Wavelet Phase Coherence Analysis between the Respiratory Activity and the Microcirculation—The Effects of Type 1 Diabetes

The microvascular perfusion is modulated by physiological functions, which have been associated with specific frequency ranges. Although cardio-respiratory interactions have been widely analyzed at a macrocirculation level, only few studies have been conducted with the aim to understand the effect of breathing on the peripheral circulation. Diabetic microangiopathy is characterized by structural and functional alterations of the blood microvessels, which reflect in a modification of the physical properties of peripheral microvascular beds, such as vascular stiffness. A wavelet phase coherence (WPC) analysis was performed to elucidate the time-phase relationship between the respiratory activity and vascular-dependent features of the peripheral pulse, reconstructed by means of a novel multi-Gaussian modeling algorithm. The present WPC analysis was conducted on a group of 24 healthy volunteers, mean age 30±15 years, in comparison with 21 type-1 diabetic (T1D) subjects, mean age 26±3 years, in order to detect the effects of T1D on the physiological coupling between breathing and microcirculation. The peripheral cutaneous perfusion was assessed on the pulp of the index finger with the laser Doppler flowmetry (LDF) technique, while the respiratory signal was simultaneously recorded with a wearable chest band. In 17 out of the 24 control subjects involved (i.e., 71%), significant WPC values were identified in the respiratory frequency range (0.145-0.6 Hz), with respect to the area beneath the diastolic portion of the peripheral pulse (median WPC: 77.9%). This outcome indicates that the diastolic phase of the pulse exhibits a marked periodicity linked to the breathing activity. The analysis conducted on the T1D group highlighted a loss of synchronization, with significant WPC levels found in only 33% of the investigated subjects. These results suggest that the proposed method is able to detect the detrimental effects of T1D on the blood microcirculation. Disclosure A. Perrella: None. M. Sorelli: None. P. Francia: None. L. Capirchio: None. R. Anichini: Advisory Panel; Self; Abbott. Speaker's Bureau; Self; Novartis Pharmaceuticals Corporation, Boehringer Ingelheim GmbH. Advisory Panel; Self; Eli Lilly and Company, AstraZeneca. Speaker's Bureau; Self; Merck & Co., Inc., Takeda Development Centre Europe Ltd.. Advisory Panel; Self; Sanofi, Janssen Pharmaceuticals, Inc.. Research Support; Self; Grünenthal Group. A. de Bellis: Speaker's Bureau; Self; Eli Lilly and Company, AstraZeneca, Novo Nordisk A/S. Research Support; Self; Grünenthal Group. M. Gulisano: None. L. Bocchi: None.