Effects of two methods of heat therapy on the acute vascular response and hemodynamics in healthy subjects

Abstract Objective Recently, non-pharmacological resources to relieve pain like hot packs and ultrasound (US) have become common in clinical practice. However, little experimental evidence is available about the possible mechanisms through which these methods bring about pain relief. We aimed to determine the effects of hot packs and US on the acute vascular response and on hemodynamic parameters in healthy subjects. Materials and methods We conducted an experimental study in 20 healthy subjects (10 men and 10 women; mean age, 22.54 ± 1.70 years). The two interventions were randomly applied: ( a ) hot packs (n = 10): 15 min at 60 °C and ( b ) US (n = 10): 15 min at 1 MHz. Before and after each intervention, the following vascular parameters were measured in the brachial artery using Doppler ultrasonography with a 7 MHz probe: arterial compliance, elastic modulus, beta stiffness index, systolic and diastolic arterial diameters, systolic flow velocity and diastolic flow velocity, systolic/diastolic ratio, resistance index, and pulsatility index. The following hemodynamic parameters were monitored: heart rate and blood pressure (systolic, diastolic, and mean). Results After the application of hot packs, we observed changes in diastolic flow velocity and in the pulsatility index ( p p Conclusions Applying hot packs or US modifies the physiology of the vascular system but does not affect hemodynamic parameters in healthy subjects.