Impaired defense of core temperature in aged humans during mild cold stress

2007 ◽  
Vol 292 (1) ◽  
pp. R103-R108 ◽  
Author(s):  
David W. DeGroot ◽  
W. Larry Kenney
Keyword(s):  
Cold Stress ◽  
Core Temperature ◽  
Laser Doppler ◽  
Group Differences ◽  
Air Exposure ◽  
Doppler Flowmetry ◽  
Vasoconstrictor Response ◽  
Baseline Group ◽  
Tissue Insulation ◽  
Doppler Flux

Aged humans often exhibit an impaired defense of core temperature during cold stress. However, research documenting this response has typically used small subject samples and strong cold stimuli. The purpose of this study was to determine the responses of young and older subjects, matched for anthropometric characteristics, during mild cold stress. Thirty-six young (YS; 23 ± 1 years, range 18–30) and 46 older (OS; 71 ± 1 years, range 65–89) subjects underwent a slow transient cold air exposure from a thermoneutral baseline, during which esophageal (Tes) and mean skin temperatures (Tsk), O2 consumption, and skin blood flow (SkBF; laser-Doppler flowmetry) were measured. Cold exposure was terminated at the onset of visible sustained shivering. Net metabolic heat production (Mnet), heat debt, predicted change in midregion temperature (ΔTmid), and tissue insulation (It) were calculated. Cutaneous vascular conductance (CVC) was calculated as laser-Doppler flux/mean arterial pressure and expressed as percent change from baseline (ΔCVC%base). There were no baseline group differences for Tes, but OS Mnet was lower (OS: 38.0 ± 1.1; YS: 41.9 ± 1.1 W · m−2, P < 0.05). Tes was well maintained in YS but fell progressively in OS ( P < 0.01 for all timepoints after 35 min). The skin vasoconstrictor response to mild cold stress was attenuated in OS (42 ± 3 vs. 53 ± 4 ΔCVC%base, P < 0.01). There were no group differences for Tsk or It, while Mnet remained lower in OS ( P < 0.05). The ΔTmid did not account for the drop in Tes in OS. Healthy aged humans failed to maintain Tes; however, the mechanisms underlying this response are not clear.

Early sign of microangiopathy in systemic sclerosis: The significance of cold stress test in dynamic laser Doppler flowmetry

2019 ◽  
Vol 71 (3) ◽  
pp. 373-378 ◽  
Author(s):  
Sebastian Yu ◽  
Stephen Chu-Sung Hu ◽  
Hsin-Su Yu ◽  
Yi-Ying Chin ◽  
Yang-Chun Cheng ◽  
...  
Keyword(s):  
Systemic Sclerosis ◽  
Cold Stress ◽  
Laser Doppler Flowmetry ◽  
Stress Test ◽  
Early Sign ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Cold Stress Test

Estimation of laser-Doppler flux biological zero using basilar artery flow velocity in the rabbit

1995 ◽  
Vol 268 (1) ◽  
pp. H213-H217 ◽  
Author(s):  
H. K. Richards ◽  
M. Czosnyka ◽  
P. J. Kirkpatrick ◽  
J. D. Pickard
Keyword(s):  
Flow Velocity ◽  
Laser Doppler Flowmetry ◽  
Basilar Artery ◽  
Maximum Flow ◽  
Laser Doppler ◽  
Absolute Difference ◽  
Doppler Flowmetry ◽  
Arterial Blood ◽  
Artery Flow ◽  
Doppler Flux

Laser-Doppler flowmetry has potential for continuous cerebral blood flow (CBF) measurement in man and experimental animals. However, laser-Doppler flux (LDFx) measured when perfusion is absent (the biological zero, 0biol) does not necessarily coincide with the instrument's electrical zero. To evaluate laser-Doppler flowmetry further we have compared LDFx in rabbits with continuous measurement of the maximum flow velocity (FVx) in the basilar artery using Doppler ultrasonography. Arterial blood pressure (ABP), FVx, and LDFx were measured continuously in anesthetized New Zealand White rabbits. ABP was altered by controlled hemorrhage with subsequent reinfusion. 0biol was estimated from regression analysis of FVx vs. LDFx and compared with 0biol obtained after death. There was a strong linear relationship between LDFx and FVx (r = 0.94). The absolute difference between estimated 0biol and true 0biol was 5.24% of control prehemorrhage LDFx. Variations in 0biol (range 4-409) suggest that percent changes in LDFx must be related to 0biol if results between individual animals are to be compared.

Role of core temperature as a stimulus for cold acclimation during repeated immersion in 20°C water

2000 ◽  
Vol 89 (1) ◽  
pp. 242-250 ◽  
Author(s):  
Catherine O'Brien ◽  
Andrew J. Young ◽  
Dae T. Lee ◽  
Avraham Shitzer ◽  
Michael N. Sawka ◽  
...  
Keyword(s):  
Skin Temperature ◽  
Cold Acclimation ◽  
Core Temperature ◽  
Air Exposure ◽  
Temperature Reduction ◽  
Metabolic Heat ◽  
Vasoconstrictor Response ◽  
Before And After ◽  
Sufficient Stimulus

The relative importance of skin vs. core temperature for stimulating cold acclimation (CA) was examined by 5 wk of daily 1-h water immersions (20°C) in resting (RG) and exercising (EG) subjects. Rectal temperature fell (0.8°C; P < 0.05) during immersion only in RG. Skin temperature fell ( P < 0.05) similarly in both groups. Physiological responses during cold-air exposure (90 min, 5°C) were assessed before and after CA. Body temperatures and metabolic heat production were similar in both groups with no change due to CA. Cardiac output was lower ( P < 0.05) in both groups post-CA (10.4 ± 1.2 l/min) than pre-CA (12.2 ± 1.0 l/min), but mean arterial pressure was unchanged (pre-CA 107 ± 2 mmHg, post-CA 101 ± 2 mmHg). The increase in norepinephrine was greater ( P < 0.05) post-CA (954 ± 358 pg/ml) compared with pre-CA (1,577 ± 716 pg/ml) for RG, but CA had no effect on the increase in norepinephrine for EG (pre-CA 1,288 ± 438 pg/ml, post-CA 1,074 ± 279 pg/ml). Skin temperature reduction alone may be a sufficient stimulus during CA for increased vasoconstrictor response, but core temperature reduction appears necessary to enhance sympathetic activation during cold exposure.

The role of baseline in the cutaneous vasoconstrictor responses during combined local and whole body cooling in humans

2007 ◽  
Vol 293 (5) ◽  
pp. H3187-H3192 ◽  
Author(s):  
Gary J. Hodges ◽  
Wojciech A. Kosiba ◽  
Kun Zhao ◽  
Guy E. Alvarez ◽  
John M. Johnson
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Local Heating ◽  
Laser Doppler ◽  
Whole Body ◽  
Local Cooling ◽  
Doppler Flowmetry ◽  
Vasoconstrictor Response ◽  
Body Cooling ◽  
Whole Body Cooling

Previous work showed that local cooling (LC) attenuates the vasoconstrictor response to whole body cooling (WBC). We tested the extent to which this attenuation was due to the decreased baseline skin blood flow following LC. In eight subjects, skin blood flow was assessed using laser-Doppler flowmetry (LDF). Cutaneous vascular conductance (CVC) was expressed as LDF divided by blood pressure. Subjects were dressed in water-perfused suits to control WBC. Four forearm sites were prepared with microdialysis fibers, local heating/cooling probe holders, and laser-Doppler probes. Three sites were locally cooled from 34 to 28°C, reducing CVC to 45.9 ± 3.9, 42 ± 3.9, and 44.5 ± 4.8% of baseline ( P < 0.05 vs. baseline; P > 0.05 among sites). At two sites, CVC was restored to precooling baseline levels with sodium nitroprusside (SNP) or isoproterenol (Iso), increasing CVC to 106.4 ± 12.4 and 98.9 ± 10.1% of baseline, respectively ( P > 0.05 vs. precooling). Whole body skin temperature, apart from the area of blood flow measurement, was reduced from 34 to 31°C. Relative to the original baseline, CVC decreased ( P < 0.05) by 44.9 ± 2.8 (control), 11.3 ± 2.4 (LC only), 29 ± 3.7 (SNP), and 45.8 ± 8.7% (Iso). The reductions at LC only and SNP sites were less than at control or Iso sites ( P < 0.05); the responses at those latter sites were not different ( P > 0.05), suggesting that the baseline change in CVC with LC is important in the attenuation of reflex vasoconstrictor responses to WBC.

Laser Doppler Flux in Normal and Varicose Long Saphenous Vein Wall

1996 ◽  
Vol 11 (4) ◽  
pp. 146-149
Author(s):  
A. Taccoen ◽  
C. Lebard ◽  
F. Zuccarelli
Keyword(s):  
Saphenous Vein ◽  
Varicose Veins ◽  
Public Hospitals ◽  
Laser Doppler ◽  
Vein Wall ◽  
Doppler Flowmetry ◽  
Long Saphenous Vein ◽  
Saphenous Veins ◽  
Private And Public ◽  
Doppler Flux

Objective: To assess the wall perfusion in normal and varicose veins. Design: Observational study. Setting: Departments of vascular surgery of private and public hospitals. Patients: Twenty-seven patients undergoing vein surgery (43 long saphenous veins) and eight controls operated on for femoral-popliteal bypass. Methods: Laser Doppler flowmetry assessing long saphenous vein wall perfusion 3 cm below the saphenofemoral junction. Results: Significantly reduced wall perfusion was shown in varicose long saphenous veins compared with normal veins: 16.3 (SD 10.3) versus 45.4 (SD 14.9); p<0.001. Conclusion: Our data suggest a primary or secondary role for lower perfusion within the vein wall in varicose veins.

The response of skin perfusion and of rheological and immunological variables to intravenous prostanoid administration in Raynaud’s phenomenon secondary to collagenosis

VASA ◽  
2005 ◽  
Vol 34 (4) ◽  
pp. 243-249 ◽  
Author(s):  
Drinda ◽  
Neumann ◽  
Pöhlmann ◽  
Vogelsang ◽  
Stein ◽  
...  
Keyword(s):  
Laser Doppler Flowmetry ◽  
Raynaud’S Phenomenon ◽  
Raynaud's Phenomenon ◽  
Plasma Viscosity ◽  
Laser Doppler ◽  
Erythrocyte Aggregation ◽  
Control Group ◽  
Long Term Effects ◽  
Doppler Flowmetry

Background: Prostanoids are used in the treatment of Raynaud’s phenomenon and acral perfusion disorders secondary to collagenosis. In subjective terms, intravenous administration of these agents produces success in more than 50% of patients. The therapeutic outcome of clinical administration of alprostadil or iloprost may vary from individual to individual. Patients and methods: The following variables were analysed in a cross-over study in 27 patients with collagenosis and Raynaud’s phenomenon: plasma viscosity and erythrocyte aggregation (rheological variables), partial pressure of oxygen and laser Doppler flowmetry in the finger region, and lymphocyte phenotyping and interleukin (IL) determinations (immunological variables). Results: Laser Doppler flowmetry revealed significant differences between patients with secondary Raynaud’s phenomenon and a control group of 25 healthy subjects. Laser Doppler readings did not change significantly as a result of the treatments. Therapy with iloprost produced a reduction in IL-1beta, L-selectin (CD 62 L) and IL-6. Conclusion: The change in immunological variables due to iloprost may explain the long-term effects of prostaglandins in the treatment of Raynaud’s phenomenon. From our results it is not possible to infer any preference for iloprost or alprostadil.

Veränderungen der Mikrozirkulation bei Patienten mit Unterschenkelerysipelen vor, während und nach antibiotischer Therapie

Phlebologie ◽  
1998 ◽  
Vol 27 (04) ◽  
pp. 131-137
Author(s):  
S. Roszinski ◽  
W. Schmeller ◽  
S. Kock
Keyword(s):  
Laser Doppler ◽  
Doppler Flux

ZusammenfassungBei 12 Patienten mit Erysipelen am Unterschenkel erfolgten Messungen der Mikrozirkulation in Ruhe und bei hämodynamischen Funktionstests. Bestimmt wurden: Hauttemperatur, Erythemstärke (a-Wert der Colorimetrie), transkutaner Sauerstoffpartialdruck (tcPO2 bei 37° C und 44° C Elektrodentemperatur) sowie Laser-Doppler-Flux (LDF). Die Messungen wurden im Zentrum der Erysipele und an den gesunden kontralateralen Beinen zu Beginn, während und eine Woche nach Ende der Antibiotikatherapie durchgeführt. Zum Zeitpunkt der akuten Entzündung zeigten alle Parameter deutliche Veränderungen; diese wiesen Reaktionsmuster auf, wie sie auch bei Dermatosen mit morphologischen Veränderungen des Kapillarsystems gefunden werden. Nach klinischer Abheilung wiesen tcPO2 bei 37° C und Laser-Doppler-Flux sowohl in Ruhe als auch bei den Funktionstests noch deutliche Veränderungen auf.

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