Deficiencies in bladder
storage capacity have considerable clinical relevance because they
significantly affect life quality and may evolve to renal failure, thus
posing
a serious health threat (BRANDT et al., 2004).
The bladder is exposed to
a variety of injuries, even during fetal development. In addition to
congenital
abnormalities, other disorders such as cancer, trauma, infection,
inflammation
and iatrogenic injuries eventually require bladder replacement or
repair
(SHOKEIR, 2002).
The most frequent causes
for performing bladder reconstruction are neoplasms of the lower
urinary tract
– mainly carcinomas – especially in humans and dogs, vesical atony,
interstitial cystitis, radiotherapy, chemotherapy, multiple bladder
surgeries
and some congenital bladder anomalies that cause incontinence. Bladder
repair
surgeries in dogs are recommended in cases of severe traumas, neoplasms
and
recurring interstitial cystitis (GREENWELL et al., 2001; PEREIRA et
al., 2002; KOUSHYAR
et al., 2007). Repair procedures seek to establish a low-pressure
reservoir
with capacity for continence, spontaneous micturition and minimum
post-micturition residue (CRANDIS et al., 1998).
Bladder reconstruction is
therefore crucial to correct disorders caused by low contention
capacity and
high pressure. Such disorders may be corrected by bladder augmentation
by
cystoplasty, which replaces part of the bladder after partial
cystectomy
(LAMESCH & DOCIU, 1983; PIECHOTA et al., 1998).
The limited amount of
urothelium available for genitourinary reconstructive surgeries has
increased
interest in the development of tissues for bladder replacement. The
gastrointestinal tract has proved to be an effective support for
bladder
reconstruction and it is available in the majority of patients
(MERGUERIAN,
2000).
Bladder augmentation
using
an ileal segment as a surgical treatment for dogs was first described
by
Tizzoni and Foggi in 1888; they anastomosed part of the ileum to the
vesical
trigone following cystectomy. The first bladder augmentation in humans
was
performed by von Mikulicz in 1889. Since then, several techniques have
been
developed to improve bladder functionality as well as to reduce
morbidity and
common complications (LAMESCH & DOCIU, 1983; GREENWELL et al.,
2001;
PEREIRA et al., 2002; TANAKA & MENDES JÚNIOR, 2007).
Improvement of
surgical techniques has resulted in acceptable life quality and longer
life for
patients (TEIXEIRA et al., 2007).
It is of crucial
importance to observe calculi and crystal formation within the urinary
tract
related to suture material, as well as to learn about its possible
causes and
prevention. Persistent crystalluria may result in crystal aggregation;
if not
excreted, crystals may lead to urolith formation, thus causing urinary
tract
injuries and predisposing to inflammations, infections, severe
obstructive
processes, bladder rupture, renal dysfunctions and death (GRAUER, 1994;
LANGSTON et al., 2008).
The use of titanium
staples on sutures during ileocystoplasties has been a source of
investigation
to several research groups, mainly because of the controversial use of
non-absorbable materials in the urinary tract. Most studies that have
related
non-absorbable staples within the urinary tract to greater urolith
formation
have analyzed staples made of stainless steel or tantalum, not
titanium. However, more recent
studies describing the use of titanium staples have shown that they are
well
tolerated by the urinary tract and that other factors may be the main
cause of
urolith formation, such as urinary stasis, bacteriuria and mucus
production.
Therefore, the use of titanium staples as a wound closure material for
the
urinary tract has aroused the interest of researchers of experimental
surgery,
human urology and veterinary medicine, standing as a possible
alternative for
bladder augmentation (JULIAN & RAVITCH, 1986; BOOTHE, 1998;
ABREU
et al.,
2005).
Further research
regarding
possible changes and benefits of titanium staples used within the
urinary tract
may provide useful information for the development of surgery
techniques, as
well as shed light on the behavior of these staples in the urinary
system.
Among these benefits is the reduction of surgical times in view of the
practicality of staples, especially for high-risk patients (JULIAN
&
RAVITCH, 1986; DALL’OGLIO et al., 2000; ABREU et al., 2005).
The purpose of this study was to determine
whether there are differences in the formation of uroliths and urinary
crystalloid after ileocystoplasty in dogs, conducted by means of
sutures with
nonabsorbable titanium staples and suture with polyglactin 910, noting
the
impact of the procedure on renal function, changes in urinary
constituents and
the time difference between surgical groups.
MATERIAL
AND METHODS
This study was assessed
and approved by the Ethics Committee of Universidade Federal de Goiás
(register
07/2008).
Twelve clinically healthy
male dogs, of undefined breed, weighing between 10 and
20 kg,
were used in
the
experiment. Prior to their random distribution in two groups of six
(groups A
and B), the animals were submitted to clinical and laboriatorial
examination
via general clinical exam, complete blood count, serum urea and
creatinine and
urinalysis. The presence of crystals in the urine exam was an exclusion
factor
in the selection of experimental units. All animals were acclimated for
approximately
20 days prior to surgical procedure.
The animals were
anesthetized and positioned in dorsal recumbency, then prepared for
surgery via
antisepsis of the surgical field. Access into the abdominal cavity was
performed by median retro-umbilical laparotomy. After locating the
bladder and
the terminal ileum at aproximately
20 cm
from the
ileocecal valve. Intestinal
content was moved away and about
10 cm
of the ileum was isolated to
interrupt intestinal
transit. Afterwards about
5 cm
of this segment was sectioned and the vascularization area of the
isolated
portion was preserved (
Figure
1A).
Intestinal continuity was
restored by termino-terminal anastomosis using simple interrupted
suture with
3-0 polyglactin 910 (Poly Suture Indústria e Comércio Ltda., São
Sebastião do
Paraíso - MG). The mesenteric opening was closed with simple separate
stitches
using the same material.
In group A,
ileocystoplasty was performed using 3-0 polyglactin 910 with continuous
Cushing
suture. After isolating the ileum portion, an incision of approximately
6 cm
transected the apex of
the bladder up to the lumen. The antimesenteric border of the isolated
portion
was sectioned, thus exposing the loop mucosa. The ileal segment was
sutured to
the bladder and the mucosa surface of the graft faced the bladder lumen
(
Figure
1B).
In group B, ileocystoplasty involved the use of
an Ethicon Proximate ® 55 linear cutter stapler (Ethicon Endo-Surgery,
Cincinnati - Ohio) containing a reload of Proximate® titanium staples
(Ethicon
Endo-Surgery, Cincinnati - Ohio). Staples measured 3,0mm/3,85mm prior
to
stapling and 1,5mm of closed height; the staple line measured 55 mm.
After isolating the ileum terminal segment, two
incisions were made on both sides of the bladder vertex up to the
lumen. One of
the anvils of the linear cutter stapler was inserted into the incisions
and
transected the apex of the bladder (
Figure
1C).
Another anvil crossed
the lumen
through the isolated ileal segment and joined it with the apex. The
ileum was
anastomosed to the bladder by the antimesenteric border. Care was taken
not to
twist or to staple the vascular pedicle of the intestinal segment. Once
the
stapler fired, the loop was sutured to the bladder at the ventral and
dorsal
portions of the apex of the bladder. Simultaneously to stapling, the
area
between the two staple rows was sectioned, thus exposing the mucosa
from the
intestinal loop segment to the bladder lumen. Regions on both sides of
the apex
of the bladder as well as open, unstapled areas of the loop ends were
then
sutured with 3-0 polyglactin 910 according to Cushing suture (
Figure
1).
In both groups the abdominal musculature was
sutured using a 2-0 nylon thread (Shalon Fios Cirúrgicos LTDA, Goiânia
- GO) in
simple separate stitches. Subcutaneous tissue approximation was
performed by
continuous suture with 2-0 nylon thread and skin suture was performed
by
continuous mattress suture with 2-0 nylon thread.
Postoperative care included antibiotic therapy
consisting of enrofloxacin (Enrotec-50, FATEC AS, São Paulo - SP)
administered
subcutaneously (5mg/kg of live weight) twice a day for 7 days.
Analgesia
included subcutaneous administration of 2,5mg/kg of tramadol
hydrochloride
(Tramadon 50mg/ml, Cristália Produtos Químicos Ltda., Itapira - SP)
twice a
day, which started immediately before anesthesia and was maintained
during the
first three postoperative days.
At 100 days postoperatively, another surgical
intervention was performed using the same laparotomic access and
anesthetic
procedure described previously. A macroscopic investigation sought
eventual
uroliths in the bladder, focusing on the visual aspect of the sutured
area and
on macroscopic characteristics of the intestinal segment. The entire
graft area
was removed. The bladder was sutured with 3-0 polyglactin 910 according
to
Cushing suture. Abdominal wall closure and postoperative care followed
initial
procedures.
Exams included total blood count, serum
biochemistry, blood smear and urinalysis. Animals selected for the
experiment
showed crystal-free urine. Urine samples were collected via a bladder
catheter.
Physical testing of samples identified color, odor, aspect, density,
mucus and
spontaneous sediment formation. Urine was assessed in terms of chemical
elements, such as nitrites, ketone bodies, urobilinogen, bilirubin,
blood and
hemoglobin. Albumin was the most predominant protein and its
concentration was
represented by crosses: one cross (+) amounted to 150mg/dl, two crosses
(++)
amounted to 300mg/dl and three crosses (+++) amounted to 500mg/dl, as
stated by
the kit manual. Urine pH was also measured on the reagent strip.
The elements found in the sediment were classified as
organized and
unorganized. The first group was formed by cells (erythrocytes,
leukocytes,
epithelial cells, bacteria, protozoa, parasite eggs, yeast, fungi and
sperms)
and cylinders. The second group was formed by crystals, mucus and
amorphous
material. The amount of elements found within the sediment, such as
sperms,
cylinders, squamous cells, crystals, leukocytes and erythrocytes was
represented by crosses: one cross (+) corresponded to 2-4 elements per
field,
two crosses (++) corresponded to 4-6 elements per field and three
crosses (+++)
corresponded to 6 elements per field.
RESULTS AND DISCUSSION
None of the animals died during surgery or
postoperative care and none revealed clinical signs of infections,
digestive
alterations such as vomit, diarrhea, constipation or obstipation,
suture
dehiscence or intestine/bladder fistulas. Animals showed quick
postoperative
recovery and maintained spontaneous micturition on surgery day; there
was no
need to eliminate urine through bladder catheterization. Urinary
continence was
preserved in all animals, was observed soon after anesthetic recovery
and was
maintained throughout the experimental period.
After 100 days of postoperative care, the
intestinal segment and its vascular pedicle were macroscopically
distinguished
from the bladder tissue in both groups. Moreover, a few adherence areas
were
observed.
The ileal segment used in ileocystoplasties
showed peristaltic movements in all animals from both groups, according
to
direct observation during the second surgical procedure. This may have
helped
to eliminate urine due to stimulus caused by distension of the
augmented
bladder.
Hematuria affected all animals during the first three
postoperative days
(
Table 1),
probably due to
surgical trauma and not as a complication of
ileocystoplasty. Protein was verified in all urine samples and even in
urinalyses performed before ileocystoplasties, though with no evidence
of
cylinders; this may suggest that the proteinuria found had a post-renal
or
physiological origin, especially given the fact that samples were
collected by
catheterization. Postrenal proteinuria may result from bleeding
traumas,
including those caused by catheterization, especially when many red
blood cells
are present. Trauma from urine collection may also be responsible for
hematuria
and for a possible irritation caused by urine in the flap.
Hemoglobinuria was observed in two animals from
each group at 90 days postoperatively, but its reduced amount did not
signal a
significant change. A considerable amount of red blood cells was found
in the
urine of the animals tested; many red blood cells were counted per
field in
three samples and three were counted in the fourth sample.
All animals showed considerable amounts of
mucus in the urine as from the first postoperative days. This was
confirmed by
the viscous aspect of urine during the first urinalysis performed 45
days
postoperatively. However, none of the animals suffered from obstructive
processes as a result of this change; therefore, catheterization for
bladder
emptying during postoperative care was not necessary.
Serum urea and creatinine exams performed prior
to surgery and 45 and 90 days postoperatively did not show any
significant
renal changes, considering reference values of up to 1.80 mg/dl for
creatinine
and up to 54 mg/dl for urea.
Stapling the ileum to the bladder revealed lower mean
intervals than the
thread suture (Group A: mean=68.17 min, standard deviation= 17.20;
Group B:
mean=42.50 min; standard deviation=7.58); bladder suture time was
reduced in
about 25.67 minutes (
Table
2). The shortest
intervention period of
stapling
surgeries was largely due to the time reduction required for bladder
sutures.
Urine extravasation in the sutured area was
observed in animals from group A during bladder sutures, which made it
necessary to reinforce the suture at several points, thus increasing
the
intervention period in the bladder. As for the animals from group B,
urine
extravasation was not reported at any point of the stapled area.
Decreased mean surgical time in group B may
also be due to the reduced time to hemostasis during bladder
augmentations. The
stapling technique resulted in effective and immediate hemostasis after
staples
were fired, and there were no reports of bleeding points along the
stapled
area. Group A required the correction of bleeding areas at various
intervals
along the suture, which resulted in differences of up to 64 minutes in
bladder
augmentation times (
Table 2).
During the second exam performed 45 days postoperatively,
a small amount
of crystalluria was observed in three animals; the urinalysis revealed
+
crystal in one animal from group A and in two animals from group B.
During the
third exam performed 90 days postoperatively, only one animal from
group A did
not have crystalluria, whereas all the others from both groups had at
least +
crystal, as it is shown in
Table
3. As regards two animals
that showed
+++
crystals, crystalluria was verified by visual inspection of the sample
and
macroscopic visualization of crystals was possible even before urine
sedimentation.
At 100 days
postoperatively it was not possible to macroscopically visualize the
suture
material used in ileocystoplasty in group A – neither by visual
inspection nor
by sectioning – when the grafted segment was removed. Exposed staples
were not
seen in group B; however, sectioning revealed completely covered
staples along
the stapled area, with the exception of one animal in which a single
staple was
exposed to the mucosa surface or triggered a rejection process.
One of the animals from group A had a small loose bladder
calculus
measuring approximately
1
mm;
in addition, uranalysis performed 90 days postoperatively on this
animal
revealed +++ crystals; these could be seen soon after urine collection,
even
before its sedimentation. The formation of a bladder calculus measuring
approximately
4
mm
was reported within the sutured area of an animal from group B.
Following
manipulation the calculus adhered to a staple exposed to the bladder
lumen
(
Figure 2).
Surgical and postoperative conditions were
similar to those found in the literature. Deaths and other
complications did
not occur.
Peristaltic movements within the ileal segment
used in bladder augmentation may help eliminate urine due to the
stimulus
caused by distension of the augmented bladder. According to LAMESCH
& DOCIU
(1983), small intestine submucosa showed contractile activity and
innervation
similar to those of the bladder.
During the second surgical intervention, the
distensibility of the graft resembled that of the bladder tissue; this
finding
has also been reported in a study performed with dogs by MERGUERIAN
(2000).
The ileal segment selected for
ileocystoplasties, at approximately 20cm from the cecum, was easily
located and
mobilized, which favored its implant within the bladder. Its vascular
anatomy
facilitates isolation, as described by GRECA et al. (2004) and TANAKA
&
MENDES JÚNIOR (2007).
According to GARCIA-NAVARRO (1996), false
hemoglobinuria may result from the rupture of red blood cells in the
urine,
leading to hematuria. Distinguishing true hemoglobinuria – originated
from
hemoglobinemia – is possible by checking intact red blood cells in the
urinary
sediment, which was observed during our experiments.
As
regards the adaptation of intestinal mucosa – in terms of structure and
functionality – in relation to bladder mucosa, obstructions such as
mucus
production and urinary retention may occur (BARROSO JÚNIOR et al.,
2000; VILAR
et al., 2004), leading to late bladder rupture, though they do not
normally do
so (KOUSHYAR et al., 2007). In association with other factors, their
presence
may be a major source of calculi in patients submitted to bladder
augmentation
using intestinal segments, as described by NURSE et al. (1996).
According to
GOUGH (2001) the mucus produced following cystoplasty may facilitate
urinary
calcium aggregation and may act as nucleus to the formation of uroliths.
Besides the fact that mucus is not easily
eliminated, the absence of a mucous layer is not recommended because it
may
protect the intestinal epithelium from urinary carcinogenesis and other
components in the urine, all of which may be incorporated by the
intestinal
segment (NURSE et al., 1996). Preserving the submucosa layer may be
crucial to
prevent fibrosis and contraction of the grafted segment, as described
by
MERGUERIAN (2000) and GREENWELL et al. (2001). Such findings extracted
from the
literature influenced our option to preserve the mucosa and submucosa
layer of
the intestinal segment.
Reduced surgical time in the group on which
titanium staples were used may help minimize risks inherent to
prolonged
surgeries, especially in critical patients, as described by JULIAN
&
RAVITCH (1986), DALL’OGLIO et al. (2000) and ABREU et al. (2005).
Although the literature fails to report
differences related to urine extravasation and to hemostasis on sutured
areas,
comparing the wound closure materials used in this study enabled us to
observe
important findings regarding surgical times.
The presence of crystals in the first urine exam
was an exclusion factor in the selection of experimental units; this
was the
reason for the absence of crystalluria in the first exam. In both
groups of
animals the amount of crystals may have resulted from factors unrelated
to
wound closure material, because their presence was observed in almost
all
experimental units, regardless of the group; this fact has also been
highlighted by NURSE et al. (1996) and HENSLE et al. (2004).
Triple phosphate
crystals were identified in all animals with crystalluria; this is
compatible
with findings in the literature (NURSE et al., 1996; BARROSO JÚNIOR et
al.,
2000; GREENWEL et al., 2001; TANAKA & MENDES JÚNIOR, 2007).
This
signal a
predominance of this type of crystal in patients submitted to bladder
augmentation using intestinal segments. According to NURSE et al.
(1996) and
BARROSO JÚNIOR et al. (2000), crystal formation may be related to
mucus,
urinary stasis and bacteriuria, not only to the type of suture material
used. Even
though cultures for bacteria identification were not performed in the
urine of
animals, the occurrence of triple phosphate crystals in all animals
with
crystalluria may suggest that bacteria in the intestinal segment
influenced
their formation directly, despite the absence of symptoms of urinary
tract
infection, as described by NURSE et al. (1996), SEAMAN &
BARTGES
(2001) and
RINKARDT & HOUSTON (2004).
The staple seen on
the mucosa surface possibly acted as the nucleus for urolith formation,
in
addition to other factors that influenced crystal precipitation. Risk
of
lithiasis increased, as it is also suggested by other studies of TANAKA
&
MENDES JÚNIOR (2007).
Quantitative
differences were not registered in bladder calculi formation in the
experimental groups. However, the location of calculi formation may
have
suffered influence from wound closure materials, particularly from the
titanium
staple that was not covered properly, as described by DANGMAN &
LEBOWITZ
(1991). According to ABREU et al. (2007), it is possible that, had the
staple
not been exposed to the bladder mucosa, calculi might not have formed
on the
stapled area. Calculi formation may not be solely linked to the
material used,
but also to factors such as excessive mucus, which was observed in all
animals
of this study and similar studies (SEAMAN & BARTGES, 2001;
RINKARDT
&
HOUSTON, 2004). According to previous study (ABREU et al., 2005),
titanium is
well tolerated by the urinary tract because of its low toxicity,
natural
corrosion resistance and biocompatibility with fluids and tissues.
The entire ileal graft was removed during the
second surgery to prevent future complications caused by its presence
within
the bladder, as the animals were put up for adoption following the
experiment.
CONCLUSION
In short, our findings reveal that the use of
titanium staples inileocystoplasties did not show significant
differences
regarding urinarycrystal and urolith formation, when compared to the
use of
polyglactin 910after 100 postoperative days; renal parameters assessed
by
clinical exam andserum urea/creatinine were in normal reference values
in both
groups; the stapling technique reduces suturing time in
ileocystoplasties
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Protocolado
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