Drains and draining

The purpose of a drain is to let blood, pus, or other fluids escape from a wound while it heals, without letting bacteria get in. Blood or pus will flow through a tubular drain or round a solid one. You will have to use a tube to drain a patient's gut, his bladder, or his pleural cavity (6.1), but when you drain a wound or his peritoneal cavity you have a choice. You can let the exudates flow down a tube, or you can let them seep away round the edge of a corrugated rubber drain. If you have the equipment for suction drainage, you may be able to suck them away. Suction drains are much more effective than corrugated ones, especially if bleeding is expected.

Not all wounds need drains, and drains have their risks: (1) Bacteria may enter from outside, especially if nursing care is poor. The risk of this is small if you use a closed drainage system and your nurses are good. (2) Bacteria may come from inside a patient and infect the tissues through which the drain passes, particularly the abdominal wall. (3) A drain may erode a vessel or a suture line, especially if you leave it in for a week or longer.

If possible, insert a tube drain with a tight seal to the tissues through which it passes, usually the abdominal wall, and lead it into a bag or bottle. There will be less soiling of the dressings and less contamination than with a corrugated rubber drain. Unfortunately, if a tubular drain blocks, it can seal infection in, so that some surgeons prefer corrugated rubber ones.

The modern trend is not to insert a drain unless there is a good reason to do so. So don't drain all wounds routinely[md]insert a drain when the advantages outweigh the risks, and follow the instructions we give for each procedure: (1) Where possible (see above), try to use a tube which will lead the exudate safely into a bottle, rather than a piece of corrugated rubber which will lead it into dressings. (2) Try to place the drain at the bottom of the cavity to be drained, so that exudate can easily flow out downwards. (3) Make it follow a straight path. (4) If a drain is in any danger of falling out, stitch it in as it passes through the skin. (5) Don't try to drain the whole peritoneum in peritonitis[md]it is impossible anyway. Instead, wash out the peritoneal cavity and instil tetracycline (6.2). (6) Finally, be sure to explain to the ward staff why you have inserted a drain, how they are to manage it, and when they are to remove it.

TUBING, red, rubber sterilizable, 2 mm wall, (a) 10 mm bore, (b) 15 mm bore, ten metres only of each size. This is multipurpose tubing, the 10 mm size is for draining air and blood, the 15 mm size is for pus. The firmness of the wall of a drainage tube is important. The tube from a chest drain should be firm enough to ensure an open pathway through the chest wall. The abdominal wall is less likely to pinch a drain closed, so a firm drainage tube is less important. If necessary, use a large bore catheter.

TUBING, drainage, Penrose, assorted sizes, five metres only. A Penrose drain is a soft latex tube 1 to 2 cm in width and of varying length filled with a wick. Being soft it is unlikely to injure neighbouring structures, but because it is soft, it needs an exit opening of adequate size. Cut these drains in suitable lengths and widths as needed. Don't rely on them for draining deep spaces, such as the subhepatic space. Some surgeons think Penrose drains inefficient because they don't keep the wound open.

DRAIN, corrugated red rubber, sheets 1[mu]50[mu]300 mm, ten sheets only. Pus drains between the corrugations. Cut the sheets to make drains of various shapes and sizes. Don't discard used sheet rubber drains[md]wash them, boil them, and store them in antiseptic solution (2.5). For tiny drains, cut up old intravenous sets or gloves.

SUMP DRAIN, rubber or plastic, five only. In an ordinary drain the holes through which fluid is sucked frequently block. A sump drain overcomes this difficulty by having two tubes, an outer one with many holes in it, and an inner one through which fluid is sucked. Fluid trickles into the outer tube and is then sucked away down the inner one. Ideally, suction down the inner tube needs to be applied with a low pressure pump. There should also be a single hole in the inner tube close to the surface to prevent too high a pressure building up in the sump. There are many kinds, and you may be able to improvise one. A sump drain is particularly useful for draining large quantities of fluid from fistulae or a large localized abscesss in the peritoneal cavity. Alternatively, use a folded catheter. Suck through one end and let air enter through the other (E, Fig. 4-12).

DRAINS [s7]AND DRESSINGS See elsewhere for underwater seal drains (65.2), intercostal drains for empyemas (6.1), and also drains for the abdomen (9.8), the urinary bladder (23.5 to 23.7) and the gall bladder.

If dressings are in short supply, wash the patient's wound with unsterilized salt solution (equal to half or full strength saline) 2 to 4-hourly and cover it with a dressing towel. See also 1.12.

LEAVING WOUNDS OPEN POSTOPERATIVELY, where you can, is a useful economy. Do this if a wound is not going to discharge. If it oozes a little, put a thin dressing of gauze or whatever you have on it for 24 hours.

LAYERS OF GAUZE AND COTTON WOOL will collect the discharges from a wound which is too shallow to let you insert a rubber drain, as in A, Fig. 4-12. Change these dressings frequently. If necessary, place a sheet of plastic or waterproof paper between the outermost layer and the patient's clothes.

INDICATIONS FOR DRAINAGE. (1) To allow the escape of blood when the control of bleeding after an operation has been incomplete. (2) To complete the drainage of an abscess cavity. (3) To drain an abscess or a local area of peritonitis (draining generalized peritonitis is impossible, see above). (4) To permit the escape of secretions from a possibly leaky suture line, for example when you have removed a stone from the ureter (23.14) or anastomosed unprepared large gut which cannot be protected by an ostomy, as when ileum is anastomosed to transverse colon.

HOW TO PLACE DRAINS. Where possible, insert a drain through a separate stab wound; if you drain pus through the main wound, it is more likely to become infected. Make sure the drain lies loosely in the cavity to be drained and follows the shortest path from the site to be drained to the exterior.

To avoid cutting blood vessels, cut only the skin with a scalpel, use a haemostat to poke a hole through the abdominal wall and then use the haemostat to push the drain through the hole.

CAUTION ! If you are draining a possibly leaky suture line, place the drain close to it but not actually touching it, or the drain may help to disrupt the sutures. Ideally, there should be no such thing as a ''leaky suture line'[md]it should not have been made so that it does leak, or if it looks like leaking, it should be made again.

CORRUGATED RUBBER DRAINS are useful for abscesses. Cut more than an adequate hole in the superficial tissues, cut a strip of rubber to fit loosely and push this into the depth of the wound (B, Fig. 4-12). Don't make the hole for the drain so small so that it is tight (C). Use a cutting needle to transfix it with a suture and anchor it to the skin, then tie the ends of the suture several times. When you shorten a drain, you may be able to leave a loop of suture material securing it. A safety pin will prevent it slipping inside the wound, but will not prevent it slipping out.

If there is severe sepsis, as in a septic Caesarean section or a typhoid perforation, make an adequate muscle cutting incision[md]large enough to take three fingers side by side. Using a scalpel, cut all layers of the abdominal wall in the line of the incision. Control bleeding with a gauze pack. If any bleeding vessels remain after 5 minutes, tie them. Even when the corrugated drain is in place you should still be able to get two fingers into the wound.

TUBE DRAINS are useful in large wounds where you expect much exudate, or in areas of infection or oozing (D). They are especially useful in the abdomen (E). Have two or three sizes of drainage tubes ready sterilized with suitable adaptors. Use silicone rubber or polyethylene, rather than red or latex rubber, which is more irritant.

TO INTRODUCE AN ABDOMINAL TUBE DRAIN try to fit a wide bore tube tightly in a small hole. Make a small incision in the skin. Use a 10 mm (30 Ch) tube, and cut side holes in the end. Make a small hole in the tissues and ''railroad' the drain in as in G, to J, Fig. 4-12. Anchor the drain to the skin with a suture. Insert a skin stitch, tie a second reef knot distal to the first one and then tie the ends of the suture round the drain with a surgeon's knot (L). Finally, tape the drain to the skin. Connect it to a sterile bottle.

CAUTION ! (1) Don't put any drain through the main incision. If it is a tube drain you will not be able to make a good seal round it, and it will make an incisional hernia more likely. (2) A tube drain which blocks is useless.

SUCTION DRAINS are ideal, especially the disposable plastic kind. More practical are the reusable ''Redivac' suction bottle type, which have disposable drainage tubes.

SUMP DRAINS (see above) are useful if you have a suction pump and you want to drain fluid, such as urine, or pancreatic juice which is welling up from the depths of a wound.

THE TIME TO REMOVE A DRAIN varies with the fluid to be drained. Here are some guidelines:

Draining blood[md]48 to 72 hours.

Draining down to a suture line[md]5 to 7 days.

Draining a septic cavity[md]until pus ceases to flow, usually in 5 to 7 days.

Don't leave a drain in longer than is necessary, because you run the risk that it may erode a vessel. There is seldom any need to leave a drain more than a week at the most, except in a very large deep abscess, as in the subphrenic space, where you may need to leave one in for 10 days. If you remove a drain too early, pus may build up and seek to discharge itself elsewhere.

If a drain is long, shorten it progressively over several days before you remove it. Shorten it by pulling it out, not by cutting it off. Place a safety pin through it and tape this to the patient's skin.

Fig. 4-12 DRAINS. A, in a superficial wound pus can drain into the dressings. B, a corrugated drain should usually consist of several corrugations and fit loosely through an incision in the superficial tissues. C, Don't push a drain tightly through a small incision. D, a chest drain (65-6). E, a sump drain. F, draining the bladder. G, to L, introducing a tube drain into the abdomen. G, making the incision. H, inserting the first haemostat. I, ''railroading' the second haemostat through. J, the second haemostat pulling a drainage tube through. K, holes cut in the end of the drainage tube. L, the drain sutured in place and the abdominal wall closed.