Download Potential risk factors for hernia formation

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
 Hematogenous
 Transvaginal

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 states and/or
instrumentation of the colon and may
be seen also with strangulated 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 Grampositive 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 50100/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 ceftazidime
1 g cefazolin
1,000 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

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

Persistently positive nasal cultures are
associated with a 3-4 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 (singlestrength 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 volume and the position of the
patient during the dwell

The supine position is associated with the
lowest IAP for a given dialysate volume;
sitting 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 patientsVentral
Epigastric
Pericatheter
Umbilical
Inguinal (direct and indirect)
Femoral
Spigelian
Richter
Foramen of Morgagni
Cystocele
Enterocele

Pericatheter hernias need to be
differentiated from masses caused by a
hematoma, seroma, or abscess
Ultrasonography
 CTscan
 MRI

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 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, in
which case hydrothorax can occur with the
first dialysis exchange, or acquired,
whereby hydrothorax can be a late
complication

They occur almost exclusively on the right
side, probably because the left
hemidiaphragm is mostly covered by heart
and pericardium

Symptoms of hydrothorax range from
asymptomatic pleural effusion to severe
shortness of breath

Such symptoms may worsen with
administration of hypertonic 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 level,
although this is not always a consistent
finding
transudative

It is typically transudate, with variable
numbers of leukocytes

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
exchanges with smaller dialysate
volumes

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, the
glucose loading from PD may contribute to
further weight gain

glucose absorption results in increased
insulin 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 therapy after the
initiation of PD

To minimize glucose absorption, patients
should be advised on appropriate salt
and 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