nerve block, the single and double injection techniques.

It is our hypothesis that a double injection peripheral nerve block technique will increase the risk of HDP when compared to a single injection technique.

The investigators will perform a prospective, blinded, randomized controlled trial to assess the two methods of supraclavicular block (single and double injection), and the resultant incidence of temporary diaphragm dysfunction, or hemi-diaphragmatic paresis (HDP) will be measured with ultrasound. Patients having forearm or hand surgery will be asked by the attending anesthesiologist if they will agree to be approached by someone from the research team for consent and possible inclusion in the study. This will be done in the anesthesia preoperative assessment clinic, or in the pre-op area on the day of surgery (if a patient was not seen in clinic).

Once consented, all patients in the study will have baseline measurements of their sensation and movement of the arm for surgery, as well as an ultrasound examination of the movement of the diaphragm.

Patients will then be randomized to either the single or double injection supraclavicular nerve block. The blocks will be performed by attending anesthesiologists with experience in regional anesthesia, or by residents and fellows under the direct supervision of such anesthesiologists.

Inclusion Criteria:

• Patients presenting for unilateral upper extremity surgery below the level of the elbow (the forearm or hand) who are having a regional block for anesthesia
• Patient must be over 18 years old
• Weight greater than 50kg
• English speaking
• Be available to be contacted by phone on post-operative day 1
• ASA physical status 1-3
• BMI under 35 kg/m2

Exclusion Criteria:

• Inability to consent to study participation
• Pre-existing neuromuscular disease or severe neurological dysfunction
• Severe coagulopathy
• Severe obstructive or restrictive lung disease
• Pregnancy
• Prior surgery in the supraclavicular region
• Allergy to medications used in the study
• Known diaphragmatic dysfunction of either diaphragm
• Inability to visualize the diaphragm with ultrasound on the side of the surgical procedure
• Highly opioid-tolerant patient (>40mg of morphine PO or equivalent per day for >1month)
• Patient requests a general anesthesia technique
• Attending anesthesiologist preference for alternate anesthetic technique
• Surgeon or attending anesthesiologist request for a different anesthesia technique
• Current involvement in another study