Tone Kristin Bergersen

Perfusion of the human finger during cold-induced vasodilatation.

We have investigated the effect of severe local cooling on the vasomotor activity of the arteriovenous anastomoses (AVAs) and other finger vessels. The right third finger was subjected to local cooling (3 degrees C) for 30-45 min in 21 healthy, thermoneutral subjects. Blood velocity in the third finger arteries of both hands was simultaneously recorded using ultrasound Doppler, and skin temperature and laser-Doppler flux from the pulp of the cooled finger were also recorded. The results demonstrate that the initial cold-induced vasoconstriction during severe local cooling involves constriction of the AVAs as well as the two main arteries supplying this finger. During cold-induced vasodilatation (CIVD), the maximum velocity values were not significantly different from those before cooling. Furthermore, the velocity fluctuations in the cooled finger were in most subjects found to be synchronous with the velocity fluctuations in the control finger. This indicates that the large blood flow to the finger and the high skin temperature during CIVD are caused by relaxation of the smooth muscle cells of the AVAs.We have investigated the effect of severe local cooling on the vasomotor activity of the arteriovenous anastomoses (AVAs) and other finger vessels. The right third finger was subjected to local cooling (3°C) for 30-45 min in 21 healthy, thermoneutral subjects. Blood velocity in the third finger arteries of both hands was simultaneously recorded using ultrasound Doppler, and skin temperature and laser-Doppler flux from the pulp of the cooled finger were also recorded. The results demonstrate that the initial cold-induced vasoconstriction during severe local cooling involves constriction of the AVAs as well as the two main arteries supplying this finger. During cold-induced vasodilatation (CIVD), the maximum velocity values were not significantly different from those before cooling. Furthermore, the velocity fluctuations in the cooled finger were in most subjects found to be synchronous with the velocity fluctuations in the control finger. This indicates that the large blood flow to the finger and the high skin temperature during CIVD are caused by relaxation of the smooth muscle cells of the AVAs.

Core body temperature and the thermoneutral zone: a longitudinal study of normal human pregnancy

Aim:  Using a longitudinal study design, we investigated changes in maternal core temperature and ambient temperatures before and after a localized cooling procedure to the right hand.

Responses in acral and non-acral skin vasomotion and temperature during lowering of ambient temperature.

Arteriovenous anastomoses (AVA) in acral skin (palms and soles) have a huge capacity to shunt blood directly from the arteries to the superficial venous plexus of the extremities. We hypothesized that acral skin, which supplies blood to the superficial venous plexus, has a stronger influence on blood flow adjustments during cooling in thermoneutral subjects than does non-acral skin. Thirteen healthy subjects were exposed to stepwise cooling from 32 °C to 25 °C and 17 °C in a climate chamber. Laser Doppler flux and skin temperature were measured simultaneously from the left and right third finger pulp and bilateral upper arm skin. Coherence and correlation analyses were performed of short-term fluctuations at each temperature interval. The flux from finger pulps showed the synchronous spontaneous fluctuations characteristic of skin areas containing AVAs. Fluctuation frequency, amplitude and synchronicity were all higher at 25 °C than at 32 °C and 17 °C (p<0.02). Bilateral flux from the upper arm skin showed an irregular, asynchronous vasomotor pattern with small amplitudes which were independent of ambient temperature. At 32 °C, ipsilateral median flux values from the right arm (95% confidence intervals) were 492 arbitrary units (au) (417, 537) in finger pulp and 43 au (35, 60) in upper arm skin. Flux values gradually decreased in finger pulp to 246 au (109, 363) at 25 °C, before an abrupt fall occurred at a median room temperature of 24 °C, resulting in a flux value of 79 au (31, 116) at 17 °C. In the upper arm skin a gradual fall throughout the cooling period to 21 au (13, 27) at 17 °C was observed. The fact that the response of blood flow to ambient cooling is stronger in acral skin than in non-acral skin suggests that AVAs have a greater capacity to adjust blood flow in thermoneutral zone than arterioles in non-acral skin.

Oscillatory pattern of acral skin blood flow within thermoneutral zone in healthy humans

The acral skin contains arteriovenous anastomoses, which probably is the main part of skin microcirculation for blood flow adjustments and thermoregulation in the thermoneutral zone. The objective was to investigate if an increase in sympathetic activation during cooling influences the oscillatory pattern of acral skin blood flow. We had measurements of bilateral acral skin blood flow (n  =  12) during lowering of ambient temperature from 32 °C to 18 °C. We quantified the oscillatory pattern as the time averaged wavelet spectral powers, coherence and phase angles in three frequency intervals (0.01-0.02 Hz, 0.02-0.05 Hz and 0.05-0.08 Hz). The differences were tested by Wilcoxon signed rank sum method between adjacent intervals. The absolute fluctuations in laser Doppler flux at 0.01-0.02 Hz, 0.02-0.05 Hz and 0.05-0.08 Hz were similar at 32 °C and 25 °C, and decreased at 18 °C (p  <  0.001). The relative fluctuations (amplitude of the fluctuations relative to median flux value) in laser Doppler flux at 0.01-0.02 Hz, 0.02-0.05 Hz and 0.05-0.08 Hz were higher at 25 °C and 18 °C as compared to 32 °C (p  <  0.002). The coherence between the oscillations of signals from right and left finger tips was highest (median coherence  >  0.89) at 25 °C, and lower at 32 °C and at 18 °C.The median phase angles between the flux signals from right and left finger tips were close to 0 radians. We found that the relative fluctuations in acral skin blood flow increased during vasoconstriction due to cooling. Wavelet analysis of acral skin blood flow oscillations could serve as a future clinical tool.

Improved Clinical Efficacy with Wound Support Network Between Hospital and Home Care Service

OBJECTIVE:The aim of this study was to test the efficacy of a wound support network model between the primary home care service and the hospital. The impact on wound healing rate, cost benefit, and transfer of knowledge was investigated. INTERVENTION:The intervention group was exposed to a wound support network (n = 32), and the control group continued standard organization of treatment (n = 21). DESIGN:Nonrandomized controlled study; observations were made before (baseline) and after the implementation of the intervention (12 weeks). PATIENTS:Patients with chronic wounds (lasting >6 weeks and with wound area >1 cm2) in Oslo, Norway. MAIN OUTCOME MEASURES:Closure of the observation wound; wound size; total number of wounds; presence of eczema, edema, and pain; number of dressings per week; time spent per dressing; and number of control appointments at the hospital. The economic impact is calculated for the hospital and for the community of Oslo, Norway. MAIN RESULTS:The number of control appointments (t = 3.80, P < .001) was significantly decreased, and the number of completed treatments (P = .02) was significantly increased after 12 weeks in the intervention group compared with the control group. A significant improvement was evident in the intervention group in terms of eczema (P = .02), edema (P = .03), and closing of the observational wound (46.7% cases in the intervention group versus 25.0% in the control group). CONCLUSIONS:A wound support network between the primary home care service and the hospital is cost-effective, improves clinical efficacy of the home care services’ work, and reduces the need for consultations at the hospital.