In the present review, we summarize the principles governing the transport of fluid and electrolytes across the peritoneum during continuous ambulatory peritoneal dialysis (CAPD) in "average" patients and during ultrafiltration failure (UFF), according to the three-pore model of peritoneal transport. The UF volume curves as a function of dwell time [V(t)] are determined in their early phase by the glucose osmotic conductance [product of the UF coefficient (L p S) and the glucose reflection coefficient (σ σ σ σ σ g )] of the peritoneum; in their middle portion by intraperitoneal volume and glucose diffusivity; and in their late portion by the L p S, Starling forces, and lymph flow. The most common cause of UFF is increased transport of small solutes (glucose) across the peritoneum, whereas the L p S is only moderately affected. Concerning peritoneal ion transport, ions that are already more or less fully equilibrated across the membrane at the start of the dwell, such as Na + (Cl -), Ca 2+ , and Mg 2+ , have a convection-dominated transport. The removal of these ions is proportional to UF volume (approximately 10 mmol/L Na + and 0.12 mmol/L Ca 2+ removed per deciliter UF in 4 hours). The present article examines the impact on fluid and solute transport of varying concentrations of Ca 2+ and Na + in peritoneal dialysis solutions. Particularly, the effect of "ultralow" sodium solutions on transport and UF is simulated and discussed. Ions with high initial concentration gradients across the peritoneum, such as K + , phosphate, and bicarbonate, display a diffusion-dominated transport. The transport of these ions can be adequately described by non-electrolyte equations. However, for ions that are in (or near) their diffusion equilibrium over the peritoneum (Na + , Ca 2+ , Mg 2+ ), more complex ion transport equations need to be used. Due to the complexity of these equations, however, non-electrolyte transport formalism is commonly employed, which leads to a marked underestimation of mass transfer area coefficients (PS). This can be avoided by determining the PS when transperitoneal ion concentration gradients are steep. Perit Dial Int 2004; 24:10-27 www.PDIConnect.com

SUMMARY In 38 patients who underwent cerebrovascular evaluation followed by angiography the Doppler ultrasound scanning technique was found to be an excellent screening procedure for detecting marked stenosis (>50%) or occlusion of the internal carotid artery (93% correlation). It is noninvasive, easily reproducible and can be performed by a qualified technician. The major problems are: the inability to detect ulcerated plaques without marked stenosis, the requirement for patient cooperation (lying still for periods of 15 minutes), and the fact that it assesses only the extracranial circulation.Screening with just the directional ophthalmic Doppler flow signal yielded a high percentage of false negatives (13%). The presence of a cervical bruit may indicate an underlying stenosis of the internal carotid artery, but may also be due to stenosis of the external carotid artery or other factors such as increased blood flow, vessel tortuosity, etc. (12% false positives). Absence of a cervical bruit does not exclude internal carotid artery disease (ulcerated nonstenotic plaque or occlusion).

SUMMARY A patient experiencing transient cerebral ischemic attacks (TIAs) was studied angiographically and found to have a symptomatic stenosis of the appropriate internal carotid artery (ICA) and three asymptomatic intracranial aneurysms. A therapeutic approach to this type of problem is discussed in this article.IN PATIENTS undergoing cerebral angiographical examination for evaluation of occlusive cerebrovascular disease, about 5% will show an unexpected aneurysm.1 ' 2 The number with multiple aneurysms is difficult to ascertain from the literature, but must be considerably less. The following case illustrates the rare association of three asymptomatic intracranial aneurysms and a symptomatic carotid stenosis demonstrated on angiographical evaluation. Case ReportA 67-year-old white woman gave a history of a fiveminute episode of left arm numbness occurring three months prior to admission. On the day of admission, April 3, 1974, she noted the onset of complete numbness and slight weakness of her left arm and leg lasting about 45 minutes. By the time she was hospitalized, the symptoms had nearly resolved.She had a history of hypertension for at least 20 years, which had been under fair control with multiple medications. She also had chronic bronchitis, headaches, and occasional depression and was being treated for hypothyroidism. There was no history of diabetes mellitus, angina or prior neurological deficits. Family history was negative for any neurological disorders.Examination on admission revealed an alert apprehensive woman with a blood pressure of 160/92 mm Hg, regular pulse of 96 per minute. Funduscopic examination showed mild arteriolar narrowing. No hemorrhages, exudates or bright plaques were seen. Ophthalmodynamometry showed a 25% difference in systolic pressures, with the left greater than the right. Her neck was supple and bruits were heard over both carotids, most prominent at the midcervical region, right greater than the left. Cardiac examination suggested left ventricular enlargement but no murmurs or gallops were heard. The rest of the general examination was normal. Neurological examination was normal except for some extinction of the left arm with two-point simultaneous stimulation testing and slight downward drift of her left arm when extended. No pathological reflexes were elicited.Complete blood count, urinalysis, blood chemistries, partial thromboplastin time, and prothrombin time were all normal. Cholesterol was 200 mg/dl, and triglyceride was 235 mg/dl. Arterial gases showed a pH of 7.44, Po 2 of 81 mm Hg, and Pco 2 of 32 mm Hg. Chest and skull x-rays were normal. EKG was suggestive of an old anteroseptal myocardial infarct. A radioisotope brain scan and flow study with 99m technetium was normal. During the 12 hours after admission, the patient had two more episodes of left arm and leg numbness with minimal weakness lasting 20 minutes. A lumbar puncture showed an opening pressure of 175 mm H 2 O, clear fluid with two mononuclear cells and no RBCs; glucose and protein were normal. She wa...

The results of continuous wave Doppler scanning of 96 common carotid arteries and their immediate branches were compared with those of selective angiography. The overall accuracy of the Doppler technique for the assessment of the common, internal and external carotid arteries was 98%, 81% and 86%, respectively with a sensitivity of 60%, 70% and 54%, and a specificity of 100%, 93%, and 96%. When stenoses of 50% were considered hemodynamically insignificant, the overall accuracy of the assessment of the common, internal and external carotid arteries rose to 100%, 93% and 93%, but the sensitivity was only 100%, 83% and 53%, whereas the specificity was 100%, 96% and 96%. This modality did not prove useful in the detection of intimal ulcers and plaques nor could the degree of stenosis be accurately graded. The above data indicate that contrast angiography remains imperative prior to surgery.