Disaster medicine - High altitude emergencies, Cold related emergencies, Crush syndrome

Question 1

Define ‘disaster’

Answer 1

WHO definition:
A serious disruption of the functioning of a
community or a society causing widespread
human, material, economic or environmental
losses , which exceed the ability of the affected
community or society to cope using its own
resources.

CRED definition:
“a situation or event, which overwhelms local capacity, necessitating a request to national or
international level for external assistance; an
unforeseen and often sudden event that
causes great damage, destruction and human
suffering”.

Question 2

List types of disaster

Answer 2

Natural:
* Earthquake, landslide, tsunami, cyclones, flood or drought.
* Biological: epidemic disease, infestations of pests.

Man-made:
* Technological: chemical substance, radiological agents, transport crashes.
* Societal: conflict, stampedes, acts of terrorism.

Question 3

Most prevalent reported disasters

Answer 3

Subtotal climato-, hydro-, meterological disasters

Floods

Transport accidents

Windstorms

Industrial accidents

Question 4

Outline the disaster management cycle

Answer 4

Question 5

Define the Sphere project minimum standard for basic disaster relief

Answer 5

Water, sanitation and hygiene promotion
- 2-4 gallons of portable water per person (including intake, hygiene and cooking needs)
- Maximum of 20 persons per toilet
- Handwashing and personal hygiene
- Avoiding mosquito exposure
- Solid waste management

Shelter
- Minimum space of 38 sqft per person
- Comfortable bedding
- Proper access for disabled

Question 6

Define the sphere project minimum standard for medical relief

Answer 6

Health services
- Trauma care
- Mental health care
- Chronic illness care
- Handling remains of the dead

Question 7

Outline the variation of needs and priority during acute phase of a disaster

Answer 7

Question 8

List some communicable diseases associated with natural disasters

Answer 8

• Water-related communicable diseases
  (diarrheal diseases, cholera, leptospirosis,
  hepatitis A and E).
• Diseases associated with overcrowding
  (measles).
• Vector-borne diseases (e.g., malaria, dengue).
• Other diseases (e.g., tetanus, fungal infections).

Question 9

Healthcare provided at acute and recovery phase of disaster management

Answer 9

Disaster medical response in acute phase
- Search and rescue
- Triage and initial stabilization
- Definitive medical care
- Evacuation

Recovery phase:
Primary care
– Children: nutrition, immunization
– Women: child birth etc
– Chronic illnesses
Public Health
– Mental health
– Disease surveillance
– Prevent/Control outbreaks of infectious ds

Question 10

Examples of mental health problems a/w disasters

Answer 10

Anxiety disorder/ Acute stress (ACU)
Moderate-severe Depression disorder (DEP)
PTSD
Psychosis
Epilepsy/Seizures
Intellectual disability
Suicide
Harmful substance abuse

Question 11

Define the HK three tier emergency response system

Answer 11

• Tier 1: isolated events such as rescuing a
  person from a car crash
• Tier 2: an event with many casualties e.g. fire
  in a high rise building
• Tier 3: events having severe and widespread
  consequences such as effects of a typhoon.

Question 12

Parties involved in the rescue phase of HK emergency response system

Answer 12

• FSD (Ambulance): on-site rescue and transport of
  casualties
• The Police: establish a Command Post at the scene and
  secure the outer cordoned zone surrounding the site.
• Hospital Authority: provision of hospital services,
  dispatch medical teams for on site triage and treatment
• HAD: coordinate relief items with Social Welfare
  Dept.(SWD), Housing Dept. and other agencies
• EMSC: update Government senior officials

Structure within HA:
EEC = Emergency Executive Committee
CCC = Central Command Committee
MICC = Major Incident Control Centre

Question 13

Is international support always needed for disaster relief

Issues with international response

Answer 13

• Depends on any unmet immediate needs after assessment
• The local population almost always covers immediate lifesaving needs
• Only medical personnel with skills not available in the affected country may be needed
  e.g. foreign military support or resource support

Problems:
- Duplication of resource
- Fragmentation of support
- Inco-ordination
- Lack of relevant experience/ competence/ capacity

Question 14

Foreign medical team (FMT) basic requirement

Answer 14

FMT trained using competency-based curriculum to provide care in austere environments

Sterilization: Basic steam autoclave or disposable equipment

Logistics: Self-sufficient team +/- OPD facility self sufficient

FMT size:
- At least 3 doctors specialists trained in emergency and primary care
- 1:3 doctor: nurse ratio
- Staff skilled in emergency and trauma care, maternal and child health, knowledge of endemic disease management
- FMT capacity: 100+ OP consultation per day for 2 weeks

Question 15

Roles of foreign medical team

Answer 15

Question 16

High altitude illness

Define high altitudes associated with altitude sickness

Answer 16

High: 2500-3500m, altitude sickness common when individual ascend rapidly

Very high: 3500-5800m, Altitude sickness common

Question 17

Physiological changes at high altitude

Answer 17

• Hypobaric hypoxia (ambient PO2 decreases with lower barometric pressure at high altitude)
• Acute mountain sickness (AMS) S/S: Headache, Loss of appetite, Dizziness, Fatigue on minimal exertion, increasing tiredness, vomiting
• High altitude cerebral edema (HACE): Altered mental status (confusion, drowsiness, ataxia)
• High altitude pulmonary edema: Dyspnea at rest, moist
  cough, rales, severe exercise limitation, cyanosis, tachypnea, tachycardia, desaturation

Question 18

Diagnosis of acute mountain sickness

Treatment

Answer 18

Lake Louise AMS score: assesses severity of illness by questionnaire of symptoms during ascent

AMS Diagnosis:
- Altitude gain + Headache + Total symptoms score ≥ 3

Mild AMS:
* Descend ≥ 500m
* Acclimatization x 1-2/7
* Avoid ascent till s/s subsided
* Acetazolamide 125-250mg bd

Moderate AMS:
* Descend
* O2 (1-2L/min)
* Portable hyperbaric therapy (2-4psi) x 6hr
* Acetazolamide 125-250mg bd
* Dexamethasone 4mg Q6H IM/PO

Question 19

Diagnosis of High Altitude Cerebral Edema (HACE)

Treatment

Answer 19

Lake Louise Criteria for HACE
- AMS + Altered mental status or Ataxis
or
- Altered mental status + Ataxia

Treatment
* Immediate descent/evacuation ≥ 1000m
* O2 to keep SpO2 ≥ 90%
* Dexamethasone 8mg stat IV/IM/PO, then 4mg Q6H
* Portable HBT if cannot descend

Question 20

Acetazolamide/ Diamox

• MoA
• S/E
• Use

Answer 20

MoA:
* Carbonic anhydrase inhibitor
* Induce renal excretion of HCO3, causing metabolic acidosis
* Counter respiratory alkalosis due to hyperventilation

Side effects: GI upset, tingling in hands

Question 21

Examples of protable hyperbaric therapy

MoA

Answer 21

Gamow Bag Inflation

MoA: Positive pressure inflation into sealed body bag, increasing local pressure and relieving hyperbaric hypoxaemia

Question 22

Ddx High-altitude SOB

Answer 22

• High-altitude pulmonary edema
• Asthma
• Bronchitis
• Heart failure
• Hyperventilation syndrome
• Mucus plugging
• Myocardial infarction
• Pneumonia
• Pulmonary embolus

Question 23

Pathophysiology of high altitude pulmonary edema

Answer 23

Question 24

High Altitude Pulmonary Edema

Diagnostic criteria

Management

Answer 24

Symptoms: at least two of:
– SOB at rest
– Cough
– Weakness or decreased exercise performance
– Chest tightness or congestion
Signs: at least two of:
– Crackles or wheezing in at least one lung field
– Tachypnea
– Tachycardia
– Central cyanosis

Management:
* O2 (4-6L/min till improved, then 2-4L/min to keep SpO2 ≥ 90%)
* Minimize exertion
* Descent/evacuation ≥ 1000m
* Portable HBT if cannot descend
* Nifedipine 10mg PO then 30mg SR QD/BD
* Inhaled B-agoinist (ventolin®)
* EPAP mask
* Dexamethasone only if HACE develops

Question 25

Define rules of 3 in survival

Answer 25

People can survive: * 3 minutes without air * 3 hours without shelter * 3 days without water * 3 weeks without food

Question 26

Define hypothermia and severity grades Method of diagnosis S/S

Answer 26

Hypothermia: Core body temperature < 35C (or 95F) Method of diagnosis: Low reading thermometer, Rectal temperature, Clinical S/S Mild 32-35: Tachypnea, Tachycardia, Dysarthria, Shivering Moderate 28-32: Loss of shivering, diminished consciousness Severe <28: Coma, Loss of reflexes, Ventricular fibrillation

Question 27

Pathophysiology of hypothermia

Answer 27

All cells and tissues affected, resulting in different organ dysfunctions * CNS depression * Cardiac depression / arrhythmia * Respiratory depression * Metabolic acidosis * Volume depletion due to cold-induced diuresis

Question 28

S/S when body temperature is between 37 - 33/ Mild hypothermia

Answer 28

Question 29

S/S when body temperature is between 32-29/ Moderate hypothermia

Answer 29

Question 30

S/S when body temp is below 28/ Severe hypothermia

Answer 30

Question 31

Management of hypothermia

Answer 31

Initial management: - ABC resuscitation - Monitoring: CVS, deep rectal temp - Prevent heat loss: Move to warm environment, shelter from wind (wind-chill effect), Insulate from ground, Insulate patient (esp. head), Remove wet clothing, Cover with vapor barrier (e.g. plastic bag) - Rewarming: Passive rewarm with insulation (simple/ space/ warmed blanket) and glucose drink, Active external rewarm with hot pad/ lying next to normothermic person in sleeping bag, forced hot air, whole body immersion ... Active core rewarm: e.g. chest tube lavage, peritoneal lavage, cardiopulmonary bypass, heated O2 mask... - Treat underlying cause: e.g. sepsis, OD, metabolic disorder rewarm - Consider evacuation (only except mild hypothermia) *do no rub cold extremities for rewarming

Question 32

Summarize management of mild, moderate and severe hypothermia

Answer 32

Mild: core temp > 32C - Passive rewarming: insulation and glucose drink - Consider external rewarming - Prevent heat loss - IV fluid replacement for prolonged exposure Moderate and severe: - Active External rewarming (hot pad, lie next to normothermic person) - Active core rewarming for cardiovascular unstable - Increase temp >1C/ hour

Question 33

Methods of active external rewarming

Answer 33

Question 34

Methods of active core rewarm

Answer 34

Question 35

Complications of rewarming hypothermia patient

Answer 35

During rewarming, beware of peripheral vasodilatation causing * rewarming shock * rewarming acidosis * afterdrop effect (decrease core temp.)

Question 36

Frostbite S/S Management

Answer 36

S/S: - cold exposure, particularly at temperatures below −15° C - Tissue hard, pale, anesthetic Management: * Treat hypothermia first * Prevent further cold injury * Maintain hydration * Protect the frostbitten tissue with dry, bulky dressing * Give ibuprofen for anti-inflammatory and analgesic effect Thawing: Circulate warm (37° to 39° C ) water around frozen tissue in a bath for 30 minutes + Analgesic for pain during rewarming

Question 37

What to avoid when treating frostbites

Answer 37

* do not rub the frozen part; * do not apply ice or snow; * do not attempt to thaw the frostbitten part in cold water; * do not attempt to thaw the frostbitten part with high temperatures e.g. by stoves, * do not break blisters * no alcohol or tobacco

Question 38

Prevention of hypothermia

Answer 38

* Keep skin dry and warm * An extremity at risk for frostbite (eg, numb, poor dexterity, pale color) should be warmed with adjacent body heat

Question 39

Common injuries in victims trapped under collapsed structures

Answer 39

Question 40

Initial assessment of patient trapped under rubble

Answer 40

- Scene safety first - Airway: assume compromised - Breathing: assume ventilation impaired secondary to dust/ noxious gas inhalation/ direct trauma - Circulation: assume hypovolemia, crush injury - Disability: assume imcomplete neurological exam - Exposure: assume hypothermia, expose body parts only if necessary for saving life

Question 41

Crush syndrome Onset time Pathophysiology S/S

Answer 41

Onset time: all patients who are crushed or immobilized for 4 hours or longer are at risk Pathophysiology: - Disintegration of striated muscles > swelling of muscles > pressure effects on surrounding structures - Rhabdomyolysis > release of muscular cell contents into the extracellular fluid > systemic manifestations = Crush Syndrome S/S: - Myoglobinuria (red urine) - Hypovolemia S/S - Electrolyte disturbances - Acute renal failure: acute tubular necrosis, myoglobin and uriate casts, microthrombi deposit in glomeruli - Arrhythmia - Sepsis - ARDS - DIC/ massive hemorrhage - Compartment syndrome

Question 42

Biochemical disturbances a/w Crush syndrome

Answer 42

* Myoglobinemia * Hyperkalemia * Hyperphosphatemia * Hypocalcemia * Hyperuricemia * ↑Creatine Kinase * ↑Creatinine / Urea * Acidosis

Question 43

Crush syndrome Management

Answer 43

ABCDE resuscitation Avoid kidney injury: - Normal saline 1L/hr (10-15mL/kg/hr), avoid all K+ containing solutions - Forced alkaline diuresis with Sodium bicarbonate and Mannitol - Aim for urine output 300ml/hr, urine pH > 6.5 - Dialysis - Call Renal Disaster Relief Task Force Manage electrolyte disturbance: - Calcium chloride to counteract hyperK on myocardium - Manage hyperK: Glucose insulin drip, Beta agonist (ventolin), Sodium bicarbonate Determine need for field amputation

Question 44

Causes of 'rescue death' (patient collapse after extrication)

Answer 44

Metabolic causes of “Rescue Death” * Influx of plasma into the muscles * Efflux of muscle breakdown products (acidosis, hyperkalemia) * Influx of calcium

Question 45

Cause of limb pain and numbness after extrication Management

Answer 45

Compartment syndrome: Compartment pressure > Filling pressures of the arterioles of the muscle 6 Ps of compartment syndrome: * Pain, * Perishingly cold, * Paresthesia, * Paralysis, * Pallor, * Pulselessness Fasciotomy usually if pressure is greater than 40 mmHg

Question 46

Determinants of field amputation

Answer 46

2 main factors * Must for urgent life saving * Salvageability of the trapped limb Salvageability: 1. Is the vascular injury reparable? 2. Can the skeletal injury be reconstructed? 3. Is the soft tissue viable, or can adequate soft tissue coverage be achieved? 4. Is innervation present or possible?