Role of histamine release in nonspecific vasodilatation during anodal and cathodal iontophoresis

Polarized light spectroscopy for measurement of the microvascular response to local heating at multiple skin sites

OBJECTIVE

To evaluate whether TiVi, a technique based on polarized light, could measure the change in RBC concentration during local heating in healthy volunteers.

METHODS

Using a custom-made transparent heater, forearm skin was heated to 42 °C for 40 minutes while the change in RBC concentration was measured with TiVi. The perfusion response during local heating was measured at the same time with Laser Doppler flowmetry.

RESULTS

Mean RBC concentration increased (91 ± 34 vs. 51 ± 34 A.U. at baseline, p < 0.001). The spatial heterogeneity of the RBC concentration in the measured skin areas was 26 ± 6.4% at baseline, and 23 ± 4.6% after 40 minutes of heating. The mean RBC concentrations in two skin sites were highly correlated (0.98 at baseline and 0.96 after 40 minutes of heating). The change in RBC concentration was less than the change in perfusion, measured with LDF. Unlike with LDF, a neurally mediated peak was not observed with TiVi in most of the test subjects.

CONCLUSIONS

TiVi is a valuable technique for measuring the microvascular response to local heating in the skin, and offers a high reproducibility for simultaneous measurements at different skin sites, provided carefully controlled experiments are ensured.

Fetal growth restriction in preterm infants and cardiovascular function at five years of age

OBJECTIVES

We have previously reported an increased cardiac workload in newborn preterm small (SGA) infants, but not in infants appropriate for gestational age (AGA). We hypothesized that these cardiovascular changes will persist at follow-up at 5 years of age.

STUDY DESIGN

We assessed blood pressure, echocardiography, and skin perfusion with laser Doppler flowmetry in 22 SGA (821 +/- 248 g, 28.5 +/- 2.5 gestational weeks) and in 25 AGA (1065 +/- 241 g, 27.6 +/- 0.8 weeks) preterm children at age 5 years. Laser Doppler flowmetry also was used in 13 control children (3982 +/- 425 g, 40.4 +/- 1.8 weeks).

RESULTS

The preterm children in both the SGA and AGA groups had similar higher systolic blood pressures, increased interventricular septum thicknesses, and smaller left ventricular end-diastolic diameters compared with population reference values. Maximal endothelium-independent perfusion to sodium nitroprusside was higher and maximal endothelium-dependent perfusion to acetylcholine reached a plateau earlier in the AGA preterm group than in the control group.

CONCLUSIONS

Prematurity may impair cardiovascular function independently of intrauterine growth restriction. Altered cardiac dimensions and differences in perfusion responses may reflect increased cardiac afterload.