Diurnal Blood Pressure Variations Are Associated with Changes in Distal–Proximal Skin Temperature Gradient

Abstract

It is generally assumed that skin vascular resistance contributes only to a small extent to total peripheral resistance and hence to blood pressure (BP). However, little is known about the impact of skin blood flow (SBF) changes on the diurnal variations of BP under ambulatory conditions. The main aim of the study was to determine whether diurnal patterns of distal SBF are related to mean arterial BP (MAP). Twenty-four-hour ambulatory measurements of BP, heart rate (HR) and distal (mean of hands and feet) as well as proximal (mean of sternum and infraclavicular region) skin temperatures were carried out in 51 patients (men/women = 18/33) during a 2-d eye hospital investigation. The standardized ambulatory protocol allowed measurements with minimal interference from uncontrolled parameters and, hence, some conclusive interpretations. The distal minus proximal skin temperature gradient (DPG) provided a measure for distal SBF. Individual cross-correlation analyses revealed that the diurnal pattern of MAP was nearly a mirror image of DPG and hence of distal SBF. Scheduled lunch and dinner induced an increase in DPG and a decline in MAP, while HR increased. Low daytime DPG (i.e. low distal SBF) levels significantly predicted sleep-induced BP dipping (r = -.436, p = .0014). Preliminary path analysis suggested that outdoor air temperature and atmospheric pressure may act on MAP via changed distal SBF. Changes in distal SBF may contribute to diurnal variation in MAP, including sleep-induced BP dipping and changes related to food intake. This finding might have an impact on individual cardiovascular risk prediction with respect to diurnal, seasonal and weather variations; however, the underlying mechanisms remain to be discovered.

Daytime variation in ambient temperature affects skin temperatures and blood pressure: Ambulatory winter/summer comparison in healthy young women

“…Based on previous findings [19] we applied a multilevel structural equation model to explain changes in MAP by changes in PET and ST. Path-analysis was performed by a two-level model with measurements nested within participants [26]. In this model person mean centering is used by default, i.e.…”

“…In a recent study under structured ambulatory conditions it could be shown that mean arterial BP exhibits an inverse 24 h pattern to STs most pronounced in distal skin regions in relation to proximal skin regions [19,20]. Unfortunately, no direct measurements of PET were recorded preventing detailed analyses and interpretation with respect to temporal changes in PET and its association with STs and BP.…”

“…Sixty healthy female residents (age: 25.0 ± 0.6) of the city of Basel (Switzerland) including rural agglomeration fulfilled the defined exclusion/inclusion criteria (Table 1) and were studied in a winter vs. summer design during 26 h. In order to obtain a study sample comprising a high variance with respect to STs women with (N = 32) and without (N = 28) thermal discomfort with cold extremities were selected [19].…”

Orexins and the cardiovascular events of awakening

“…56 A study on human subjects claimed that the more negative are the values of DPG during daytime activities, the greater is the nocturnal ABP dipping. 55 This suggests that changes in skin SNA may play a key causal role in driving the changes in ABP during NREM sleep. However, evidence on experimental models does not appear consistent with this suggestion.…”

“…Accordingly, human subjects reportedly show a relative vasodilation of distal (wrist and ankles) skin compared with proximal (infraclavicular and sternal) skin during sleep, so that the temperature difference between distal and proximal skin sites, termed the distal-proximal skin temperature gradient (DPG), becomes less negative and tends to 0 during sleep. 55 Upon awakening from sleep, conversely, the DPG rapidly becomes negative again, mainly because of a decrease in distal skin temperature. 56 A study on human subjects claimed that the more negative are the values of DPG during daytime activities, the greater is the nocturnal ABP dipping.…”