Penetrating injury

Penetrating injury is trauma in which an object breaches the skin and enters the tissues or a body cavity, from stabbing, gunshot, impalement, blast fragments, glass, animal horns or industrial accidents. Wound size does not reflect the depth of injury, and a small wound can cause fatal haemorrhage or visceral injury. The work is to control bleeding, identify the trajectory, decide who needs immediate operation and who can be observed or imaged, and prevent infection.

Clinical relevance. Penetrating trauma causes death mainly through haemorrhage, with cardiac, great vessel and neck injuries being the most lethal. Gunshot wounds carry far higher mortality than stab wounds, and about a third of stab wounds to the anterior abdomen need laparotomy compared with over 80% of gunshot wounds to the abdomen.

Mechanism and energy.

• Low velocity (stab wounds, handgun bullets under 300 m/second) damage the tract of the wound.
• High velocity (rifle bullets, over 600 m/second) cause a temporary cavity with damage beyond the tract, fragmentation and larger exit wounds.
• Shotgun wounds cause multiple pellets at close range with massive local tissue loss, and wadding and clothing carried into the wound.
• Blast and fragmentation injuries combine penetration, blunt and thermal injury.
• Impalement: the object stays in place and often tamponades bleeding.

Classification by region.

• Neck: zone I (clavicles to cricoid cartilage), zone II (cricoid to angle of the mandible), zone III (angle of the mandible to the skull base). Platysma penetration defines a penetrating neck wound.
• Chest: the cardiac box (sternal notch to xiphoid, and nipple to nipple), the thoracoabdominal region (between the nipples and the costal margin, where the diaphragm rises to the fourth intercostal space on expiration), and the remainder.
• Abdomen: anterior (costal margin to inguinal ligament, anterior axillary lines), flank, back and pelvis.
• Limbs, groin and perineum, head and face, and spine.

Key distinctions. An impaled object is stabilised in place and removed only in theatre. A stab wound with peritonism or shock goes to theatre without further imaging. Anterior abdominal stab wounds without these features can be investigated and observed. Gunshot wounds crossing the midline, the diaphragm or a body cavity are explored or imaged in a stable patient.

History.

• Weapon type (knife length, firearm calibre, number of shots), distance, number of attackers, direction, and time of injury.
• Scene blood loss, loss of consciousness, prehospital fluids and interventions (tourniquet, chest seal), and transport time.
• Symptoms by region: dyspnoea and chest pain, abdominal pain, haematemesis, haematuria, hoarseness, dysphagia, limb weakness or numbness, and neck pain.
• Allergies, medicines (anticoagulants), tetanus status, alcohol and drug use, and comorbidities.
• Forensic details: preserve clothing and objects, record the account in the patient's words, and note any safeguarding concern.

Examination.

• Primary survey with catastrophic haemorrhage control first: airway (with cervical spine consideration only where there is a blunt component or neurological deficit), breathing, circulation, disability, and exposure with a complete undressing and log roll.
• Count and map every wound, including the back, axillae, buttocks, groin, perineum, scalp and between the fingers and toes. Entry and exit wounds, tattoos and skin folds can hide wounds.
• Neck: expanding or pulsatile haematoma, active bleeding, bruit or thrill, subcutaneous emphysema, hoarseness, stridor, haemoptysis, dysphagia, and neurological deficit.
• Chest: breath sounds, percussion, tracheal position, jugular venous distension, muffled heart sounds, and paradoxical movement.
• Abdomen: peritonism, distension, evisceration, and blood on rectal or vaginal examination.
• Limbs: pulses, capillary refill, temperature, motor and sensory function, and compartments.
• Spine: motor and sensory function and anal tone.
• Do not probe, remove or manipulate impaled objects, and do not clamp blindly in wounds.

Red flags.

• Shock (tachycardia over 120 beats/min, systolic pressure under 90 mmHg, cool peripheries, altered consciousness) or a non-responder to fluid.
• Hard signs of vascular injury: active pulsatile bleeding, expanding or large haematoma, absent distal pulses, bruit or thrill, distal ischaemia.
• Airway signs in neck injury: stridor, expanding neck haematoma, subcutaneous emphysema, voice change.
• Tension pneumothorax (hypotension, tracheal deviation, absent breath sounds, distended neck veins), open pneumothorax, massive haemothorax, or cardiac tamponade (Beck triad: hypotension, muffled heart sounds, distended neck veins).
• Peritonism, rigidity, evisceration, haematemesis or rectal blood.
• Any wound to the cardiac box, the neck with platysma penetration, or the thoracoabdominal region.
• Neurological deficit (cord injury, nerve injury).
• Penetrating injury to the head, face or eye, or a retained intracranial object.
• Impaled object, and multiple wounds.
• Traumatic cardiac arrest.

Special groups. Children need weight based fluids and doses, and are at risk of hypothermia. Pregnant patients need left lateral tilt after 20 weeks and obstetric review, as the uterus is injured more often than the foetus. Patients on anticoagulants bleed more. Older adults tolerate haemorrhage poorly and may not mount tachycardia.

Thoracic injuries. Simple pneumothorax, tension pneumothorax, open pneumothorax, haemothorax, massive haemothorax, cardiac tamponade, myocardial laceration, coronary artery injury, thoracic aortic and great vessel injury, tracheobronchial injury, oesophageal injury, diaphragmatic injury, pulmonary contusion, air embolism, retained bullet embolus.

Abdominal injuries. Hollow viscus perforation (stomach, small bowel, colon), solid organ injury (liver, spleen, kidney, pancreas), mesenteric and vascular injury (aorta, inferior vena cava, iliac vessels), diaphragm injury, bladder and urethral injury, ureteric injury, retroperitoneal haematoma, uterine and foetal injury.

Neck and head injuries. Airway injury (larynx, trachea), carotid and vertebral artery injury, jugular vein injury, pharyngeal and oesophageal injury, thyroid injury, cervical cord injury, cranial nerve injury, intracranial penetration, orbital and globe injury.

Limb and soft tissue injuries. Arterial and venous injury, nerve transection, fracture (open or comminuted), tendon injury, joint penetration, compartment syndrome, retained foreign body, degloving injury, traumatic amputation.

Spinal injuries. Cord transection, Brown-Sequard syndrome from a penetrating wound, cauda equina injury, vertebral fracture, cerebrospinal fluid leak, epidural haematoma.

Conditions that mimic or complicate the picture:

• Blunt injury in the same patient (assault with a weapon and blows).
• Non-penetrating wound (graze, tangential wound, ricochet fragment).
• Self-inflicted injury (hesitation marks, multiple superficial wounds, with underlying psychiatric illness).
• Pre-injury illness causing collapse (arrhythmia, seizure, intoxication).
• Fat embolism, coagulopathy, hypothermia and acidosis.
• Intoxication confounding examination.

Step 1. Primary survey and resuscitation, with direct pressure and tourniquets for catastrophic limb bleeding.

Step 2. Immediate bedside tests:

• Extended focused ultrasound for free fluid, pericardial effusion, haemothorax and pneumothorax. A pericardial effusion in a penetrating chest wound with shock needs a surgeon at once.
• 12 lead electrocardiogram.
• Portable chest radiograph (pneumothorax, haemothorax, mediastinal widening, projectile position), and pelvic radiograph in unstable patients.

Step 3. Decide on route.

• Unstable, with peritonitis, evisceration, haemodynamic instability, persistent haemorrhage, or hard signs of vascular injury: direct to theatre without CT.
• Stable: CT with intravenous contrast of the region, with the number and direction of wounds guiding imaging. Include the neck, chest, abdomen and pelvis in multiple wounds or unclear trajectory.
• CT angiography of the neck for zone I to III wounds without immediate operative indications, and of limbs for soft signs.
• Anterior abdominal stab wound without peritonitis: local wound exploration to check fascial penetration, or serial examination every 4 to 6 hours for 24 hours, or CT, or diagnostic laparoscopy.
• Tangential or superficial wounds: wound exploration and evaluation to establish depth.
• Limb wounds: ankle brachial index or arm pressure index (under 0.9 suggests arterial injury) and CT angiography for soft signs.
• Swallowing and airway evaluation: flexible endoscopy, oesophagography with water soluble contrast or CT in neck and chest wounds with suspicion of aerodigestive injury.

Step 4. Laboratory tests:

• Full blood count, group and crossmatch, coagulation and fibrinogen.
• Lactate, blood gas and base deficit.
• Urea, creatinine, electrolytes, ionised calcium and glucose.
• Creatine kinase in crush or limb ischaemia, and troponin in chest wounds.
• Urinalysis (haematuria needs imaging of the renal tract), and alcohol and toxicology.

Step 5. Serial reassessment of the patient with repeated examination, because injuries evolve.

Interpretation. Shock index (heart rate over systolic pressure) over 0.9 predicts need for transfusion. A base deficit over 6 mmol/L, lactate over 4 mmol/L or falling haemoglobin suggests ongoing haemorrhage. Absence of free fluid on ultrasound does not exclude hollow viscus injury.

Limitations. Ultrasound misses retroperitoneal, hollow viscus and diaphragm injuries and is operator dependent. Plain radiographs can be normal in early pneumothorax. CT misses small bowel, mesenteric and diaphragm injuries. Early clinical examination can be misleading in intoxicated or distracted patients.

Immediate priorities. Control external bleeding first with direct pressure, haemostatic dressing, wound packing or a tourniquet. Apply the tourniquet 5 to 7.5 cm proximal to the wound, tighten until bleeding stops, record the time and keep it on until surgery. Then manage the airway, breathing and circulation. Call the surgical, anaesthetic and theatre team and activate the massive transfusion process for shock. Early surgery is the treatment for ongoing haemorrhage.

Haemorrhage and circulation.

• Damage control resuscitation: two large bore intravenous cannulae or intraosseous access, and blood products in a balanced ratio (red cells, plasma and platelets in 1:1:1 or whole blood) given through a warmer. Avoid large volumes of crystalloid (limit to 1 litre).
• Permissive hypotension until haemorrhage control: target systolic pressure 80 to 90 mmHg (mean arterial pressure 50 to 60 mmHg) in penetrating torso trauma with a palpable radial pulse and normal consciousness.
• Do not use permissive hypotension with head injury or spinal cord injury (target systolic pressure 110 mmHg or more, and mean arterial pressure 85 to 90 mmHg in cord injury), or in prolonged transport.
• Tranexamic acid 1 g IV over 10 minutes then 1 g IV over 8 hours, started within 3 hours of injury. Reduce the dose in kidney impairment, with creatinine over 120 micromol/L; monitor for seizures.
• Calcium: calcium gluconate 10% 30 mL IV (or calcium chloride 10% 10 mL via a central line) after each 4 units of blood to keep ionised calcium over 1.1 mmol/L.
• Keep temperature over 36 degrees Celsius and pH over 7.2, and avoid dilutional coagulopathy: fibrinogen concentrate 2 to 4 g or cryoprecipitate 10 units for a fibrinogen under 1.5 g/L.
• Vasopressors are not given routinely during haemorrhage.

Airway and breathing.

• Neck wounds with airway compromise, expanding haematoma or subcutaneous emphysema: early intubation by the most experienced operator with a surgical airway ready. Use rapid sequence induction with ketamine 1 to 2 mg/kg IV and rocuronium 1.2 mg/kg IV, and maintain blood pressure during induction.
• Control neck bleeding with direct pressure. When direct pressure fails and a surgeon is on the way, use a Foley catheter balloon inflated in the wound tract (with the catheter clamped). Do not explore neck wounds in the emergency department.
• Open pneumothorax: vented occlusive chest seal or a three sided dressing, then a chest drain at a site distant from the wound.
• Tension pneumothorax: immediate decompression by finger thoracostomy (preferred) or needle thoracostomy, then a chest drain. For needle thoracostomy use a 14 gauge, 8 cm cannula in the fifth intercostal space, anterior to the mid axillary line, or the second intercostal space in the mid clavicular line in children.
• Haemothorax or pneumothorax: chest drain 28 to 32 Fr in the fifth intercostal space in the anterior axillary line, with prophylactic antibiotic cover. Immediate thoracotomy for initial drainage of 1500 mL or more of blood, ongoing losses over 200 mL/hour for 2 to 4 hours, or persisting shock.
• Resuscitative thoracotomy for traumatic cardiac arrest from a penetrating chest wound with signs of life in the last 15 minutes (shorter for non-chest wounds), in a team with surgical expertise.
• Cardiac tamponade is treated by thoracotomy or sternotomy (pericardiocentesis is a bridge only).

Operative indications (torso).

• Haemodynamic instability, peritonitis, evisceration, haematemesis or rectal bleeding, positive ultrasound in an unstable patient, free air or a positive CT for hollow viscus injury, a gunshot wound crossing the peritoneum, and CT showing active bleeding that cannot be embolised.
• Stable patients with anterior abdominal stab wounds without these signs are observed with serial examination, or explored with laparoscopy, and discharged after 24 hours with a normal course. Solid organ injuries may be managed non-operatively in stable patients, with angioembolisation.

Vascular and limb injuries.

• Hard signs: direct operative exploration or on table angiography, with shunting for ischaemia time over 6 hours and fasciotomy when indicated.
• Soft signs (history of bleeding, nearby nerve deficit, small haematoma, proximity): arterial pressure index and CT angiography.
• Fractures with penetrating wounds are managed as open fractures, with urgent debridement and stabilisation.
• Gunshot wounds of limbs without fracture, vascular or nerve injury are low risk: irrigation, simple dressing and short oral antibiotics.

Impaled objects. Leave in place, stabilise with bulky dressings, and remove under direct vision in theatre. Cut the external part only to allow transport, using stabilisation to avoid movement.

Antibiotics and tetanus.

• Chest drain: cefazolin 2 g IV (3 g if weight over 120 kg) as a single dose.
• Abdominal wounds with hollow viscus injury, give one of these regimens within 1 hour of injury:
  • Cefazolin 2 g IV every 8 hours (maximum 6 g daily) plus metronidazole 500 mg IV every 8 hours (maximum 1.5 g daily).
  • Ceftriaxone 2 g IV every 24 hours (maximum 4 g daily) plus metronidazole 500 mg IV every 8 hours.
  • Piperacillin with tazobactam 4.5 g IV every 6 hours (every 8 hours for CrCl 20 to 40 mL/min and every 12 hours under 20 mL/min).
• Stop antibiotics within 24 hours after repair when contamination is limited. Extend to 4 to 7 days for faecal contamination or established peritonitis.
• Abdominal wounds, penicillin allergy: ciprofloxacin 400 mg IV every 12 hours (maximum 1.2 g daily; monitor QTc and tendon symptoms) plus metronidazole.
• Open limb wounds and fractures: cefazolin 2 g IV every 8 hours (3 g if weight over 120 kg; maximum 6 g daily; half the dose every 12 hours for CrCl 10 to 34 mL/min) for 24 hours after wound closure.
• Add gentamicin 5 mg/kg IV once daily for high energy or heavily contaminated wounds (up to 72 hours; reduce or avoid with CrCl under 60 mL/min; monitor creatinine).
• Open limb wounds, penicillin allergy: clindamycin 600 to 900 mg IV every 8 hours (maximum 2.7 g daily).
• Low risk wounds treated in the outpatient setting: cefalexin 500 mg orally every 6 hours for 3 to 5 days (maximum 4 g daily; reduce in CrCl under 30 mL/min).
• Tetanus: vaccine when more than 5 years since the last dose or unknown. Give human tetanus immunoglobulin 250 units IM at a different site when immunisation is incomplete or unknown (500 units if the wound is over 24 hours old or heavily contaminated).

Analgesia. Paracetamol 1 g IV every 6 hours (maximum 4 g daily; 3 g daily if weight under 50 kg, malnutrition, alcohol excess or liver disease) with morphine 2 mg IV boluses every 5 minutes titrated to pain. Maximum 10 mg before reassessment; reduce in older adults and kidney impairment; monitor sedation and respiratory rate. Fentanyl 25 to 50 micrograms IV every 5 minutes is an alternative. Ketamine 0.1 to 0.3 mg/kg IV is an alternative that spares blood pressure. Regional blocks for limb injuries once compartment syndrome is excluded.

Wound care. After the life threatening injuries are managed, irrigate with warm isotonic saline, debride devitalised tissue, remove accessible foreign bodies, and leave contaminated wounds open for delayed closure. Bullet fragments are left when deep, inaccessible and not in a joint, a disc space or near a vessel or nerve. Retained intra-articular bullets are removed because of the risk of synovitis and lead toxicity.

Venous thromboembolism prophylaxis. Enoxaparin 40 mg subcutaneously once daily once bleeding is controlled, typically at 24 to 48 hours. Use 20 mg daily if CrCl 15 to 30 mL/min, or unfractionated heparin 5000 units subcutaneously every 8 to 12 hours if CrCl under 15 mL/min. Monitor platelets from day 4 and creatinine.

Monitoring.

• Vital signs every 5 to 15 minutes during resuscitation, then hourly; urine output hourly.
• Lactate and base deficit every 2 to 4 hours until normal.
• Haemoglobin, coagulation and ionised calcium after each round of transfusion; temperature.
• Neurovascular checks of injured limbs hourly.
• Repeated abdominal examination every 4 to 6 hours in non-operative management.

Referral and escalation. Trauma surgeon and anaesthetist at once for any shock or torso wound. Cardiothoracic, vascular, ENT or maxillofacial, neurosurgical, urology, orthopaedic and plastic surgery as indicated. Interventional radiology for embolisation. Critical care. Safeguarding, police notification as required by local law, violence intervention and psychological support.

Admission criteria. All patients with penetrating torso or neck injury, any abnormal vital sign, any positive imaging, abdominal stab wounds needing observation (for 24 hours), retained foreign body, limb injuries with neurovascular or bone involvement, and any gunshot wound apart from isolated low risk superficial wounds.

Discharge and safety netting. Discharge only after a full survey, a normal repeated examination, and stable observation (at least 6 hours for isolated superficial chest wounds with a normal repeat chest radiograph, and 24 hours for abdominal wounds). Patients return for fever, spreading redness, discharge, new pain, shortness of breath, vomiting, abdominal pain, haematuria, or numbness. Wound check in 48 to 72 hours, suture removal by site (face 5 days, trunk 7 to 10 days, limbs 10 to 14 days), and review of tetanus and psychological recovery.