This lecture teaches you to manage a patient who arrives in the emergency department after a gang fight with chopping and stabbing injuries. The core philosophy is: treat what kills first, then save the limb, then reconstruct function. The lecture integrates ATLS principles (primary/secondary survey), biomechanics of injury (blunt vs penetrating), wound classification (chopped vs stabbed), and the specific management of peripheral vascular and nerve injuries in the extremities. Understanding why a partially severed artery bleeds more than a completely severed one, and why Seddon's classification of nerve injury determines prognosis, are the two conceptual pillars examiners love to test.

1. Understand the correct priority in the management of patients with multiple injuries
2. Recognize the differences between chopped (cut) and stabbed wound (penetrating injury versus blunt injury)
3. Understand the basic principles of evaluation of these injuries
4. Basic principles on blood vessel and peripheral nerve injuries

"ATLS program is to treat the greatest threat to life first" ^[1]

"The lack of a definitive diagnosis and a detailed history should not slow the application of indicated treatment for life-threatening injury, with the most time-critical interventions performed early" ^[1]

Why this matters from first principles: Trauma patients often present unconscious, with incomplete history, and multiple simultaneous injuries. Without a systematic approach, life-threatening injuries get missed because clinicians focus on the most dramatic-looking wound (e.g. a chopped limb) rather than the most dangerous one (e.g. a tension pneumothorax). ATLS gives you a reproducible algorithm so you never skip a lethal condition.

The continuous process: ATLS starts at the point of injury and continues through:

1. Initial assessment
2. Life-saving intervention
3. Re-evaluation
4. Stabilisation
5. Transfer to specialised care (trauma centre) ^[1]

The primary survey identifies and treats immediately life-threatening conditions. It runs simultaneously with resuscitation.

"Should occur simultaneously with primary survey" ^[1]

• Oxygenation and ventilation
• Shock management: intravenous lines, warmed IV fluids
• Management of life-threatening problems identified in primary survey ^[1]

Why warmed fluids? Cold fluids worsen hypothermia → impair clotting cascade → more bleeding → more transfusion needed (vicious cycle).

Visual recognition (adjuncts slide): the photograph captioned "Intubated and chest drain" shows simultaneous airway control and pleural decompression/drainage — adjuncts are not paperwork after ABC; they run with resuscitation. ^[1]

"Begins when: Primary survey ABCDE is complete and secured; Resuscitation efforts are well established; Patient's vital signs are stabilised" ^[1]

What it involves:

• Head-to-toe, front-to-back examination
• Log roll with neck collar on — to examine the back and spine
  • Spinal injury may result in motor/sensory loss, incontinence, lax anal tone
  • Spinal shock = flaccid paralysis, autonomic dysfunction ^[1]
• Systematic examination: Head, neck, chest, abdomen, pelvis, perineum, extremities ^[1]

AMPLE History:

Why "Last meal"? A full stomach increases aspiration risk during intubation/anaesthesia. Knowing the last meal time helps the anaesthetist decide on rapid sequence induction.

"The force is dissipated over a wide area, minimising energy transfer at one spot"

This is a classic exam list — learn it systematically from head to toe:

Head injury → Cervical injury → Vertebral wedge fracture → Pelvic fracture → Tracheo-bronchial dislocation → Pneumothorax/haemothorax → Rupture or dissection of aorta → Liver or spleen laceration → Rupture of bowel → Lower limb/ankle/fracture of calcaneum or metatarsals

Why calcaneum? In axial loading (landing feet-first), force transmits directly through the heel. Calcaneal fractures are pathognomonic of falls from height and should prompt you to check the lumbar spine for associated compression fractures (same axial loading mechanism).

"Kinetic Energy (KE = mass/2 × velocity²) is transferred to tissues surrounding the track of the weapon or missile"

Why velocity matters more than mass: KE depends on velocity squared. A bullet (small mass, very high velocity) transfers far more energy than a knife (larger presenting area, low velocity). This is why gunshot wounds cause massive cavitation while knife wounds cause a narrow track.

Factors determining injury severity:

• Mean presenting area of weapon
• Tendency of weapon to deform, change pathway, or fragment
• Density/characteristics of tissue (solid organs like liver sustain more damage than lungs)
• Impact velocity/damage to neighbouring tissues

Three consequences of penetrating trauma: ^[1]

1. Functional and mechanical disruption of neighbouring tissues and energy transfer
2. A core of covering clothing is carried deep into the wound → contamination
3. In gunshot wounds: exit wound is usually larger than entry wound (temporary cavitation effect extends along wound track; some missiles fragment on contact)

Life-threatening conditions need to be ruled out, presume cardiac and lung injuries until proven otherwise:

• Cardiac tamponade
• Open pneumothorax
• Massive haemothorax

Why presume until proven otherwise? A small external wound can mask a lethal internal injury. A stab wound in the "cardiac box" (bordered by clavicles, nipple lines, and costal margin) has a high probability of cardiac injury.

Key point from slides: "Big wound but less chance of injury to the underlying organs (not true)" ^[1] — The lecture explicitly debunks the myth. A large chopping wound of the chest wall may look dramatic but the blade may not have penetrated deeply. Conversely, a tiny stab wound may reach the heart.

Management of pneumothorax/haemothorax: ^[1]

1. Give Oxygen
2. Insert chest tube
3. Treat local wound
4. Urgent thoracotomy if massive bleeding

What the chest trauma photograph shows: a penetrating/open lateral chest wound with a chest tube already in situ and blood visible in the tubing — the slide's four management points are not theoretical; they are the sequence you should already be executing when this image appears in resus. ^[1]

When is thoracotomy indicated? If chest tube drainage shows > 1500 mL immediately or > 200 mL/hour for 2–4 hours (massive haemothorax). Also for cardiac tamponade unresponsive to pericardiocentesis.

Exsanguinating external bleeding (may be from external jugular vein)

Expanding haematoma → endotracheal intubation to protect airway → operative exploration

If unsure of diagnosis: wound deeper than platysma → requires exploration

Why platysma is the key layer: The platysma is a thin superficial muscle in the neck. If a wound penetrates deeper than platysma, it can potentially injure major vessels (carotid, jugular), the airway (trachea, larynx), the oesophagus, or nerves (vagus, recurrent laryngeal). Wounds superficial to platysma can be managed conservatively.

Surface anatomy matters:

• Thoracoabdominal area (nipple line to costal margin) — remember the diaphragm! A stab wound here may injure both chest and abdominal organs
• Anterior abdomen
• Flank
• Back

Management algorithm:

Why CT first if stable? CT triple-contrast can identify specific organ injuries, guide selective non-operative management, and avoid unnecessary laparotomy. But an unstable patient cannot wait — they need surgical haemostasis immediately.

Visual recognition: one slide shows a large gaping anterior abdominal laceration (transverse/oblique with active bleeding) — dramatic surface findings still do not dictate the algorithm; haemodynamic stability does. Another operative photograph is captioned exploratory laparotomy for haemostasis and repair of caecum, with bowel loops exposed under retractors — the teaching point is source control + hollow-viscus repair, not a leisurely inventory of every bruise. ^[1]

This is a classic exam concept:

Partially severed artery → incomplete contraction/retraction → massive bleeding & formation of pseudoaneurysm

Completely severed (divided) artery → contraction and retraction → less bleeding

Why does this paradox occur? An artery has smooth muscle in its wall (tunica media). When completely transected, the circular smooth muscle can contract fully, and the elastic recoil causes the cut ends to retract into surrounding tissue, partially sealing the vessel. When only partially cut, the remaining intact wall prevents full contraction and retraction — the wound in the vessel wall is held open by the intact portion, causing more profuse bleeding. The partially cut vessel can also develop a pseudoaneurysm (contained rupture) because blood continues to pulse through the defect.

1. Right axillary penetrating injury — can damage axillary artery and brachial plexus ^[1]
2. Transected brachial artery & nerve injuries — requires interposition vein graft ^[1]
3. RTA with fracture and free-floating knee & pulseless leg → External fixation + angiogram showing abrupt cut-off at distal SFA → SFA to below-knee popliteal artery reversed long-saphenous vein bypass graft ^[1]

What the operative / imaging sequence shows: ^[1]

• Axilla: wide open right axillary wound with deep bleeding — treat as combined vascular + brachial-plexus territory until proven otherwise; examine the whole limb, not only the hole.
• Arm: green arrows on a transected brachial artery with adjacent nerve ends in the same field — proximal/distal vascular control and planned nerve repair travel together.
• Floating knee + pulseless leg: long-leg radiographs with comminuted distal femur / proximal tibia–fibula disruption → spanning external fixator first for skeletal stability in a pulseless limb.
• Angiogram: abrupt cutoff at distal SFA (arrowed) → operative exploration of SFA and below-knee popliteal with vessel loops — anatomy of the bypass targets, not just “do an angiogram.”
• Two weeks later: 3D CT still shows the severe peri-knee comminution while the limb remains in the fixator frame — temporary spanning fixation buys time for soft-tissue and vascular recovery before definitive reconstruction.

Why "proximal and distal control first"? Before you open a vascular injury, you must have clamps or tourniquets on both sides to prevent catastrophic haemorrhage during repair.

1. Save life
2. Haemostasis and blood replacement
3. Primary repair (proximal and distal control of arteries first)
4. Limb salvage
5. Rehabilitation
6. Late reconstruction

"A peripheral nerve is an enclosed bundle of axons. A neuron is an electrically excitable cell that processes and transmits information through electrical and chemical signals."

"A nerve provides a common pathway for electrochemical impulses transmitted along each axon to peripheral organs." ^[1]

A peripheral nerve has three connective tissue layers (outermost → innermost):

• Epineurium — outermost, surrounds entire nerve
• Perineurium — surrounds fascicles (bundles of axons)
• Endoneurium — surrounds individual axons

Blood vessels are also present within the nerve between and around the fascicles, supplying the vasa nervorum. ^[1]

Understanding these layers is critical because the classification of nerve injury is based on which layers are disrupted.

This is the most commonly examined nerve injury classification:

"Axons sprouts to repair at 1mm per day" ^[1]

Clinical implication: If a nerve is injured at a point 30 cm from the target muscle, recovery takes approximately 300 days (~10 months). This is why proximal nerve injuries have worse prognosis — the axon must grow a longer distance, and the target muscle may undergo irreversible atrophy before reinnervation occurs (> 12–18 months without reinnervation → permanent muscle atrophy).

While the lecture focuses on Seddon, examiners may reference Sunderland's 5-grade system. Here's how they map:

• Mechanism: Chopping weapon (cleaver, machete) vs stabbing weapon (knife, screwdriver) vs gunshot
• Time since injury: Critical for ischaemia time (golden 6 hours for vascular repair)
• Symptoms: Pain, numbness, weakness, inability to move fingers/toes
• AMPLE history for ATLS

1. Primary survey ABCDE — always first
2. Secondary survey — systematic head-to-toe
3. Limb examination:
   • Skin: wound characteristics, contamination
   • Vascular: 5 P's of ischaemia — Pain, Pallor, Pulselessness, Paraesthesia, Paralysis (and Poikilothermia = cold limb)
   • Nerve: test motor and sensory function of each major nerve
   • Tendon: test active movement
   • Bone: deformity, XR

Immediate:

• ATLS primary survey and resuscitation
• Direct pressure for haemorrhage control (tourniquet as last resort in extremity)
• Blood replacement (cross-match, activate massive transfusion protocol if needed)

Definitive:

• Chest: chest tube → thoracotomy if massive haemothorax
• Abdomen: laparotomy if unstable
• Limb vascular: proximal/distal control → primary repair or vein graft
• Nerve: primary repair if neurotmesis (clean sharp transection), or delayed repair (2–3 weeks) if wound contaminated
• Open fracture: debridement, external fixation, antibiotics (Gustilo-Anderson classification) ^[3]
• Tetanus prophylaxis

Rehabilitation:

• Physiotherapy for joint mobilisation
• Occupational therapy for hand function
• Serial nerve examination to monitor recovery (Tinel's sign advancing distally = good sign)

1. "Blunt vs penetrating": Both chopped AND stabbed wounds are penetrating/sharp injuries — examiners love to trick you into calling a chopped wound "blunt" because a cleaver is heavy.

2. Partially vs completely severed artery: Remember the paradox — partial = MORE bleeding. This is tested in MCQs as a "which bleeds more" question.

3. Primary survey before limb: Never describe limb repair before confirming ABCDE is complete. In SAQs, always state "after stabilization" before discussing definitive limb management.

4. Neuropraxia vs neurotmesis: If the question says "complete functional recovery expected," it's neuropraxia. If "surgical repair indicated," it's neurotmesis. Axonotmesis is the middle ground — good recovery but takes months.

5. Axon growth rate: 1 mm/day — this comes up in calculations of expected recovery time.

6. Stab wound of chest: Always rule out cardiac tamponade, open pneumothorax, massive haemothorax — even if the wound looks minor.

7. Wound deeper than platysma in the neck: This is the threshold for mandatory exploration.

8. Exit wound > entry wound in gunshot: Due to cavitation effect.

9. FAST scan: The lecture mentions both FAST and DPL as adjuncts. In modern practice, FAST has largely replaced DPL, but the lecture lists both — follow lecture framing for the exam.