Regional analgesia via caudal neuraxial blockade provides pain relief for pediatric patients following urological and lower extremity procedures. The injection of local anesthetic into the caudal epidural space causes a sensory loss. This sympathetic blockade in turn causes a vasodilation, or increased blood flow, to the lower extremities.

The purpose of this study is to determine whether the FLIR ONE thermographic camera, a smartphone attachment which utilizes an application ("app") to measure the temperature at a site on an image of the lower extremity, will be able to differentiate between caudal, non-caudal, and failed caudal images.

Inclusion Criteria:

• Children from 6mos to 5 years of age requiring general anesthesia and a caudal block for a surgical procedure

Exclusion Criteria:

• Patients with preexisting conditions that could affect the skin temperature on the lower extremities such as infection, edema, vascular disorder, etc.
• American Society of Anesthesiologists comorbidity ranking of 4 or greater
• Patient with contraindications for a caudal block such as: history of allergic, reactions to local anesthetics, coagulopathy, infection at the injection site, spinal abnormality, peripheral neurological disease, Raynaud's disease