Blood pressure (BP) measurements in adults

The author discusses issues that relate to devices used for measuring blood pressure

Acute changes in peritoneal morphology and transport properties with infectious peritonitis and mechanical injury

Acute changes in peritoneal morphology and transport properties with infectious peritonitis and mechanical injury. Peritoneal clearance studies were performed in rats undergoing acute peritoneal dialysis. Some of these animals were then exposed to laparotomy and mechanical drying of the peritoneum. Peritoneal clearance studies were repeated at intervals up to 11 days. Another group of rats was placed on daily peritoneal dialysis and allowed to spontaneously develop peritonitis which was not treated. These rats underwent peritoneal transport studies at differing durations of infection. In all groups, animals were sacrificed at the time of the last transport studies for morphological assessment of the peritoneum by light microscopy, scanning electron microscopy, and transmission electron microscopy. The results showed similar decreases in drainage volume and increases in glucose absorption and protein losses with both infection and drying. Both types of injury resulted in extensive mesothelial structural changes. While drying caused mainly denudation of the mesothelial surface, infectious peritonitis was associated with separation of mesothelial cells, and the appearance of numerous white blood cells between and on mesothelial cells. Exposure to peritoneal dialysis alone had no obvious effects on anatomy. Although changes in the peritoneal microcirculation and deeper structures cannot be excluded as contributing to peritoneal transport alterations, the findings suggest that alterations of mesothelium might explain some of the changes in peritoneal transport properties under the conditions of these studies.Modifications aiguës de la morphologie et des propriétés de transport du péritoine par péritonite infectieuse et lésion mécanique. Des études de clearance péritonéale ont été entreprises chez des rats en dialyse péritonéale aiguë. Certains de ces animaux étaient soumis à une laparotomie et à un séchage mécanique du péritoine. Les études de clearance péritonéale étaient répétées à des intervalles allant jusqu'à 11 jours. Un autre groupe de rat était placé en dialyse péritonéale journalière, et il pouvait développer spontanément une péritonite qui n'était pas traitée. Chez ces rats ont été effectuées des études de transport péritonéal à différents stades d'infection. Dans tous les groupes, les animaux étaient sacrifiés lors de la dernière étude de transport afin d'étudier morphologiquement le péritoine par microscopie optique, microscopie électronique à balayage, et microscopie électronique par transmission. Les résultats ont montré des diminutions du volume de drainage et des augmentations de l'absorption du glucose et des pertes protéiques identiques avec l'infection ou le séchage. Les deux types de lésions ont entrainé des modifications structurelles mésothéliales importantes. Tandis que le séchage entrainait principalement une dénudation de la surface mésothéliale, la péritonite infectieuse était associée à une séparation des cellules mésothéliales, et à l'apparition de nombreux globules blancs entre et sur les cellules mésothéliales. L'exposition à la dialyse péritonéale seule n'avait pas d'effets anatomiques évidents. Bien que la contribution aux altérations du transport péritonéal de modifications de la micro-circulation péritonéale et des structures plus profondes ne puisse être exclue, ces résultats suggèrent que les altérations du mésothélium pourraient expliquer certaines des modifications des propriétés de transport péritonéal dans les conditions de ces études

Determinants of low clearances of small solutes during peritoneal dialysis

Peritoneal dialysis plasma clearances of large molecular weight solutes such as inulin (5,200 daltons) usually equal or exceed plasma clearances of such solutes seen with extracorporeal dialyzers, [1–4]. Clearances of smaller solutes such as urea (60 daltons), however, are usually 15% or less of urea clearances with extracorporeal dialysis systems. In Table 1, typical values for clearances of urea and inulin, dialysis solution flow rate (QD), blood flow rate (QB), and surface area are compared for peritoneal and extracorporeal (hemodialysis) techniques. Effective peritoneal capillary blood flow rate is unknown. Gross total anatomical peritoneal surface area is estimated to be approximately equal to body surface area [2, 4]

The influence of solution composition on protein loss during peritoneal dialysis

A number of recent studies in man [1–3] and rats [1, 4, 5] has investigated the influence of the composition of commercial peritoneal dialysis solutions on the microcirculation and on the removal of solutes during peritoneal dialysis. One of those studies [3] demonstrated that dialysis with a normal osmolality Krebs solution greatly enhanced the concentration of protein in the drainage solution in comparison to that obtained with commercial, 1.5% dextrose solutions. We proposed that these results represented an effect of osmolality on interstitial movement of protein [6]. Since protein movement in the interstitium probably occurs through water channels in the gel-like matrix of the interstitium [7, 8], a change to a high osmolality dialysis solution could dehydrate the interstitium. This would increase the resistance to protein movement and thus decrease the loss of protein in the dialysate. During the first few exchanges, the high osmolality of commercial dialysis solutions could also pull residual protein out of the interstitium because it produced a generalized dehydration of the interstitial tissues. This would lead to large concentrations of protein in the drainage solution during the first few exchanges and then a progressive fall in dialysate protein with subsequent exchanges. An alternative hypothesis to explain such results would be that there is simply a washout of residual protein from the peritoneal cavity or from tissue spaces within the cavity.The following studies were designed to test which of these two hypotheses, an increased resistance to protein movement through dehydration of the interstitial tissue or a washout of residual protein already present in the peritoneal cavity, could explain our previous findings [3]

An hypothesis to explain the ultrafiltration characteristics of peritoneal dialysis

Net removal of fluid and sodium from the body during peritoneal dialysis is accomplished with dialysis solutions that contain high glucose concentrations and are hyperosmolar to body fluid [1]. Commercially available peritoneal dialysis solutions contain glucose concentrations ranging from 1.5 to 4.25 g/dl and have osmolalities ranging from 334 to 490 mOsm/kg H2O. The solutions also contain concentrations of sodium, chloride, magnesium, and calcium that approach those of normal extracellular fluid. Acetate or lactate, rather than bicarbonate, is used as the nonchloride anion. Potassium may be added or, depending on the need for potassium removal, solutions may be potassium-free