George K. Lewis

Pilot clinical studies of long duration, low intensity therapeutic ultrasound for osteoarthritis

Osteoarthritis is one of the leading causes of disability in the aging population. Long duration, low intensity therapeutic ultrasound has had promising impact in animal models to slow the progression of the disease and provide joint relief. Two pilot studies were conducted using a novel, wearable platform for delivering ultrasound to evaluate the potential clinical benefits of ultrasound therapy on knee osteoarthritis. There was a pain reduction effect from using ultrasound, as high as fifty two percent in one study. As well, initial data demonstrates that mobility may be increased for patients experiencing mild to moderate arthritis of the knee.

Therapeutic Ultrasound Enhancement of Drug Delivery to Soft Tissues

Effects of exposure to 1.58 MHz focused ultrasound on transport of Evans Blue Dye (EBD) in soft tissues are investigated when an external pressure gradient is applied to induce convective flow through the tissue. The magnitude of the external pressure gradient is chosen to simulate conditions in brain parenchyma during convection‐enhanced drug delivery (CED) to the brain. EBD uptake and transport are measured in equine brain, avian muscle and agarose brain‐mimicking phantoms. Results show that ultrasound enhances EBD uptake and transport, and the greatest enhancement occurs when the external pressure gradient is applied. The results suggest that exposure of the brain parenchyma to ultrasound could enhance penetration of material infused into the brain during CED therapy.

Wearable long duration ultrasound therapy pilot study in rotator cuff tendinopathy

Approximately one-third of the westernized adult population will experience some type of shoulder pain. The purpose of this pilot study was to evaluate a novel self-applied wearable therapeutic ultrasound device in the management of shoulder pain from rotator cuff tendinopathy. The Institutional Review Board of Cayuga Medical Center (CMC) approved this study and informed consent for the study was obtained from all subjects. The wearable ultrasound device provides 90 mW/cm2, 2.95 MHz, continuous-wave ultrasound for 5.5 hours on a single charge. Four subjects meeting the studies inclusion criteria, presenting with rotator cuff tendinopathy, and demonstrating cognitive and functional ability to apply the pager-size device were enrolled at the outpatient physical therapy center of CMC. Subjects were instructed to wear the device for 3-4 hours per day for 12 consecutive treatment sessions, and record their daily pain score on the visual analog scale (1 to 10) and global rate of health improvement scale (-7 to ...

Ultrasonic modeling and hydrophone measurements of dual divergent transducers for wearable therapeutic ultrasound device

This paper models and experimentally measures the acoustic interference from two low intensity 3MHz continuous ultrasound transducers of the sam® wearable ultrasound device. Resulting data show that placement configuration, which dictates interference depth, and frequency phase variation are the main factors to acoustic pressure distribution. Mathematical analysis reveals that the acoustic pressure distribution from continuous ultrasound is modulated by near field variations at shallow tissue depths. This observation is useful in the application of sam® and in the further research of its therapeutic benefits.

“SonoBandage” a transdermal ultrasound drug delivery system for peripheral neuropathy

Peripheral neuropathy (PN) is a difficult disease to manage. Symptomatic treatment focuses primarily on pain relief, using NSAIDs, opioids, tri-cyclic antidepressants, and selective serotonin norepinephrine reuptake inhibitors. There is potential for ultrasound transdermal drug delivery to improve the quality of care provided to patients with PN, since it is well-suited to peripheral nerves which are close to the skin. In addition, targeted delivery avoids many of the systemic consequences of taking a drug. We developed a wearable ultrasound drug delivery system called “SonoBandage” that combines low-impedance miniaturization of ultrasound transducer, RF electronics, and battery power supply, with a novel hydrogel coupling bandage loaded with salicylic acid NSAID. The design of the SonoBandage allows the device to be used over a range of ultrasound frequencies (0.1–3 MHz), intensities (0.1–3 W/cm2), and durations (0.25–4 h) increasing system flexibility for drug delivery protocols. The SonoBandage with NS...

Skin temperature increase mediated by wearable, long duration, low-intensity therapeutic ultrasound

One of the safety concerns with the delivery of therapeutic ultrasound is overheating of the transducer-skin interface due to poor or improper coupling. The objective of this research was to define a model that could be used to calculate the heating in the skin as a result of a novel, wearable long-duration ultrasound device. This model was used to determine that the maximum heating in the skin remained below the minimum threshold necessary to cause thermal injury over multiple hours of use. In addition to this model data, a human clinical study used wire thermocouples on the skin surface to measure heating characteristics during treatment with the sustained ultrasound system. Parametric analysis of the model determined that the maximum temperature increase is at the surface of the skin ranged from 40-41.8° C when perfusion was taken into account. The clinical data agreed well with the model predictions. The average steady state temperature observed across all 44 subjects was 40°C. The maximum temperature...

Sustained Acoustic Medicine: A Novel, Long Duration Approach to Biomodulation Utilizing Low Intensity Therapeutic Ultrasound

Therapeutic ultrasound is an established technique for biomodulation used by physical therapists. Typically it is used to deliver energy locally for the purpose of altering tissue plasticity and increasing local circulation. Access to ultrasound therapy has been limited by equipment and logistic requirements, which has reduced the overall efficacy of the therapy. Ultrasound miniaturization allows for development of portable, wearable, self-applied ultrasound devices that sidestep these limitations. Additionally, research has shown that the timescale of acoustic stimulation matters, and directly affects the quality of result. This paper describes a novel, long duration approach to therapeutic ultrasound and reviews the current data available for a variety of musculoskeletal conditions.

Intramuscular Heating Characteristics of Multihour Low-Intensity Therapeutic Ultrasound

CONTEXT The heating characteristics of a stationary device delivering sustained acoustic medicine with low-intensity therapeutic ultrasound (LITUS) are unknown. OBJECTIVE To measure intramuscular (IM) heating produced by a LITUS device developed for long-duration treatment of musculoskeletal injuries. DESIGN Controlled laboratory study. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS A total of 26 healthy volunteers (16 men, 10 women; age = 23.0 ± 2.1 years, height = 1.74 ± 0.09 m, mass = 73.48 ± 14.65 kg). INTERVENTION(S) Participants were assigned randomly to receive active (n = 20) or placebo (n = 6) LITUS at a frequency of 3 MHz and an energy intensity of 0.132 W/cm(2) continuously for 3 hours with a single transducer or dual transducers on the triceps surae muscle. We measured IM temperature using thermocouples inserted at 1.5- and 3-cm depths into muscle. Temperatures were recorded throughout treatment and 30 minutes posttreatment. MAIN OUTCOME MEASURE(S) We used 2-sample t tests to determine the heating curve of the LITUS treatment and differences in final temperatures between depth and number of transducers. RESULTS A mild IM temperature increase of 1 °C was reached 10 ± 5 minutes into the treatment, and a more vigorous temperature increase of 4 °C was reached 80 ± 10 minutes into the treatment. The maximal steady-state IM temperatures produced during the final 60 minutes of treatment at the 1.5-cm depth were 4.42 °C ± 0.08 °C and 3.92 °C ± 0.06 °C using 1 and 2 transducers, respectively. At the 3.0-cm depth, the maximal steady-state IM temperatures during the final 60 minutes of treatment were 3.05 °C ± 0.09 °C and 3.17 °C ± 0.05 °C using 1 and 2 transducers, respectively. We observed a difference between the temperatures measured at each depth (t78 = -2.45, P = .02), but the number of transducers used to generate heating was not different (t78 = 1.79, P = .08). CONCLUSIONS The LITUS device elicited tissue heating equivalent to traditional ultrasound but could be sustained for multiple hours. It is a safe and effective alternative tool for delivering therapeutic ultrasound and exploring dosimetry for desired physiologic responses.

Human Factors Engineering and Testing for a Wearable, Long Duration Ultrasound System Self-Applied by an End User

One of the major challenges in the design of a new class of medical device is ensuring that the device will have a safe and effective user interface for the intended users. Human Factors Engineering addresses these concerns through direct study of how a user interacts with newly designed devices with unique features. In this study, a novel long duration, low intensity therapeutic ultrasound device is tested by 20 end users representative of the intended user population. Over 90% of users were able to operate the device successfully. The therapeutic ultrasound device was found to be reasonably safe and effective for the intended users, uses, and use environments.

Sustained acoustic medicine for stimulation of wound healing: A translational research report

The healing of both acute and chronic wounds is a challenging clinical issue affecting more than 6.5 million Americans. The regeneration phase of wound healing is critical to restoration of function, but is often prolonged because of the adverse environment for cell growth. Therapeutic ultrasound increases nutrient absorption by cells, accelerates cellular metabolism, and stimulates production of ECM proteins, which all increase the rate of wound healing. To test the effect of long duration ultrasound exposure, an initial study of wound healing was conducted in a rat model, with wounds sutured to prevent closure via contraction. In this study, a 6 mm wound healed in 9±2 days when exposed to 6 hours of ultrasound therapy, and 15±1 days with a placebo device (p<0.01). Following IRB approval of a similar protocol for use in humans, a case study was performed on the wound closure of a chronic wound. Four weeks of daily LITUS therapy reduced the wound size by 90% from its size after 21 days of treatment with s...