Introduction and epidemiology
Penetrating missile wounds, injuries from blast phenomena and burns are the typical features of modern conventional war. This chapter is concerned only with missile wounds and blast injury. Missile wounds are caused by bullets or by fragments from exploding shells, mines or bombs. Exposure to blast phenomena may result in unique and complex injury patterns, and these will be described.
There is a wealth of data on the cause and distribution of wounds in wars over the last 30 years. Care is needed in interpretation as the number of wounded varies greatly in each series. For example, Vietnam data cover over 17 000casualties. In contrast, Gulf war data are restricted to 63 casualties, Inclusion criteria are also very variable and many fail to record multiple injuries to different body systems in single casualties — the hallmark of modern war injury. While care is needed in interpreting the available data, some broad statements concerning war injury can be made. The most common wounding agent in surviving casualties is a fragment wound, not a bullet wound as many erroneously believe. Limb injuries predominate, pointing to the high lethality of hits to the trunk and head. The most startling revelation is the emerging incidence of multiple hits to multiple body regions in survivors. This is a deliberate policy —the aim in modern war is to incapacitate, not kill. The reason is clear: large numbers of surviving casualties are a major financial and logistic burden on a nation engaged in total war.
In conclusion, the factors that govern the nature, severity and outcome of a war wound are many and include the weapon systems deployed, the environment in which the weapon systems are deployed, and the quality and timing of medical management. In short, there is no single entity that merits the description ‘the war wound’.
Wound ballistics and mechanisms of Injury
As a missile traverses the body it causes injury by transferring some or all of its available energy, and this is manifested by lacerating and crushing tissues in its path and, in some cases, injury remote from the missile path (see below). The amount of energy transferred may be expressed by the formula:
K.E – = 1/2M (v12-v22)
where KE is the available energy, M is the mass, and V1and V2 are the velocities at entry and at exit, respectively. In general, bullets fired from handguns and most modern fragment munitions are propelled at low velocity, have low available energy (100—5 00 J) and result in low-energy transfer wounds. Missiles with high available energy (2000—3000 J) include high-velocity assault rifle bullets (> 900 m/second) and some large fragments, and have potential to cause high-energy transfer wounds. Some modern high-performance handguns are now capable of firing high-velocity bullets with high available energy.
By convention, missile wounds are now described in terms of energy transfer, not velocity as was the custom, recognising that velocity is merely one factor determining energy available and its transfer to tissues. Low-energy transferwounds are characterised by injury confined to the wound track. High-energy transfer wounds also cause local laceration and crush injury but have, in addition, the potential to cause injury remote from the wound track associated with a phenomenon known as temporary cavitation.
The extent of cavitation depends upon the density and elasticity of the target organ or structure, and in certain circumstances is associated with injury many centimetres away from the missile wound track.
Cavitation within solid organs such as the liver, spleen and kidney results in shattering with high morbidity and mortality. The extent of injury to bowel is variable. In general, the small bowel fares better than the colon, particularly if the latter is loaded with faeces. A similar event in an elastic tissue such as the lung may result in quite modest injury. In the limb the position is more complex and controversial. While voluntary muscle may merely stretch if injured in isolation, bone fares badly. As a rule, bone involvement results in severe injury due to high-energy transfer with disruption of the missile and involved bone, with generation of secondary missiles. Extensive devitalisation of muscle is a typical finding. Devitalised muscle in the depths of a missile wound provides the perfect culture medium for the growth of pathogenic bacteria, a fact recognised by military surgeons for centuries. Nerves and blood vessels respond unpredictably with injury, ranging from minimal bruising to complete disruption.
Within the closed skull there is, in addition, a rapid, high-pressure shock wave causing widespread disruption and injury at a distance. Thus, vital centres at the base of the brain may be injured by a wound of the cranium.
Management of missile Injuries
Missile wounds of soft tissue
Management of the soft tissue wound is a formal procedure consisting of clearly defined stages. This is the part of early management most frequently neglected by surgeons with limited or no experience of war surgery. The entrance and exit wounds do not indicate the considerable damage that may have occurred to deeper structures.
This can only be detected by full exploration. In limb wounds, exploration is followed by thorough wound excision, after which, with very few exceptions, the wound should be left open. Delayed primary closure should follow within 4—7 days after injury. Having followed the Advanced Trauma Life Support (ATLS®) guidelines, the patient will have been completely undressed prior to surgery, but it is wise to retain any pressure dressings over a wound until the operation is due to begin. The operation should consist of the following stages.
- After photographing the wound and cleaning it with au antiseptic, generous longitudinal incisions are made through the skin to allow visualisation and access to the deeper structures and to facilitate subsequent extension of the exposure, should this be required. A minimal amount of skin edge (i.e. only that which has been contaminated) should be excised around the entrance and exit wounds. Skin is remarkably resistant to injury — scrubbing with a nail brush will remove most contaminants and indriven debris, allowing skin excision to be kept to a minimum.
- The deep fascia is exposed over the length of the skin incisions, and must be incised in a longitudinal direction to allow full inspection of the area damaged by the wounding missile and to decompress the underlying muscle which will swell subsequently. This is the true meaning of the much misused term débridement.
- Neurovascular bundles in the wound track must be identified and examined, but nerves should not be dissected out at the initial exploration. Nerves considered to be injured and warranting later exploration may have their position marked with a nonabsorbable suture marker to ease subsequent identification. It is important to examine the patient for nerve injury before the operation if this is possible and to record in the operation notes the nature of the nerve injury. The majority of nerve injuries is neuropraxias which do recover.
- ‘Débridement (unbridling or unleashing). The term was introduced by Baron Dominique Jean Larrey, 1766—1842, Surgeon to Napoleon’s Imperial Guard. He used it to describe the process of laying a wound open to facilitate removal of bullets, bits of loose cloth, detached pieces of bone and soft tissue. He and his contemporaries did not excise tissue in the modern sense and his procedure was much less extensive than the formal wound excision practised today.
- Foreign matter should be removed from the wound. Pieces of clothing are especially sought, both in the missile track and in the tissue planes on either side. It is not necessary to remove every piece of metal seen on a radiograph. Multiple, very small metal fragments from modern munitions may, in any case, be very difficult to locate and remove.
- Dead muscle that does not bleed or contract, is mushy in consistency or has an unhealthy colour must be excised. These criteria comprise is the ‘4 Cs’ for muscle excision
The 4 Cs’
• Capillary bleeding
- Tendon repair should not be performed at this initial procedure. Tattered ends should be trimmed.
- Major artery and vein damage must be noted. Where possible, the ends should be trimmed and sutured. If any tension is likely to develop, a reversed vein graft may be inserted to bridge the gap and the repair covered by healthy muscle. The rest of the wound should be left open for delayed primary closure. Synthetic grafts must not be used. A plastic shunt inserted into an injured artery can be used to revitalise tissue distal to the site of injury prior to definitive repair. In combined arterial and venous injury, concomitant shunting of both vessels may be undertaken. Temporary shunting has a vital role where major vascular damage is associated with fractures of long bones. In this instance, blood flow is established via the shunt(s), and the fracture is reduced and immobilised using an external fixator, after which definitive vascular repair is undertaken.
- Bone shattered by high-energy transfer will in many instances still have attachment to periosteum or muscle. Such fragments must not be discarded. Loss of bone may result in malunion (e.g. shortening) or nonunion. Contaminated bone may be cleaned by using that useful instrument of military surgery, the Volkmann’s spoon or curette.
- Injured joints need thorough inspection and cleaning by copious irrigation with saline to remove organic matter. Any exposed articular cartilage should be covered by at least one layer of healthy tissue, preferably synovium, otherwise muscle or skin should be used.
- At the end of the operation the wound should be irrigated thoroughly with saline to remove any remaining debris. Haemostasis should be secured with the aid of hot packs and the wound left open without closure of either fascial layer or skin, even in the presence of exposed bone. A lightly fluffed gauze dressing should be placed over the wound to allow free drainage. Packing must be avoided.
- Immobilisation in a well-padded splint allows the soft tissues to recover, a principle expounded by Hugh Owen Thomas at the turn of the century. Split plaster of Paris splints are ideal even in the absence of a fracture. Femoral shaft fractures should be immobilised in a traction splint.
- Antibiotic cover is advised for all wounds; third-generation cephalosporins or agents with an equivalent spectrum being ideal. In all abdominal, pelvic and perineal wounds, metranidazole is given in addition.
Delayed primary closure
All wounds treated by wound excision and left open should be inspected about 4—6 days after injury. Provided the wound looks healthy, delayed primary closure is indicated. This should be by interrupted suture, split skin graft or a combination of both.
Traumatic amputations should be surgically tidied, completed at the lowest level possible and the skin left open for delayed primary closure. If there is much skin loss or if a limb is very swollen, split skin grafting may be used to effect wound closure in order to avoid skin tension. If, at the time of delayed primary closure, dead muscle is found, which is not uncommon in traumatic amputation due to antipersonnel mines, the muscle is excised and the wound left open for a further period before closure.
Missile wounds of the abdomen
Every penetrating and perforating missile wound of the abdomen should be explored by laparotomy. Before surgery, a nasogastric tube should be passed into the stomach and a urinary catheter into the bladder. Bladder catheterisation must be preceded by a digital rectal examination. Timing of exploration will vary. In some cases, operation will be undertaken as part of resuscitation leaving little or no time for planning. In others, preoperative stabilisation is possible and time is available for investigation, including haematology, biochemistry and radiology. In all cases blood in realistic quantities must be available.
A full midline incision from xiphisternum to pubis is recommended. It has the advantage of facilitating rapid access and extension laterally or into the chest where required. The commonest source of bleeding in survivors is from the small bowel mesentery, but major haemorrhage may come from the solid organs, such as liver or spleen, or from the major vessels. Haemorrhage must be controlled and careful examination is then made of all the abdominal contents.
In all wounds of the stomach, the lesser sac must be opened to inspect the posterior gastric wall. Retroperitoneal haematoma in the region of the duodenum requires inspection of its posterior wall by Kocher’s method. Haematoma surrounding the retroperitoneal parts of the ascending and descending colon may also necessitate exploration, but nonexpanding retroperitoneal haematomas over the kidneys are best left undisturbed.
Small intestinal perforations are either excised and closed transversely, or the damaged section is resected if there are multiple holes in a short length Mesenteric tears may also require bowel resection.
Colon and rectal wounds
For most injuries of the right side of the colon, primary repair or primary resection is satisfactory. Occasionally, where severe wounding with extensive contamination has occurred, a vented ileotransverse anastomosts is warranted. Rarely, the two ends are brought to the surface as proximal ileostomy and distal mucous fistula, respectively.
On the left side a one-stage procedure may be undertaken if favourable circumstances pertain, i.e. minimal peritoneal contamination, limited blood loss, and a time interval between injury and operation of less than 8 hours. However, if injury is associated with high-risk factors, the injured colon is resected and the proximal end brought out as a colostomy and the distal end as a mucous fistula. If the distal end cannot be brought to the surface, as in low sigmoid or rectal injuries, it may be closed off as in a Hartmann procedure. Subsequent restoration of bowel continuity will be required.
Extraperitoneal rectal injuries are repaired if feasible and defunctioned by establishing a sigmoid end colostomy.Gooddependent drainage is best achieved by a presacral, retrorectal drain brought out between the tip of the coccyx and the anus. The control of haemorrhage in pelvic injuries can be difficult and may require ligature of the internal iliac artery.
Rectal in jury
Renal injury is best treated conservatively if this is possible. Fortunately, immediate nephrectomy is rarely indicated. A divided ureter may be brought to the surface or may be repaired over a ‘pigtail’ stent.
Bladder and urethral injuries
Bladder and urethral injuries are treated by suprapubic cystostomy with placement of a suprapubic drain after wound excision.
In 50 per cent of cases of hepatic injury surviving to reach a surgical centre, bleeding has stopped and is not a problem at laparotomy, a reassuring statistic for the youthful surgeons usually faced with such cases. Where bleeding is still occurring, damage control techniques are particularly appropriate in a warfare setting. Manual compression and perihepatic packing are recommended, and may allow a patient to survive to reach a more sophisticated surgical facility in the rear of the fighting area, If these simple measures do not work, and provided that the operator is experienced, finger fracture with exposure of bleeding points followed by individual ligation, or more formal resection procedures, will be needed. These are rare eventualities. In all cases, generous drainage of the spaces surrounding the liver is important.
Damage to the spleen and pancreas
Damage to the spleen and tail of pancreas may require resection, although in some cases splenorrhaphy may be feasible. Missile injury of the head of the pancreas is seldom seen in the operating room because injury to it and surrounding structures is usually fatal. In a very few cases it may be possible to apply a Roux loop of jejenum to create an internal fistula.
Using warm saline, it is important to assist the removal of all spilled bowel contents and blood clot.
The laparotomy wound is closed using the mass closure technique. The missile entrance and exit wounds should be excised as described earlier and left open initially with a view to delayed primary closure at 4—6 days.
Missile wounds of the chest
Penetrating missile wounds of the chest are common in war and are associated with a high mortality if simple life-saving measures are neglected. Iris important to secure an airtight seal of open wounds of the chest to prevent a potentially fatal open pneumothorax. This is immediately followed by tube thoracostomy. This should been done during the primary survey. Failure to do so will result in collapse of the lung on the affected side with alteration of the ventilation/perfusion ratio and, in addition, will progressively decrease the quantity and quality of air entering the affected lung. As dyspnoea increases due to anoxia, the mediastinum shifts on respiration and decreases venous return to the heart — the clinical picture in the later stages is identical to a tension pneumothorax.
All penetrating wounds of the chest require adequate venting of the pleura by formal tube thoracostomy. This simple procedure will prevent the accumulation of blood or air under tension. The position of the tube should be confirmed by chest radiography. Once pulmonary function has been stabilised, missile entry and exit wounds are excised. During the excision of a large chest wall wound, the pleural cavity is often entered; this need not cause concern. The opportunity should be taken to remove any retained foreign material, arrest haemorrhage (usually from an intercostal or internal mammary vessel) and to oversew or staple holes in the adjacent lung. On completion the pleural opening must be sealed either by direct pleural closure (often difficult) or by utilising overlying healthy soft tissue, and the wound(s) left open for subsequent delayed primary closure.
These simple measures will suffice for more than 80 per cent of chest wounds. The remainder will require formal thoracotomy, often urgently. The usual indications are listed below.
Indications for formal thoracotomy
• More than 1.5 litres initial blood loss
• Continuing loss of > 200 mI/hour
• Cardiac tamponade
• Other mediastinal injuries
• Persistent air leak
• Retained foreign bodies > 1.5 cm in diameter
Even in cases where thoracotomy is indicated, considerable delay can often be tolerated provided adequate resuscitation is initiated quickly. Thoracotomy for retained foreign bodies is often a late and planned procedure.
In thoracoabdominal injuries, the thoracic component is treated by tube thoracostomy and the abdominal component by laparotomy through a midline incision. Formal thoracoabdominal incisions risk contamination of the chest cavity by faeces and should be avoided.
Missile wounds of the head
The penetrating high-energy transfer missile wound of the head is usually lethal. The management of penetrating low-
energy transfer and tangential wounds depends initially on measures described in the primary survey and resuscitation phases. These will ensure a protected airway, adequate ventilation, and maintenance of blood pressure and perfusion pressure to permit oxygenation of the brain. Good radiographs are mandatory to localise foreign bodies and bone fragments. Computerised tomography (CT) images are invaluable in planning surgical exploration. Wound excision should be carried out using gentle irrigation and suction to remove devitalised brain and bony fragments. Every effort, including the use of temporalis fascia or fascia lata, should be made to close overlying dura. The skin overlying the head and face is an exception to the delayed primary closure rule. Blood supply is excellent, allowing primary closure which also serves to control blood loss from the scalp.
Intermittent positive pressure ventilation (IPPV) assists in the reduction of intracranial pressure by reducing brain swelling. Intracranial pressure transducers inserted through burr holes may be employed to monitor intracranial pressure in the postoperative phase.
Accidents from large-bore shotguns are common and often lethal when injury is sustained at close range. It is never possible to retrieve all the shot and, indeed, to do so would result in unacceptable damage to uninjured soft tissues. Wound excision should be carried out on the major wound, particularly looking for indniven wadding and plugs of clothing. Laparotomy is essential if it is thought that any of the shot has traversed an abdominal viscus. The retention of lead shot in the body can result in a dangerously high lead oncentration, which should be monitored. After a time, this 2oncentration will fall as a result of encapsulation of the lead pellets by fibrous tissue.
Summary: dos and don’ts of missile injuries
•incise skin generously;
•incise fascia widely;
• identify neurovascular bundles; excise all devitalised tissue;
•remove all indriven clothing;
• leave wound open at end of surgery;
•dress wounds with fluffed gauze;
•record all injuries in the notes.
•excise too much skin;
•practise keyhole surgery; repair tendons or nerves;
•remove attached pieces of bone; close the deep fascia;
•insert synthetic prostheses;
•pack the wound;
•close the skin.
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