Introduction

Abdominal drains have the ability to continually remove fluid from the abdominal cavity. After surgery, even if peritoneal lavage and surgical suction have been performed, additional inflammatory fluid accumulates and cannot be reabsorbed by natural peritoneal drainage. In addition, inflammation reduces the effectiveness of both the peritoneum and omentum (Sturgeon 2016). Therefore, placing an abdominal drain might be the best option to avoid fluid accumulation in the abdominal cavity.

The two main options for peritoneal drainage include open peritoneal drainage and closed suction drainage (Devey 2013).

The traditional method of open peritoneal lavage might be detrimental to protein levels and requires continuous patient monitoring. The use of an active-suction drain instead of an open technique allows more accurate measurement of the drained fluid without further debilitating the patient and takes away the need for a surgical approach to close the coeliotomy site (Sturgeon 2016).

Indications

Abdominal drains are often used in patients after surgical treatment of septic peritonitis as a method of evacuating peritoneal effusion and monitoring for evidence of ongoing infection or surgical site dehiscence. They can even be used after elective gastrointestinal surgery, especially in those patients with decreased wound healing capabilities. The most common causes of septic peritonitis are gastrointestinal perforation with food content leakage, abdominal trauma, necrotising pancreatitis, bile leakage, pancreatic, hepatic or splenic abscesses, rupture of pyometra or prostatic abscessation (Culp, Holt 2010; Goethem 2015). Abdominal drainage may be required after the underlying disease has been treated, but there are no guidelines as to whether the abdomen should be left open or not after surgery, and the decision lies with the individual surgeon.

Thus, the main goals of abdominal drainage are:

• Avoiding the accumulation of peritoneal fluid;
• Avoiding secondary increased intra-abdominal pressure;
• Removing bacterial contamination; and
• Monitoring fluid volume and characteristic changes that may predict infection or dehiscence.

Drain Selection

Drains may be passive or active. Passive drains rely on gravity, capillary action, natural pressure gradients or overflow to control gas/fluid outflow. An example of a passive drain commonly used is a Penrose drain. Drain efficacy depends upon its exit position. Passive drains are more often used in wound management.

Active drains create and rely on negative pressure (suction) to promote outflow of gas or fluid. The most commonly used tube for abdominal drainage is the Jackson-Pratt drain (Figure 1). The flat, white, silicone part is specifically designed to prevent occlusion of the fenestrations by abdominal structures (omentum).

Figure 1. Jackson-Pratt drain

The ideal drain should be soft, comfortable for the patient, inert, radio-opaque and non-reactive (Lanz 2011). Drains are typically made of latex, red rubber, polyethylene, polyvinyl chloride or silicone rubber. Polyethylene, polyvinyl chloride and silicone rubber are fairly inert (Goethem 2015).

Technique

The two main options for peritoneal drainage include open peritoneal drainage and closed suction drainage (Devey 2013). In cases where the source of contamination cannot be identified, contamination is severe or longstanding or the virulence of organisms is high, such as that seen with faecal contamination, open peritoneal drainage is advocated.

Open Peritoneal Drainage

Open peritoneal drainage is a process by which the linea alba and skin are left partially or completely open and covered with sterile dressings, which are changed at frequent intervals (Lanz 2011).

Open peritoneal drainage was applied in human patients in response to persistently high morbidity and mortality rates associated with gross peritoneal contamination.

After the abdominal procedure is completed, a portion of the abdominal incision is left open to drain, with the opening large enough to allow a gloved hand to be inserted (Fossum 2012). This technique is accomplished by loose simple continuous monofilament suture closure of the linea alba. Falciform fat is normally excised and omentum can be removed, but potentiation of peritonitis has been suggested with partial omentectomy. For ease of postoperative management, closure of the caudal third of the linea alba is recommended. The cranial two thirds of the wound are left opened and this is covered with sterile bandages. Urinary catheterization with a closed collection system is recommended to prevent urine contamination of the bandage (Fossum 2012; Kirby 2012).

The main advantages of open peritoneal drainage are that it allows unimpeded drainage of fluid and exudate from the peritoneal cavity, effective removal of excessive amounts of fluid, easier access for re-exploration of the peritoneal cavity, creation of an environment unfavourable to anaerobic bacteria, increased efficiency of removal of bacteria, foreign material and inflammatory mediators from the peritoneal cavity, improves metabolic status and decreases abdominal adhesion formation (Culp, Holt 2010; Lanz 2011).

Disadvantages and/or complications of this technique are protein loss, electrolyte abnormalities, fluid loss, evisceration risk, adhesion of the abdominal viscera to the bandages, contamination of the abdominal cavity with cutaneous organisms. Apart from these, there is always a high risk of nosocomial infections and all efforts should be made to avoid this (Culp, Holt 2010; Kirby 2012).

Closed Suction Drainage

A variety of different drain materials and types have been experimentally and clinically used in patients with septic peritonitis (Kirby 2012).

Closed gravity dependent drainage is reported to be ineffective because of the creation of a vacuum. Sump-tube drainage provides an air vent to overcome this vacuum phenomenon but also allows airborne bacteria access to peritoneal cavity. Filters have been added to sump drains to eliminate this airborne route of contamination (Kirby 2012).

At surgery, a drain, e.g., a Jackson-Pratt drain, is placed into the abdomen before closure. Small dogs and cats will only need one drain placed between the liver and diaphragm whereas large dogs may require a second drain into the caudal ventral abdomen. Drain(s) exit(s) through the body wall via an incision and is/are sutured to the skin of the abdominal wall with a roman sandal suture. The abdomen is routinely closed and the suction reservoir bulb is attached to the tubing and a vacuum applied. Then, a sterile protected bandage is placed around the tube-skin interface. The bulb should always be handled and emptied using aseptic technique and the volume of fluid recorded. The drain is removed by cutting the suture and applying gentle traction (Fossum 2012).

The closed suction technique is much more effective, allowing accurate measurement of the amount of fluid drained and minimizing morbidity.

The main disadvantage of this technique is that drains may become occluded. Fluid that is more serous in nature may be best managed by closed suction drainage, whereas fluids that are exudative in nature may occlude the drain. In this case, open peritoneal drainage is a better option (Fossum 2012). Other disadvantages include ineffective drainage of the entire peritoneal cavity and nosocomial bacterial contamination of the peritoneal cavity even when a filter is added (Kirby 2012).

After Care and Maintenance

Drains should be handled in a strict aseptic manner and all drains should be protected by a bandage (Fossum 2012).

With open abdominal drainage, the bandage should be changed once daily or more frequently as necessary to prevent moist bacterial strike-through. Omental adhesions to the open wound can be gently disrupted with a sterile gloved finger to facilitate drainage if needed. The bandage should be weighed at each dressing change to quantify fluid loss in the peritoneal effusion (Kirby 2012).

When a drain is placed, the drain, tubing and skin exit site should be kept clean and inspected several times daily for evidence of contamination or damage to the drain system. The frequency of emptying the reservoir will depend on the volume of abdominal effusion produced; highly effusive peritonitis patients could require drainage every 2–4 hours depending on the size of the reservoir (Clarke, Winkler 2017).

Proper hygiene is essential for drain handling, including gloves and preventing contact with the reservoir and container being used for fluid collection and quantification (Clarke, Winkler 2017).

Removal of Drain

Retrospective studies report a duration of open abdominal drainage from 1 to 9 days, with a mean duration of 4 days. However, duration of open peritoneal drainage up to 14 days has been described (Kirby 2012).

When a drain is placed, it should be removed as soon as possible in order to reduce the risk of bacterial colonization. The longer it is kept the higher the risk. The decision to remove the drain is based on the quantity and type of drained fluid. The decision for removal is made when the amount of fluid decreases and reaches a plateau, while turning increasingly serosanguineous. Serial cytology can be performed to evaluate the characteristics of the fluid (Goethem 2015; Lanz 2011).

Drains should be left in place until the fluid amount being produced is within the physiologic limits (1–2 ml/kg/day) and its cytology shows no signs of active inflammation or infection (Devey 2013).

Conclusions

Based on the current human surgical literature, definitive need for abdominal drainage has not been proven and may contribute to longer hospital stays and postoperative complications (Clarke, Winkler 2017). While similar conclusions cannot be drawn from the current veterinary literature, closed suction abdominal drains appear safe for the management of septic peritonitis but have limited value to predict infection or dehiscence (Clarke, Winkler 2017).

References

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