Effects of Low Intensity Therapeutic Ultrasound on Endothelial Function

Universidade Federal de Santa Maria22 enrolled

Overview

Endothelium is a cell layer that interposes blood and smooth muscle of vessels. This biological sensor reacts to physical and chemical stimuli by synthesis and/or liberation of regulatory substances like nitric oxide (NO), which acts on vascular tone, growth of muscle cells and platelet aggregation and leukocyte. Clinically, endothelial function measured by technique flow-mediated dilation (FMD) is a strong predictor of cardiovascular events and all-cause mortality. Previo study demonstrated that continuous and pulsed therapeutic 1-MHz ultrasound waveforms improved endothelial function in health volunteers and this vasodilation persisted for 20 min, which provided them with anti-inflammatory vascular effects. In subjects with type 2 diabetes (DM2) the chronical hyperglycemia and dyslipidemia reduce NO bioavailability causing endothelial dysfunction. Low intensity therapeutic ultrasound is an electrotherapeutic instrument employed in musculoskeletal injuries that promotes endothelium-dependent vasodilation, and its mechanism of action has not been studied on DM2. The aim of our study is evaluate endothelial function of patients with DM2 after different waveforms (placebo, continuous and pulsed) of therapeutic ultrasound. Therapeutic ultrasound is a electrotherapeutic instrument that can changes arterial endothelial function of subjects with DM2 because of NO bioavailability increasing, which implies anti-inflammatory and vasodilatory beneficial alterations for diabetic patients.

Evaluation of endothelial function will be made by flow-mediated dilation (FMD). The therapeutic ultrasound will applied over brachial artery using continuous (CUT: 0,4W/cm2), pulsed (PUT: 20% duty cycle, 0,08W/cm2SATA) and Placebo (equipment off) waveforms during 5min in 3 intercalated days.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Enrollment

Interventions

Low intensity therapeutic ultrasoundOTHER

The ultrasound equipment (Sonopulse III, 1 MHz, IBRAMED, Brazil) was calibrated with the radiation force method. In study, the head of the transducer will be positioned and applied for 5 min over the brachial artery at the same point that will be evaluated the endothelium function (Cruz et al., 2016). Continuous waveforms of ultrasound therapy (CWUT) are applied in the stationary mode for 5 minutes at a spatial averaged temporal intensity (SATA) of 0.4 W/cm2 using a transducer 1-MHz. A pulsed waveform of ultrasound therapy (PWUT) are applied (5 minutes) with a 20% duty cycle (2 ms on, 8 ms off), which represents a constant intensity of 0.08 W/cm2 SATA. In the placebo intervention, all of the procedures above are repeated, but with the ultrasound equipment powered off (Cruz et al., 2016).

Eligibility

Sex: ALLMin age: 25 YearsMax age: 65 Years

Medical Language ↔ Plain English

Inclusion Criteria: * The subjects that joined the study will be alphabetized volunteers * Age between 25 and 65 years old, * Absence of morbid obesity, * Non-smokers, * With no symptoms of skeletal muscle disorders, * No previous performing cardiovascular surgery, * No previous diagnose of rheumatic, neurological, oncological, immune or hematologic diseases, * Without evidence of psychiatric diseases and/or cognitive deficit. Exclusion Criteria: * Insulin dependent diabetes * Leukocytosis, impaired fasting glycemia (\<70 and \>300 mg/dL) and * Brachial artery diameter less than 2.5mm and larger than 5.0mm. * On the day of the assessments have consumed of the alcoholic drink, caffeine and citrus juice

Outcomes

Primary Outcomes

Percentage of the endothelium-dependent vasodilation (%FMD)

Vessel diameter responses to reactive hyperemia are expressed as percentage change in relation to diameter before cuff inflation (%FMD = \[(hyperemia maximum diameter - baseline precuff diameter)/(baseline precuff diameter)\] / 100) (Corretti et al. 2002; Thijssen et al. 2011). Baseline precuff diameter is expressed in millimeter (mm). Hyperemia maximum diameter is expressed in millimeter (mm). Arterial endothelium-dependent vasodilation are evaluated by technique flow-mediated dilation (FMD) with high-resolution vascular ultrasound and a 5- to 12-MHz linear transducer (Logiq P6, GE Healthcare, GE Ultrasound Korea), according to the American Heart Association Guidelines (Corretti et al. 2002), with adjustments (Thijssen et al. 2011).

Time frame: Five minutes after application of therapeutic ultrasound

Secondary Outcomes

Percentage of the endothelium-independent vasodilation (%NMD)

Endothelium-independent vasodilation is measured after sublingual nitroglycerin (NMD) spray (0.4 mg). Vessel diameter responses nitroglycerin are expressed as percentage change in relation to diameter before cuff inflation and before drug administration (%NMD = \[(nitroglycerin maximum diameter - baseline precuff diameter)/(baseline precuff diameter)\] / 100) (Corretti et al. 2002; Iida et al. 2006; Thijssen et al. 2011). Baseline precuff diameter is expressed in millimeter (mm) and Nitroglycerin maximum diameter is expressed in millimeter (mm).