Limitations and technical considerations of ultrasound-guided peripheral nerve blocks: Edema and subcutaneous air

Objective: Despite advantages of ultrasound-guided peripheral nerve blocks as compared with established techniques, various limitations may exist. We present 2 trauma patients in whom the usefulness of ultrasound techniques was limited by edema and Subcutaneous air. Case Report: Two male patients were admitted to the Intensive Care Unit due to multiple trauma. in the first patient, tissue edema and obesity (body mass index, calculated as weight [kg]/height [m(2)] = 35), and in the second patient, Subcutaneous emphysema, were significant limitations for the application Of Ultrasound-guided peripheral nerve blocks. These factors made 2-dimensional ultrasound imaging difficult despite the use of tissue harmonic technique and advanced ultrasound equipment. Neurostimulation technique alone, or combined with ultrasound imaging eventually led to successful nerve block. Conclusions: Ultrasound technique limitations do exist. We present 2 conditions, edema and Subcutaneous air, which contributed to ultrasound failure to provide a clear image of the targeted nerves.