Drainage refers to inducing, decompressing, and draining fluid, exudate, transudate, blood, pus, etc. trapped in the animal's subcutaneous, thoracic, abdominal and other cavities to the outside of the body.

When implementing drainage, it is necessary to correctly select, set up and manage the drainage tube according to the purpose, which is very important for effective drainage. Successful drainage can shorten postoperative management time and thereby reduce the pain of the animal.

In this article, various drainage tubes for small animals will be introduced, divided into general chapters (general knowledge) and individual monographs (incision and layout, abdominal and thoracic drainage, and tube feeding).

General knowledge of traffic diversion

Although drainage is often used during surgical procedures and after surgery, this article will provide an overview of the purpose, principles, and methods of drainage. During surgical treatment and after surgery, the animal owner will directly observe the catheter. The veterinarian should explain the setting of the catheter, the time of extubation, etc., so that not only can the postoperative management be carried out well, but also the patient can be maximized. Reduce the anxiety of livestock owners.

Classification and application of traffic diversion

1. Therapeutic drainage

It is to remove secretions (exudate, leakage, blood, fluid, etc.) and air from the pig under the skin of the animal after surgery, in the chest or abdominal cavity, in order to promote wound healing. Special drainage includes biliary drainage performed to alleviate acute cholecystitis and yellow fever when it occurs, and intraperitoneal drainage during peritoneal dialysis. Drainage can also be used when intradermal or subcutaneous swelling, hematoma (accompanied by infection), perimenal swelling, peritonitis, pericardial tamponade, pleural effusion, pneumothorax, etc. occur.

2. Preventive drainage

If it is predicted that blood, exudate, humidifying fluid, or air will remain in the chest or abdominal cavity after surgery, preventive drainage can be performed. Preventive drainage is suitable for various incisions, thoracotomy, and laparotomy. It can be used if the wound healing is slow due to infection at the surgical site, malnutrition, diabetes, liver disease, long-term administration of steroids, etc.; lobectomy or It is also applicable when a large cavity is formed after liver lobectomy.

3. Diagnostic (information) drainage

After surgery, bleeding, incomplete suturing, infection, etc. may occur in the chest or abdominal cavity. In order to quickly diagnose and investigate these complications before they cause clinical symptoms such as fever and anemia, diagnostic drainage is often performed. The indications are the same as preventive subsidence. For surgical procedures with a high possibility of complications, drainage is performed at the site where complications may occur. After the purpose of installing a drainage tube in an animal is clear, it must also be understood by the postoperative manager. If it is a postoperative diagnostic drainage, a small amount of fluid discharge will not cause much problems; but if it is a therapeutic drainage, a small amount of fluid discharge may mean that the fluid is not drained and overflow occurs. Need to investigate the cause, and solve it.

Classification according to the principle of drainage

Drainage is divided into passive drainage that uses natural pressure differences, gravity, overflow, and capillary phenomena and active drainage that actively attracts by creating negative pressure. Passive drainage uses a drainage tube and gauze to connect the discharge end of the drainage camp to the outside, an open type, or a closed type, where the end of the drainage tube is connected to the liquid storage bag. Active drainage is also divided into a closed type that is connected to a continuous suction machine, and a semi-closed type that uses multiple tubes to send air and cleaning solution into the lumen, which is not commonly used in the field of small animal medical treatment (Figure 3).

Types of drainage tubes

The types of drainage camps include catheter type, membrane type, multi-lumen type, Shirley type, etc. (Figure 4). The advantages and disadvantages of various types of drainage camps are listed in Table 1. Although the catheter remains in the animal's body for a short period of time, ranging from a few days to dozens of days, the catheter material must not change elasticity and strength during this period of time and have strong anti-thrombotic ability. In many cases, it is necessary to confirm the position of the drainage tube in the body cavity, which requires the catheter to be X-ray impermeable or to have an X-ray impermeable marker.

1. Catheter type drainage (Tube Drain)

The material of the guide camp is silicone, rubber, etc., and there are single-hole type, wrinkle type, etc. It is often used for treatment and prevention purposes. It can maintain the shape of the inner cavity even under certain external pressure; liquids with high viscosity can also be discharged. It is mainly suitable for drainage of the chest and abdominal cavity. In addition, fluid can be injected and drained, making it easy to clean the lumen and drainage site. Single-hole catheters may bend, causing the lumen to become completely blocked.

2.Film type drainageCFilm Drain)

The soft sheet made of silicone mainly uses capillary action (the phenomenon in which an object containing fine pores comes into contact with a liquid, causing the liquid to rise, penetrate or fall along the pores) to fill the liquid remaining in the body. It is divided into Penrose type, film (flat plate) type and porous type, and is used to drain intracutaneous, subcutaneous and intra-abdominal fluids. The material is soft, easy to insert into complex parts, and causes less discomfort to animals. However, under pressure, the lumen will be blocked; blood clots, necrotic tissue, and viscous fluid will also block the lumen, causing flow failure. The film type (flat type) can be rolled up and used, and the thickness is easy to process and adjust.

3. Multi-lumen tube drainage (Sump Drain)

Although there is negative pressure in the lumen, it will not adsorb surrounding tissue. In order to enable continuous suction, the lumen structure has multiple structures, including double-lumen type and triple-lumen type (Shirley type). Although the animal's movement needs to be restricted, continuous inhalation is possible (Figure 5).

Methods of traffic diversion

1. Local incision and drainage

Local incision and drainage is the simplest way to place a drainage tube. It can be set up by incising the area that needs drainage. It is suitable for intradermal and subcutaneous abscesses or hematomas. Incision and drainage can be made from just above the affected area under local anesthesia or without anesthesia to promote the healing of the wound. Especially for perforated wounds caused by cat scratches, etc., this method is suitable for most cases where the wound heals early due to the rapid knotting, resulting in the formation of subcutaneous swelling (Figure 6).

2. Catheter drainage during surgery

This is the most common drainage tube installation method. After various surgeries are completed, settings can be made according to actual needs. All types of drainage tubes can be selected, and the drainage tubes can be accurately drained and fixed.

3. Drainage through puncture

If intrabody drainage is performed, blind methods or X-ray fluoroscopy and ultrasound devices can be used for positioning (Figure 7); compared with the aforementioned method of surgically setting a drainage tube, this method is less invasive to the animal, but the animal needs to be carefully restrained. and special equipment. In addition, the surgeon must have operating experience.

Complications of drainage

Complications of drainage may occur with the insertion (setting) of the drainage tube and the care after insertion. The former will cause inflammation, the infection will spread to the surroundings, the insertion channel will invade the tissue, etc. The latter will mostly cause the occlusion of the drainage tube, retrograde infection, detachment, breakage and dislocation of the drainage tube, etc. Especially when using a hard catheter, the catheter will pull the wound and cause discomfort to the animals. The animals will pull out the catheter due to the discomfort of the wound, causing wound infection. This requires wearing an Eliza collar to prevent it; in addition, it cannot Ignore the outflow end of the fixed catheter. The drained fluid is a good culture medium for bacteria, so the site where the drainage tube is set up must be kept clean to prevent retrograde infection in the wound and inner cavity.

(Figure 6-Ä)

(Figure 6-8)

(Figure 6) Subcutaneous eye swelling in a beagle dog (2 places), after incision and drainage, a Penrose-type catheter was installed (A is before surgery, B is after surgery). With active drainage, the exudate was discharged within a few days after the operation and the patient healed well.

(Figure 7) The ultrasonic inspection device is equipped with a positioning probe and the wire on the needle screen. After puncture, a drainage catheter is left in place.