Peritoneal dialysis during peritonitis

The peritoneal dialysis orders objective structured clinical examination (OSCE): A formative assessment for nephrology fellows

Background:

Peritoneal dialysis (PD) management is a fundamental nephrology skill, especially with the recent emphasis on home dialysis. We report a prospective multicentre cohort study of a formative objective structured clinical examination (OSCE) assessing competence in managing PD-associated bacterial peritonitis, using the unified model of construct validity.

Methods:

The OSCE was developed by the principal investigators and reviewed by two subject matter experts. The test committee (eight nephrologists and one PD nurse) assessed test item difficulty/relevance and determined passing score. There were 22 test items (7 evidence-based/standard-of-care questions). Passing score was 16/22 (73%). No item had median relevance less than ‘important’, and all were easy to medium difficulty. Content validity index was 0.91. Preliminary validation (16 board-certified volunteers): mean score was 19 ± 2, with 94% (15/16) passing. Kappa = 0.85 [95% confidence interval (CI) 0.77–0.94]. Cronbach’s α = 0.70.

Results:

Eighty-seven fellows (16 programmes) were tested; 67% passed. Fellows scored significantly less than validators: 17 ± 3 versus 19 ± 2, p < 0.001 [95% CI 1.2–3.6]. Eighty-six per cent of evidence-based/standard-of-care questions were answered correctly by validators versus 54% by fellows; p < 0.001. Ninety-three per cent of fellows recognized that sufficient criteria were present to diagnose peritonitis, but only 17% correctly indicated all three. Seventy-seven per cent recognized peritonitis-associated ultrafiltration failure, but only 17% prescribed 21 days of antibiotic treatment for gram-negative peritonitis. Eighty-five per cent of fellows surveyed agreed/strongly agreed that the OSCE was useful in self-assessing proficiency. Second-year in-training examination and OSCE scores were positively correlated (Pearson’s r = 0.57, p < 0.00).

Conclusions:

The OSCE may be used to formatively assess fellow proficiency in managing PD-associated peritonitis.

Peritoneal Surface Area and Its Permeability in Rats

Objective

Evaluation of peritoneal surface area and its permeability during dialysis in rats of various ages.

Design

Study I: planimetry of peritoneum and its topographic areas was performed in 47 rats of various ages (8 -30 weeks). Study II: net ultrafiltration (UF), dialysate-to-serum ratios for urea, creatinine, albumin, and total protein as well as their peritoneal permeability coefficients, were measured during a 1-hour peritoneal exchange with Dianeal 2.5%, in 21 rats of different ages (9 30 weeks) and with various peritoneal surface areas. Animals: Male Wistar rats.

Results

The peritoneal surface area in rats increases during aging, but young animals with lower body weight have a relatively larger peritoneal surface area than older, larger animals. The area of the topographic fragments of peritoneum expressed as a percentage of the total peritoneal surface is steady during aging. Efficiency of transperitoneal water removal expressed as net UF per amount of absorbed glucose declines in older animals, with larger peritoneal surface areas. Dialysate/serum ratio of solutes transported from blood to dialysate is proportional to peritoneal surface area. Permeability coefficient (K) of peritoneum to urea and creatinine is unchanged during the aging of animals. However peritoneal permeability (K) to albumin increases during aging, with the opposite tendency for total proteins.

Conclusions

Kinetics of peritoneal dialysis in rats of different ages is determined by peritoneal surface area and permeability of peritoneum to individual solutes.

Anabolic Steroids and Malnutrition in Chronic Renal Failure

Objective

To determine whether anabolic steroids are useful in the management of the malnutrition of chronic renal failure.

Data Source

Original research studies and book chapters about anabolic steroids and their use in uremia and various illnesses associated with malnutrition. We included studies that describe the benefits of anabotic steroids in the treatment of anemia and sexual dysfunction of chronic renal failure. Forty-two such studies were published between 1942 and 1992.

Results

Anabolic steroids improve the nutritional status and sexual dysfunction of uremic men. In addition, anabolic steroids have a recognized place in the treatment of the anemia of chronic renal failure.

Conclusions

Based on the findings of noncontrolled studies, one may conclude that anabolic steroids exert a beneficial effect in the malnutrition of renal failure. We believe that their efficacy should be established by controlled studies.

The Longitudinal Effect of a Single Peritonitis Episode on Peritoneal Membrane Transport in CAPD Patients

Objective

To evaluate the longitudinal effect of a single peritonitis episode on peritoneal membrane transport.

Design

A prospective longitudinal study.

Setting

Department of nephrology in a university hospital.

Patients

Eighteen continuous ambulatory peritoneal dialysis patients with peritonitis.

Methods

Peritoneal transport for low, middle, and high molecular weight (MW) solutes was evaluated by peritoneal equilibration test (PET). The first PET was performed on the day following the diagnosis of peritonitis. The test was repeated at weeks 1, 2, 4, 12, and 24 and the results were compared to baseline PET data obtained before peritonitis. In addition, dialysate CA125 concentration and leukocyte count were measured.

Results

During peritonitis there were significant increases in dialysate-to-plasma (D/P) ratios for all low, middle, and high MW solutes except potassium, and decreases in D4/D0 glucose ratio and ultrafiltration (UF) volume. Over the subsequent 2 weeks, solute transport gradually decreased to the baseline values then remained unchanged during follow-up. Although net UF volume demonstrated a similar course during the study, it did not completely return to the baseline value. No decrease in D/P sodium ratio was found at 60 minutes during the PET performed 24 weeks after peritonitis. The percent change in solute transport during peritonitis compared to baseline value was significantly correlated with a solute's MW ( r = 0.776, p = 0.014). The slope of the regression line for D/P ratios versus MW, in double logarithmic scale, before peritonitis (-0.73 ± 0.09) was steeper than the slope during peritonitis (-0.59 ± 0.08).

Conclusions

These findings indicate that a single peritonitis episode does not permanently affect peritoneal solute transport. However, the loss of net UF that accompanies peritonitis is not completely recovered, probably due to impairment of transcellular water transport. The transport changes associated with peritonitis may be due to the combined effect of increased effective peritoneal surface area and intrinsic permeability. Our findings suggest that the latter mechanism seems to be more important.

The Mutual Relationship Between Peritonitis and Peritoneal Transport

♦

BACKGROUND

Preservation of the peritoneum is required for long-term peritoneal dialysis (PD). We investigated the effect of multiple peritonitis episodes on peritoneal transport. ♦

METHODS

Prospectively collected data from 479 incident PD patients treated between 1990 and 2010 were analyzed, using strict inclusion criteria: follow-up of at least 3 years with the availability of a Standard Peritoneal Permeability Analysis (SPA) in the first year after start of PD and within the third year of PD, without peritonitis preceding the first SPA. For the purpose of the study, we only included patients who remained peritonitis-free (n = 28) or who experienced 3 or more peritonitis episodes (n = 16). ♦

RESULTS

At baseline the groups were similar with regard to small solute and fluid transport. However, the frequent peritonitis group had lower peritoneal protein clearances compared to the no peritonitis group, resulting in lower dialysate concentrations of proteins: albumin 196.5 mg/L vs 372.5 mg/L, IgG 36.4 mg/L vs 65.0 mg/L, and α-2-macroglobulin (A2M) 1.9 mg/L vs 3.6 mg/L, p <0.01. No differences in serum concentrations were present. A comparison between the transport slopes over time in both groups showed a positive time trend of mass transfer area coefficient (MTAC) creatinine (p = 0.03) and glucose absorption (p = 0.09) and a negative trend of transcapillary ultrafiltration (p = 0.06), when compared to the no peritonitis group. Frequent peritonitis did not affect free water transport. ♦

CONCLUSIONS

Slow initial peritoneal transport rates of serum proteins result in lower dialysate concentrations, and likely a lower opsonic activity, which is a risk factor for peritonitis. Patients with frequent peritonitis show an increase in small solute transport and a concomitant decrease of ultrafiltration. In long-term peritonitis-free PD patients, small solute transport decreased, while ultrafiltration increased. This suggests that frequent peritonitis leads to an increase of the vascular peritoneal surface area without all the structural membrane alterations that may develop after long-term PD.

Lack of Utility of Routine Screening Tests for Early Detection of Peritonitis in Patients Requiring Intermittent Peritoneal Dialysis

A prospective study was undertaken to examine the clinical presentation of peritonitis in patients maintained on intermittent peritoneal dialysis and to determine the value of qualitative and quantitative dialysate cultures, gram stain, neutrophil counts, and a semiquantitative leukocyte test strip for case detection. Seven cases of peritonitis developed among 30 patients who underwent 553 dialyses. In most cases, neutrophil counts, cultures, and leukocyte test strip determinations were done within 48 hours prior to the clinical onset of peritonitis and in all instances failed to provide clues for incipient infection. Peritonitis was associated with a dialysate neutrophil count of >500/mm3 and leukocyte test strips were highly sensitive and specific for the detection of this quantity of neutrophils. A total of 16 dialysate cultures was positive in asymptomatic patients who did not have peritonitis. None of these patients subsequently developed peritonitis with the same organism. Dialysate gram stains, cultures, neutrophil counts or leukocyte test strips did not provide an early diagnosis of peritonitis and their use in the absence of symptoms is therefore not recommended.

2009 Japanese Society for Dialysis Therapy guidelines for peritoneal dialysis

The guidelines for peritoneal dialysis (PD) of the Japanese Society for Dialysis Treatment were prepared at 2009. Upon presenting a concrete frame of PD practiced in Japan, it aims to promote PD as a standardized therapy in Japan. Notably, the guidelines recommended combination therapy of PD and hemodialysis as a part of integrated renal replacement therapy for end-stage renal disease, as well as timely PD withdrawal by peritoneal degeneration in order to prevent progression of encapsulating peritoneal sclerosis.

Free-water transport in fast transport status: A comparison between CAPD peritonitis and long-term PD

BACKGROUND

Ultrafiltration failure (UFF) in continuous ambulatory peritoneal dialysis (CAPD) is a transient phenomenon during acute peritonitis and a permanent complication in long-term peritoneal dialysis (PD). The high solute transport rates during acute peritonitis are probably caused by an increased number of perfused peritoneal capillaries. Long-term PD is associated with an increased number of peritoneal microvessels, leading to an enlargement of the anatomic vascular surface area. This leads to high mass transfer area coefficients (MTAC) and to UFF. Impaired conductance to glucose, leading to a reduction in free-water transport, may be a contributing factor to UFF in long-term PD. We hypothesized that UFF during acute peritonitis is, in the absence of permanent structural changes, only caused by an increased vascular surface area, while in long-term patients it is often the result of an increased surface area in combination with an impaired conductance to glucose. Therefore, the peritoneal transport parameters of patients with acute peritonitis were compared to those in long-term PD patients.

METHODS

A standard peritoneal permeability analysis (SPA) was done in 10 PD patients during the first 48 hours after the diagnosis of peritonitis. The results were compared to those obtained in 10 long-term PD patients matched for the MTAC creatinine. In addition, the results of 8 peritonitis patients were compared with SPA results of 8 recently started PD patients, matched for MTAC creatinine.

RESULTS

Peritonitis patients had a deeper maximal dip in D/P sodium, corrected for diffusion, than long-term patients (0.058 vs. 0.039, P < 0.05). Most parameters of peritoneal fluid transport were not different, except that t50 (i.e., the time to reach 50% of the maximum transcapillary ultrafiltration) was reached earlier during the dwell in peritonitis than in long-term PD-128 versus 175 minutes, P < 0.05. This confirmed the difference in the shape of the intraperitoneal volume versus time curve, which was blunted in the long-term patients. No differences were found for the parameters of solute transport between peritonitis patients and recently started patients.

CONCLUSION

In contrast to patients with long-term PD, the osmotic conductance to glucose is unaffected in peritonitis, despite the lower net ultrafiltration caused by high solute transport. This implies that impaired free- water transport in chronic PD must be regarded as a contributing factor to UFF.

Transperitoneal transport of glucose in vitro

The effect of fluid mixing intensification, damage of mesothelial cells, gentamicin, and icodextrin on the diffusive glucose transport across the peritoneal membrane were evaluated in in vitro studies. A mathematical model of mass transport was used to calculate the diffusive permeability, expressed as a diffusive permeability coefficient (P). In the control conditions, the rate of glucose transfer from the interstitial to the mesothelial side of membrane (I-->M) and in the opposite direction (M-->I) remained constant, and the P value at mean was 2,731 +/- 1,493 x 10-4 (cm x s-1). The change of the stirring rate from 5.5 to 11 ml/min increased P values by about 74% for transport direction I-->M and 58% for M-->I, and the change from 11 to 22 ml/min enhanced P at mean by about 42% for both directions. The damage of the mesothelial layer, using sodium deoxycholate (2.5 mmol/L; 103.6 mg%), increased the glucose transfer from the interstitial to the mesothelial side of the peritoneum by 41% and to the opposite direction by 70%. Addition of icodextrin to the glucose solution increased glucose bidirectional transport at mean by about 14% for I-->M and 24% for M-->I. Furthermore, gentamicin did not change the I-->M transfer, but diminished M-->I transport by about 12%. In conclusion, the reduction of unstirred fluid layers at the mesothelium and the interstitium-fluid interfaces, removal of mesothelium, and addition of icodextrin increased the diffusive glucose transport in vitro; unstirred fluid layers restricted glucose transfer (I-->M) more than the mesothelium; and peritoneal glucose transport, directed from the mesothelial to the interstitial side of the peritoneum, decreased slightly after the addition of gentamicin.

Peritoneal dialysis. Prevention and control of infection

In spite of the reduction in peritonitis and catheter-related infection rates in patients undergoing peritoneal dialysis, these infections remain major sources of morbidity and transfer to haemodialysis. Touch contamination at the time of doing the exchanges is still a major cause of peritonitis and leads to Gram-positive organisms (coagulation-negative staphylococcus) being the most common pathogens. Newer exchange techniques have reduced this incidence but the more serious pathogens (Staphylococcal aureus, pseudomonas and fungi) remain a major problem. Treatment has to be immediate, and hence empirical, giving adequate cover for both Gram-positive and Gram-negative organisms. The use of vancomycin as an initial antibacterial has been discontinued because of the problem of vancomycin-resistant enterococcus. Recent guidelines advocate the use of a first generation cephalosporin combined with ceftazidime (if the urine output is >100 ml/day) or an aminoglycoside in anuric patients. Subsequent therapy changes are made upon bacterial isolation and sensitivities. Vancomycin is reserved for methicillin-resistant staphylococcus. Peritoneal catheter-related infections (exit site and tunnel) are predominantly caused by S. aureus and pseudomonal organisms and can be difficult to eradicate. Tunnel infections invariably involve the catheter dacron cuffs and therefore are more likely to lead to peritonitis; in this situation catheter removal is the treatment of choice. Treatment of exit-site infections is with oral antibacterials (penicillinase-resistant penicillins, cefalexin). Vancomycin is avoided if possible. The identification that nasal carriage of S. aureus predisposes to exit-site and tunnel infections has led to prophylactic regimens to combat this problem. Mupirocin applied at the exit site leads to a reduction in catheter-related infections and peritonitis.

Are phospholipase A2 and nitric oxide involved in the alterations in peritoneal transport during CAPD peritonitis?

The alterations in peritoneal permeability characteristics during peritonitis can only partly be explained by the increased concentrations of prostaglandins and cytokines in the dialysate. Fifteen patients undergoing continuous ambulatory peritoneal dialysis (CAPD) with 16 peritonitis episodes were examined in the acute phase of the infection by using standard peritoneal permeability analyses (SPAs). In 9 of these patients, a control SPA could be performed. The contribution of nitric oxide (NO), prostaglandins, and the acute phase reactants C-reactive protein (CRP) and secretory phospholipase A2 (sPLA2) were analyzed. The mass transfer area coefficients (MTACs) of low-molecular-weight solutes increased during peritonitis: urea 26%, creatinine 45%, and urate 45%. The MTAC of CO2, calculated to estimate peritoneal blood flow, was 71 mL/min (34 to 254 mL/min) during peritonitis and 55 mL/min (42 to 63 mL/min) after recovery, P < or = .05. The peritoneal protein clearances were also greater during peritonitis, but this increase was not related to the molecular weight of the protein. Therefore the restriction coefficients to macromolecules were not different. The net ultrafiltration in all peritonitis episodes was lower as compared with the control dwells: -97 mL (-196 to 19 mL) versus 25 mL (-132 to 216 mL), P = .03. The prostaglandin concentrations in dialysate were greater during peritonitis than after recovery. The median increase was 199% for prostaglandin E2 (PGE2), 68% for 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), and 44% for thromboxane B2 (TxB2). Plasma sPLA2 values were 22.7 microg/L (7.3 to 407.6) during peritonitis and 8.9 microg/L (5.5 to 11.5) after recovery, P < .01. The increased plasma sPLA2 during peritonitis correlated with plasma CRP (r = .6; P = .02). The peritoneal clearances of sPLA2 were greater during peritonitis, but this could be attributed completely to the increased peritoneal transport. Both during peritonitis and after recovery, the sPLA2 clearances did not exceed the predicted values based on transport from the circulation to the dialysate. No evidence was found for local production of nitrite or nitrate. However, the MTAC of cyclic guanosine monophosphate (cGMP) was greater during the experiments performed 48 to 72 hours after the onset of peritonitis, which suggests the synthesis of NO. It can be concluded that peritonitis does not induce detectable local release of sPLA2 and that the inflammation-induced increase in the vascular surface area could not be attributed to NO in the acute phase. The activation of inducible NO synthase may occur after 48 hours.

Nursing interventions related to peritonitis

Effective management of peritonitis in chronic peritoneal dialysis patients requires a multidisciplinary approach. Nursing's role begins with the prevention of peritonitis by the development of sound program policies and procedures and effective patient education. Nursing activities at the time of infection focus on assessment and patient education. Nurses are also responsible for maintaining peritonitis data as well as directing or participating in related quality improvement activities.

Rusty peritoneal dialysis fluid after intravenous administration of iron dextran

Rusty-colored peritoneal dialysate fluid was observed after intravenous administration of iron dextran to a patient with peritonitis being treated with vancomycin and rifampicin. The discoloration gradually cleared over a 24-hour period. Analysis of the fluid demonstrated that the discoloration could not be explained by the presence of erythrocytes or free hemoglobin. Iron (52 micrograms/dL) was detected in the fluid and decreased to undetectable levels as the discoloration cleared. Addition of iron dextran to an unused bag of peritoneal dialysis fluid to achieve an iron concentration of 52 micrograms/dL resulted in no discoloration. Addition of rifampicin at a clinically relevant serum concentration (10 micrograms/dL) to a different unused bag caused a light orange discoloration. Addition of iron dextran and rifampicin simultaneously in the concentrations mentioned to an unused bag caused a rusty discoloration almost as dark as that observed in our patient. We postulate, therefore, that a combination of iron and rifampicin caused the marked discoloration of our patient's peritoneal effluent.

Mechanisms of polymorphonuclear leukocyte mediated peritoneal mesothelial cell injury

To determine the susceptibility of human peritoneal mesothelial cells to injury mediated by activated polymorphonuclear leukocytes (PMNs), we exposed cultured human peritoneal mesothelial cells to 1250, 2500, 3750, and 5000 PMNs/mm3 activated with 50 ng/ml phorbol myristate acetate (PMA) or with 10(-7) FMLP/cytochalasin B for one to five hours. PMN adhesion to mesothelial cells was determined with radiolabeled PMNs. Mesothelial cell injury was determined in five different cell lines by measuring ATP depletion and 51chromium release. In each mesothelial cell line, PMN adhesion was significantly (P < 0.001) increased when PMNs were activated; 64 +/- 1.0 to 92.5 +/- 7.0% of the activated PMNs were adherent to mesothelial cells compared to 6 +/- 1.8 to 27 +/- 2.4% of resting PMNs. Mesothelial cells responded to PMN mediated injury with a fall in ATP levels and 51chromium release that was significant (P < 0.05) by three to four hours. At five hours, ATP levels were markedly depressed to 5 to 41% of control values. Increasing concentrations of activated PMNs caused significantly (P < 0.05) greater mesothelial cell injury as determined by ATP depletion and 51chromium release. PMN adhesion, ATP depletion and 51chromium release were significantly (P < 0.01) prevented by an anti-CD18 monoclonal antibody that inhibits the CD11/CD18 adhesion molecule complex on PMNs. Similar injury and protection from injury was demonstrated when mesothelial cells were exposed to PMNs activated with FMLP/cytochalasin B.(ABSTRACT TRUNCATED AT 250 WORDS)

Risks of peritoneal membrane failure in children undergoing long-term peritoneal dialysis

Children undergoing long-term peritoneal dialysis are at risk for membrane injury, necessitating conversion to hemodialysis. We analyzed the incidence and risk factors for membrane failure (inadequate ultrafiltration with or without peritoneal adhesions and decreased peritoneal surface area) in 68 children maintained with peritoneal dialysis for more than 3 months at our institution. The overall incidence of membrane failure was 16.2% (11/68). Kaplan-Meier estimates of peritoneal membrane survival were 88% at 24 months, 72% at 36 months, 65% at 48 months, and 52% at 60 months. Logistic regression analysis demonstrated that the risk of membrane failure increased with the number of episodes of peritonitis (odds ratio 1.61). The rate of peritonitis was 1 per 7.02 patient months in children who developed membrane failure compared with 1 per 9.18 patient months in children without membrane failures but the rate of peritonitis was not predictive of membrane failure (P = 0.09). Multiple logistic regression analysis demonstrated that peritonitis caused by Pseudomonas aeruginosa or alpha streptococcal organisms were independent predictors of membrane failure. We conclude that peritoneal membrane survival declines substantially with time on peritoneal dialysis and that membrane failure is associated with peritonitis, particularly peritonitis caused by Pseudomonas aeruginosa and alpha streptococcal organisms. The mechanism(s) of membrane injury are unknown but may be related to the inflammatory response initiated during peritonitis.

Nitrogen losses and cephalothin absorption in peritonitis treated by hourly peritoneal dialysis

The effects of peritonitis on dialysate nitrogen losses were investigated. Eight patients who developed peritonitis while undergoing peritoneal dialysis were compared to seven noninfected dialysis patients. Dialysate protein losses increased during peritonitis, but nitrogen losses into the dialysate did not increase. These findings were caused by reduced urea nitrogen losses in the peritonitis group, which proportionately, more than made up for the increased nitrogen losses from protein. We speculate that the smaller loss of urea nitrogen was due to diminished intake of food. Cephalothin uptake from the peritoneal cavity was unaltered by peritonitis and a dialysate flow rate of 2 L/hour averaged 26 +/- 2 mL/minute and 27 +/- 2 mL/minute in the noninfected and infected groups, respectively.

Neutrophil function in patients on continuous ambulatory peritoneal dialysis

Frequent and recurrent episodes of peritonitis are a major cause of morbidity in patients on continuous ambulatory peritoneal dialysis (CAPD). One factor contributing to this problem may be an abnormality of neutrophil function in these patients. We have therefore quantified phagocytosis and killing by circulating and peritoneal neutrophils from patients on CAPD with and without peritonitis. Circulating neutrophils from uninfected patients showed reduced phagocytosis of both Staphylococcus epidermidis and Candida guilliermondii because of an opsonic defect in CAPD serum and because of a defect of the neutrophils themselves. In contrast, phagocytosis by circulating and peritoneal neutrophils from patients with peritonitis was normal. Intracellular killing of C. guilliermondii was normal in all groups of neutrophils but killing of S. epidermidis, the organism most commonly isolated in CAPD peritonitis, was reduced. The possible mechanisms for the enhanced neutrophil activity seen in peritonitis, and for the decreased killing of S. epidermidis in contrast to normal killing of C. guilliermondii are discussed. A defect in killing of S. epidermidis may explain why peritonitis caused by this organism can be difficult to erradicate.

Once weekly intraperitoneal therapy for gram-positive peritonitis

The pharmacokinetics and clinical outcome following a 30 mg/kg/2 L intraperitoneal (IP) dose of vancomycin, which was administered once a week for 3 weeks, was studied in ten continuous ambulatory peritoneal dialysis patients with peritonitis. Vancomycin was 91% absorbed following the first dose and rapidly achieved therapeutic serum concentrations, 19 +/- 8 mcg/mL at 1 hour and a peak of 37 +/- 8 mcg/mL at 6 hours. Vancomycin was eliminated slowly with a mean total clearance of 7 +/- 3 mL/min/70 kg and a distribution volume of 1.2 +/- 0.3 L/kg. The resultant mean serum t1/2 over the first week was 184 hours and the mean serum concentration at 168 hours was 10 +/- 4 mcg/mL. Based on the positive clinical outcome (100% cure) among patients with uncomplicated gram-positive peritonitis, the potential use of this alternative vancomycin dosing regimen is proposed.

Peritoneal lavage combined with volume therapy in porcine hemorrhagic pancreatitis. Effects on hemodynamics, microcirculation, and peritoneal morphology

Acute hemorrhagic pancreatitis was induced in 15 piglets, after which 8 of the piglets were treated with saline infusion only and 7 were treated with saline infusion and peritoneal lavage. Hemodynamic variables were measured hourly. Organ and peritoneal blood flow was determined at 0, 1, and 5 h with radioactive microspheres. Peritoneal morphology was studied at 0, 1, 3, and 5 h with light microscopy and scanning electron microscopy. According to the results, changes in cardiac output, mean blood pressure, and peritoneal blood flow and the peritoneal inflammatory reaction were similar in the two groups. However, a significant increase in heart rate and a significant decrease in the blood flow to the pancreas, liver, and spleen were observed in the saline group, in contrast to the lavage group. In addition, blood flow to the adrenal glands was significantly higher in the saline group after 1 h. In conclusion, peritoneal lavage prevented the increase in heart rate and the development of a significant decrease in pancreatic blood flow in experimental hemorrhagic pancreatitis. The significance of these findings remains to be further evaluated.

Alterations in the peritoneal transport of water and solutes during peritonitis in continuous ambulatory peritoneal dialysis patients

The in situ intraperitoneal volume and the mass transfer area coefficients (MTC) of urea, lactate, creatinine, glucose, kanamycin, inulin, beta 2-microglobulin, albumin and IgG were studied in eight continuous ambulatory peritoneal dialysis (CAPD) patients. All patients were studied during a 4-h dialysis dwell, first during peritonitis and subsequently after recovery from the infection. The maximal intraperitoneal volume was reached at 68 min during peritonitis and at 150 min in the study after recovery (P less than 0.01), suggesting increased water transport during the infection. For all investigated solutes MTCs were higher in the presence of peritonitis than after recovery. This increase was most marked for the proteins (greater than 100%). The power curve relationships between MTCs and molecular weight indicated that peritoneal transport of the low- and middle-molecular weight solutes was determined by free diffusion and that the infection-induced rise was due to an increase in effective surface area. For protein transport restricted diffusion was found. The increase of this transport during peritonitis was probably caused by both a larger effective surface area and a higher vascular permeability.

Protein losses and tobramycin absorption in peritonitis treated by hourly peritoneal dialysis

The effects of peritonitis on dialysate protein losses of IgG, IgA, IgM, transferrin, and complement were investigated. Thirteen patients who developed peritonitis while undergoing peritoneal dialysis were compared with seven noninfected dialysis patients. Dialysate protein losses increased during peritonitis, but IgG, IgA, IgM, transferrin, and complement losses did not. The ratio of the amount of these proteins to the total amount of protein, measured by trichloroacetic acid precipitation, was unaltered by peritonitis, suggesting that albumin is the predominant protein lost during peritonitis. The infected patients absorbed 55% of the administered dose of tobramycin, at 17 mL/min, and the noninfected 44%, at 13 mL/min.

Prostaglandin-mediated loss of proteins during peritonitis in continuous ambulatory peritoneal dialysis

The loss of proteins into the dialysate and the peritoneal generation of the immunoreactive prostanoids PGE2, 6-keto-PGF1 alpha, PGF2 alpha, and TXB2 were studied in 12 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) during 16 episodes of peritonitis and in inflammation-free periods. Protein permeability, defined as the ratio of dialysate/plasma protein (D/P), decreased with increasing molecular weight, independent of the condition of the peritoneum. With peritonitis a general rise of permeability was noticed for total protein (TP) and the individual proteins beta 2-microglobulin (beta MG), albumin (Alb), immunoglobulin G (IgG), and alpha 2-macroglobulin (alpha MG) (P less than 0.001). Simultaneously, an increase of dialysate prostanoids occurred with predominance of the vasodilative acting prostaglandins PGI2, determined as its metabolite 6-keto-PGF1 alpha, and PGE2 by factors of 8.4 and 9.7, respectively (P less than 0.001), in comparison to peritonitis-free control. In the early phase of peritonitis (0 to 12 hr after the onset of therapy) the augumented peritoneal prostaglandin synthesis correlated positively with the increased permeability of TP (r greater than or equal to 0.7446, P less than 0.01) and the individual proteins beta MG, Alb, IgG, and alpha MG (r greater than or equal to 0.5970, P less than 0.05). Inhibition of cyclo-oxigenase activity by local administration of indomethacin inhibited both the generation of 6-keto-PGF1 alpha and PGE2 by 39 and 42%, respectively (P less than 0.05), and the peritoneal loss of TP by 34% (P less than 0.05). In the absence of peritonitis indomethacin only diminished the synthesis of PGE2 whereas the generation of the other prostanoids remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hemodialysis and peritoneal dialysis on aztreonam pharmacokinetics

Aztreonam, a new monobactam, will be widely used because of its broad aerobic gram-negative bacterial coverage and its apparent low risk of allergic phenomena in penicillin/cephalosporin-sensitive patients. We examined aztreonam kinetics in patients during hemodialysis and in the interdialytic period and in patients on continuous ambulatory peritoneal dialysis (CAPD), and related aztreonam to urea clearance (CL). In hemodialysis patients, aztreonam serum half-life was 7.9 hr between and 2.7 hr during dialysis sessions. CLserum, CLrenal, and CLother were 24.4, 0.5, and 23.9 ml/min, respectively, during the interdialytic period. Four hours of dialysis removed 38.2% (range, 27 to 58%) of antibiotic. CL of aztreonam by hemodialysis was 36.6 to 43.2 ml/min, 50 to 77% greater than interdialytic CL. CL of urea by hemodialysis was 112.4 to 115.6 ml/min; CLaztreonam/CLurea ratio was 0.28 to 0.33 during the hemodialysis sessions. During CAPD, aztreonam serum half-life after intravenous dosing was 7.1 hr; dialysate recovery, 9.7% of the dose; CLserum, CLrenal, CLperitoneal dialysis, and CLother were 23.8, 0.5, 2.1, and 21.3 ml/min, respectively. CLurea by CAPD was 6.5 ml/min. Thus, CLaztreonam during CAPD was 32% of CLurea. Aztreonam was detectable in dialysate at 48 hr (eight exchanges) after peritoneal administration in the first exchange. Hemodialysis and CAPD patients given aztreonam treatment should receive the standard dose of aztreonam as a loading dose, followed by one-fourth the loading dose at standard dose intervals. Hemodialysis patients should receive a supplemental dose equal to half their usual maintenance dose immediately after each dialysis session. For CAPD patients with peritonitis due to susceptible organisms, a 1-g i.v. loading dose followed by a 0.5-g i.p. dose every 6 hr is suggested. In any individual patient undergoing hemodialysis or CAPD, the relationship between CLurea and CLaztreonam should allow appropriate antibiotic dose adjustment.

Stimulation of peritoneal synthesis of vasoactive prostaglandins during peritonitis in patients on continuous ambulatory peritoneal dialysis

The peritoneal generation of arachidonic acid metabolites was studied in eight patients with end-stage renal disease undergoing continuous ambulatory peritoneal dialysis (CAPD) during infection-free periods and during bacterial peritonitis. The prostacyclin metabolite 6-keto-PGF1 alpha was found to be the major prostanoid generated by human peritoneal mesothelium (1090 ng (6h)-1, SEM 86, n = 8) followed by lesser amounts of PGE2 (142 ng (6 h)-1, SEM 26, n = 8), PGF2 alpha (162 ng (6 h)-1, SEM 27, n = 8) and TXB2 (59 ng (6 h)-1, SEM 5, n = 8). During peritonitis a significant increase of all prostaglandins and TXB2 occurred (P less than 0.001). The ratio of the vasodilating prostaglandins and their metabolites (PGE2 and 6-keto-PGF1 alpha) to the vasoconstrictors and their metabolites (PGF2 alpha and TXB2) increased from 6.6 to 10.5 during peritoneal inflammation. Augmented peritoneal clearances of creatinin and urea and increased losses of proteins during peritonitis as well as the enhanced peritoneal generation of prostanoids were reduced to basal values by adequate antibiotic therapy. The present results suggest that the increased peritoneal blood flow during peritonitis, probably responsible for the observed changes of peritoneal transport properties, may be induced by a change in the ratio of vasoactive prostaglandins generated by peritoneal mesothelial cells.

Evaluation of a peritoneal dialysis solution containing polymer

Glucose is used in peritoneal dialysate to produce the gradient for ultrafiltration. The peritoneal membrane's low reflection coefficient for glucose imposes a demand for high transmembrane concentrations, perhaps adding unwanted body burden of glucose. A polymer with a lower permeation rate used as an osmotic agent would circumvent this. We evaluated the mass transfer coefficient (mtc), T1/2 disappearance from the peritoneal cavity and ultrafiltration capabilities of a 900 dalton (Mn) starch derived polymer. We compared an 8% (455 mOsm/L) and a 10% (484 mOsm/L) polymer (Pol) solution to available dialysate solutions containing 2.5% (399 mOsm/L) and 4.25% (491 mOsm/L) X glucose (Glc). The dialysate compositions were otherwise similar. Using a randomized complete block design, 5 anephric dogs maintained on chronic peritoneal dialysis were studied. The mtc (ml/min) was greater for the glucose than the polymer solutions (p less than 0.05): 2.5%-13 and 4.25%-14 vs 8%-5 and 10%-6. The T1/2 disappearance (min) was also greater (p less than 0.05): 2.5% Glc-112 and 4.25% Glc-111 vs 8% Pol-281 and 10% Pol-252. Over a 180 min. period the 2.5% glucose solution generated the least volume of ultrafiltrate (ml, p less than 0.05): 2.5% Glc-113 and 4.25% Glc-589 vs 8% Pol-640; 10% Pol-912. We conclude that the lower permeation rate of the polymer yields ultrafiltration at a lower dialysate osmolality. A polymer solution may be a feasible alternative to glucose.

Dialysate flow rate and peritoneal clearance

We evaluated the influence of dialysate flow rates upon peritoneal clearance of urea, creatine, protein losses into dialysate, glucose disappearance from dialysate, sodium removal from the patient during dialysis, and ultrafiltration rate in 64 patients undergoing intermittent peritoneal dialysis. We evaluated three dialysate flow rates: 2 L/h, 3 L/h, and 4 L/h. All dialysate contained 1.5% glucose. The clearance of urea in milliliters per minute (2-L series 14.0, 3-L series 15.1, 4-L series 17.6) and creatinine in milliliters per minute (2-L series 9.3, 3-L series 10.6, 4-L series 11.6) determined at a dialysate flow rate of 4 L/h was significantly greater than the clearances determined at 3 and 2 L/h of dialysate flow (P less than 0.05). The clearance of glucose from the peritoneal cavity in milliliters per minute (2-L series 6.9, 3-L series 7.9, 4-L series 8.9) was significantly greater for the 4-L series as compared with the 2-L series (P less than 0.05). There were no other significant differences. Neither sex, race, previous episodes of peritonitis, nor etiology of renal failure influenced the results. Given the high cost of dialysate, we recommend dialysate flows of 2 L/h if a patient has a residual renal clearance of 2.5 mL/min. Although increasing dialysate flow rate may compensate for renal clearances significantly less than this, we believe the patient should be offered hemodialysis, continuous cyclic peritoneal dialysis (CCPD), or continuous ambulatory peritoneal dialysis (CAPD).

Bacterial growth and killing in chronic ambulatory peritoneal dialysis fluids

We determined the ability of Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli to survive and grow in peritoneal dialysis fluids from patients undergoing chronic ambulatory peritoneal dialysis. Staphylococci did not survive in commercially available dialysis solutions but grew readily in peritoneal effluents obtained from patients after the dialysis dwell time. The number of CFU doubled 6 and 13 times in 24 h for S. epidermidis and S. aureus, respectively. E. coli grew well in both the pre- and postdialysis peritoneal fluid. Peritoneal macrophages as well as peripheral blood leukocytes inhibited bacterial growth in peritoneal dialysis fluid. However, 10(6) phagocytes per ml were minimally required to obtain a bacteriostatic effect. The addition of serum to peritoneal dialysis fluid increased the antibacterial activity of macrophages and blood leukocytes. The capacity of the aminoglycoside antibiotic tobramycin to reduce bacterial CFU in peritoneal dialysis fluid was only 10% of its bactericidal capacity in standard Mueller-Hinton brush. Peritoneal dialysis fluid had no effect on the antibacterial activity of imipenem.

Protein loss induced by complement activation during peritoneal dialysis

A variable loss of macromolecules during peritoneal dialysis has been noted in both humans and experimental animals. We investigated the potential role of the complement system for inducing protein loss during peritoneal dialysis, both to shed light on clinical variability of protein loss and to develop a model for quantitatively studying complement-induced microvascular protein leakage. Rats received intra-arterial injections of a fluorescent dye conjugated to rat serum albumin and underwent a 3.5-hr series of 15-min peritoneal dialysis exchanges. After the control exchanges, rats received either intra-arterial zymosan-activated rat serum, saline, unactivated rat serum, or endotoxin; other rats received an intraperitoneal injection of endotoxin, histamine, phenylephrine, or nitroprusside. The drainage volume from each exchange was measured, and the concentrations of labeled albumin, total protein, and urea were determined by spectroscopy. Zymosan-activated rat serum and endotoxin injections (both intraperitoneal and intra-arterial), each of which may activate the alternative pathway of complement, produced a dramatic increase in dialysate protein concentrations. In addition, histamine, which is a vasodilator but which may also be involved as a mediator of the activated complement system and/or endotoxemia, also produced an increase in dialysate protein concentrations. On the other hand, drugs which may alter peritoneal blood flow such as the vasodilator nitroprusside or the vasoconstrictor phenylephrine, did not affect dialysate protein concentrations. These data suggest that activation of the alternative pathway of complement may cause variation in protein loss during peritoneal dialysis and that in some situations, pharmacological control of this system could be an important therapeutic consideration.

Evaluation of continuous ambulatory peritoneal dialysis

This study was undertaken to ascertain whether 19 patients maintained on continuous ambulatory peritoneal dialysis (CAPD) for at least 1 year experienced any deterioration in peritoneal membrane function. Selected serum chemistries and skinfold measurements were also evaluated to determine whether patients dialyzed by CAPD could maintain a normal nutritional status. This study demonstrates that patients maintained on CAPD had stable dialysate protein losses, glucose absorption from the dialysate, and constant urea, creatinine, and sodium removal. When these patients were subdivided by incidence of peritonitis, the group with a lower incidence of peritonitis (one episode every 349 +/- 155 SEM days) showed stable serum protein concentration and improvement in upper arm area whereas the group with a high incidence of peritonitis (one episode every 95 +/- 7 SEM days) showed a reduction in upper arm muscle area. Thus, our data suggest that over a 1-year period, there is no deterioration in peritoneal membrane characteristics and CAPD is effective in maintaining the nutritional status of the patient. However, both membrane function and nutritional status may be impaired by frequent episodes of infection.

Augmentation of peritoneal clearance by dipyridamole

We performed a double blind crossover trial in which dipyridamole was administered to ten patients undergoing intermittent peritoneal dialysis at 2 liters/hour (10 min infusion, 30 min intraperitoneal dwell of dialysate and 20 min drainage of dialysate). After the patients received the drug for 3 days at a dose of 75 mg three times daily, peritoneal inulin clearance increased by 1.2 ml/min (P less than 0.05), and glucose absorption increased by 12.1 g (P less than 0.05). The mechanism of the observed drug-induced effects is unknown.