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A L Imholz

Publications and source records attributed to A L Imholz.

28 records · Page 2Linked to original sources
PubMed1993

The effect of glucose polymers on water removal and protein clearances during CAPD.

Two selected groups of 5 continuous ambulatory peritoneal dialysis (CAPD) patients (3 female, 7 male), mean age 60 years, were studied twice with an interval of 4 weeks. The first study was done with glucose-containing dialysate and the second study with dialysate containing glucose polymers (Dextrin 7.5%) after they had been treated with this solution (night dwell) for 4 weeks. The patients collected night bags for 3 consecutive days during the tests. Protein clearances were determined for beta 2-microglobulin, albumin, IgG, fibronectin, and alpha 2-macroglobulin in both periods to examine the influence of crystalloid-induced convection versus "colloid"-induced convection. Group I normally used 1.50% glucose and was therefore considered to have a "high ultrafiltration";group II was the "low ultrafiltration" group because they needed 4.25% glucose dialysate. For their usual glucose solutions the net ultrafiltration was not different between both groups, but the clearance of beta 2-microglobulin was higher in group II:839 +/- 98 microL/min (group I) and 1135 +/- 131 microL/min (group II) (p = 0.08). For glucose polymers the net ultrafiltration increased in both groups, but this was more pronounced in group II: 657 +/- 104 mL (group I) and 918 +/- 85 mL (group II) (p = 0.06). Also, the clearance of beta 2-microglobulin increased with the glucose polymer solution: 1268 +/- 94 microL/min (for glucose polymer) and 987 +/- 85 microL/min (for glucose) (p < 0.05), but the clearances of the larger serum proteins remained unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

The effect of amphotericin B on fluid kinetics and solute transport in CAPD patients.

Loss of net ultrafiltration capacity is an important complication in long-term continuous ambulatory peritoneal dialysis (CAPD). It has been reported in animal studies that the drained volumes after a dwell period were larger when amphotericin B had been given intraperitoneally. In this study the effect of intraperitoneally administered amphotericin B on fluid kinetics was evaluated in 3 CAPD patients. The first patient lost 2.5 kg body weight during the first 4 days of treatment, whereas the net ultrafiltration in the second patient was higher in the treatment period compared with the nontreatment period (750 +/- 38 mL/day vs 438 +/- 34 mL/day (mean +/- SEM), p < 0.0001). In the last patient it can be demonstrated that the increase in the net ultrafiltration was caused by an increase in the transcapillary ultrafiltration (570 vs 454 mL/4 hours), but that lymphatic absorption was not different (251 vs 265 mL/4 hours). The higher transcapillary ultrafiltration capacity is probably caused by an increase in the hydraulic permeability. It is likely that this phenomenon is governed by the interaction of amphotericin B with membrane-bound cholesterol leading to the formation of transcellular pores. However, the administration of amphotericin B caused a chemical peritonitis, probably due to its solvent, sodium desoxycholate. Therefore, before amphotericin B can be used for the treatment of CAPD patients with ultrafiltration failure, further investigations are necessary to obtain a solvent for amphotericin B that is nontoxic and causes no chemical peritonitis.

Amphotericin B↗
PubMed1992

Effects of tracer, volume, osmolarity and infection on fluid kinetics during CAPD.

A review is given on various aspects of using the disappearance rate of intraperitoneally administered macromolecules for the determination of fluid kinetics in CAPD patients. The rationale and mathematics for the calculation of transcapillary ultrafiltration and of indirect measurement of lymphatic absorption are described. A comparison is made between autologous haemoglobin, human albumin and dextran 70. Dextran 70 appeared most useful; one brand of human albumin increased solute transport. Lymphatic absorption was higher after the installation of a 3-litre dialysate volume than after a 2-litre one, and also higher during peritonitis than after recovery from infection. A gradual increase in intraperitoneal volume, as obtained with glucose 3.86% dialysate, had no apparent effect on the disappearance rate of dextran 70. It is concluded that intraperitoneally administered dextran 70 is a clinically useful marker for the description of fluid kinetics in CAPD patients under various conditions.

Ascitic Fluid↗
PubMed1992

Use of the disappearance rate for the estimation of lymphatic absorption during CAPD.

Several studies are discussed which investigated the usefulness of the disappearance rate of macromolecules from the peritoneal cavity for estimating convective fluid loss from the peritoneal cavity into the peritoneal lymphatic system. It is shown that dextrans are removed from the peritoneal cavity by a size-independent process at a mean rate of 1.37 +/- 0.15 ml/min, whereas the clearance from blood to dialysate of dextrans is size-dependent. The fluid removal rate estimated by the difference in bidirectional transport of inulin (1.79 +/- 0.38 ml/min; p < 0.0005) was of the same order of magnitude as has been found using the removal rate of macromolecules from the peritoneal cavity. Also, the role of local accumulation of macromolecules was studied during continuous administration of dextrans. No differences were found in the dextran disappearance rate before and after saturation of the peritoneal interstitium with dextran (1.1 +/- 0.6 vs. 1.0 +/- 0.4 ml/min). During a study using a hypoosmotic solution we calculated a net transcapillary backfiltration of fluid, whereas the dextran removal rate was in the same order of magnitude as found using commercially available dialysate. In our opinion, the disappearance rate of macromolecules is an estimate of convective fluid loss from the peritoneal cavity into the peritoneal lymphatic system.

Absorption↗
PubMed1992

Residual volume measurements in CAPD patients with exogenous and endogenous solutes.

Accurate residual volume (RV) measurements are needed in studies on fluid kinetics during CAPD. In this study 10 stable CAPD patients were examined twice within 1 week. On both occasions RV after drainage was calculated by the indicator dilution method. Exogenous (dextran 70, inulin) and endogenous (albumin, IgG, urea, creatinine) solutes were used as markers. RV calculated with endogenous solutes (mean +/- SD) were significantly higher than those calculated with dextran (232 +/- 77 mL) and inulin (223 +/- 73): albumin (389 +/- 123), IgG (497 +/- 180), urea (465 +/- 129) and creatinine (429 +/- 109). The relationship between RV calculated with exogenous solutes was much better than between those calculated with endogenous solutes: dextran vs inulin (r = 0.91), albumin vs IgG (r = 0.69) and urea vs creatinine (r = 0.63). Since mass transport of endogenous solutes during rinsing time exceeds mass transport of dextran and inulin, RV was also calculated after corrections had been made for diffusive mass transport of endogenous solutes during the rinsing procedure. After this correction only albumin was similar to exogenous solutes (244 +/- 111 mL) and had an acceptable confidence interval when compared to dextran. No correlation was found between RV on the first and second day, suggesting large intra-individual variability. We conclude that RV should be calculated with dextran or inulin. When no exogenous solutes are used, albumin is the best alternative. However, only rough estimations are obtained when no correction for diffusion is applied.

Adult↗
PubMed1991

Initial blood pressure fall on stand up and exercise explained by changes in total peripheral resistance.

To elucidate the underlying mechanisms of the initial fall in blood pressure on standing upright from the supine position, we measured the beat-to-beat changes in intra-arterial pressure in eight healthy male subjects in response to standing. Changes in stroke volume, cardiac output, and total peripheral resistance were computed from the pressure waveform using a pulse contour method. To determine possible mechanisms for the changes observed on standing, similar measures were made on passive tilting and a brief (3-s) bout of cycle exercise. Standing elicited a transient 25% (23-mmHg) fall in mean blood pressure as a result of a 36% fall in total peripheral resistance. Head-up tilt elicited a gradual change in haemodynamic parameters, which reached plateau levels in 20-30 s. Cycling elicited a transient 17% (18-mmHg) fall in blood pressure and a 41% fall in total peripheral resistance. In addition, we measured right atrial and esophageal pressures in two subjects on standing and cycling and found a 10- to 15-mmHg rise in right atrial pressure without a corresponding change in esophageal pressure. This points to the cardiopulmonary reflex as the primary effector of peripheral vasodilation, but we cannot exclude the possibility that 1) local metabolic vasodilation and 2) central command-mediated cholinergic vasodilation contributed to the fall in vascular resistance.

Adult↗
PubMedDate not supplied

IgG subclasses in CAPD patients.

OBJECTIVE: To make a comparison of serum levels of immunoglobulin G (IgG) subclasses in adult continuous ambulatory peritoneal dialysis (CAPD) patients with those in age- and sex-matched hemodialysis patients and healthy volunteers, and to analyze the contribution of removal of these proteins in peritoneal effluent to their plasma values. DESIGN: A cross-sectional study. SETTING: A renal unit of a university hospital. PATIENTS: Twenty-three CAPD patients, 21 hemodialysis patients, and 21 healthy volunteers. Peritoneal transport studies were done in 8 of the 23 CAPD patients. METHODS: IgG subclasses were measured in serum by nephelometry. For the peritoneal transport studies an ELISA method on ethylenediamine tetracetic acid plasma was used. The same method was used in seven-to-ten-fold concentrated peritoneal dialysate. RESULTS: CAPD patients had lower IgG2 and IgG4 levels than hemodialysis patients and healthy volunteers (p < 0.01). IgG2 values below 1.5 g/L were present in 43% of the CAPD patients (p < 0.001 compared to healthy volunteers). Peritonitis incidence was not different between CAPD patients with low or normal IgG2 plasma levels. Peritoneal clearance of IgG3 was lower than that of the other subclasses. Evidence was obtained for a depressed synthesis of IgG2 and IgG4 in CAPD patients. The hypothesis that interleukin-2 may be involved in the low synthesis rate of IgG2 is discussed. CONCLUSION: Low serum IgG2 and IgG4 levels are present in stable, adult CAPD patients. These were not caused by increased peritoneal loss, but by decreased synthesis.

Adult↗
PubMedDate not supplied

Icodextrin's effects on peritoneal transport.

OBJECTIVE: To give a survey of the principles of peritoneal fluid transport in general, followed by an analysis of the effects of icodextrin on the transport of fluid and solutes. DESIGN: A review of the literature and of data on the effects of icodextrin in continuous ambulatory peritoneal dialysis (CAPD) patients at the Academic Medical Center, Amsterdam. RESULTS: Icodextrin had no effect on the mass transfer area coefficients of low molecular weight solutes. Also no effect was found on the clearances of albumin and larger serum proteins. Due to convective transport, the clearance of beta 2-microglobulin was greater with icodextrin than with glucose solutions. Icodextrin was especially superior to glucose in the induction of net ultrafiltration during long dwells, during peritonitis, and in patients with ultrafiltration failure caused by a large effective peritoneal surface area. CONCLUSION: Icodextrin has no effect on the permeability characteristics of the peritoneal membrane, but increases convective flow through the small-pore system. As a result, the peritoneal clearance of beta 2-microglobulin is higher than with glucose-based solutions. Icodextrin is especially indicated for long dwells and in patients with impaired ultrafiltration caused by a large peritoneal surface area, leading to high transport rates of low molecular weight solutes.

Biological Transport↗