Blisters on the anterior shin in 3 research subjects after a 1-MHz, 1.5-W/cm , continuous ultrasound treatment: a case series.

CONTEXT: Clinicians should consider multiple factors when estimating tissue-heating rates.

OBJECTIVE

To report 3 separate occurrences of blisters during an ultrasound treatment experiment.

BACKGROUND

While we were conducting a research experiment comparing the measurement capabilities of 2 different intramuscular temperature devices, 3 female participants (age = 26.33 +/- 3.79 years, height = 169.34 +/- 3.89 cm, mass = 63.39 +/- 3.81 kg) out of 16 healthy volunteers (7 men: age = 22.83 +/- 1.17 years, height = 170.61 +/- 7.77 cm, mass = 74.62 +/- 19.24 kg; 9 women: age = 24.22 +/- 2.73 years, height = 171.88 +/- 6.35 cm, mass = 73.99 +/- 18.55 kg) developed blisters on the anterior shin after a 1-MHz, 1.5-W/cm (2) continuous ultrasound treatment delivered to the triceps surae muscle.

DIFFERENTIAL DIAGNOSIS: Allergies; chemical reaction with cleaning agents; sunburn; negative interaction between the temperature measurement instruments and the ultrasound field; the ultrasound transducer not being calibrated properly, producing a nonuniform field and creating a hot spot or heating differently when compared with other ultrasound devices; the smaller anatomy of our female subjects; or a confounding interaction among these factors.

TREATMENT: Participants were given standard minor burn care by a physician.

UNIQUENESS: (1) The development of blisters on the anterior aspect of the shin as a result of an ultrasound treatment to the posterior aspect of the triceps surae muscle and (2) muscle tissue heating rates ranging from 0.19 degrees C to 1.1 degrees C/min, when ultrasound researchers have suggested tissue heating in the range of 0.3 degrees C/min with these settings.

CONCLUSIONS

These adverse events raise important questions regarding treatment application and potential differences in heating and quality control among different ultrasound devices from different manufacturers.