The current standard of care for neuroaxial anesthesia procedures (i.e. epidural and spinal anesthesia) is manual palpation of spinal bone landmarks followed by """"""""blind"""""""" needle insertion. However, in the obese segment of the population, estimated at approximately 33.9% of the total US population, spinal bone landmarks are covered with thick layers of fat and are not detectable via palpation. As a result, procedure failures occur at high rates (i.e. 40% - 80%) resulting in numerous health complications: headache, hematoma, backpain, vascular puncture, pleural puncture, pneumothorax, and paralysis. Alternative approaches to the blind method include fluoroscopy and ultrasound guidance. Fluoroscopy lacks portability, has a higher cost, and exposes the patient to ionizing radiation. Recent studies have shown that conventional ultrasound improves success rates (e.g. 65% from 32%). However, failure rates remain high due to poor image quality of bone with ultrasound. New medical device technology is needed to overcome limitations of standard ultrasound and improve neuroaxial anesthesia success rates in the obese. This Phase I proposal seeks funding to support the development and feasibility testing of a low-cost, handheld medical device for neuroaxial anesthesia guidance in the obese. Key technological innovations of this project include an ultrasound system with a low number of single-element transducers and multi-modality position sensing, which is technologically advanced over standard ultrasound due to reduced device cost, greater portability, and mitigation of off-axis reflection artifacts. In addition, this project includes an active shape model-based bone surface position estimation method for automated identification of needle insertion location, which enables more intuitive image interpretation than with standard ultrasound alone. The long-term goal of the proposed project is to commercialize a portable, low-cost, ultrasound-based medical device to lower the risk of adverse health outcomes from neuroaxial anesthesia procedures. The Phase I hypothesis of the proposed research is that a low-cost handheld ultrasound-based medical imaging device can be developed and demonstrated to achieve bone image resolution better than 2.5 mm at image depths up to 10 cm in ex vivo bone, tissue, and body fat-mimicking phantom experiments. A functional handheld ultrasound prototype with real-time image display and electronic signal-to-noise ratio (SNR) from bone >15 dB at image depths of 10 cm will be demonstrated. In addition, model-based spinal bone anatomy position estimation techniques will be developed in simulation and the device will be experimentally validated in ex vivo phantom experiments to demonstrate imaging resolution <2.5 mm. Research plans for Phase II include industrial design, software and user interface development, and an in vivo pilot study at the University of Virginia Hospital. With an estimated 18 million procedures performed in the US per year, the estimated US market size is approximately $208 M/yr with a worldwide market of $566 M/yr.

Public Health Relevance

The current standard of care for neuroaxial anesthesia procedures includes blind needle insertion based on manual palpation of spinal bone landmarks. Failures occur at high rates (i.e. 40% - 80%) in the obese where landmarks are impalpable, which results in numerous health complications: headache, hematoma, back pain, vascular puncture, pleural puncture, pneumothorax, and paralysis. The long-term goal of this project is to demonstrate a portable, low-cost, ultrasound-based medical device that facilitates neuroaxial anesthesia in the obese, improves success rates, and lowers the risk of associated health complications.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Small Business Innovation Research Grants (SBIR) - Phase I (R43)
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Special Emphasis Panel (ZRG1-SBIB-T (10))
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Krosnick, Steven
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Rivanna Medical, LLC
United States
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Tiouririne, Mohamed; Dixon, Adam J; Mauldin Jr, F William et al. (2017) Imaging Performance of a Handheld Ultrasound System With Real-Time Computer-Aided Detection of Lumbar Spine Anatomy: A Feasibility Study. Invest Radiol 52:447-455
Tiouririne, Mohamed; Nguyen, Sarah; Hossack, John A et al. (2014) Handheld real-time volumetric imaging of the spine: technology development. J Med Eng Technol 38:100-3