Objective:To compare changes in IM temperature during similar ultrasound treatments with 2 different coupling media. Background: Gel pads are gaining popularity as an ultrasound coupling medium. Intramuscular temperatures during ultrasound with gel pads and standard gel have not been compared.

Methods and Measures: Subjects were 13 student volunteers (21.3 ± 1.4 years of age) without lower-extremity pathology. Ultrasound treatments were administered in a laboratory on 2 separate occasions 48 hours apart, each with a different coupling medium (standard ultrasound gel or gel pad). One-MHz continuous ultrasound was administered for 7 minutes at 1.5 W/cm 2 with the transducer head moving 3 to 4 cm/s over an area approximately twice the size of the transducer head. Tissue temperature was measured every 10 seconds using implantable thermocouples inserted at a 3-cm depth to the surface of the right medial calf. Data were analyzed using an ANCOVA with pretreatment temperature as the covariate.

Results: Tissue temperatures increased during both treatments, with the mean and standard deviation peak temperature during the gel pad treatment reaching 39.4° ± 1.5°C compared to 39.2° ± 2.4°C during the normal gel treatment. Statistical analysis revealed no difference in temperature between ultrasound treatments using gel and those performed using gel pads.

Conclusions: Because temperature changes were similar with both treatments, we conclude that these coupling methods are equivalent under the ultrasound application parameters tested.

J Orthop Sports Phys Ther. 2002; 3(5):216–220.

Key Words: acoustic transmission, coupling medium, thermocouple

Study Design: A counterbalanced, repeated-measures design with ultrasound device (Omnisound 3000C, Dynatron 950, Excel Ultra III) as the independent variable. The 2 dependent variables were intramuscular (IM) temperature at 6 minutes and at the end of a 10-minute treatment. Objective: To compare IM temperatures produced by identical 3-MHz ultrasound treatments between 3 different ultrasound devices. Background: Most recent studies prescribing intensity and duration parameters for thermal ultrasound treatments have been performed using an Omnisound device, but have not been verified in other common ultrasound devices. Methods and Measures: Six uninjured volunteers (mean age ± SD, 22 ± 3.4 years; mean height ± SD, 171.9 ± 11.0 cm; mean mass ± SD, 66.1 ± 11.1 kg) gave informed consent and served as subjects. Separate ultrasound treatments using identical parameters (3 MHz, 1.5 W/cm2 , 10 minutes, treatment area equal to twice transducer surface area) were administered at 24 or 48 hours intervals using a different ultrasound device for each treatment. Left medial calf IM temperature was recorded every 20 seconds using implantable thermocouples at a depth of 1.6 cm below the treatment surface. Data were analyzed using MANOVA with Sidak adjusted multiple comparisons post hoc. Results: Tissue heating using the Omnisound device was greater than with either the Dynatron or the Excel. The results of treatments using Dynatron or Excel devices did not differ. The Omnisound was the only device to consistently produce IM temperatures above the 40°C therapeutic threshold and did so in less than 6 minutes. The other devices did not reach this threshold within the 10-minute treatment session. Subjects routinely reported heating sensations approaching discomfort when the IM temperature reached the 40°C therapeutic threshold. Conclusions: Because there are differences in thermal effects between ultrasound devices, our results suggest that recently published parameters for ultrasound intensity and duration parameters will not produce equally therapeutic effects for all ultrasound devices.

 J Orthop Sports Phys Ther. 2003;33(7):379-385.

Key Words: clinical efficacy, sonication, thermotherapy