Intraoperative Bier's block as supplement to insufficient axillary block anesthesia in upper extremity surgery

The authors reviewed 52 patients who underwent Bier's block, as supplementary anesthesia for insufficient axillary block in upper extremity surgical procedures. Prior to proceeding to the Bier's block, the mean value of pain using the visual optical analogue scale (VAS) was 7.0. In 48 of the patients supplementation with the Bier's block was sufficient (mean VAS score of 1.0) and all patients were comfortable throughout the procedure. In the remaining four patients supplementation with narcotics and sedatives via the other i.v. line was required. Intraoperative Bier's block provides a safe and effective alternative way of successfully compensating for an insufficient axillary block in upper extremity surgical procedures.     

Evaluation of the sensitivity of Aedes aegypti and Anopheles gambiae complex mosquitoes to two insect repellents: DEET and KBR 3023

We conducted laboratory tests to assess the sensitivity to the insect repellent 1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-, 1-methylpropylester (known as KBR 3023 or Picaridin, trade name Bayrepel) of West African strains of the yellow fever mosquito Aedes aegypti and of malaria vectors of the Anopheles gambiae complex, in comparison with the standard repellent N,N-diethyl-3-methyl-benzamide (DEET). Test mosquitoes were exposed according to a 'separate arms' protocol to logarithmic dose increments applied on one arm of human subjects to evaluate the relative potency, and the median effective dosages (ED50 and ED90). According to a logistic regression model fitted to the experimental data, the dose-response relationship for the two repellents was the same within each species, thus pooled ED values were assessed for each mosquito separately. The median ED of KBR 3023 and DEET was estimated at 0.78 (95% confidence limits (CI): 0.57-1.04) and at 0.018 microg/cm2 (0.004-0.052) for mosquitoes of the An. gambiae complex and Ae. aegypti, respectively. ED90 values were 125.6 (81.4-201.3) and 24.0 microg/cm2 (5.7-208.5) for An. gambiae s.l. and Ae. aegypti, respectively. The relative potency of KBR 3023 was not significantly different from that of DEET for An. gambiae s.l. (95% confidence limits 0.7-1.0), whereas in the case of Ae. aegypti it was with 95% probability 1.1-2.0 times more potent than DEET. On the basis of available evidence, KBR 3023 represents a promising alternative to DEET for personal protection against bites of these important vectors of disease in the Afrotropical region.     

Pressure-independent contribution of sodium to large artery structure and function in hypertension

BACKGROUND: Sodium sensitivity is usually studied in terms of change of blood pressure (BP) but the specific effects on conduit arteries have not been addressed. EXPERIMENTAL STUDIES: In genetic models of hypertension, chronically increased sodium diet is associated with aortic hypertrophy and development of extracellular matrix independent of BP. These alterations, often associated with increased stiffness and secretory properties of vascular smooth muscle, are reversed by lowering sodium intake and/or giving diuretics, independently of BP changes. The arterial changes are chronically modulated by hormonal counterregulatory mechanisms since, when sodium intake is high, bradykinin blockade produces more carotid hypertrophy, and when sodium intake is normal, less aortic collagen accumulates because of AT(1)-receptor blockade. CLINICAL STUDIES: In longitudinal studies on hypertensive subjects, increased sodium intake not only increases BP but also decreases brachial artery diameter, implying pressure-independent mechanisms acting on the arterial wall. The antihypertensive effect of diuretics is associated with little change of arterial geometry and stiffness, probably resulting from marked angiotensin-induced increase of arterial stiffness. This latter effect is blocked by converting-enzyme inhibition. All these arterial changes may be genetically modulated since in salt-sensitive hypertensives, increased sodium intake is associated with decreased arterial distensibility, and in some hypertensive subjects, a polymorphism of the AT(1)-receptor gene has been described in association with increased aortic stiffness and is reversed by converting-enzyme inhibition independent of BP. CONCLUSION: In genetic models of human and rat hypertension, increased sodium intake is associated with specific alterations of the structure and function of conduit arteries involving extracellular matrix, but independent of BP and atherosclerosis.     

Post-synaptic alpha-blockade and brachial artery compliance in essential hypertension

Central (six patients) and brachial (12 patients) haemodynamics were studied in men with sustained essential hypertension before and after intravenous administration of an alpha post-synaptic adrenergic blocking drug, urapidil. Brachial arterial compliance was evaluated non-invasively from the simultaneous measurement of pulse wave velocity and arterial diameter. In basal conditions, arterial compliance was reduced in hypertensives. Urapidil caused a significant drop in blood pressure, due to a significant decrease in total peripheral resistance with no change in cardiac output and heart rate. Brachial arterial diameter and compliance did not change significantly. The results show that the decreased arterial compliance in hypertensive patients was not due exclusively to the elevation of blood pressure or to a predominant activation of the autonomic nervous system, or both. Such observations suggest that, in men with sustained essential hypertension, the decreased compliance was probably related to structural alterations of large arteries.