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Injuries and medical problems in sport > Diving medicine > Flashcards

Diving medicine Flashcards

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Sports Trivia flashcards USMLE® Step 1 flashcards
1
Q

physiological changes with free diving

A
  • reduced heart rate
  • blood flow
    and volume is redistributed towards vital organs by
    means of a reflex vasoconstriction
  • body cooling
  • Risk of hypoxic blackout and drowning
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2
Q

How is buoyancy controlled in scuba diving

A

Buoyancy compensator or buoyancy control device.
Volume of air in the
jacket is varied

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3
Q

ideal gas law

A 
PV = nRT
P= absolute pressure, V= volume, n= number of moles,
R= universal gas constant, T= temperature
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4
Q

Boyle’s law

A

P and V inversely related

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5
Q

Gay-Lussac’s law

A

P and T directly related

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6
Q

Charles law

A

V and T directly related

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7
Q

implications of the gas laws in diving

A 
Fall in temp:
- pressure of
the cylinder drops
- volume of the air in
lungs/BCD jacket drops.

Pressure increases:
- volume of air in lungs/BCD jacket drops.

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8
Q

Dalton’s Law

A

The total pressure exerted by a mixture of gases is equal to
the sum of the pressures that would be exerted by each of the gases if it alone were present and occupied the total volume.
PTotal= Pp1+ Pp2+

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9
Q

Henry’s Law

A

The amount of any given gas that will dissolve in a liquid at a given temperature is a function of the partial pressure of the gas that is in contact with the liquid and the solubility coefficient of the gas in the particular liquid

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10
Q

Implications of Dalton’s and Henry’s

law in diving

A
  • For every 10m depth pressure
    increases by 1 bar.
  • Therefore more gas will dissolve into the blood and
    body tissues
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11
Q

What causes nitrogen narcosis?

A
  • As depth increases, gas pressure increases –> partial pO2 and PN2 increase
  • increased nitrogen into the blood stream
  • divers may experience
    alterations in reasoning, memory and response time and idea
    fixation, overconfidence or calculation errors.
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12
Q

Aetiology of decompression sickness

A

Increased descent –> increased pressure –>
nitrogen dissolves and accumulate in the lipid component of tissues.
- Diver ascends –> lag –> saturated tissues release
nitrogen back into the blood.
- When a critical amount of nitrogen is dissolved in the tissues, ascending too quickly causes the dissolved nitrogen to return to its gas form while still in the blood or tissues
- Bubbles form- in the tissue–> local problems
- in the blood –> embolisation may result.

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13
Q

Decompression sickness prophylaxis

A 
1- tables/dive
computers are used 
for given depth of water / time a diver
can stay down
2- decompression stop (10m/min during ascent) and safety stop (every 5m during descent)
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14
Q

Type I Decompression

sickness (DCS) Sx

A
  • Pain (the bends)- (70-85%) patients with type I
    DCS.
  • Pruritus- mottling/papular violaceous rash.
  • Oedema
  • Anorexia/excessive fatigue
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15
Q

Type II DCS Sx

A
  • Pulmonary: burning, sub-sternal discomfort on inspiration, nonproductive coughing that can become paroxysmal, and severe
    respiratory distress
  • Circulatory: hypovolemic shock
  • Nervous system involvement: low back pain may progress to paresis,
    paralysis, paraesthesia, loss of sphincter control, headaches or
    visual disturbances, dizziness, tunnel vision, and changes in
    mental status.
  • Pain- only 30% of cases
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16
Q

Sx onset DCS

A 
Usually quick (60% within 3 hours and 98% within
the first 24 hours)

Increased risk if –> high altitude within 24h

17
Q

AGE pathophysiology

A

Pulmonary over-pressurisation –> large gas emboli –> pulmonary vein –> lodge in coronary, cerebral, and other systemic arterioles.

Gas bubbles continue to expand as ascending
pressure decreases, —> increasing the severity of clinical signs.

18
Q

Sx Arterial gas Embolisation

A

Much faster Sx onset (10-20min)
Depends on location of emboli
- coronary artery –> MI
- Cerebral artery –> stroke/seizures
- May occur suddenly or gradually (dizziness,
headache, profound anxiousness)
- More severe symptoms (shock/seizures) = sudden onset

19
Q

Differentiating cerebral AGE from type II neurologic

DCS

A
  • AGE
  • Any type of dive
  • onset is immediate (< 10-120 min)
  • neurologic deficits
    manifest mainly in the brain.
DCS 
- dive must be of sufficient duration to
saturate tissues
- onset is latent (0-36 h)
- neurologic deficits manifest in spinal cord and brain.
20
Q

Hx info needed for suspected AGE or DCS

A

Diving info: Location of the dive, timing of events during the dive and over the prior 72 hours
(length and depth of dives, safety stops, flying, and method of timing used [e.g., watch with tables,
dive computer]) , gases and equipment used (compressed air, rebreathing equipment, mixed gases)
Problems encountered : violation of no–decompression-limit dive tables, equipment, entanglement,
dizziness, marine bites or stings
Patient’s physical condition before, during, and after the dive : fatigue, drug or alcohol intake,
fever, vertigo, nausea, overexertion, pulled muscles
First aid delivered : oxygen, medications, fluids
General symptoms: profound fatigue, weakness, sweating or anorexia
Musculoskeletal symptoms: joint pain, back pain, or heaviness of extremities
Mental-status symptoms: confusion, unconsciousness, changes in personality
Eye and ear symptoms: scotomata , diplopia, tunnel vision, blurring, tinnitus, or partial hearing loss
Skin symptoms: pruritus or mottling
Pulmonary symptoms: dyspnoea, non-productive cough, or haemoptysis
Cardiac symptoms: sharp or burning chest pain
Gastrointestinal symptoms: abdominal pain, faecal incontinence, nausea, or vomiting
Genitourinary symptoms: urinary incontinence or urinary retention
Neurological symptoms: paraesthesia (general or over a joint), paresis, paralysis, migrainous
headache, vertigo, dysarthria, or ataxia
Lymphatic symptoms: oedema

21
Q

Ix for DCS

A

No specific tests exist for DCS diagnosis.

Consider (only if doesn’t delay HBO therapy):
- Blood glucose level, FBC, clotting, U+Es,
magnesium, calcium and phosphorous levels
- ETOH and drug screen
-carboxyhaemoglobin level
 Oxygen saturation

22
Q

Mx for AGE/DCS

A

If shock: resuscitation
Do not delay HBO therapy

  • Administer 100% oxygen
  • Do not put the patient into the Trendelenburg position
  • Consider IV fluids, if available

Transport to the nearest ED and hyperbaric facility and try to
keep all diving gear with the diver

23
Q

Predisposing factors to DCS- diving factors

A
  • Inadequate decompression (inc increased depth and
    duration of dives and repeated dives)
  • Inadequate surface intervals (i.e. failure to decrease accumulated nitrogen)
  • Failure to take recommended safety stops
  • Flying or going to higher altitude soon (12-24 h) after diving
  • Rapid ascent due to panic. Anxiety traits
24
Q

Predisposing factors to DCS- individual

A

Obesity (nitrogen is lipid soluble)

  • Fatigue
  • Age
  • Poor physical condition
  • Dehydration
  • Illness affecting lung or circulatory efficiency (Patent foramen ovale)
  • Prior MSK injury (scar tissue decreases diffusion)
  • Smoking
25
Q

Predisposing factors to DCS- Environmental factors

A

Cold water (vasoconstriction decreases nitrogen offloading)

  • Heavy work
  • Rough sea conditions/poor buoyancy
  • Heated diving suits (leads to dehydration)
26
Q

Cylinder content- 3 options

A

most common = air: 21% oxygen, 78% nitrogen, approximately 1%
other trace gases, primarily argon.
Safe depth limit is about 40 m

Pure oxygen: mainly used to speed the shallow decompression
stops (military and commercial dives)
only safe down to a
depth of 6 m

Nitrox: a mixture of oxygen and air. accelerates
in-water decompression stops or to decrease the risk of
decompression sickness

27
Q

Sx oxygen toxicity

A

disorientation, seizures, breathing

problems, vision changes (retinal detachment), death

28
Q

Oxygen toxicity- pathophysiology

A
  • collapse of the alveoli in the lungs–>
    hypoxia
  • destruction of cell membranes –>
  • chemical toxicity + haemolysis –> hepatic and renal
    damage, neural toxicity
29
Q

most common medical problem divers

A

Barotrauma can affect the external, middle, or inner ear.
Middle ear
barotrauma (MEBT) is the most common (10-30% divers)
Due to insufficient equilibration of the middle ear

30
Q

inner ear barotrauma Sx

A

Inner ear barotrauma (IEBT) is less common
Can lead to:
- conductive and sensori- neural hearing loss
- vertigo
- auditory
hypersensitivity.

31
Q

breath-holding on ascent leads to…

A

Pulmonary barotrauma

Compressed gas in the lungs expands –>
ruptures lungs
No associated pain.

32
Q

Adjust buoyancy techniques

A

Before the dive:

  • weights
  • wetsuit
  • water temperature

During the dive:

  • BCD
  • exhale/inhale
  • swimming position
33
Q

Leading causes of death diving

A
  • Drowning (80%).
  • Asphyxia
  • Arterial gas embolism (AGE), caused overwhelmingly by emergency ascent with insufficient gases
    >40yr- cardiovascular disease.
34
Q

Prognosis AGE

A

Morbidity is directly related to time to HBO treatment.

If recompression with HBO occurs within 5 minutes- death rate is only 5% with little residual morbidity

If delayed 5 hours- mortality increases to 10% with residual symptoms
in 50%

35
Q

Diving contraindications

A

Neuro:

  • Epilepsy controlled by medication
  • unexplained syncopal episodes
  • Stroke/TIA
  • Intracranial aneurysm, AVM or tumour
  • Progressive neurological problems eg severe MS/Parkinson’s/ MND
Severe heart disease: 
-congenital heart defects
- severe valve problems
- severe IHD
- post-MI with left ventricular
dysfunction
- medication to control dysrhythmias

Pulmonary:

  • bullae
  • severe asthma
  • COPD
  • Hx of spontaneous pneumothorax

Blood disorders:

  • severe bleeding disorders (e.g. haemophilia)
  • malignancy
  • Pregnancy
  • MH issues
  • Inability to equalise pressure in the middle ear

Injuries and medical problems in sport (17 decks)

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