RESCUED: Phase I: Regional Anesthesia for Sickle Cell Crisis Using Ultrasound in The Emergency

Phase I: The feasibility cohort will consist of a convenience sample. Dr. Glassberg will wear the SCD-FNB pager at all times and will enroll patients whenever logistically possible.

Participants: ED patients aged >18 who require admission for vasoocclusive pain involving the lower extremities. Vasoocclusive pain is defined as acute onset of corporeal pain, not controlled by oral analgesics, in a patient with SCD with no other apparent cause.

Description of Standard Analgesic Practices: All patients enrolled in the study will receive standardized care based on ED computer order sets designed by Drs. Shi & Glassberg and other members of the Hematology and Emergency departments (appendix E). Based on NIH52 and American Pain Society53 guidelines and current clinical evidence, these protocols were established to ensure delivery of optimal opiate therapy for patients with VOC pain. Initially, the patient will receive IV doses of opiates at the EP's discretion, followed by initiation of morphine or hydro-morphone PCA (patient controlled analgesia). PCA will continue when patient is moved to the inpatient floor, where care will also be guided by standardized order sets.

Description of the FNB Intervention: Throughout the FNB procedure, the patient will have continuous EKG, NIBP and O2 saturation monitoring. With the patient in the supine position, the leg to be blocked will be slightly abducted and externally rotated. The femoral crease and the area approximately 3 inches above and below is prepped and draped in usual sterile fashion. 1-2 ml of local anesthetic will be injected at the probable site of insertion. A sterile ultrasound probe is used to identify the femoral vessels and the femoral nerve, which usually lies 1-2 cm lateral to the artery. The femoral nerve sheath is then entered under direct visualization. Before injection, the syringe will be gently aspirated with negative blood return to ensure that the needle is not intravascular. 20mL of 0.25% bupivicaine will then be given, and deposition of anesthetic will be visualized within the nerve sheath. Intermittent aspiration and continuous ultrasound visualization during anesthetic delivery will ensure that the tip of the needle has not migrated. Injection will also be stopped and the needle repositioned if the patient complains of new or worsening pain, as this may indicate intraneural injection. If subjects are experiencing pain in both lower extremities, both extremities will be blocked; if subjects are experiencing pain in one lower extremity, only the affected extremity will be blocked.

Outcomes: This study is not exploring the efficacy of the intervention, nor is the intervention being compared to a control. Phase one is simply to verify that FNB is a feasible procedure to be performed in the ER in this population.