Gas-gangrene presents itself under three different forms: the septicaemic type, the grave local type, and gas-cellulitis.

(a) The septicaemic form is particularly frequent in fractures of the femur with serious muscular laceration.

After a few hours the patient has nausea and vomits. He is agitated. The pulse is rapid, small, indistinct. However, the patient does not yet complain of great pain in his limb, and there is little gas to be discovered. This appears, clinically, several hours later than the general phenomena. Death comes before the limb has had time to necrose. Amputation is urgent, to have even a feeble chance of saving the patient's life.

{b) Local gas-producing infection, which does not act at the very outset on the patient's general condition, if suitable treatment be adopted, is the most frequently recovered from. Two principal forms may be distinguished, superficial and a deep form. The superficial gangrene evolves chiefly in the sub-cutaneous cellular tissue. Gas rapidly spreads, far from the site of trauma. Open-ing-up shows that cellular tissue almost alone is invaded, and that muscles are not gangrenous, save in the immediate neighbourhood of the wound. This form is fairly benign. Numerous incisions implicating at the same time both the skin and the superficial fascia are made wherever crepitation can be felt. Tubes are placed in each incision.

Deep gangrene involves more particularly the muscles. Pain and agitation are often the earliest symptoms. Pain extends in the direction of the trunk, along muscular sheaths. It is the path which the infection itself has followed. If the limb is not yet completely necrosed, it is needful, after having set free the muscles attacked, to open up vascular sheaths. When the muscles of the calf are attacked, the femoral sheath should be incised between Scarpa's triangle and Hunter's canal. Finally, all around the limb are made incisions about ten centimetres (four inches) long, including both skin and fascia. This local form may call for amputation. If muscles are found to be gangrenous, and in addition the vessels obliterated, it is prudent to remove the limb.

Amputation is practised at a short distance from the seat of injury. Moreover, the vascular sheath must be laid open, in order to make sure that infection has not already invaded it. The stump is left quite open. A tube, perforated with small holes in its middle third, is placed loop-wise on the stump (Fig. 51). At the same time, instilling tubes are placed in the vicinity of the vascular sheaths. After an amputation of the thigh, three tubes are used - for the internal saphenous, the femoral vessels, and the profunda.

(c) Localised Gangrene. - This is a benign form of gas-producing gangrene. It is often found localised in a muscular sheath. For example, it may be limited to the anterior muscles of the leg, or the peroneal muscles. It may even affect only part of a muscle. To lay it open freely will suffice, the incisions extending beyond the lesion in every direction. Then the instillation tubes are placed in position, care being taken to lead them into muscular interstices and into the muscles themselves. The course of local gas-gangrene, under the influence of hypochlorite of soda, is very favourable. Swelling and redness disappear, the junction of the limb with the trunk remains supple and free from oedema, the patient is no longer in pain, and his general condition is excellent. Elimination of mortified tissues takes place very quickly, because hypochlorites dissolve necrosed muscle. Often by the seventh day, there is no longer a trace of gangrenous tissues.

A still more benign form of gas-producing infection exists, gas-abscess. A simple incision will suffice.

2. Phlegmonous Form. - The clinical aspects of the phlegmonous form are extremely varied. Reticular lymphangitis may be seen around a superficial wound, or a line of inflammation of a lymphatic trunk extending to the proximal extremity of the affected limb, or a serious local inflammation with redness and great swelling of the limb, or slight inflammation coincident with a grave general condition. In the case of lymphangitis of either variety, the wound is sterilised by Dakin's solution, and a hot fomentation applied over the limb. If a lymphangitic abscess should form, it is incised and the cavity sterilised by Dakin's solution.

When the muscles are concerned in the injury, and the phlegmonous inflammation extends to the whole thickness of a muscle-group, it is necessary to lay open the focus of inflammation, and also the intermuscular spaces in which the infection is being produced (generally due to haematoma). But surgical interference should be limited to this. It is not wise to seek for projectiles or foreign bodies, nor to remove the splinters from a seat of fracture. In these highly infected wounds, meticulous exploration is more dangerous than useful. The seat of fracture is kept freely open, and into every diverticulum is inserted an instilling tube. It is dangerous to use the scalpel to wounds from which blood-stained serum is coming. An attempt must be made, in the first place, to lessen the infection by antiseptic treatment. If a tube instilling hypochlorite can be introduced into the track resulting from a previous operation, it is well to be content with this therapeusis. Perhaps it may be needful to lay open a wound still more freely in order to introduce the tube which will supply the antiseptic liquid. Then an incision is made in which one or two tubes are placed quite in the bottom of the track, without further traumatism of the tissues. At the same time, rigorous immobilisation of the limb is insisted on.

To resume, the treatment of a patient with a phlegmonous wound differs from the treatment of a case in the pre-inflammatory stage. Preventive therapeusis of infection calls for minute surgical cleansing, which at that stage of infection presents no danger. But when, on the contrary, infection is well established in a wound, it is necessary in the first place to check it by the simplest means at hand, and to postpone to a more favourable opportunity the surgical treatment called for by anatomical lesions and the presence of projectiles.