ORIGINAL STUDIES

Evaluation of Data From 35 Dogs Pertaining to Dehiscence Following Intestinal Resection and Anastomosis Emily E. Mouat, VMD*y, Garrett J. Davis, DVM, DACVS, Kenneth J. Drobatz, DVM, DACVIM, DACVECC, Koranda A. Wallace, VMD

ABSTRACT The objectives of this study were to evaluate blood and abdominal fluid lactate and glucose, fluid cytology, culture, and volume 24 and 48 hr following intestinal resection and anastomosis in dogs with and without closed-suction drains and to correlate findings with survival. Thirty-five client-owned dogs that underwent intestinal resection and anastomosis were prospectively enrolled in the study. Abdominal fluid was submitted for culture at surgery and again 24 hr postoperatively. Twenty-four and 48 hr postoperatively, blood and abdominal fluid glucose and lactate were measured and fluid was submitted for cytology. Abdominal fluid was collected either from a closed-suction drain or by abdominocentesis. Patients were followed either for 14 days or until death. Comparisons were made based on development of dehiscence and presence or absence of a drain. Patients with dehiscence were more likely to have positive cultures at 24 hr and to have had more bowel resected. Surviving patients without drains had significantly smaller differences in blood and fluid glucose and lactate both 24 and 48 hr postoperatively than surviving patients with drains. The significant differences identified between patients with and without drains suggests a need for further research into the effect of drains on abdominal fluid values. (J Am Anim Hosp Assoc 2014; 50:254–263. DOI 10.5326/JAAHA-MS-6111)

Introduction

During the immediate postoperative period, when patients

Intestinal resection and anastomosis (R&A) in dogs has a reported

are hospitalized and recovering from surgery, it would be ideal if

dehiscence rate of up to 16%, with mortality due to dehiscence

there were an easy, inexpensive, and minimally invasive way to

1–3

Pre-

detect impending dehiscence or detect dehiscence as soon as it

operative peritonitis, hypoalbuminemia, intraoperative hypoten-

occurs so that appropriate treatment could be initiated sooner,

sion, and presence of a foreign body are factors that have been

decreasing morbidity and mortality. Unfortunately, in veterinary

shown to increase the risk of dehiscence.1,2,4 One study found

medicine, there is currently no way to detect impending dehiscence

and resultant septic peritonitis ranging from 20 to 80%.

3

foreign bodies to be protective against dehiscence. Dehiscence

of an intestinal R&A.7–9 Available tests, including positive culture

most commonly occurs between 3 and 5 days, although occur-

of abdominal fluid, only determine if dehiscence has already oc-

1,2,5,6

rence has been reported 0–10 days postoperatively.

curred, and those tests may have false negative or false positive

From the Surgery Department, Red Bank Veterinary Hospital, Tinton Falls, NJ (E.M., G.D.); and Section of Critical Care, Department of Clinical Studies (K.D.) and Laboratory of Pathology and Toxicology (K.W.), Matthew J. Ryan Teaching Hospital, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA.

D, dehiscence group; ND, no dehiscence group; DCS, dehiscence with

Correspondence: [email protected] (E.M.)

†

a closed-suction drain group; NDCS no dehiscence with a closed-suction drain group; NDNCS, no dehiscence and no closed-suction drain group; R&A, resection and anastomosis *E. Mouat’s updated credentials since article acceptance are VMD, DACVS. E. Mouat’s present affiliation is Puget Sound Veterinary Referral Center,

Tacoma, WA.

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ª 2014 by American Animal Hospital Association

Dehiscence Following Intestinal Resection and Anastomosis

results.9–11 Abdominal fluid culture also has the drawback of a

recorded and were not analyzed in this study. No attempt was

delay of several days before results are available.12 If dehiscence

made to leave more or less fluid in the abdomen prior to closure.

is suspected, re-exploration of the abdomen is recommended;

A closed-suction drain was placed and an aerobic culture takenc

however, that carries a poor prognosis. In one study, two of three

at the discretion of the primary surgeon. IV fluid rates, intra-

dogs and in another study two of two cats that were re-explored

and postoperative antibiotics, and duration of hospitalization

for dehiscence died perioperatively.2,10

varied and were determined by the primary clinician.

Intestinal healing is negatively affected by local inflamma-

When abdominal drains were present, the reservoirs were

tion, infection, and poor blood supply, all of which may develop

either emptied and quantified q 2 hr in the immediate postop-

in the pre-, intra-, or postoperative period.6,13–15 Evaluation of

erative period or when they became full. Starting between 6

abdominal fluid and blood work in the perioperative period

and 12 hr postoperatively, drain reservoirs were emptied and

should reflect inflammation, infection, and local ischemia. It is

quantified approximately q 4 hr until removal, death, or eutha-

plausible that those factors, evaluated either individually or to-

nasia. If fluid production later increased, reservoirs were emptied

gether, may be able to predict intestinal dehiscence, directing

more frequently. Quantification of fluid from drains was not

clinicians toward additional medical treatments or abdominal

evaluated in this study.

re-exploration to prevent dehiscence from occurring.

7,16,17

Approximately 24 hr postoperatively, an abdominal ultra-

The goals of this study were to evaluate blood and ab-

soundd,e was performed to look for fluid. The ultrasound was

dominal fluid glucose and lactate, fluid cytology, and volume

often performed just before scheduled emptying of the drain

at 24 and 48 hr postoperatively and fluid culture at 24 hr post-

reservoir (when the suction was suspected to be lower) to try to

operatively from dogs that had undergone R&A with and without

increase the volume of retrievable fluid. The fluid volume was

closed-suction abdominal drain placement. The study authors

subjectively assessed and graded on a scale from 0 to 4. A grade of

hypothesized that this evaluation would reveal significant dif-

0 was given when no fluid was seen in the abdomen. A grade of

ferences between patients that would develop dehiscence and

1 was given when one small pocket of fluid was seen. A grade of

those that would not and that there would not be any significant

2 was given when more than one small pocket or one medium to

differences in values between dogs with and without abdominal

large pocket of fluid was seen. A grade of 3 was given when

drains.

several medium to large pockets of fluid were seen. A grade of 4 was given when a border of free fluid could be seen around

Materials and Methods

multiple organs. Grades were assigned by one of three surgical

All cases of canine intestinal R&A performed between October

residents. If a closed-suction abdominal drain was present, gloves

2010 and May 2012 were prospectively enrolled in the study.

were worn, the drain was clamped with a hemostat, the grenade

The hospital medical board approved the study, and informed

removed, the tip of the drain swabbed with alcohol, and a mini-

verbal consent for enrollment in the study was obtained from

mum of 2 mL of fluid removed and discarded from the drain

the owners following surgery. Preoperative factors, including sig-

prior to collection of fluid for analysis (previous evaluation

nalment, history, preoperative treatments, and preoperative blood

found drains at the authors’ hospital, which were frequently cut

work, were recorded. Age of patient and preoperative albumin,

to a shorter length, held an average of 2 mL of fluid). Up to 6 mL

glucose, blood urea nitrogen, and creatinine were evaluated sta-

of fluid was collected prior to replacing the grenade and re-

tistically. Intraoperative factors were recorded, including dura-

moving the hemostat. If , 0.1 mL could be collected, this was

tion of anesthesia, location and length of bowel resected, reason

recorded and no fluid was submitted. If a drain was not present,

for resection, if other procedures were performed, if intestinal

fluid was collected by ultrasound-guided abdominocentesis. After

perforation was present, if a culture was submitted, and if a

locating a fluid pocket, the skin was briefly scrubbed with alcohol

closed-suction drain was placeda. Except for location of resec-

prior to abdominocentesis. The needle was changed prior to

tion and reason for resection of these, all factors were evaluated

dispensing fluid into culturettes. Abdominocentesis was per-

statistically. Surgery was performed by either one of three board-certified

formed by one of three surgical residents or one board-certified surgeon if a volume grade of 3 or 4 was assigned. Otherwise,

surgeons or one of three surgical residents. All intestinal R&As

abdominocentesis was performed by one of three board-certified

were closed with 4-0 polydioxanoneb in a simple interrupted pat-

internists.

tern. The volume of abdominal fluid used to flush the abdomen

Within 5 min of abdominal fluid collection, blood was drawn

and volume suctioned from the abdomen were not consistently

from a peripheral vein and both fluid and blood samples were

JAAHA.ORG

255

analyzed within 10 min of blood collection for glucose and lactate

The Shapiro-Wilk test was used to evaluate normality for

levelsf. If abdominal fluid could not be obtained, blood was not

all continuous variables (i.e., age, preoperative serum albumin,

collected.

glucose, creatinine, blood urea nitrogen, duration of anesthesia,

Part of the remaining fluid was submitted for aerobicg and

length of bowel resected, subjective fluid volume, cytologic white

anaerobic culture and sensitivity. Lastly, four slides of unspun

blood cell count, paired serum, and abdominal fluid glucose

fluid and four slides of spun fluidi (3500 revolutions/min for

and lactate). Because nearly all continuous variables were not

10 min for blood and 1600 revolutions/min for 10 min for

normally distributed, the median (range) was used to describe

fluid) were made and submitted, along with any remaining

these variables. The Wilcoxon rank sum test or the Student t test

fluid, for cytologic evaluation by a single clinical pathology

(depending on if the data were not normally or were normally

residentj. Fluid samples received by the laboratory were pro-

distributed, respectively) was used to compare continuous var-

cessed within 2 hr of acquisition according to standard labo-

iables between groups. Similarly, the paired t test or Wilcoxon

ratory procedure as follows. Leukocyte and red blood cell counts

signed rank test was used to compare continuous variables be-

of each fluid were obtained and recorded. If the leukocyte

tween time periods. The Fisher’s exact test (if the expected value

counts were , 2 3 109 cells/L cytospin slides were prepared.

in any cell was , 5) or x2 test was used to compare categorical

If cells counts were 2–30 3 109 cells/L, sedimented slides were

variables (i.e., if other gastrointestinal surgery was performed,

prepared by centrifugation of the samplel (1600 revolutions/min

if intestinal perforation was found at the time of surgery, if

for 3 min). If cell counts were . 30 3 10 cells/L, direct pre-

cultures were positive or negative, if a closed suction drain was

parations were made. If red blood cell counts were . 1 3 10,

placed, if bacteria were seen cytologically, and if dehiscence

h

k

9

buffy coat slides were prepared. All slides (i.e., those premade

occurred or not) between groups. A P , .05 was considered

at time of sample collection and those made in the laboratory)

significant for all comparisons. All analyses were performed

were routinely stained with Wright-Giemsa. All slides were mi-

using a statistical software programm.

6

croscopically evaluated and a 200 cell count differential performed and recorded. The presence of any microorganisms, neoplastic

Results

or atypical cells, and any degenerative changes were recorded.

Thirty-five cases of canine intestinal R&A were included in this

Samples were classified as pure transudate (, 2.5 3 10 cells/L and

study. Mean age was 6.5 yr (range, 6 mo to 12 yr). Sex of the

, 0.025 g/L protein), modified transudate (. 2.5 3 109 cells/L or

patients included 14 castrated males, 18 spayed females, and

protein . 0.025g/L) or exudate (. 5 3 10 cells/L).

3 intact females. Patients were hospitalized a median of 2 days

9

9

At approximately 48 hr postsurgically, the above procedures

(range, 1–5 days). Reasons for intestinal R&A included neoplastic

were repeated, with the exception of the culture and sensitivity

and non-neoplastic masses (n ¼ 16), foreign bodies (n ¼ 11),

unless the patient had died, been euthanized, or discharged prior

intussusception (n ¼ 3), leaking previous surgery site (n ¼ 3),

to the 48 hr collection time. Patients were followed until death,

self-trauma (n ¼ 1), and idiopathic ischemic bowel (n ¼ 1).

euthanasia, or the 2 wk recheck examination, and were categorized

Additional procedures performed included liver biopsy (n ¼ 10),

as either having had an intestinal dehiscence or not having had

gastrotomy (n ¼ 7), splenectomy (n ¼ 6), lymph node biopsy

a dehiscence. If a patient died or was euthanized, the reason and the

(n ¼ 6), enterotomy (n ¼ 1), gastric biopsy (n ¼ 1), cholecys-

number of days from surgery were recorded. If the patient was

tectomy (n ¼ 1), adrenalectomy (n ¼ 1), ovariohysterectomy

reexamined prior to 14 days postoperatively or did not return for

(n ¼ 1), liver lobectomy (n ¼ 1), and omental biopsy (n ¼ 1).

evaluation, their owners were contacted by phone after 14 days.

Regions of intestine resected in dogs developing dehiscence

For analysis of the preoperative, intraoperative, and post-

included the mid-jejunum (n ¼ 3), distal jejunum to transverse

operative factors previously listed, patients were divided into the

colon (n ¼ 1), and distal duodenum and proximal jejunum

following group comparisons: (1) patients that developed dehis-

(n ¼ 1). Regions of intestine resected in dogs that did not develop

cence (D) and those that did not (ND), (2) patients that had a drain

dehiscence included proximal duodenum (n ¼ 1), mid-duodenum

placed and did (DCS) or did not (NDCS) develop dehiscence, (3)

(n ¼ 2), distal duodenum (n ¼ 1), distal duodenum to proximal

patients that did not develop dehiscence and did (NDCS) or did

jejunum (n ¼ 1), distal duodenum to mid-jejunum (n ¼ 1),

not (NDNCS) have a drain placed, (4) patients that did not have

proximal jejunum (n ¼ 2), mid-jejunum (n ¼ 12), mid- and

a drain placed and did (DNCS) or did not (NDNCS) develop

distal jejunum (n ¼ 2), distal jejunum (n ¼ 5), distal jejunum

dehiscence, and (5) patients that developed dehiscence that did

and ileum (n ¼ 1), mid-jejunum to ileum (n ¼ 1), and distal

(DCS) and did not (DNCS) have a drain placed.

jejunum to ascending colon (n ¼ 1).

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Dehiscence Following Intestinal Resection and Anastomosis

Five dogs either died or were euthanized within 14 days of

glucose at 24 hr. Forty-eight and 42 patients, respectively, would

surgery, all due to dehiscence (median, 3 days; range, 1–5 days).

be needed when comparing differences in serum and fluid lac-

The remaining dogs were alive at the time of the follow-up ex-

tate and glucose at 48 hr. It would be necessary to have 233 and

amination (22 dogs) or when the follow-up phone call was made

178 patients in the DNCS group when being compared with the

(8 dogs) at least 14 days postoperatively. Four of the five dogs were

NDNCS group for differences in serum and fluid lactate and

euthanized, one on days 1, 2, 4, and 5 postoperatively. Three of

glucose at 24 hr, respectively, and 75 and 3719 patients when

those patients had intestinal dehiscence noted during necropsy,

comparing those groups for differences in serum and fluid lac-

and one had copious abdominal effusion and fluid cytology

tate and glucose at 48 hr, respectively.

consistent with dehiscence (i.e., degenerative neutrophils with

Power was calculated for the comparisons of differences in

intracellular bacteria). One dog died 3 days postoperatively, which

blood and fluid glucose and lactate between the other groups.

was , 24 hr after abdominal re-exploration. At the time of

Power was highest when comparing the NDCS and NDNCS

death, that patient had cytology consistent with intestinal dehis-

groups (0.44 and 0.75 for differences in blood and fluid glucose at

cence (i.e., numerous intracellular bacteria and intestinal debris).

24 and 48 hr, respectively, and 0.66 and 0.66 for differences in

Three of the five patients that developed dehiscence had an R&A

blood and fluid lactate at 24 and 48 hr, respectively). That com-

performed for masses (one sarcoma, one chronic hematoma, one

parison would have required the fewest patients to reach a power of

lymphoplasmacytic enteritis) and two for foreign bodies. Rate of

0.8, with the NDCS group requiring between 12 and 36 patients

survival to 14 days postoperatively was 85.7%, and the rate of

and the NDNCS group requiring between 10 and 22 patients.

dehiscence was 14.3%.

Power was lower when comparing the D and ND groups (0.22 and

Fluid was collected twice in 22 patients, once in 7 patients

0.1 for differences in blood and fluid glucose at 24 and 48 hr,

(because 5 of those patients had either too little or no fluid to be

respectively and 0.11 and 0.56 for differences in blood and fluid

collected on the second day, one was discharged , 48 hr post-

lactate at 24 and 48 hr, respectively). That latter comparison would

surgically, and one patient was euthanized , 48 hr post-

have required between 32 and 367 patients in the D group and 8

surgically), and 6 patients did not have any abdominal fluid

and 81 patients in the ND group to reach a power of 0.8.

collected (because 5 patients had either too little or no fluid to be

Preoperative blood work was evaluated for differences in

collected on either day and 1 patient was discharged , 24 hr

total WBC count, albumin, blood urea nitrogen, creatinine, and

postsurgically). Complications associated with abdominocentesis

glucose. There were no significant differences between any of the

were only encountered in one patient because bowel contents

groups.

were aspirated at 24 hr. A second attempt at aspiration was suc-

Age of patient at time of surgery, length of bowel resected,

cessful and collection at 48 hr occurred without complication.

duration of anesthesia, if bowel perforation was discovered at the

That patient was doing well when the owner was contacted by

time of surgery, and if other gastrointestinal surgical procedures

phone 21 days postoperatively.

were performed were evaluated for differences between groups.

When patients were divided into groups for comparisons,

The age at surgery was significantly older in the DCS group

there were 5 dogs in the D group, 30 in the ND group, 10 in the

(median, 112.5 mo; range, 84–134 mo) than the NDCS group

NDCS group, 4 in the DCS group, 1 in the DNCS group, and 20

(median, 48 mo; range, 12–96 mo; P ¼ .011). The length of bowel

in the NDNCS group. Only one patient was included in the

resected was significantly longer in the D group (median, 8 inches;

DNCS group; therefore, no comparisons were made between

range, 1–28 inches) than the ND group (median, 24 inches;

either the DNCS and DCS groups or the DNCS and NDNCS

range, 8–30 inches; P ¼ .015). Duration of anesthesia was not

groups. The presence of only one patient in the DNCS group

significantly different between groups. Surviving patients that

also prevented calculation of power for comparison between the

had a drain placed (the NDCS group) were significantly more

DNCS group and the other groups. Assuming the ratio of animals

likely to have had a bowel perforation that was discovered at the

would be consistent between groups and assuming a power of

time of surgery than the NDNCS group (P , .001). There was

0.8 and an a of 0.05, the number of patients needed to find

no significant difference in performance of additional gastroin-

a significant difference between the DNCS group and the other

testinal procedures between groups.

two groups was calculated for differences in serum and fluid

Median subjectively assessed fluid volume scores were higher

glucose and lactate at 24 and 48 hr. It would be necessary to have

at 24 and 48 hr in the D than ND group, but that difference was

40 patients in the DNCS group when comparing that group to

not significant (Table 1). When comparing scores of abdominal

the DCS group for differences in serum and fluid lactate and

effusion at 24 to 48 hr in the NDCS and NDNCS groups, the

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TABLE 1 Values for Fluid Volume Score Subjectively Assessed on Abdominal Ultrasound at 24 and 48 hr and the Change in Score Between Times Fluid volume score at 24 hr reported as median (range)

Category D

Fluid volume score at 48 hr reported as median (range)

Change in fluid volume score reported as median (range)

4 (3–4)

3.5 (2–4)

20.5 (21–0)

2.5 (0–4)

2 (0–4)

21 (22–0)

DCS

4 (4–4)

4 (3–4)

0 (21–0)*

NDCS

3 (1–4)

2 (0–3)

21 (21–0)*,y

1.5 (0–3)

1 (0–3)

21 (22–0)y

ND

NDNCS

*Denotes a comparison between groups for which P ¼ .075. Denotes a comparison between groups for which P ¼ .06. y

NDCS patients trended toward having significantly less volume

patients with drains having significantly greater differences in

decrease over time (P ¼ .06).

glucose.

Serum lactate and glucose and abdominal fluid lactate and

Fifteen patients had cultures of abdominal fluid taken

glucose were evaluated independently and compared with each

intraoperatively. Nine of the 15 cultures were positive. Four of the

other at 24 and 48 hr postoperatively between three groups

cultures grew two bacteria and five cultures grew one. Bacteria

(Tables 2A, 2B). Changes in glucose and lactate over time were

cultured included Enterococcus spp. (seven dogs), Escherichia coli

also compared for serum and abdominal fluid individually and

(three dogs), Pasteurella spp. (one dog), and Kluyvera cryocrescens

compared with each other. There were no significant differences

(one dog). Six of the bacteria cultured were resistant to six or

between the D and ND groups. Change in serum lactate from

more antibiotics. Three of the five patients that developed de-

24 to 48 hr and difference in blood to fluid lactate at 48 hr

hiscence had positive cultures at surgery. The cultures of two of

trended toward significance when comparing the D and ND

those patients grew Escherichia coli and Enterococcus spp. and the

groups (P ¼ .074 and P ¼ .074).

other patient’s culture grew Kluyvera cryocrescens. One culture

There was a significant difference in serum and fluid lactate

of bile and choleliths was also taken and grew highly resistant

values at 24 hr (P ¼ .013) and 48 hr (P ¼ .016) in the NDCS and

Enterobacter sakazakii and Enterococcus spp. There were no sig-

NDNCS groups with patients with drains having significantly

nificant differences in cultures taken at the time of surgery be-

greater differences in lactate. There was also a significant dif-

tween any groups.

ference in serum and fluid glucose values at 24 hr (P ¼ .029)

Twenty-nine patients had cultures of abdominal fluid taken at

and 48 hr (P ¼ .011) in the NDCS and NDNCS groups with

24 hr postoperatively. Of those 29 cultures, 16 were positive. Of

TABLE 2A Values for Serum and Fluid Glucose Levels and Difference Between Those Values at 24 and 48 hr Serum glucose reported as median (range) mmol/L

Fluid glucose reported as median (range) mmol/L

Serum2fluid glucose reported as median (range) mmol/L

Sample time

Group

24 hr

D

5.27 (4.22–8.16)

4.44 (2.05–5.61)

1.28 (20.33–6.11)

ND

5.45 (2.97–7.93)

4.85 (1.27–9.92)

0.25 (23.03–2.53)

DCS

5.98 (4.19–8.10)

3.44 (2.039–5.46)

2.01 (20.22–6.061)

NDCS

5.12 (3.97–6.01)

3.80 (2.10–6.50)

0.99 (20.66–2.53)*

NDNCS

6.01 (2.98–7.93)

5.57 (1.27–9.92)

0.17 (23.03–2.53)*

D

5.12 (4.52–6.56)

3.50 (2.7–5.12)

1.16 (0.39–3.80)

ND

5.21 (2.2–7.66)

4.46 (0.55–8.26)

0.58 (21.05–3.97)

DCS NDCS

5.51 (4.52–6.56) 5.39 (4.57–7.60)

2.76 (2.7–5.12) 3.0 (0.61–6.45)

1.81 (0.39–3.80) 2.20 (20.17–3.97)y

NDNCS

5.21 (2.20–7.66)

5.15 (1.82–8.26)

0.11 (21.05–3.25)y

48 hr

*Denotes a comparison between groups for which P ¼ .029. y Denotes a comparison between groups for which P ¼ .011.

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TABLE 2B Values for Serum and Fluid Lactate Levels and Difference Between Those Values at 24 and 48 hr

Sample Time 24 hr

Group D ND

48 hr

Serum lactate reported as median (range) mmol/L

Fluid lactate reported as median (range) mmol/L

4 (1.79–4.56) 1.56 (0.56–3.64)

Serum2fluid lactate reported as median (range) mmol/L

6.74 (3.79–10.26)

22.74 (27.23–0.77)

2.53 (1.54–6.7)

20.98 (28.07–1.71)

DCS

3.51 (3.0–4.56)

7.07 (3.79–10.26)

24.18 (27.23–0.77)

NDCS NDNCS

1.26 (0.56–2.33) 1.83 (0.81–3.64)

4.62 (1.58–6.7) 2.0 (1.54–9.37)

23.36 (25.26 to 20.57)* 20.31 (28.07–1.71)*

D

1.72 (1.4–3.2)

5.92 (5.45–9.37)

24.27 (26.17 to 23.91)

ND

1.075 (0.5–2.9)

2.66 (0.5–12.1)

21.55 (210.75–1.12)

DCS

1.9 (1.4–3.2)

6.0 (5.84–9.37)

NDCS

0.91 (0.5–1.34)

4.37 (0.5–12.09)

NDNCS

1.67 (1.01–2.95)

24.6 (26.17 to 23.94) 23.455 (210.75–0)y 20.29 (28.04–1.12)y

2.0 (1.33–10.41)

*Denotes a comparison between groups for which P ¼ .013. y Denotes a comparison between groups for which P ¼ .016.

those cultures, 12 grew one bacterium, three grew two, and one grew

spp. at 24 hr), and two of which did not (Enterococcus spp. at

four. Bacteria cultured included Staphylococcus pseudintermedius

surgery, coagulase-positive Staphylococcus pseudintermedius at

(four dogs), Escherichia coli (four dogs), Staphylococcus schleiferi

24 hr; and Escherichia coli at surgery and coagulase-positive

(three dogs), Enterococcus spp. (two dogs), Pseudomonas aerugi-

Staphylococcus pseudintermedius at 24 hr).

nosa (two dogs), Morganella morganii (one dog), Clostridium spp.

Four of five patients that developed dehiscence had positive

(one dog), Enterobacter cloacae (one dog), nonpathogenic Dip-

cultures at one or both sampling times for Escherichia coli,

theroid spp. (one dog), Micrococcus spp. (one dog), nonpathogenic

Enterobacter spp., or Enterococcus spp. Patients were significantly

Bacillus spp. (one dog), and Enterobacter sakazakii (one dog).

more likely to develop dehiscence if they cultured enteric bacteria

Seven of the bacteria cultured were resistant to six or more

(Escherichia coli, Enterococcus spp., Enterobacter spp.) at any time

antibiotics. All five of the patients that developed intestinal de-

point (P ¼ .026)

hiscence had positive cultures at 24 hr postoperatively. The

Total cell count for abdominal fluid at 24 and 48 hr was

cultures of three of those patients grew one bacteria each

compared between groups and no significant differences were

(Escherichia coli in two cases and Enterobacter species in one

found (Table 3). Patients in the D group (mean, 30,700 cells;

case), one culture grew two bacteria (Morganella morganii and

range, 4200–779,000 cells) had higher cell counts than the ND

Clostridium spp.), and one culture grew four bacteria (Escherichia coli, Pseudomonas aeruginosa, Enterococcus spp., and coagulasepositive Staphylococcus pseudintermedius). There were significantly more positive cultures in the D group than the ND group at 24 hr (P ¼ .044). Fourteen patients had cultures taken at both times, and six of

TABLE 3 Values for Total Cell Count and Neutrophils of Abdominal fluid at 24 and 48 hr Median (range) 3 109cells/L

Median percent (range) of neutrophils

those patients were positive at both times (three of those de-

Sample time

Group

veloped dehiscence). It approached significance for the D group

24 hr

D

30.7 (4.2–779.0)

ND

14.6 (0.6–77.0)

95 (86–98)

DCS

28.4 (4.2–40.1)

93 (90–96)

NDCS

17.1 (3.3–43.6)

96 (86–97)

NDNCS

12.35 (0.6–77.0)

to have positive cultures at both time points compared with the D group (P ¼ .055). Only two patients grew the same bacteria in both cultures (Escherichia coli in one patient that developed dehiscence, Enter-

48 hr

D

36.2 (32.8–39.6)

95 (90–96)

95 (89–99) 94 (92–97)

obacter sp. in a patient that did not). Four patients grew different

ND

8.5 (1.4–70.8)

92 (87–97)

bacteria, two of which developed dehiscence (Escherichia coli and

DCS NDCS

36.2 (32.8–39.6) 20.4 (3.0–70.8)

94 (92–97) 92 (87–97)

NDNCS

6.25 (1.4–50.7)

Enterococcus spp. at surgery, Morganella morganii and Clostridium spp. at 24 hr; and Kluyvera cryocrescens at surgery, Enterobacter

92.5 (88–97)

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group at 24 hr (mean, 14,600 cells; range, 600–77,000 cells) and

between age and dehiscence when comparing the D and ND

48 hr. In the D group, mean was 36,200 cells and range was

groups, there was a significant difference between the DCS and

32,800–39,600 cells, and in the ND group, mean was 8500 cells

NDCS groups. Again, that finding may be due to the small

and the range was 1400–70,800 cells).

number of patients in this study. Age has not been associated

Abdominal fluid was neutrophilic in all patients in which it

with an increased risk of dehiscence in previous studies.2,4 The

was collected. The percentage of neutrophils in the abdominal

NDCS group of patients was more likely to have perforations of

fluid at 24 and 48 hr was compared between groups and no

the gastrointestinal tract than the NDNCS group of patients.

significant differences were found (Table 3).

That finding makes sense because patients with perforation and

Bacteria were seen cytologically in only four patients, all at 24 hr. Two of those patients developed intestinal dehiscence and

gross abdominal contamination would have been more likely to have drains placed.

two did not. Degenerative neutrophils were seen in two of these

Blood to abdominal fluid glucose and lactate cut-off values

four patients, both at 24 hr, one of which developed dehiscence

have been successfully determined for diagnosis of preoperative

and one of which did not. One of the two patients that developed

cases of septic peritonitis.12,14,18 Poor blood flow to the intestines

dehiscence had a positive culture at surgery and at 24 hr. The

results in increased anaerobic metabolism and resultant increased

other patient was not cultured at surgery, but had a positive

abdominal fluid lactate and decreased abdominal fluid glucose

culture at 24 hr, as well as intracellular bacteria and degenerative

concentrations. Lactate is also increased, and glucose decreased

neutrophils seen cytologically at 24 hr. The two patients that did

secondary to bacterial infection.13,18 There is a strong correlation

not develop dehiscence had negative cultures at surgery. One

between blood and serum lactate and glucose values and preop-

patient had intracellular bacteria seen on cytology but that was

erative septic peritonitis.11,14,18 A difference in serum lactate and

not cultured at 24 hr. The other patient had extracellular bacteria

abdominal fluid lactate of , 22.0 mmol/L is 100% sensitive and

and degenerative neutrophils seen cytologically at 24 hr and grew

63% specific for septic peritonitis, abdominal fluid lactate

a nonpathogenic Bacillus spp. at 24 hr.

. 2.5 mmol/L is 91% sensitive and 100% specific for septic peritonitis, and a difference in serum glucose and abdominal

Discussion

fluid glucose . 1.1 mmol/L is 100% sensitive and 100% specific

Although the results of this study did not show significant dif-

for septic peritonitis in dogs.11,18 It was not possible to deter-

ferences in abdominal fluid to blood glucose or lactate values,

mine cut-off values for blood to abdominal fluid glucose and

abdominal fluid volume, or cytology in patients that did and did

lactate for predicting postoperative dehiscence and need for

not develop dehiscence, the number of patients was small and the

abdominal re-exploration in the patients included in this study.

power was low. Many of the comparisons trended toward sig-

The difference in blood to fluid lactate at 48 hr and the change

nificance, suggesting that a study with a larger number of patients

in blood to fluid lactate from 24 to 48 hr trended toward sig-

might find significant differences that could be used to create cut-

nificance, warranting further evaluation in future studies.

off values to guide the decision to surgically re-explore the ab-

Fluid volume subjectively evaluated at 24 and 48 hr post-

domen. Based on the authors’ analyses, it may be necessary to have

operatively found that patients that developed dehiscence had

several hundred patients enrolled in a study to find significant

more fluid than patients that did not and that patient with drains

differences between the D and ND groups’ blood and fluid glu-

had more fluid than patients without drains, although those

cose and lactate. This study was short in duration because it was

differences were not significant. There are several limitations to

based around the mean historical hospitalization time of about 48

the fluid volume evaluation in this study. Lavage fluid used in

hr for patients following intestinal R&A. A study that extended

surgery was not standardized and abdominal drains were present

past 48 hr postoperatively may also be more likely to find dif-

and regularly emptied in many of the patients, which could have

ferences between patients that do and do not develop dehiscence

significantly affected fluid volume. Most of the patients that

considering that dehiscence occurred a mean of 3 days postoper-

developed dehiscence had drains placed; however, it is not pos-

atively in this study and 3–5 days in other reports.1,2,5,6

sible to know how much of the fluid production was related to

Length of bowel resected is infrequently reported. The results

dehiscence compared with inflammation secondary to the pres-

of this study suggest that resection of longer lengths of bowel may

ence of a drain. In addition, a validated technique for evaluating

be associated with an increased risk of dehiscence, which differs

fluid volume ultrasonographically was not used, and multiple

from one previous study that found no association between length

individuals assessed fluid volume in included patients. To

resected and survival.2 Although this study found no association

the authors’ knowledge, there are no papers evaluating fluid

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Dehiscence Following Intestinal Resection and Anastomosis

volume ultrasonographically postoperatively after R&A, only

or from other sources, such as from either an incisional infection

after trauma.19

or abdominal drain.12,21 False-positive and false-negative results

Past studies have suggested that cytologic evaluation of ab-

have been shown postoperatively in other studies.12,19,22 There

dominal fluid, via either abdominocentesis or diagnostic peri-

was a high prevalence of gram-positive Staphylococcus spp. cul-

toneal lavage, can be used to gauge the intra-abdominal environment

tured at 24 hr compared with predominately gram-negative bac-

pre- and postoperatively. This study found no significant dif-

teria, such as Escherichia coli and Enterobacter spp. and other enteric

ference in WBC numbers between any of the groups although

bacteria such as Enterococcus spp. at the time of surgery. That

the D group did have a higher median WBC count than the ND

finding suggests that either contamination of the abdomen peri-

group, which was consistent with previous studies. Abdominal

operatively or of the culture sample at the time of collection may

fluid cytology in a normal dog collected by diagnostic peritoneal

have occurred. It is interesting to note that even though cultures

lavage should reportedly have a WBC count , 0.5 3 10 cells/L

rarely grew the same bacteria at both sample times, patients that

with nondegenerate neutrophils predominating.7,13,20 WBC count

cultured enteric bacteria at any point were more likely to develop

has been shown to increase in the postoperatively period after

dehiscence.

9

celiotomy alone (15.1 3 109 cells/L 1 day postoperatively), in-

To date, veterinary medicine has focused on evaluation of

testinal R&A (18.0 3 10 cells/Lin the first 3 days postopera-

different abdominal wall closure techniques to decrease risk of

tively) and to be highest after experimental R&A dehiscence

dehiscence or detect dehiscence early. Closure techniques include

(31.7 3 10 cells/L 1 day postoperatively and 686.0 3 10 cells/L

closed suction drains, open abdominal drainage, sump Penrose

2 days postoperatively).12,13 Unfortunately, those studies were

drainage, planned abdominal re-exploration, and vacuum-assisted

primarily experimental, and in most cases had collected fluid via

closure, which has had some success in human medicine.10,23–26

diagnostic peritoneal lavage, making it difficult to compare those

So far, results showing one closure method as superior to an-

9

9

results to this study.

9

12,13,20

One human study suggested using

other has been lacking.

10,23,25,27

It is unclear how the presence

a cut off WBC count . 5.0 3 10 cells/L along with the ap-

or absence of a drain affects the intra-abdominal environment.

pearance and smell of the fluid and gram stain results to sur-

In the current study, there were significant differences in blood

gically re-explore the abdomen, with some success.7

to fluid glucose and lactate between patients that survived with

9

The authors of the current study found that significantly

and without a Jackson-Pratt drain, with patients without drains

more patients that developed dehiscence had a positive culture

having lower differences, or “more normal” values, at both 24

at 24 hr. That finding correlates with preoperative sepsis being a

and 48 hr. Those results are similar to a recent study that looked

risk factor for dehiscence, which was shown in previous papers.1,2,4

at the effect of Jackson-Pratt drains on glucose and lactate

It also suggests that culture results could help predict dehiscence

postceliotomy, finding that after the first 2–4 days values became

as early as 24 hr postoperatively. Unfortunately, the clinical utility

consistent with a septic abdomen.12 The differences in fluid

of a positive culture is limited due to delay in results. It should

parameters between patients with and without drains may be

also be noted that, in this study, patients developing dehiscence

due to either a change in the abdominal environment or a change

did so within 5 days of surgery. It is unclear if patients with de-

within the drain tubing. The study authors attempted to elim-

hiscence over 5 days postoperatively may be less likely to have

inate the chance of the differences being due to a change within

positive culture results at 24 hr.

the drain tubing by discarding a minimum of 2 mL of fluid prior

This study found no correlation between visualization of

to analysis. The study authors suspect that the presence of an

bacteria on cytology of abdominal fluid and dehiscence. This

abdominal drain alters the environment within the abdomen

may have been due to the small number of cases of dehiscence

resulting in values consistent with sepsis. It is also possible that

and to the limited duration of the stud. Three of the patients

there was a selection bias, with more significant abdominal pa-

developed dehiscence after 48 hr, and bacteria may have been

thology leading to the decision to place a drain, regardless of ulti-

visualized in those patients if the study duration had been in-

mate survival or death.

creased. Two of the four cases with bacteria seen on cytology at

A recent study evaluated vacuum assisted closure after sur-

24 hr did not progress to intestinal dehiscence. Thus, positive

gery on dogs with septic abdomens. Although there were only

cytology alone cannot be used as criteria to surgically re-explore

three surviving patients, it is interesting to note that their blood

the abdomen. Bacteria in the abdominal cavity postoperatively

to abdominal fluid glucose and lactate differences improved to

can originate from the intestinal tract during surgery, from the

within normal values within 2 days postoperatively.25 The values

intestinal tract postoperatively through incisional dehiscence,

were most similar to those of the patients in the NDNCS group,

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261

all of which had “normal” differences between their serum and fluid lactate and glucose at 24 and 48 hr. It may be that, for an unknown reason, vacuum-assisted closure with continuous suction may be less likely to cause changes consistent with a septic abdomen than Jackson-Pratt closed-suction drains. Alternately, vacuum-assisted closure may be more successful at removing fluid, resulting in either fluid spending less time sitting in the abdomen or drain where it could be developing falsely elevated lactate or decreased glucose. A test to determine what patients would develop dehiscence or had a high probability of dehiscence would be useful. The authors did not find a single parameter that could reliably predict those cases that would develop dehiscence. Some future areas of research that have shown promise in human medicine include evaluation of intra-abdominal pressure and the use of microdialysis catheters at the resection site to measure glucose, lactate, lactate/pyruvate ratio, and inflammatory cytokines.16,17,28,29 Work in this area has shown that lactate/pyruvate ratios during the first 2 days postoperatively may be able to predict future dehiscence and that positioning of the catheter near the R&A site yields more reliable results. The primary shortcoming of this study is the small number of cases, which may have precluded differences in blood to abdominal fluid glucose and lactate from reaching significance and precluded comparison between certain groups, such as patients that died that did and did not have drains. Having . 2 days of evaluation may have improved results. The evaluation of fluid volume was also subjective and difficult to standardize. Further experimental or prospective clinical studies with larger numbers of cases should be undertaken to determine if cut-off values for blood to abdominal fluid glucose and lactate and abdominal fluid volume exist, and to evaluate abdominal fluid lactate/pyruvate levels and cytokine levels. A study to evaluate the impact of closed-suction drains on abdominal fluid values after intestinal surgery would also be useful to resolve the uncertainty over the trustworthiness of values obtained from a closed-suction drain.

Conclusion This study did not show a difference in any values between patients that did or did not have intestinal dehiscence, with the exception that patients with intestinal dehiscence were significantly more likely to have a positive culture of abdominal fluid at 24 hr postoperatively and to have had a longer section of bowel resected. There was, however, a significant difference in blood to abdominal fluid glucose and lactate in patients with and without drains, suggesting further research is needed regarding the impact of closed-suction drains on postoperative abdominal fluid values.

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FOOTNOTES a Jackson-Pratt Wound Drainage Systems; Cardinal Health, Dublin, OH b PDS suture material; Ethicon, LLC; Johnson & Johnson, New Brunswick, NJ c Aerobic culture and sensitivity test; Antech Diagnostic Laboratory, Lake Success, NJ d GE Cares LOGIQ Book XP; GE Healthcare, Buckinghamshire, UK e GE Cares LOGIQ 5 PRO; GE Medical Systems, Milwaukee, WI f IDEXX Catalyst Dx; IDEXX Laboratories Inc., Westbrook, ME g COPAN Test Swabs; COPAN Diagnostics Inc., Murrieta, CA h BD BBL Prepared Culture Media Port-A-Cul Tubes; Becton Dickinson and Company, Franklin Lakes, NJ i LW Scientific Straight 8-5K Horizontal Centrifuge; LW Scientific, Lawrenceville, GA j University of Pennsylvania School of Veterinary Medicine, Laboratory of Pathology and Toxicology, Philadelphia, PA k Scil vet ABC hematology analyzer; Scil Animal Care Company, Gurnee, IL l BD Sero-Fuge centrifuge by Clay Adams; Becton Dickinson and Company, Franklin Lakes, NJ m Stata 11.0 for Windows; Microsoft, College Station, TX REFERENCES 1. Ralphs SC, Jessen CR, Lipowitz AJ. Risk factors for leakage following intestinal anastomosis in dogs and cats: 115 cases (1991–2000). J Am Vet Med Assoc 2003;223(1):73–7. 2. Wylie KB, Hosgood G. Mortality and morbidity of small and large intestinal surgery in dogs and cats: 74 cases (1980–1992). J Am Vet Med Assoc 1994;30:469–74. 3. Grimes JA, Schmiedt CW, Cornell KK, et al. Identification of risk factors for septic peritonitis and failure to survive following gastrointestinal surgery in dogs. J Am Vet Med Assoc 2011;238(4): 486–94. 4. Allen DA, Smeak DD, Schertel ER. Prevalence of small intestinal dehiscence and associated clinical factors: A retrospective study of 121 dogs. J Am Vet Med Assoc 1992; 28:70–6. 5. Ellison GW. Wound healing in the gastrointestinal tract. Semin Vet Med Surg (Small Anim) 1989;4(4):287–93. 6. Coolman BR, Ehrhart N, Marretta SM. Healing of intestinal anastomoses. Comp Cont Educ Pract 2000;22(4):363–72. 7. Halpern NA, McElhinney AJ, Greenstein RJ. Postoperative sepsis: reexplore or observe? Accurate indication from diagnostic abdominal paracentesis. Crit Care Med 1991;19(7):882–6. 8. Fossum TW, Hedlund CS. Gastric and intestinal surgery. Vet Clin North Am Small Anim Pract 2003;33(5):1117–45, viii. 9. Swann H, Hughes D. Diagnosis and management of peritonitis. Vet Clin North Am Small Anim Pract 2000;30(3):603–15, vii. 10. Mueller MG, Ludwig LL, Barton LJ. Use of closed-suction drains to treat generalized peritonitis in dogs and cats: 40 cases (1997–1999). J Am Vet Med Assoc 2001;219(6):789–94. 11. Bonczynski JJ, Ludwig LL, Barton LJ, et al. Comparison of peritoneal fluid and peripheral blood pH, bicarbonate, glucose, and lactate concentration as a diagnostic tool for septic peritonitis in dogs and cats. Vet Surg 2003;32(2):161–6. 12. Szabo SD, Jermyn K, Neel J, et al. Evaluation of postceliotomy peritoneal drain fluid volume, cytology, and blood-to-peritoneal

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