IN THE NAME OF GOD

F.SAMADIAN NEPHROLOGIST

Peritonitis and Exit Site Infection

the introduction of Y-set and double-bag disconnect systems has reduced this to approximately one episode per patient every 24 months

Potential routes of infection: Intraluminal Periluminal Transmural HematogenousTransvaginal

Intraluminal:

This allows bacteria to gain access to the peritoneal cavity via the catheter lumen

Periluminal:

Bacteria present on the skin surface can enter the peritoneal cavity via the peritoneal catheter tract

Transmural: Bacteria of intestinal origin can enter the

peritoneal cavity by migrating through the bowel wall

This is the usual mechanism of peritonitis associated with diarrheal statesdiarrheal states and/or instrumentation of the coloninstrumentation of the colon and may be seen also with strangulated herniastrangulated hernia

Hematogenous:

Less commonly, peritonitis is due to bacteria that have seeded the peritoneum from a distant site by way of the bloodstream

Transvaginal:

it may explain some instances of Candida peritonitis

The responsible pathogen is almost always a bacterium, usually of the Gram-positive variety

The occurrence of fungal peritonitis (e.g., Candida) is uncommon

Infections with Mycobacterium tuberculosis or other type of mycobacteria have been reported but are unusual

Diagnostic criteria for peritonitis: At least two of the following three conditions

should be present: symptoms and signs of peritoneal inflammation cloudy peritoneal fluid with an elevated

peritoneal fluid cell count (more than 100/mcL) due predominantly (more than 50%) to neutrophils

demonstration of bacteria in the peritoneal effluent by Gram stain or culture

Symptoms and signs:

The most common symptom of peritonitis is abdominal pain

However, peritonitis should be suspected whenever a patient suffers from generalized malaise, particularly if nausea, vomiting, or diarrhea is also present

Not all abdominal pain in a patient receiving PD is peritonitis

Strangulated hernia is a common mimic for peritonitis

Cloudiness of the fluid:

The peritoneal fluid generally becomes cloudy when the cell count exceeds 50-100/mcL

In most patients, sudden onset of cloudy fluid with appropriate abdominal symptoms is sufficient evidence of peritonitis to warrant initiation of antimicrobial therapy

However, peritoneal fluid cloudiness may be due to other factors (e.g., fibrin, blood, or, rarely, malignancy or chyle)

On the other hand, a relatively translucent peritoneal fluid does not completely exclude the possibility that peritonitis is present (early in the course of peritonitis)

The absolute peritoneal fluid cell count in CAPD patients is usually <50 cells/mcL and is often <10 cells/mcL

Normally, the peritoneal fluid contains predominantly mononuclear cells (macrophages, monocytes, and, to a lesser extent, lymphocytes)

The percentage of neutrophils does not normally exceed 15% of the total nonerythrocyte cell count and a value >50% strongly suggests peritonitis, whereas one >35% should raise suspicion

Vancomycin or a first-generation cephalosporin such as cefazolin or cephalothin is used in combination with an antibiotic to cover Gram-negative organisms such as ceftazidime

It is now recommended that aminoglycosides be avoided if possible in patients with residual renal function because of their nephrotoxicity

CAPD Loading dose: Infuse 2 L of 1.5% dextrose

dialysis solution containing:1 g ceftazidime1 g cefazolin1,000 units/L heparin  Allow to dwell for 3-4 hours.

Continue regular CAPD schedule. Add 125 mg per L ceftazidime, 125 mg/L cefazolin, and 1,000 units/L heparin to each dialysis solution bag

If a patient appears toxic recommend a single loading dose IV

Duration of therapy: If patient improvement is prompt,

antimicrobial therapy should be continued for a total of 14 days

If a cephalosporin is being used, then some physicians will switch to PO therapy after the first 5 days

Severe S. aureus infections require antimicrobials for 3 weeks, and treatment with one IP antistaphylococcal drug plus PO rifampin is recommended

Patients in whom S. aureus peritonitis develops not uncommonly are found to carry this organism in the nose nose

This can be accomplished with intranasal mupirocin (b.i.d. for 5 days every 4 weeks) or oral rifampin (300 mg b.i.d. for 5 days every 3 months

Exit site infection

Approximately one fifth of peritonitis episodes are temporally associated with exit site and tunnel infections

Etiology and pathogenesis: Exit site infections are predominantly due to S.

aureus or Gram-negative organisms, particularly Pseudomona

In contrast to peritonitis, S. epidermidis is the causative organism in <20% of patients

eradication of the carrier state is very helpful to effective management

Treatment is dependent on whether there is erythema alone or erythema in conjunction with purulent drainage

In the former case, topical treatment with hypertonic saline compresses, hydrogen peroxide, or mupirocin 2% ointment is usually sufficient

Treatment is more problematic and more prone to failure when there is purulent drainage

some exit site infections extend into the subcutaneous tunnel

The major risk factor for exit site infection is staphylococcal nasal carriage nasal carriage

Persistently positive nasalpositive nasal cultures are associated with a 3-4 fold3-4 fold increase in risk of staphylococcal exit site infection

Protocols used include

-rifampin (600 mg PO for 5 days),

-mupirocin (2% ointment twice daily for 5 days every 4 weeks)

-trimethoprim-sulfamethoxazole (single-strength tablet three times weekly)

Mechanical Complications of Peritoneal Dialysis

The instillation of dialysis fluid into the peritoneal cavity is accompanied by an increase in intra-abdominal pressure (IAP)

The two principal determinants of the magnitude of the increased IAP are dialysate volumevolume and the positionposition of the patient during the dwell

The supine supine position is associated with the lowest IAP for a given dialysate volume; sittingsitting entails the highest

Hernia formation

as many as 10%-20% of patients may develop a hernia at some time on peritoneal dialysis

Potential risk factors for hernia formation -Large dialysis solution volume -Sitting position -Isometric exercise -Valsalva maneuver (e.g., coughing) -Recent abdominal surgery -Pericatheter leak or hematoma -Obesity -Multiparity -Congenital anatomical defects

Many different types of hernias have been described in the peritoneal dialysis patient

Types of hernias reported in peritoneal dialysis patientsVentralEpigastricPericatheterUmbilicalInguinal (direct and indirect)FemoralSpigelianRichterForamen of MorgagniCystoceleEnterocele

Pericatheter hernias need to be differentiated from masses caused by a hematoma, seroma, or abscess

Ultrasonography Ultrasonography CTscan CTscan MRIMRI

Small hernias pose the greatest risk of incarceration or strangulation of bowel

Abdominal wall and pericatheter leak

Abdominal wall leak may be difficult to diagnose clinically

It may be mistaken for ultrafiltration failure when dialysate returns are less than the instilled volume

The diagnosis should be considered with:

-decreased effluent volumes

-weight gain

-protuberant abdomen

-absence of generalized edema

The patient should stand during the examination as this may reveal asymmetry of the abdomen

Diagnosis can be proven using contrast CT scanning

Pericatheter leak usually occurs as a postoperative complication of catheter implantation

In most cases, the leak seals spontaneously

If it persists, the catheter should be removed and reinserted at another site

In contrast to pericatheter leaks, abdominal wall leaks can occur early or late

Sometimes surgical repair is feasible

Vaginal leaks can also occur

Some may result from tracking of dialysate through the fallopian tubes and may resolve with tubal ligationtubal ligation

Genital edema:

Dialysate can reach the genitalia by two routes

One is by traveling through a patent processus vaginalis to the tunica vaginalis, resulting in hydrocele

The second route is through a defect in the abdominal wall, often associated with the catheter

This complication is often painful and distressing to the patient who is quick to bring it to medical attention

CT peritoneography should be performed to distinguish which route has led to the genital swelling (i.e., anterior abdominal wall or processus vaginalis)

Peritoneal dialysis should be temporarily stopped

Bed rest and scrotal elevation are helpful

A leak via a patent processus vaginalis can be repaired surgically

If the leak is through the anterior abdominal wall, replacement of the catheter can be helpful

Respiratory complications:

Hydrothorax

Under the influence of raised IAP, dialysate can travel from the peritoneal to the pleural cavity, leading to a pleural effusion composed of dialysis effluent

These defects may be congenital,congenital, in which case hydrothorax can occur with the first dialysis exchange, or acquiredacquired, whereby hydrothorax can be a late complication

They occur almost exclusively on the right right sideside, probably because the left hemidiaphragm is mostly covered by heart and pericardium

Symptoms of hydrothorax range from asymptomaticasymptomatic pleural effusion to severe severe shortness of breath shortness of breath

Such symptoms may worsen with administration of hypertonic dialysatehypertonic dialysate, which raises IAP

Thoracentesis can be done for diagnosis or to relieve symptoms

The most diagnostic feature of the pleural fluid is the very high glucose levelvery high glucose level, although this is not always a consistent finding

It is typically transudatetransudate, with variable numbers of leukocytes

transudative

Radionuclide scanning with technetium is also helpful

Back pain:

The presence of dialysate in the peritoneal cavity both raises IAP and swings the center of gravity forward, producing lordotic stress on the lumbar vertebrae and paraspinal muscles

Some patients benefit from the performance of more frequent frequent exchanges with smaller dialysate exchanges with smaller dialysate volumesvolumes

Metabolic Complications of Peritoneal Dialysis

Glucose absorption

Glucose has the advantage of being cheap, stable, and relatively nontoxic to the peritoneum

up to 100g per day of glucose may be absorbed, which represents 500-800 kcal per day

This constitutes a significant portion of the recommended total energy intake of about 2,500 kcal per day (35 kcal/kg per day) in a 70-kg patient

In some patients, this provides a welcome source of calories since achieving the nutritional recommendation for PD is often difficult

In patients who start PD obese obese, the glucose loading from PD may contribute to further weight gain

glucose absorption results in increased insulin secretioninsulin secretion, which together with insulin resistance (a common feature of chronic renal failure) results in plasma insulin levels that are persistently high

Hyperinsulinemia may be an independent risk factor for the development of atherosclerosis

Patients who were previously well controlled on oral hypoglycemics often require increased doses of these medications, and they may even require a change to insulin therapyinsulin therapy after the initiation of PD

To minimize glucose absorption, patients should be advised on appropriate salt appropriate salt and water managementand water management, which will diminish the need for hypertonic solutions to maintain fluid balance

Lipid abnormalities

patients on PD have a variety of lipid abnormalities

Typically, they have high total and LDL cholesterol, high triglycerides, low HDL cholesterol, high apoB, low apoA-I, and high lipoprotein(a) levels

Compared with hemodialysis patients, the most striking differences are the high apoB protein and LDL cholesterol levels, which are usually normal in hemodialysis patients

Protein loss:

PD is associated with significant loss of protein across the peritoneum

This loss is about 0.5 g/L of dialysate drainage, but may be higher and account for as much as 10-20 g per day

The major component of the protein losses is albumin

Acute peritoneal inflammation is associated with substantially greater protein losses, and a rapid reduction in serum albumin is common during episodes of peritonitis

The protein loss itself may become an indication to terminate peritoneal dialysis temporarily or, on occasion, permanently

Hypokalemia/hyperkalemiakm: PD solution contains no potassium Usually only patients who are

noncompliant in performing their dialysis exchanges or who have excessive potassium intake have ongoing problems with hyperkalemia

However, hypokalemia has been reported in 10%-30% of CAPD patients

These cases are usually associated with poor nutritional intake, and most can be managed by liberalizing the diet

Dialysis solution calcium level

PD solutions are available with 2.5 mEq/L or 3.5 mEq/L calcium concentrations

The 3.5 mEq/L dialysis solution keeps the patient in positive calcium balance

The standard solution is now considered to be the 1.25 mM (2.5 mEq/L) calcium solution

Hypocalcemia is not common in patients on PD because of the widespread use of calcium-based phosphate binders and vitamin D