In situ assessment of the brain microcirculation in mechanically-ventilated rabbits using sidestream dark-field (SDF) imaging.

Assessment of the cerebral microcirculation by on-line visualization has been impossible for a long time. Sidestream dark-field (SDF) imaging is a relatively new method allowing direct visualization of cerebral surface layer microcirculation using hand-held probe for direct contact with target tissue. The aim of this study was to elucidate the feasibility of studying the cerebral microcirculation in situ by SDF imaging and to assess the basic cerebral microcirculatory parameters in mechanically ventilated rabbits. Images were obtained using SDF imaging from the surface of the brain via craniotomy. Clear high contrast SDF images were successfully obtained. Total small-vessel density was 14.6+/-1.8 mm/mm(2), total all-vessel density was 17.9+/-1.7 mm/mm(2), DeBacker score was 12.0+/-1.6 mm(-1) and microvascular flow index was 3.0+/-0.0. This method seems to be applicable in animal studies with possibility to use SDF imaging also intraoperatively, providing unique opportunity to study cerebral microcirculation during various experimental and clinical settings.

Maternal and foetal outcomes in pregnant patients with active lupus nephritis.

The objective of this study was to determine the impact of lupus nephritis disease activity on maternal and foetal outcomes in pregnant patients with systemic lupus erythematosus (SLE). Medical records of all pregnant patients with SLE treated at our institution between 1976 and 2007 were reviewed. All patients met American College of Rheumatology classification criteria for SLE. Demographic data, history of lupus nephritis, nephritis disease activity and maternal and foetal outcomes of pregnancy were abstracted. Active lupus nephritis was defined as the presence of proteinuria >0.5 g/day and/or active urinary sediment with or without an elevation in serum creatinine (Cr). Quiescent lupus nephritis was confirmed in the presence of proteinuria <0.5 mg/day and inactive urinary sediment. We identified 58 patients with 90 pregnancies. Compared with pregnancies in SLE patients without renal involvement (n = 47), pregnancies in patients with active lupus nephritis (n = 23) were associated with a higher incidence of maternal complications (57% vs 11%, P < 0.001), whereas those with quiescent lupus nephritis (n = 20) were not (35% vs 11%, P = 0.10). Women with active lupus nephritis were more likely to deliver preterm than women without lupus nephritis, median of 34 weeks vs 40 gestational weeks, respectively (P = 0.002) and were more likely to suffer foetal loss (35% vs 9%, P = 0.031). Active, but not quiescent, lupus nephritis during pregnancy is associated with a higher incidence of maternal and foetal complications compared with pregnancies in SLE patients without renal involvement.

Evaluating tissue perfusion using labelled water indicator microdialysis in a rat model of haemorrhagic shock.

The indicator microdialysis technique with (3)H(2)O was evaluated as a method for assessing local blood flow in skeletal muscle and liver in a rat model of haemorrhagic shock. Microdialysis probes were inserted into the hind limb muscle and liver of 12 rats and perfused with a solution containing (3)H(2)O. Haemorrhagic shock was induced in eight rats by repeated blood withdrawals; four rats were used as a control group. The outflow to inflow (O/I) ratio of water activity, lactate and pyruvate contents in the dialysate were repeatedly measured. The ratio of lactate to pyruvate (L/P) was calculated. There was no correlation between blood loss and O/I ratio (r = 0.323 for liver, r = 0.300 for muscle), between the mean arterial pressure and O/I ratio (r = 0.460 for liver, r = -0.301 for muscle) or between the concentration of lactate and O/I ratio (r = -0.237 for liver, r = 0.454 for muscle). A significant correlation was found between blood loss and lactate concentration in muscle (r = 0.619, p < 0.0001). We suppose that microdialysis with (3)H(2)O cannot be used as a sensitive method to estimate regional blood flow changes during haemorrhagic shock in rats. Measuring lactate, pyruvate and L/P ratio in the microdialysate seems to be a superior method to assess tissue hypoperfusion caused by haemorrhagic shock in rats.