Introduction

Subcutaneous closed suction drains are widely used in human and veterinary medicine for wound and postoperative surgical site management.^1,2 Closed suction drains allow evacuation of necrotic tissue, bacteria, inflammatory mediators or serous fluid from an enclosed space which may help prevent infection, delayed healing and discomfort.²

Closed suction drains comprise a plastic or glass reservoir to store fluid produced from the cavity and a silicone drainage tube with fenestrations at the distal end.^1,3 Active closed suction drains employ a suction generating reservoir to actively pull fluid through the drainage tube.¹ These are reported to be superior to passive drains because the suction effect results in better apposition between tissue surfaces for healing and carries a lower risk of introducing nosocomial infection.^3,4

Closed suction subcutaneous drains are commonly used in human medicine for procedures such as radical mastectomy, and total hip and knee arthroplasty.^5–7 It is common practice for patients to be discharged with continued postoperative drain management at home prior to removal.⁶ In prosthetic breast reconstruction procedures, closed suction drains are removed at day 7 postoperatively or if the drain fluid is less than 30 mL within a 24-hour period.^6,7 In total knee and hip arthroplasty procedures, drains are removed as early as 24 hours postoperatively; most (91%) drain production occurs within the first 24 hours, and drain placement > 24 hours is associated with an increased degree of contamination.^4,7 In human medicine, additional reported benefits of early drain removal include decreased dressing-associated costs, lower risk of scar-formation, decreased drain-associated discomfort and accumulative anxiety leading up to drain removal.⁶

Animals in veterinary medicine are typically not discharged from hospital until removal of closed suction drains due to the risk of premature dislodgement or removal, inaccurate drain production quantification, as well as owner difficulty managing drains at home.^2,8 Despite drain removal being a requirement for discharge in many veterinary facilities as reflective of current literature,^9,10 the timing of drain removal is still highly debatable and is dependent on practitioner experience and preference, drain production trends, type of drain, size of cavity and the weight of the animal.^2,8 There is a reported reduced incidence of seromas when drains are removed at a production rate of less than 0.2 ml/kg/h.⁹

As a result, animals are often hospitalized for long periods of time solely due to the presence of a subcutaneous drain.^2,10 Prolonged hospitalization is associated with increased cost¹¹ and increased risk of nosocomial infection,¹² therefore, discharging an animal with ongoing drain management at home may expedite hospital discharge and help to mitigate such risks. In human medicine, outpatient drain management is commonplace to reduce the duration of hospitalization.¹³ To date, there is little information in veterinary medicine regarding postoperative management of subcutaneous drains in the outpatient setting and associated complications.

The objective of this study was to retrospectively describe and compare intraoperative and postoperative complications reported in a cohort of dogs and cats that had an active closed suction subcutaneous drain surgically placed and were either managed completely in the hospital setting (drain removed prior to discharge) or discharged home for ongoing outpatient care (drain in place at time of discharge). We hypothesized that the risk of complications associated with being discharged home with a closed suction drain in place would be minimal and not significantly different compared with animals having drains removed prior to discharge from hospital.

Materials and Methods

Results

Discussion

To the authors’ knowledge, this is the first retrospective case series comparing perioperative and postoperative complications in a large number of dogs and cats that had an active closed suction subcutaneous drain surgically placed and were either managed completely in the hospital setting (removed prior to discharge, Group ND), or discharged home with drain for ongoing outpatient care (drain in place at time of discharge, Group D).

In this study, being discharged home with a subcutaneous drain in place (Group D) significantly increased the odds of experiencing drain-associated complications compared with having a drain removed prior to discharge (P = .001). The majority of reported complications were classified as minor, including drain dislodgement, wound dehiscence, seroma formation, recurrent swelling and wound discharge, difficulty managing drains at home or surgical site infection, which either self-resolved with time or were easily managed with antimicrobials and repeat bandaging.

The complication types and rates of minor complications in this study (29%) are in close agreement with a previous veterinary closed suction drain study² that reported minor complication rates between 33.8% and 35.3%. That particular study² examined drains managed only in the hospital setting, and not managed in the outpatient situation. Therefore, although there was an overall comparable rate of complications, their rate of complications for drains managed in hospital was much greater than this study. The discrepancy could be secondary to strict asepsis and effective management protocol in our hospital. It is also possible that some minor complications in Group ND were underrepresented in our study. The majority of reported drain complications observed in Group D were minor in nature, such as drain dislodgement, difficulty managing the subcutaneous drain at home and discharge around the drain site; therefore, it is possible that less severe complications may not have been recorded by the hospital staff in Group ND experienced in managing subcutaneous drains as they would have been perceived as insignificant.

No veterinary studies report specific risks associated with subcutaneous drains managed in the outpatient setting as a comparison. The risks of outpatient subcutaneous drain management is significantly lower in humans, with a minor complication rate of 5.6% to 9.6% which include seroma formation, local erythema and surgical site infection.^19,20 This could be related to a standardized and longer-established drain management protocol set in place by human hospitals and better compliance with patients managing their own drain versus owners having to manage their pet’s drain where unexpected incidents may occur despite good owner compliance.

We also reported similar rates of major complications (n = 5) to previous veterinary studies.² Major complications may have been overrepresented in our study. It was challenging to determine if reported complications were directly correlated to the presence of the subcutaneous closed suction drain. For example, the dog with reported tumor recurrence may be related to the type, grade and resected margins of the mass rather than the presence of the drain harboring neoplastic cells leading to contamination of the incision site.²¹ The dogs that developed surgical site dehiscence may have been secondary to tissue necrosis from inciting trauma or surgery, or poor owner compliance in imposing strict exercise restriction, rather than the drain itself.

Despite the increased risk of minor complications seen in our study associated with having a subcutaneous drain managed in the outpatient setting, benefits were experienced in this group. In this study, we found that animals discharged with subcutaneous drains in place (Group D) were hospitalized for a significantly shorter duration, compared with animals that had drains removed prior to hospital discharge (Group ND). Although not examined directly in this study, from previous literature,^6,22 it can be extrapolated that earlier discharge from hospital would be associated with a considerable reduction in the overall cost of hospitalization. For owners with financial constraints, earlier discharge from hospital may allow them to proceed with the recommended treatment plan without sacrificing the benefits of a subcutaneous drain. Furthermore, longer hospitalization can increase animal stress and anxiety, and requires additional hospital personnel and resources.^23–25

Interestingly, despite the longer median duration of drain placement in Group D (5.6 days vs 3.1 days), there was no association detected between the duration of drain placement and the risk of complications. This finding suggests that the increased risk of complications in Group D is more likely the result of outpatient-specific factors or drain management itself and is not associated simply with the risk of longer drain duration. In human medicine, patients with a closed suction drain are discharged with instructions for frequent showering, washing the drain exit site before and after emptying, and recording the volumes drained.¹⁹ In veterinary patients, regular cleaning and maintenance of the drain site is more challenging, particularly in the outpatient setting, secondary to increased environmental contamination, difficulty keeping the drain site clean, non-trained personnel, and decreased animal compliance. This may have increased the risks of drain site contamination and infection in the outpatient setting.

Veterinary patients also carry the added risk of self-trauma. The risk of premature drain dislodgement or disruption in the outpatient setting was found to be low (n = 5/77), with only 1 dog requiring replacement of their subcutaneous drain. Fortunately, the majority of animals that dislodged the drain at home either did not have to have it replaced or dislodged the drain in its entirety, therefore additional surgical intervention was not warranted. Despite the possible risks of self-trauma to the external drain components, it appeared that good owner compliance was achieved in the majority of cases based on the recommended treatment protocol.

Longer hospitalization periods have been associated with an increased risk of acquired nosocomial infections in human and veterinary studies.^{2,14,15,26,27} However, an increased risk of postoperative infection in animals hospitalized for a longer period was not supported in this study (P = .254). Group ND was associated with a longer duration of hospitalization (P = < .0001), but not an increased risk of postoperative infections. In fact, no postoperative infections were reported in this cohort. Furthermore, the rate of positive cultures collected intraoperatively at the time of drain placement was not statistically different between groups (P = .013), signifying that Group ND was not inherently less contaminated as a group to start. The lack of postoperative infections observed may be associated with a good hospital protocol with aseptic measures to minimize cross-contamination between animals and between the hospital environment and the animal.

Despite 45% of animals in our study having a positive bacterial culture at the time of surgery, the overall infection rate was low at 2%. This finding is similar to Reiffel et al²⁰ where 63.4% of patients that underwent plastic surgery with an indwelling drain placed had positive bacterial cultures, but overall wound infection rate was low at 5.6%.²⁰ This may be related to appropriate initiation of prophylactic broad-spectrum antimicrobial treatment intra- and postoperatively to reduce risk of wound-associated and nosocomial infections. Human studies have supported the use of prophylactic antimicrobials while subcutaneous drains are in situ.⁷

Interestingly, the degree of surgical site contamination did not increase the risk of complications in our study (P = .427). This was contrary to previous findings Carvalho et al²⁸ found that surgeries classified as clean-contaminated, contaminated and dirty/ infected exhibited an increase of 54%, 167%, and 105% respectively, in terms of chances developing a surgical site infection compared to clean wounds.^28,29 This could be due to good owner compliance and a standardized drain management protocol put in place. Further investigation is required to determine the efficacy of our study’s postoperative drain management protocol in reducing the risk of SSI.

There were several limitations of this study, primarily attributed to its retrospective nature. A number of animals were lost to follow-up (n = 11 short term and 18 long term). Their respective owners and referring veterinarians were contacted for records and information could not be retrieved. Some of the lost data may potentially cause a bias in the results obtained, and the number of complications reported may potentially be higher than described.

Drain fluid production volumes were not included due to a lack of data and non-standardized documentation in many patients with outpatient drain management. Although owners were instructed to record the drain volume at least twice a day (or more frequent if the reservoir was full), not all owners were compliant and recorded data when present, was frequently incomplete. This made it challenging to trend and quantify drain production throughout a patient’s disease course and at the time of drain removal. Such information may have provided valuable insight into increased causes of postoperative risks (ie, seroma formation, infection, wound discharge). For outpatients, owners were instructed to return at 3 to 5 days postoperatively and the decision to pull the drain was dependent on the owner’s subjective interpretation of drain production volumes at home. This may have resulted in some cases of either premature or prolonged drain removal. At home drain production interpretation was likely much more challenging to interpret than in the hospital setting by trained veterinary hospital staff.

Not every surgical site was cultured for the presence of microorganisms. The decision to perform culture and sensitivity was dependent on its class of contamination. Dogs and cats with traumatic wounds had culture samples performed due to the level of perceived contamination of the surgical site (ie, Class IV – infected/ dirty), whereas most animals undergoing elective tumor/mass excision did not have cultures performed due to a perceived cleaner surgical classification (ie, Class I). Despite this assumption, there are animals with fast growing tumors which may develop secondary infection of the tumor/surgical site prior to surgery due to self-trauma from irritation or discomfort caused by the tumor. Culture and sensitivity results should have been performed in all patients to reduce bias and to obtain a better representative sample. Some animals were also prescribed antimicrobials prior to the procedure, which may have affected culture and sensitivity results.

Last, it is also possible that more complicated wounds were more likely to be managed in hospital than on an outpatient basis. This selection bias may have caused the complication rate reported in Group D to be proportionally much higher than Group ND, and the majority of complications reported in Group ND to be minor.

In conclusion, this study found that there was a higher risk of complications discharging an animal home with a subcutaneous active closed suction drain versus removing the drain prior to discharge. These complications, however, are considered minor and are either easily managed medically or do not require additional treatment. The complications associated with discharging an animal home with a drain should still be discussed with the owners prior to discharge. There was no difference between the degree of surgical site contamination and the risk of developing complications associated with SSI. Duration of hospitalization is significantly shorter when animals are discharged with continued drain care at home. The decision to discharge a stable animal home with a drain should ultimately depend on the temperament of the animal, owner compliance in terms of management and return for follow-up, as well as the additional comorbidities of the animal.

Supplementary Materials

Supplementary materials are posted online at the journal website: avmajournals.avma.org