Laser Doppler flowmetry (LDF) and reflection photoplethysmography (PPG) are standard technologies to access microcirculatory function in vivo. However, different light frequencies mean different interaction with tissues, such that LDF and PPG flowmotion curves might have distinct meanings, particularly during adaptative (homeostatic) processes. Therefore, we analyzed LDF and PPG perfusion signals obtained in response to opposite challenges. Young healthy volunteers, both sexes, were assigned to Group 1 (n = 29), submitted to a normalized Swedish massage procedure in one lower limb, increasing perfusion, or Group 2 (n = 14), submitted to a hyperoxia challenge test, decreasing perfusion. LDF (Periflux 5000) and PPG (PLUX-Biosignals) green light sensors applied distally on both lower limbs recorded perfusion changes for each experimental protocol. Both techniques detected the perfusion increase with massage, and the perfusion decrease with hyperoxia, in both limbs. Further analysis with the wavelet transform (WT) revealed better depth-related discriminative ability for PPG (more superficial, less blood sampling) compared with LDF in both challenges. Spectral amplitude profiles consistently demonstrated better sensitivity for LDF, especially regarding the lowest frequency components. Strong correlations between components were not found. Therefore, LDF and PPG flowmotion curves are not equivalent, a relevant finding to better study microcirculatory physiology.

The impact of effleurage, a well-known massage procedure used in human rehabilitation, in the lower limb hemodynamics, is demonstrated. When applied in a sole limb, massage increases skin microcirculatory flowmotion not only locally but also beyond, affecting systemic hemodynamics. This observation is an interesting example of the efficacy of cardiovascular integration mechanisms involving distal microcirculatory homeostasis. The proposed methodology allows a mechanistic view over skin flowmotion regulation, being applicable to further explore massage and its impact on microcirculatory physiology.

Peripheral vascular disease (PVD) comprises many pathological entities, and a variety of clinical expressions, being the 3rd most reported cause of cardiovascular disease. PVD continues to motivate more and better research to Photoplethysmography (PPG) is a classic non-invasive technique used to explore in vivo circulation, progressively invasive measurement techniques after a massage manoeuvre in the human leg . This exploratory study involved during (II) and after the massage manoeuvre (III). Other variables, including pulse and respiratory rates and blood Microcirculation; LDF; PPG; massage; vascular regulation Resumo A doença vascular periférica (DVP) compreende muitas entidades patológicas e uma variedade de expressões clínicas, sendo a terceira causa principal da doença cardiovascular. A DVP ainda continua a motivar mais e melhor investigação para compreender as muitas complexidades envolvidas, e desenvolver medidas preventivas e Avanços recentes permitiram o desenvolvimento de um novo sistema FPG que parece melhorar claramente a aplicabilidade desta técnica. Neste estudo, aplicamos e comparamos estas duas técnicas de medição não-invasiva das técnicas. Além disso, também mostram que, nestas condições, a massagem melhora a perfusão do membro inferior em ambos os membros (teste e controlo).

Biomedical and Biopharmaceutical Research J o r n a l d e I n v e s t i g a ç ã o B i o m é d i c a e B i o f a r m a c ê u t i c aCombining laser-Doppler flowmetry and photoplethysmography to explore in vivo vascular physiology AbstractLaser Doppler flowmetry (LDF) and photoplethysmography (PPG) are two well-known optical techniques, allowing sensible real-time in vivo recording of blood flow. Only a few studies have used simultaneous perfusion recordings with both techniques, meaning that not much is known regarding the utility of their combined use. Our aim was to assess the vascular response of healthy individuals to a challenge maneuver with both techniques. Twelve subjects (both sexes, 26.0 ± 5.0 years old), were selected after informed written consent. The chosen maneuver was the leg pending maneuver, with LDF and PPG being assessed in both feet, and with transcutaneous O2 (tc) pressure obtained by gasimetry, and pulse rate (PR) calculated from the PPG signal, being also registered. The Wilcoxon signed-rank test was used for phase comparisons (p<0.05). Leg pending significantly reduced perfusion on both feet, although more clearly on the pending foot. The venoarterial reflex explains this vasoconstriction while, in the unmoved foot, a centrally-mediated reflex might be involved. tcpO2 increased significantly during leg lowering, suggesting that the heat from the probe cancelled the venoarteriolar reflex (VAR) on the measurement region. No changes were seen in HR. This study seems to confirm that the combined use of LDF and PPG might help to look deeper into peripheral microcirculation mechanisms.