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Gunshot, blast and stab wounds

  • Gunshot and blast wounds are increasingly seen in civilian practice
  • Military and civilian wounds however differ in several key respects
  • Military wounds are often heavily contaminated with delays in treatment
  • The same principals apply to their treatment

Physical properties

  • Penetrating missiles include both munition fragments and bullets
  • Often divided into 'high' and 'low' velocity
  • Velocity per se is not important
  • The amount of kinetic energy transferred to tissues is they key factor
  • Kinetic energy transfer depends on:
    • Velocity
    • Presenting area of fragment
    • Mechanical properties of tissue

Fragment injuries

  • Fragments are usually small and numerous
  • Are of low velocity (100 - 500 m/s) and low energy (10-100 J)
  • They have poor tissue penetration
  • Injuries often numerous but are usually limited to fragment track

Bullet wounds

  • Hand gun bullets are of low velocity (<250 m/s) and low energy (200-300 J)
  • Rifle bullets are high velocity (750-1000 m/s) and high energy (2-3 kJ)
  • Physiological effects depend on degree of energy transfer
  • High velocity bullets can result in low energy transfer wounds

Pathophysiology

  • The effects of bullets can result from both direct and indirect effects
  • In low energy transfer wounds injury results from direct effects along bullet track
  • In high energy transfer wounds indirect effects are more important
  • Radial forces perpendicular to tract result in cavitation

A high velocity bullet passing through a gel block

  • Generates contusions and lacerations away from tract
  • Negative pressure within cavity can suck in environmental contaminants
  • Rifle bullets also tumble (yaw) within the wound
  • Increases presenting area and increases energy transfer
  • Can result in small entry and exit wounds but large wound cavity
  • Radial energy transfer can cause indirect fractures
  • Bullet and bone fragmentation can cause secondary tracts and further unpredictable damage

High velocity round within the liver

Treatment

  • In military environment the standard treatment of gunshot wounds has involved.
    • Wound debridement
    • Wound excision
    • Antibiotic prophylaxis
    • Dressing change and delayed primary suture at 5 days
  • Similar wound management protocols have been advocated by the Red Cross
  • Approach may be modified in civilian environment

Abdominal stab wounds

  • Abdominal stab wounds cause less trauma than gunshot wounds
  • Therefore associated morbidity and mortality is reduced
  • The upper abdomen is most commonly involved, particularly the left upper quadrant
  • Peritoneal violation occurs in up 70% of abdominal stab wounds
  • Only half of those with peritoneal violation sustain an intra-abdominal injury requiring operative intervention
  • The liver and small bowel are the commonest organs injured
  • Multiple stab wounds are present in up to 20% of patients and 10% of abdominal stab wounds enter the chest
  • Potential intra-thoracic injuries include pneumothorax and pericardial tamponade

Clinical features

  • Assessment should gain knowledge of the implement used, its site of entry and likely track
  • Examination should look for signs of evisceration, haemorrhage and peritonitis
  • Digital exploration or probing of the wound will determine whether the peritoneum has been breached
  • A plain abdominal x-ray may show signs of free gas but this investigation has limited sensitivity
  • Abdominal CT is better at assessing peritoneal penetration and the extent of intra-abdominal injury

Management

  • In the past surgical dictum mandated exploratory laparotomy for all patients with abdominal stab wounds
  • New diagnostic techniques have rendered such a dogmatic approach obsolete
  • Imaging has reduced the number of non-therapeutic laparotomies
  • Evisceration, hypovolaemia and peritonitis are indications for a laparotomy without the need for extensive investigation
  • If the penetrating object is still in-situ, it should remain so until after induction of anaesthesia
  • If there are no clinical or radiological signs of bleeding or visceral perforation then most abdominal stab wounds can be managed conservatively
  • Patients should be actively observed for 24-48 hours

Bibliography

Como J J,  Bokhari F,  Chiu W C et al.  Practical management guidelines for the selective non-operative management of penetrating abdominal trauma.  J Trauma 2010:  68:  721-733

DePalma R G,  Burris D G,  Champion H R et al.  Blast injuries.  N Engl J Med 2005;  352:  1335-1342.

Inaba K,  Demetriades D.  The nonoperative management of penetrating of penetrating abdominal trauma.  Adv Surg 2007;  41:  851-62.

Saadia R,  Schein M.  Debridement of gunshot wounds:  semantics and surgery.  World J Surg 2000;  24:  1146-1149.

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