Retrospective evaluation of the use of small‐bore wire‐guided catheters for the management of peritoneal effusion in cats and dogs

Abstract Objective To describe the use of small‐bore wire‐guided catheters in the management of peritoneal effusion in cats and dogs and to detail any associated adverse events. Design Retrospective study. Setting University teaching hospital Animals Forty‐five client‐owned animals that had peritoneal catheters placed for management of peritoneal effusion between July 2010 and June 2021. Interventions None. Measurements and Main Results Forty‐five cases were included (25 dogs and 20 cats). Twenty‐eight animals had the catheter placed to aid management of a uroabdomen, 8 of which recovered without surgical management, 11 had the catheter placed to allow autotransfusion of hemoabdomen, 3 had peritonitis, and 3 had ascites secondary to cardiac disease. Twenty‐seven cases (15 dogs and 12 cats) received sedation (n = 24) or local anesthesia alone (n = 3) to facilitate catheter placement, and 6 cases had the catheter placed while under general anesthesia. Median length of catheter persistence was 24 hours (range: 2–144 h). The most common adverse events reported were impaired drainage (n = 7) and leakage at the insertion site (n = 4). Conclusions Peritoneal catheters can be inserted percutaneously for management of peritoneal effusion. Indications include stabilization and conservative management of uroabdomen, and autotransfusion. They can often be placed with minimal or no sedation and adverse events appear infrequent in occurrence.


INTRODUCTION
Peritoneal drainage catheters are frequently placed surgically in cats and dogs for postoperative management of septic peritonitis, 1 uroabdomen, 2 and other inflammatory or exudative states. [3][4][5] In people, the use of percutaneously placed peritoneal drainage catheters has been described for management of urogenital tract rupture, 6,7 malignant ascites, 8 postsurgical peritoneal fluid, [9][10][11][12] post-laparoscopy peritoneal gas, 13 and intraabdominal or pelvic abscesses. 14 In veterinary medicine, percutaneously placed small-bore guidewire-inserted chest drains are predominantly used for the management of pleural space disease 15 including pyothorax, 16 but their use in the management of pericardial effusions has also been described. 17 These drains are placed by a modified Seldinger technique and generally do not require general anesthesia to be placed; they can be placed in conscious animals under sedation, with local anesthesia. 15 They can also be placed into the peritoneal cavity of dogs and cats, but this technique has not previously been described in the literature.
Various techniques for performing abdominocentesis have been described including with needles, intravenous catheters, and peritoneal dialysis catheters. 18,19 Abdominocentesis can be considered therapeutic when used to improve patient comfort or alleviate clinical signs associated with ascites such as tachypnea 20 or inappetence, 21 or where removal of the fluid carries other clinical benefits such as limiting peritonitis or preventing re-absorption of nitrogenous waste products, as in the case of uroabdomen. 22 If repeated or ongoing drainage is deemed clinically necessary, having a peritoneal catheter secured in place may be advantageous, allowing drainage to be performed by a single suitably trained person.
This retrospective study aimed to describe the use of percutaneously placed small-bore wire-guided catheters for the management of peritoneal effusion in cats and dogs, detailing indications, duration of use, and any adverse events seen.

STATISTICAL METHODS
All continuous data were assessed for normality by histogram inspection and descriptive data calculated as appropriate using commercially available software. b Mean (± standard deviation) is presented for normally distributed variables and median (range) for skewed data.

RESULTS
Fifty-two cases where a percutaneously placed, wire-guided peritoneal catheter was placed were identified. Five cases (4 cats and 1 dog) were excluded as the catheter was placed in order to facilitate peritoneal dialysis, not to manage peritoneal effusion. Two cases were excluded as they had peritoneal catheters placed to manage suspected uroabdomen; however, they were subsequently diagnosed with intrin-

Uroabdomen
Twenty-eight cases had a peritoneal catheter placed to aid the management of uroabdomen. Of these, 19 were cats and 9 were dogs. Eleven of the 28 uroabdomen cases did not undergo surgical management and the catheters were maintained in place for a median of 34 hours (range: 6.5-144 h). In 7 of these 11 cases, catheter production details were available for review and a median total volume of 32.6 ml/kg (range: 1.08-89.9 ml/kg) was removed on initial drainage. Subsequent drainage revealed a mean rate of fluid retrieval of 1.57 ml/kg/h (±3.38) and drainage took place every 2-8 hours.
Two cases had a closed collection system attached to the peritoneal catheter but specific details were unavailable for the remaining cases.
Catheters were removed due to cessation of urinary tract leakage (n = 8) (confirmed by positive contrast radiography study in 3 cases), cardiopulmonary arrest (n = 2), and euthanasia (n = 1). In the 8 cases that were successfully managed without surgery, the site of urine leakage was found to be the bladder (n = 4), the ureter (n = 1), or the urethra (n = 1). Leakage sites were not documented in 2 cases.

Hemoabdomen
Eleven peritoneal catheters were placed in cases with hemoabdomen.
Of these, 10 were dogs and 1 was a cat. The cause of hemoabdomen was neoplasia in 8 cases (3 splenic masses, 1 adrenal mass, and 3 hepatic masses), blunt trauma in 1 case, uncharacterized coagulopathy in 1 case, and post-ovariohysterectomy hemorrhage in 1 case.
All 11 cases had a peritoneal catheter placed for blood retrieval and autotransfusion purposes; autotransfusions were performed once in 8 cases, twice in 1 case, and 3 times in 1 case, and 1 case was euthanized before autotransfusion could be performed. The retrieved blood was processed with a cell salvage device c prior to autotransfusion of packed red blood cells (PRBC) (n = 9), or was directly autotransfused as whole blood collected from the drain into syringes with anticoagulant citrate phosphate dextrose adenine solution (n = 2).
In the 8 cases where it was documented, the median total volume of blood retrieved from the abdomen via the peritoneal catheter was Six cases underwent surgical correction of the hemorrhage, which took place on the same day as peritoneal catheter placement (n = 3), the following day (n = 2), or 3 days after catheter placement (n = 1).

Peritonitis
One dog had a peritoneal catheter placed to aid the medical management of spontaneous bacterial peritonitis with small volume effusion.
The catheter was used for drainage and then lavage on 2 occasions, being connected to a negative-pressure closed collection system in between saline instillations. On initial catheter placement, 0.1 mg/kg fluid was removed but drainage was positional and the catheter was removed after 24 hours. The dog recovered and was discharged successfully.
Two dogs had peritoneal catheters placed to manage postoperative effusions. One had the catheter placed as an intraoperatively placed, Jackson-Pratt drain was nonfunctional (after surgery to correct gastric dilation and volvulus). The peritoneal catheter was also nonfunctional and fluid was noted to continuously leak from the insertion sites of both the Jackson-Pratt drain and the peritoneal catheter. The peritoneal catheter was in place for less than 24 hours before the dog was euthanized. The other case had a peritoneal catheter placed to manage a large volume, nonseptic effusion and improve patient comfort after surgical repair of a perforated duodenal ulcer. This catheter was in place for 120 hours before the patient was euthanized due to a suspected pulmonary thromboembolism.

Cardiac ascites
Three dogs had a peritoneal catheter placed for drainage of ascites associated with right-sided congestive heart failure. On placement,

Antimicrobials
Ten

Adverse events
The most frequently reported adverse events were difficulties draining, or failure to retrieve fluid from the catheter (n = 6) ( Table 1). This was successfully managed in 3 cases (2 uroabdomen cases and 1 congestive heart failure case) where the catheter was either flushed with sterile saline (n = 1), repositioned within the abdomen (n = 1), or had a closed collection system attached (n = 1). In 2 cases (1 uroabdomen and 1 septic peritonitis case), the peritoneal catheter was unproductive despite the continued presence of peritoneal effusion, and the catheter was removed. In 1 uroabdomen case, a closed collection system was initially attached to the catheter at the time of placement; however, drainage was reported to be poor and manual drainage was performed successfully.
The second most frequent adverse event was leakage around the catheter insertion site in 3 cases (1 case each of uroabdomen, hemoabdomen, and ascites due to cardiac disease). The catheter was patent and functional in 3 of these cases and the leakage was managed as part of the patients' nursing care.
In 2 cases of uroabdomen, it was suspected that the presence of the peritoneal catheter was associated with local discomfort due to pain on abdominal palpation in 1 case, and aggression on abdominal palpation in the other case. However, this could not be definitively attributed to the catheter due to the underlying disease, patient temperament, and the presence of a local surgical site.
Difficulty placing the peritoneal catheter was noted in 1 case where the catheter was only successfully placed on the fourth attempt.
It is not clear in the clinical notes why the first 3 attempts were unsuccessful.

DISCUSSION
This study describes the most frequent indications for percutaneous placement of a peritoneal catheter at this referral hospital: management of animals with uroabdomen and hemoabdomen. Patients presenting with uroabdomen often benefit from medical stabilization prior to definitive treatment. 23 The treatment options for these patients depend on the site of urogenital tract rupture and the presence or absence of ongoing leakage. 4,[24][25][26] The most frequent indication for placement of a peritoneal catheter in this study was stabilization of patients with uroabdomen (n = 28), but in 8 of these, it provided successful urinary diversion, along with urinary catheterization, and served as definitive treatment.
The use of peritoneal catheters to facilitate autotransfusion has not been previously described. Typically, collection of blood for autotransfusion would be performed by needle paracentesis using a needle or butterfly catheter, 27 or intraoperatively using a suction device 28 or syringe. 29 Preoperative collection of peritoneal blood can allow patient stabilization without reliance on autologous blood products (which may be expensive or difficult to source). The use of a peritoneal catheter may enable faster drainage compared to needle paracentesis and it could be hypothesized that hemolysis due to shear injury would be decreased. It may also aid the maintenance of sterility as the need for repeated percutaneous puncture would be removed.
In this study, 3 catheters were placed to manage fluid accumulation in dogs with peritonitis. This practice is described in people 10-12 and in veterinary medicine for postoperative care in animals, 1,30,31 but a benefit to their use cannot be inferred from this study. The peritoneal catheters in these cases seemed to be used to retrieve existing inflammatory or infective fluids where that was deemed beneficial by the attending clinicians.
Another indication for the placement of a peritoneal catheter is to manage large-volume ascites and the associated increase in intraabdominal pressure and discomfort. 32 Symptoms such as respiratory difficulty, abdominal pain, and restricted mobility have been reported in people due to increased abdominal pressure. 10 38 These thoracostomy tubes had a diameter of 20 Fr and were therefore significantly wider than the 14-g catheters used in this study. The use of small-bore catheters is recommended in people due to lower rates of infection, as well as fewer insertional complications, when compared to larger bore drains. 17 Further research into rates of insertion site infection and peritonitis associated with the use of small-bore peritoneal catheters could be warranted if they are used longer term.
Leakage at the insertion site has been reported to occur more frequently in percutaneously placed catheters (20.5%) when compared with surgically placed catheters (6.8%) in people. 38 This study has demonstrated that 6.7% of cases leaked, which can be considered a reasonably low frequency. Furthermore, a similar rate of failure of placement was observed in this study (2.2%) compared to that in people (2.6%). 38 The retrospective nature of this study means that it is not possible to accurately capture and describe the clinical decision-making process used in the management of cases described. The placement and removal of the peritoneal catheters were at the clinician's discretion, and it is also possible that there may have been unreported adverse events. It was often not possible to determine the technique used when draining the peritoneal catheters. Future questions to interrogate would include whether the peritoneal catheters expedite stabilization or confer a benefit in patients with uroabdomen if urinary diversion is achieved by other means, such as urethral catheterization. Infectious complication rates are perhaps best assessed by prospective evaluation of peritoneal catheters indwelling for longer periods than those described here. Direct comparison of hemoabdomen blood collection by peritoneal catheter with other techniques, including evaluation of sampling artefact, volume collected, and ease of collection, may also be considered.
In conclusion, the placement of peritoneal catheters may be considered for single timepoint or ongoing removal of peritoneal effusions. In cases where repeated abdominocentesis or continuous drainage may be required, or where patient temperament is challenging, the placement of an indwelling peritoneal catheter may improve patient comfort as well as allow more frequent and complete drainage of the peritoneal cavity without chemical restraint. Although adverse events were noted associated with percutaneous peritoneal catheter placement and use, these were easily managed. These catheters offer a minimally invasive therapeutic option in cases of uroabdomen that are amenable to conservative treatment, or for autotransfusion purposes.