Surgery SC083: Trauma Evaluation And Management (TEAM)

Question 1

TEAM, Goals / Principles of Trauma Care

Answer 1

TEAM: Trauma Evaluation and Management

Goals:

1. Rapid, accurate, physiologic assessment
2. Resuscitate, stabilise, monitor by priority
3. Prepare for transfer to definitive care
4. Team work for optimal, safe patient care

Question 2

Need for Early TEAM

Answer 2

• Leading cause of death from 1-44 yo
• Disabilities exceed deaths by ratio of 3:1
• Trauma-related costs >$400 billion per year
• Lack of public awareness for injury prevention

Question 3

Injury Prevention (ABCDE)

Answer 3

ABCDE:

1. Analyse injury data
2. Build local coalitions
3. Communicate the problem
4. Develop prevention activities
5. Evaluate the interventions

Question 4

Trimodal death distribution of trauma

Answer 4

1. Immediate deaths (death at scene)
   - most patients
   - **airway compromises, **C-spine injuries, ***breathing: pneumothorax, haemothorax, hypoxia
   - need prevention from policies
2. Early deaths (2 hours after injury)
   - **bleeding: “Blood on the floor and Four more”
   —> On the floor: Bleeding from visible wound
   —> Four more: Chest, Abdomen, Pelvis, Fractured long bone (e.g. femur)
   - preventable by **golden hour management + early transfer to appropriate care
3. Late deaths (A few weeks later)
   - usually due to surgical complications e.g. multiorgan failure, pneumonia (preventable by ICU care), renal failure, sepsis, UTI, aspiration, post-op complications

Question 5

TEAM Principles

Answer 5

1. Treat greatest threat to life first
   - Secure Airway, C-spine —> then treat Breathing (e.g. pneumothorax, give O2) —> Circulation (e.g. give fluid)
2. Definitive diagnosis less important
3. Physiologic approach
   - correct any aberrant physiology first then getting the diagnosis
4. Time is of the essence
5. Do no further harm
6. Teamwork required for TEAM to succeed

Question 6

TEAM members

Answer 6

1. Team leader
2. Airway manager
3. Nurse
4. Assistant x2

Trauma call:

1. Surgeon
2. Junior surgeon
3. Anaesthetist
4. AED physician
5. Orthopaedic surgeon
6. Neurosurgeon (if head injury, reduced consciousness)
7. Nurse

Question 7

Pre-hospital preparation and In-hospital preparation

Answer 7

Pre-hospital preparation:

• Closest, appropriate facility
• Transport guidelines / protocols
• On-line medical direction
• Mobilisation of resources
• Periodic review of care

In-hospital preparation:

• Pre-planning essential
• Team approach
• ***Trained personnel
• ***Proper equipment (e.g. ETT tube, Laryngoscope, Bag-valve mask, Fluids, IV cannula)
• ***Environment (e.g. Resuscitation room)
• Lab / X-ray capabilities
• Standard precautions (cap, gown, gloves, mask, shoe covers, goggles / face shield)
• Transfer agreements
• Quality Improvement (QI) program

Question 8

Triage

Answer 8

Sorting of patients according to:

• ABCDE
• Available resources
• Other factors e.g. Salvageability

Question 9

TEAM Sequence

Answer 9

1. Primary Survey + Resuscitation of vital functions
   - ABCDE
   - Adjuncts
   —> Pulse oximeter
   —> Capnography (end-tidal CO2)
   —> BP monitor
   —> ABG
   —> ECG
   —> Urinary catheter for Urine output (aim ***0.5 ml/kg/hr)
   —> X-ray (Chest (pneumothorax, broken ribs, mediastinum, diaphragm, lung shadows, soft tissues, placement of chest tubes), C-spine, Pelvis)
   —> FAST scan (Pelvis, Perihepatic (Morrison’s pouch X look at parenchyma), Perisplenic / Splenorenal recess, Subxiphoid for pericardium)
   —> DPL
   —> Orogastric tube to decompress stomach / prevent aspiration (unless confident no head trauma —> NG tube)
   —> Take blood: CBC, Cross match, Type and Screen etc.
2. Secondary survey + Re-evaluation of vital functions
   - Head-to-toe examination (skeletal survey, CT, log-roll to see the back)
   - Adjuncts
3. Continuous re-evaluation
4. Safe transfer
5. Definitive care

Question 10

***Primary survey (ABCDE)

Answer 10

• **ABCDE:
  1. Airway with C-spine protection
• ask for the name: A: patent airway, B: some degree of breathing, C: adequate cerebral perfusion, D: not confused
• assess airway patency
• hoarseness, stridor, snoring, gurgling, rocking chest wall motions, charcoal particles (if burn)
• maxillofacial trauma / laryngeal injury
• C-spine injury

2. Breathing / Ventilation / Oxygenation / Life-threatening chest injury
   - noisy breathing
   - tracheal deviation
   - auscultate chest
   - foreign body / blood in airway
   - signs of pneumothorax —> chest tube to decompress
   (- chest rise, symmetry, expansion pattern (Kussmaul?)
   - air entry
   - RR / Effort
   - SaO2
   - accessory muscles
   - tracheal position
   - central cyanosis
   - sensorium (hypoxic, confused, AMS)
   - diaphoresis
   - chest wall injury
   - JVP)
3. Circulation / Stop the bleeding
   - large bore IV access (>16F) —> IV fluid (warm crystalloid) to resuscitate / volume replacement —> up to ***1L initially for adults —> if no response —> give blood
   - large intraabdominal bleeding —> emergency laparotomy
   (- monitor BP / P / ECG)
4. Disability (Neurological status) / Intracranial mass lesion (e.g. ICH)
   - pupillary responses
   - GCS score (Comatose: <8: need intubation)
5. Exposure / Environment / Body temp
   - room temperature should be high enough

Question 11

***Adjuncts

Answer 11

1. Take blood
   - CBC
   - LRFT
   - ***Cross match / Type and Screen
   - Clotting
   - Glucose
   - Amylase
   - Toxicology: Alcohol, Paracetamol, Salicylate
   - Pregnancy test in child-bearing age women
2. **Urinary catheter
   - Blood?
   - Decompress bladder
   - Monitor urine output (aim **0.5 ml/kg/hr)
   - Caution: pelvic fracture, blood at urethral meatus, ecchymosis at perineum, high-riding prostate
3. Gastric catheter / ***Orogastric tube
   - Blood / bile?
   - Decompress stomach
   - Caution: skull base fracture (CSF rhinorrhea / otorrhoea, periorbital ecchymosis, mid-face instability, haemotympanum)
4. ***Monitor
   - Vital signs
   - ABG
   - ECG
   - Pulse oximeter
   - End-tidal CO2
5. **Diagnostic tool
   - **X-ray: Chest / Pelvic / C-spine (not compulsory ∵ CT scan available now)
   —> CXR: pneumothorax, broken ribs, mediastinum, diaphragm, lung shadows, soft tissues, placement of chest tubes
   - ***FAST —> Pelvis, Perihepatic (Morrison’s pouch X look at parenchyma), Perisplenic / Splenorenal recess, Subxiphoid for pericardium (may miss retroperitoneal space e.g. haematoma around kidneys / aorta but not rupture into peritoneal cavity)
   - DPL (not use now)
   - CT scan (ONLY when haemodynamically stable)
6. Consider need for transfer

Question 12

Decision making

Answer 12

Haemodynamically normal patients:
- ***ample time for full evaluation of patients to decide on treatment strategy

Haemodynamically stable patients:
- investigations aiming at establishing ***source of bleeding + whether the bleeding stops

Haemodynamically unstable patients:
- CT not possible (contraindicated)
- FAST scan: operator dependent, good at identifying intra-abdominal free fluid (e.g. blood)
- DPL: accurate, fast, negative finding in shock patients —> may signify retroperitoneal bleeding
Positive DPL:
—> presence of bowel content / frank blood
—> RBC >=100,000
—> Unspun specimen WCC >=500

Question 13

Resuscitation: Airway

Answer 13

1. Chin lift / Modifed jaw thrust
   - No head tilt to maintain C-spine immobilisation
2. Look, listen, feel
   - obstruction (foreign body, loose teeth, vomitus)
   - laryngeal deformities
3. Remove particulate matter
4. Definitive airway as necessary
   - Intubate if necessary (see indications next slide) —> monitor with end-tidal CO2
   - ETT
   - Airway adjuncts: OPA
   - Cricoid pressure: prevent aspiration
   - Cricothyroidotomy
5. Reassess frequently
   - e.g. inhalational burn injury —> swollen airway
6. Protect C-spine
   - neutral position of head and neck with bimanual in-line stabilisation

(7. Medications
- BDZ, Opioid, Short-acting muscle relaxants)

Question 14

Indications for Intubation

Answer 14

1. Airway problems
   - Obstruction (e.g. facial injury, burns)
   - GCS <=8
2. Breathing problems
   - Paralysis: Spinal injury, Drug-induced
   - GCS <=8
   - Apnea
   - CO2 retention with respiratory acidosis
   - Hypoxaemia
   - Haemodynamic instability

Question 15

Resuscitation: Breathing

Answer 15

1. Observe
   - Chest rise, symmetry, expansion pattern (Kussmaul?)
   - Air entry
   - RR / Effort
   - SaO2
   - Accessory muscles
   - Tracheal position
   - Central cyanosis
   - Sensorium (hypoxic, confused, AMS)
   - Diaphoresis
   - Chest wall injury
   - JVP
2. Supplemental O2
   - High flow O2 (even for COAD patients —> if too much O2 inhibit respiratory drive —> simply mechanically ventilate —> so don’t worry)
3. Ventilate as needed
   - Variable performance device: Facial mask
   - Fixed performance device: Venturi mask, Ventilator
   - Monitor with end-tidal CO2
   - Minute volume: 6-8L (8-10 ml/kg BW)
   - Frequency: 12-14 / min
   - ***Avoid hyperventilation + Ensure PaCO2 35-40mmHg —> Avoid respiratory alkalosis —> left shift of O2 dissociation curve —> ↑ Hb O2 affinity + ↓ tissue O2 availability
4. Tension / Open pneumothorax —> tackled in Primary survey
   - Tension pneumothorax: needle then chest tube decompression (size 16, 8 cm, 5th ICS, MAL)
   - Open pneumothorax: occlusive 3 sided dressing
5. Reassess frequently

Question 16

Resuscitation: Circulation

Answer 16

1. Haemorrhagic shock (until proven otherwise)
   - Blood on the floor + Four more
   - **External: Apply direct pressure / tourniquet (need to mark down time of putting on, do not release until arrive hospital / OT)
   —> avoid blind clamping
   - **Internal: Chest, Abdomen, Pelvis, Retroperitoneum
   —> pelvic binder, rotate ankles internally to further decrease size of pelvis
   —> interventional embolisation
   —> +ve FAST scan (large intraabdominal bleeding) —> emergency laparotomy
   —> -ve FAST scan —> review other causes of shock + CT for retroperitoneal haemorrhage
   - ***Long bone fracture: Traction splint
   - Identify: history, P/E, investigations
2. Non-haemorrhagic shock
   - Cardiac tamponade —> Pericardiocentesis + Direct operative repair
   - Tension pneumothorax —> Needle decompression + Tube thoracostomy
   - Massive haemothorax —> Volume resuscitation + Tube thoracostomy
   - Neurogenic shock (rare) (cardinal feature: warm periphery vs cold clammy in haemorrhagic shock (bradycardia may still been seen in ↑ICP, ∴ not cardinal feature))
   - Septic (late complication)
3. Assess organ perfusion
   - level of consciousness
   - skin colour
   - pulse rate, character
   - have to stop bleeding!!! —> if simply give fluid to maintain adequate BP —> bleeding may ↑ with ↑ BP
   - maintain reasonable BP before operation —> maintain adequate cerebral perfusion but not too high BP —> ***normotension before definitive measures may cause more bleeding

S/S:

• Tachycardia
• Vasoconstriction
• ↓ CO
• Narrow pulse pressure
• ↓ MAP
• ↓ Blood flow

Caution:

• Children (lower BP generally)
• Elderly (higher BP generally)
• Athletes (may be bradycadic originally)
• Pregnancy (hypervolaemic)
• Medications

4. Large IV bore access
   - **x2 on each arm
   - **Size >16
   - **Warm IV fluid (Ringer’s lactate / Normal saline)
   - **1-2L full rate
   - **Packed RBC if transient response / no response
   - **Consider early transfusion for transient / non-responder
   - Group O blood
   - FFP if coagulopathy
   - Platelet concentrates
   - Class 1 / 2 shock (<30% loss): Crystalloid, not much further intervention
   - Class 3 / 4 shock (>30% loss): Crystalloid + Blood, require further investigation with FAST / CT / Laparotomy
5. Surgery
6. Reassess frequently

Question 17

Fluid resuscitation

Answer 17

Large IV bore access:

• ***x2 on each arm
• ***Size >16
• ***Warm IV fluid (Ringer’s lactate / Normal saline)
• ***1-2L full rate
• ***Packed RBC if transient response / no response

***Consider early transfusion for transient / non-responder:
- Dilutional effect of fluid resuscitation (crystalloid only improves volume but not O2 capacity) to blood O2 carrying capacity
- CO = HR X SV
—> SV depends on 1. Preload (IV volume) 2. Afterload (Peripheral resistance), 3. Contractility (possible cardiac failure in elderly / diseased heart)
(Rmb: CO cannot be increased if venous return does not increase)

Size matters:
- Maximum flow rate (ml/min)
—> 14G (brown): crystalloid (125), colloid (90)
—> 16G (grey): crystalloid (85), colloid (65)
—> 18G: crystalloid (60), colloid (35)

Crystalloid vs Colloid:

• t1/2 of crystalloid (balanced salt solution BSS): ~20 mins
• t1/2 of colloid (e.g. Gelofusin): ~4-6 hours
• NO evidence to support superiority of colloid over crystalloid —> crystalloid reduce risk of fluid overload (colloid: may induce ***hypersensivity (gelatin), impair clotting (starch))
• trauma leads to leaky cells in pulmonary capillary bed —> greater risk of ***pulmonary edema with colloid

Question 18

Blood transfusion

Answer 18

• No level 1 evidence to define threshold for transfusion
• Transient / Non-responder: Blood transfusion indicated
  —> when infusion of BSS >30 ml/kg —> transfusion indicated
  —> ratio of RBC:FFP:Plt = 1:1:1
• ***NO steroid, vasopressor to treat hypovolaemic shock in trauma patients
• Surgical intervention: stop the bleeding!!!

Complications:
1. Storage defect in blood product
- 2,3 DPG degradation: ↓ O2 affinity
- HyperK (40-70 mmol/L)
- Coagulation abnormality: Factor 5 / 8 decline quickly for 24 hours after collection
- Haemostatic failure
—> Hypothermia
—> Acidosis (citrate + lactate)

2. Blood transmitted infections:
   - HBV / HCV
   - HIV
   - CMV
   - Malaria
3. Haemolytic transfusion reactions
4. Immunosuppression
   - ↑ ratio of suppressor to helper T cell —> infection
5. Massive blood transfusion protocols
   - whole blood / packed cells / platelets / FFP

Question 19

Resuscitation: Disability

Answer 19

1. Baseline neurologic evaluation
   - Pupillary response
   - GCS score
   - Neurosurgical consult as indicated
2. Observe for neurologic deterioration
3. ICP can rise rapidly past threshold of compensation —> Hernia

Question 20

Resuscitation: Exposure

Answer 20

1. Completely undress patient
2. Remove helmet if present
3. Look for visible / palpable injuries
4. Log-roll, protect spine
5. Prevent hypothermia

Question 21

Resuscitation: Summary

Answer 21

1. If in doubt, establish definitive airway (cricothyroidotomy if needed)
2. O2 for all trauma patients
3. Chest tube may be definitive for chest injury
4. Stop the bleeding
5. 2 Large caliber IV
6. Prevent hypothermia

Question 22

Special considerations in Children

Answer 22

• Trauma: leading cause of death
• Immature anatomic / mechanical features
  1. Airway
• larynx anterior + cephalad
• short tracheal length

2. Breathing
   - chest wall pliability
   - mediastinal mobility
3. Circulation
   - vascular access (may need ***Intraosseous access), fluid volume, vital signs, urinary output
4. Neurologic
   - vomiting, seizures, diffuse brain injury (***hypotension is enemy of neurosurgery)
5. Musculoskeletal
   - immature skeleton
   - different fracture patterns

• Vigorous physiologic response
• Limited physiologic reserve
• Size, dosage, equipment, surface area, psychology
• Outcome depends on early, aggressive care

Question 23

Special considerations in Pregnancy

Answer 23

• Anatomic / Physiologic changes modify response to injury
  1. Viscera
• pushed upward

2. Circulation
   - relative hypervolaemic state
   - physiologic anaemia
   - supine hypotension (∵ pressure on IVC)
3. Breathing:
   - ↓ gastric emptying —> risk of aspiration
   - hyperventilatory state —>↓ PCO2
4. Resuscitation
   - IVC compressed by fetus —> limit venous return to heart
5. Gestation and position of uterus
6. Isoimmunisation
   - may need to give Anti-RhD to Rh -ve mothers during blood transfusion
7. Sensivity of fetus
   - see if need delivery

• Need for fetal assessment
• 1st Priority: Maternal resuscitation (best way to resuscitate baby is to resuscitate the mum)
• Rupture amniotic membrane —> inevitably need to deliver baby (dead / alive)
• Outcome depends on early, aggressive care

Question 24

Special considerations in Elderly

Answer 24

• Injury: 5th leading cause of death

1. Diminished physiologic reserve / response
   - Cannot mount compensatory response effectively e.g. tachycardia, vasoconstriction
2. Comorbidities: Diseases
   - Co-existing HT —> mask underlying haemorrhage (normal BP may already signify shock)
3. Medications
   - Aspirin, Anticoagulants —> coagulopathy
   - β-blockers: mask tachycardic response

• Outcome depends on early, aggressive care

Cardiovascular:

• Diminished pump function + lower CO
• Inability to mount appropriate response to intrinsic / extrinsic catecholamines
• Reduced flow to vital organs
• Co-existing medication blunting normal physiologic response

Respiratory:

• Decreased lung elasticity + pulmonary compliance
• Atrophy of bronchial epithelium leading to decreased clearance of particulate foreign matter

Renal:

• Decrease in renal mass
• Increased vulnerability to nephrotoxic agents

Musculoskeletal:

• Osteoporosis with inclination to fractures
• Decrease in muscle mass

Comorbidities:
- DM / Liver disease / Malignancy / Neurological / Spinal disease

Question 25

***Secondary survey

Answer 25

- Start after
—> Primary survey completed (i.e. patient stabilised / improved)
—> Resuscitation in process
—> ABCDE reassessed
—> Vital functions returning to normal

1. ***Head to toe examination
   - Undressing + log-roll

• Head
  —> complete neurologic exam
  —> GCS score determination
  —> comprehensive eye / ear exam (pupillary response, otoscopic exam, visual acuity)
  —> caution: unconscious patient, periorbital edema, occluded auditory canal

- Maxillofacial
—> bony crepitus / instability
—> palpable deformity
—> comprehensive oral / dental exam
—> caution: potential airway obstruction, cribriform plate fracture, frequently missed injury

- C-spine
—> palpate for tenderness
—> complete motor / sensory exams
—> reflexes
—> C-spine imaging (preferably CT scan)
—> caution: injury above clavicles, altered LOC, other severe / painful injury

- Neck
—> blunt vs penetrating
—> airway obstruction, hoarseness
—> crepitus, haematoma, stridor, bruit
—> caution: delayed S/S, progressive airway obstruction, occult injuries

- Chest
—> inspect, auscultate, palpate, percuss
—> re-evaluate frequently
—> CXR
—> caution: missed injury, ↑ chest tube drainage

- Abdomen
—> inspect, auscultate, palpate, percuss
—> re-evaluate frequently
—> FAST, DPL, CT
—> caution: hollow viscus and retroperitoneal injuries (not apparent on FAST scan), excessive pelvic manipulation (may disrupt haematoma —> further bleeding)

- Perineum
—> contusions
—> haematoma, ecchymosis
—> lacerations
—> urethral blood

- Rectum
—> blood
—> sphincter tone
—> high-riding prostate
—> pelvic fracture
—> rectal wall integrity

• Vagina
  —> blood, lacerations
  —> caution: pregnancy (amniotic fluid leaking)

- Musculoskeletal
—> potential blood loss
—> limb / life threat (Primary survey)
—> missed fractures
—> soft tissue / ligamentous injury
—> occult compartment syndrome (esp. with altered LOC / hypotension)
—> examine patient’s back
—> splint long bones, analgesia

- Pelvis
—> pelvic fracture (major source of haemorrhage —> volume resuscitation, reduce pelvic volume, external fixator, angiography / embolisation)
—> pain on palpation
—> symphysis width ↑
—> leg length discrepancy
—> instability
—> pelvic X-ray

- CNS
—> frequent re-evaluation
—> prevent secondary brain injury
—> imaging as indicated
—> early neurosurgical consultation

- Spine
—> stepping / local tenderness
—> complete motor + sensory exam
—> imaging as indicated
—> maintain in-line immobilisation
—> early neurosurgical consultation
—> caution: incomplete immobilisation, subtle ↑ in ICP with manipulation, rapid deterioration

2. Adjuncts
   - Blood tests
   - Urinalysis
   - X-ray
   - CT
   - Urography
   - Angiography
   - USG / Echo
   - Bronchoscopy
   - Esophagoscopy
   —> do NOT delay transfer
3. ***AMPLE history
   - Allergy
   - Medication (Antiplatelet, Anticoagulant, β-blockers, Anti-HT)
   - Past medical history / Pregnancy
   - Last meal
   - Events / Environment
4. Complete neurologic examination
5. Special diagnostic tests
   - Skeletal survey (e.g. femoral X-ray, skull X-ray)
6. Re-evaluation
   - Vital signs
   - Interventions (e.g. chest tube still in place?)
   - Missed injury
   —> high index of suscipion
   —> frequent re-evaluation
   —> continuous monitoring
   —> rapidly recognise patient deterioration

Question 26

Preparation for operation

Answer 26

1. Inform anaesthetist + OT staff
2. Initiate massive transfusion protocol
   - replacement of 100% of patient’s blood volume <24 hours
   - administration of 50% of patient’s blood volume in 1 hour
3. +/- Arrange post-op ICU care
4. Maintain reasonable BP before operation —> maintain adequate cerebral perfusion but not too high BP —> ***normotension before definitive measures may cause more bleeding
   - SBP ~90
   - MAP ~70
5. Warm operating theatre
6. Prepare fluid warmer, suction
7. Prepare cell saver (i.e. Scavenge the lost blood —> for autotransfusion)

Question 27

***Operative management

Answer 27

1. Generous midline laparotomy incision
   - from xiphisternum to pubic symphysis
2. 4 quadrants packing
   - RUQ + LUQ + R iliac fossa + L iliac fossa
3. Scoop out all blood clots
4. Allow anaesthetist to administer blood products + clotting factors
5. Remove packs from least bleeding site first (one by one)
   - Locate the bleeding site
6. Definitive surgery (if stable) / Damage control surgery (DCS)
   DCS:
   - Stop bleeding
   - Control contamination: staple off injured bowel ***without anastomosis
   - Temporary abdominal closure: limit heat / fluid loss + protect bowels
   - After DCS —> Correction of acid/base balance, clotting, body temp —> Allow more time in definitive surgery since physiology is optimised —> Definitive surgery in 24-48 hours

Question 28

Pattern of injury

Answer 28

Depends on:

1. Anatomy
2. Physiology
3. Mechanism of injury

Question 29

Burn injury

Answer 29

1. Inhalation injury: Intubate, 100% O2
2. Chemical burns: Brush + irrigate (large amount)
3. Administer ***2-4 mL/kg/% BSA burn in 24 hours (+ Maintenance in children) —> Parkland formula
4. Monitor urine output
5. Expose + prevent hypothermia
6. Antibiotic + Tetanus prophylaxis

Measurement:

• Palm + Fingers = 1% BSA
• Rule of 9
• BSA: ***only for >=2nd degree burn (NOT for 1st degree burn)

Question 30

Cold injury

Answer 30

Frost bite:

• Rewarm with moist heat (40oC)
• Wait for demarcation

Hypothermia:
- Passive / Active rewarming

Monitor:
- Not dead until warm and dead

Question 31

Pain management

Answer 31

• Relieve pain + anxiety as appropriate
• Fast acting, IV opioid
• Careful patient monitoring is essential (SaO2, BP, End-tidal CO2, RR, HR)

Question 32

Safe transfer

Answer 32

When patient’s needs > institutional resources

• think about it during Primary survey
• use time before transfer for resuscitation
• do NOT delay transfer for diagnostic tests
• physician-to-physician communication

Transfer to:

• Trauma centre
• Specialty centre

Question 33

Emergency preparedness

Answer 33

• Simple plan
• Command structure
• Disaster triage scheme
• Traffic control system