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Sports and Exercise Medicine iBSc > Diving > Flashcards

Diving Flashcards

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1
Q

Scuba diving

A

Self-contained underwater breathing apparatus

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2
Q

Free diving

A

Breath-holding

Spearfishing, photography etc

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3
Q

Free diving mechanism

A

Reduced HR
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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4
Q

Competitive apnoea

A

Free diving
Attempt to attain great depths, times or distances on single breaths
11 disciplines, pool (apnoea) and depth (using weights etc)

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5
Q

AIDA records- depth

A

253.2m

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6
Q

AIDA records- time

A

11 mins 35s

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7
Q

AIDA records- distance

A

30m

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8
Q

DAN

A

Annual number of breath-hold competitive and non-competitive incident cases captured from 2004 through 2013 (mean±standard deviation) was 65±18 (range 30-82).
Majority fatal incidents (2010-2013: 81% fatal)

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9
Q

Scuba diving buoyancy equipment

A

Buoyancy compensator or buoyancy control device (BCD)

Buoyancy controlled by adjusting the volume of air in the jacket

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10
Q

Scuba diving breathing equipment- Diving cylinders

A

Usually contain air (mixture 21% )2, 78% N, 1% other gases mainly argon) or pure oxygen or nitrox (mixture of O2 and air)
Regulator mechanism to control gas pressure
Submersible pressure gauges
Open circuit used more commonly (exhausts exhaled air to the environment)- exhale through mouth

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11
Q

What happens to vol. of gas in your lungs or BCD jacket as you descend deeper in water

A

It decreases (Boyle’s)

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12
Q

What happens to vol. of gas in lungs or BCD jacket as you descend in colder water

A

Drops

charles

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13
Q

What happens to gas pressure of cylinder when you enter into cold water?

A

Drops

gay loussac

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14
Q

Ideal gas law

A

Pv=nRT

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15
Q

Ideal gas law- what is P

A

Absolute pressure

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16
Q

Ideal gas law- what is v

A

Volume

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17
Q

Ideal gas law- what is N

A

Number of moles

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18
Q

Ideal gas law- what is R

A

Universal gas content

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19
Q

Ideal gas law- what is T

A

Temperature

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20
Q

Boyle’s law

A

P and V inversely related

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21
Q

Gay-Lussac’s law

A

P and T directly related

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22
Q

Charles law

A

V and T directly related

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23
Q

Implications of gas law in diving

A

Temp gets colder –> pressure of cylinder may drop + vol of air in lungs/BCD drops
As pressure increases in deeper diving, vol of air in lungs/BCD drops
More gas will diffuse into tissues as depth of diving increases

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24
Q

Dalton’s law

A

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

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25
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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26
Q

Pressure vs depth

A

As depth increases, gas pressure increases
–> partial pressures of the O2 and N in the breathing air increase
As depth increases, more gas will dissolve into the blood and body tissues

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27
Q

For every 33 feet depth in sea water, the pressure increases by

A

1 bar

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28
Q

Nitrogen narcosis

A

Increased nitrogen into the blood stream can lead to a narcotic feeling at depth

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29
Q

How many feet is equivalent to effects of 1 alcoholic drink

A

Every 50ft (15m)

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30
Q

What can divers experience at 150ft (46m)

A

Alterations in reasoning, memory and response time
Idea fixation
Overconfidence
Calculation errors

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31
Q

Nitrogen narcosis physiology

A

As diver descends and pressure increases, increasing amounts of N dissolve and accumulate in lipid component of tissues
As long as pressure is maintained, regardless of quantity of gas that has dissolved in tissues, gas will remain in solution

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32
Q

Nitrogen narcosis ascending

A

When diver ascends, a lag occurs before saturated tissues start to release nitrogen back in blood
When critical amount of N is dissolved in tissues, ascending too quickly causes dissolved N to return to its gas form while still in blood or tissues, causing bubbles to form

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33
Q

Nitrogen narcosis bubbles

A

If bubbles still in tissues, can cause local problems
If in blood, embolization may result
Further reductions in pressure while flying or ascending to higher altitude also contribute to bubble formation

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34
Q

Diving safety

A

Tables/dive computers used to show relationship between given depth of water + time diver can stay down
Safety stop every 5 metres, and not to ascend at pace more than 10m/min

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35
Q

Safety stop every … metres

A

5

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36
Q

Don’t ascend at a pace more than

A

10 metres/min

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37
Q

DCS stands for

A

Decompression sickness

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38
Q

Type I DCS sympoms

A

Pain (the bends) occurs in most patients (70-85%)
Pruritus, or ‘skin bends’
Oedema
Anorexia or excessive fatigue

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39
Q

Type I DCS- pain- what joint is most affected

A

Shoulder

40
Q

Type I DCS- what is pain like

A

Initially mild
Slowly becomes more intense
Many divers attribute early DCS symptoms to overexertion or a pulled muscle

41
Q

Type II DCS Symptoms categories

A

Pulmonary
Circulatory
Nervous system involvement
Pain

42
Q

Type II DCS- Pulmonary

A

Burning
Sub-sternal discomfort on inspiration
Non-productive coughing that can become paroxysmal
Severe respiratory distress (2% of all DCS and can cause death)

43
Q

Type II DCS- Circulatory

A

Hypovolaemic shock

44
Q

Type II DCS- NS involvement

A

Low back pain may start within few mins to hours after dive
May progress to paresis, paralysis, paraesthesia, loss of sphincter control, headaches or visual disturbances, dizziness, tunnel vision, and changes in mental status

45
Q

Type II DCS- Pain

A

Reported in only about 30% of cases

Because of anatomic complexity of the central and peripheral NS, S+S are variable and diverse

46
Q

Type II DCS Symptom onset

A

Usually quick
60% within 3 hours and 98% within first 24 hours
Can be delayed as long as 36 hours
Increased risk if diver went on high altitude within 24 hours of a deep dive

47
Q

Arterial Gas Embolization (AGE) physiology

A

Pulmonary over-pressurization can cause large gas emboli to enter into the pulmonary vein + systemic circulation
gas emboli can lodge in coronary, cerebral, and other systemic arterioles
These gas bubbles continue to expand as ascending pressure increases –> increased severity in clinical signs

48
Q

AGE symptoms and signs

A

Depend on where emboli travel

49
Q

AGE- coronary artery embolization

A

Can lead to MI or dysrhythmia

50
Q

AGE- Cerebral artery emboli

A

Can cause stroke or seizures

51
Q

AGE symptoms occur

A

Within 10-20 minutes of surfacing (usually)

52
Q

AGE symptoms

A

Multiple symptoms may be involved
Clinical features may occur suddenly or gradually
Dizziness, headache, profound anxiousness
Unresponsiveness, shock, and seizures
Death

53
Q

AGE vs. Neurological DCS II

A

Based on suddenness of symptoms
AGE- Any type of dive can cause it, onset is immediate (<10-120 min) + neurologic deficits manifest mainly in brain
DCS- dive must be of sufficient duration to saturate tissues, onset is latent (0-36h) + neurological deficits manifest in spinal cord + brain

54
Q

AGE neurological deficits manifest mainly in

A

Brain

55
Q

DCS II neurological deficits manifest mainly in

A

Spinal cord and brain

56
Q

Treatment of AGE + DCS II

A

Both require re-compression

Therefore differentiating between them not great importance

57
Q

DCS management

A

Do not delay HBO therapy
Administer 100% oxygen
Do not put patient in Trendelenburg position
Consider IV fluids if available
Transfer to nearest ED + hyperbaric facility- try to keep all gear to use for clues as to why problems
Transfer to HBO facility even if improvements, as can relapse
If shock- resuscitation
In-water recompression not believed to be safe, but do if in remote areas without reachable HBO chamber support

58
Q

Predisposing factors DCS- Diving factors

A

Inadequate decompression or surpassing no-decompression limits (includes increased depth + duration of dives, + repeated dives)
Inadequate surface intervals (i.e. failure to decrease accumulated N)
Failure to take recommended safety stops
Flying or going to higher altitude soon (12-24hrs) after diving
Rapid ascent can be due to panic- identify anxiety traits

59
Q

Predisposing factors DCS- individual

A 
Obesity (N is lipid soluble)
Fatigue
Age
Poor physical condition
Dehydration
Illness affecting lung or circulatory efficiency
Prior musculoskeletal injury
Smoking
60
Q

Dehydration

A

Study found significant decrease in venous bubble formation with pre-dive hydration

61
Q

Illness affecting lung or circulatory efficiency

A

Patent foramen ovale

62
Q

Prior musculoskeletal injury

A

Scar tissue decreases diffusion

63
Q

Predisposing factors DCS- environmental factors

A

Cold water
Heavy work
Rough sea conditions or poor buoyancy
Heating diving suits

64
Q

Cold water

A

Vasoconstriction decreases nitrogen offloading

65
Q

Heavy work

A

Vacuum effect in which tendon use causes gas pockets

66
Q

Heated diving suits

A

Leads to dehydration

67
Q

Cylinders- Air

A 
21% O2
78% N
1% other traces, mainly argon
Safety depth limit about 40m
Max operating depth is 66.2m
68
Q

Cylinders- pure O2

A

Mainly used to speed the shallow decompression stops (military + commercial dives)
Only safe down to depth of 6m before O2 toxicity sets in

69
Q

Cylinders- nitrox

A

Mixture of O2 and air
Can be used to accelerate in-water decompression stops or decrease risk of decompression sickness
Has shallower max operating depth than air

70
Q

Oxygen toxicity

A

Harmful effects of breathing molecular O2 at elevated pressures

71
Q

O2 toxicity symptoms

A 
Disorientation
Seizures
Breathing problems
Vision changes (retinal detachment)
Death
72
Q

O2 toxicity pathophysiology

A 
Collapse of alveoli in lungs
Hypoxia
Destruction of cell membrane which can lead to chemical toxicity and haemolysis
Hepatic + retinal damage
Neural toxicity
73
Q

Ear barotrauma

A

Can affect external, middle or inner ear

74
Q

Middle ear barotrauma

A

Most common being experienced between 10-30% of divers

Due to insufficient equilibration of middle ear

75
Q

External ear barotrauma

A

May occur on ascent if high pressure air is trapped in external auditory canal either by tight fitting diving equipment or ear wax

76
Q

Inner ear barotraums

A

Less common
Can lead to varying degrees of conductive and sensori-neural hearing loss as well as vertigo and auditory hypersensitivity

77
Q

Pulmonary barotrauma

A

Usually caused by breath holding on ascent
Compressed gas in lungs expands as ambient pressure decreases, causing lungs to over expand and rupture unless diver breathes out
No associated pain

78
Q

Buoyancy

A

An object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object
Maintaining neutral buoyancy is key to easy diving

79
Q

Adjust buoyancy before dive

A

Weights
wetsuit
water temp

80
Q

Adjust buoyancy during dive

A

BCD
Exhale/inhale
Swimming position

81
Q

Too buoyant

A

Harder work to stay done

can’t do safety stop on ascent

82
Q

Too heavy

A

Difficult adjusting buoyancy at different depths

Constantly having to add or remove air using BCD

83
Q

Divers Alert Network

A

169 deaths involving recreational scuba diving during 2016
Diving fatalities are a global hazard, occurring in tropical seas and colder waters alike.
In 2016, 4 out of 5 decedents were male-similar to previous years
In 2016 the leading cause of death was drowning, and the leading disabling injury that led to death was cardiovascular-related problems

84
Q

Mortality and morbidity

A

Fewer than 1% of divers experience DCS
Most common cause of dive-related death is drowning (80%)
Asphyxia (due to entrapment and insufficient gases): common cause of death

85
Q

AGE death causes

A

Overwhelmingly caused by emergency assent with insufficient gases as key contributing factor
For those older than 40, association with CV disease

86
Q

AGE- HBO treatment

A

Mortality + morbidity directly related to HBO treatment
If recompression within HBO occurs within 5 mins, death rate 5% with little residual morbidity in survivors
If delayed 5 hours, mortality increases o 10% with residual symptoms in half the survivors

87
Q

How many deaths

A

Fewer than 2 deaths per million recreational scuba divers

88
Q

Absolute contraindictions

A

Epilepsy controlled by medication
Unexplained syncopal episodes
Stroke and TIA
Intracranial aneurysm, arterial-venous malformation or tumour
Progressive neurological problems- severe MS, Parkinson’s, MND
Severe heart disease
Post coronary bypass surgery with violation of pleural spaces
Lung problems
Blood disorders
Pregnancy
Severe mental health problems + drug abuse
Inability to equalize pressure in middle ear by auto-inflation or acute perforation of the tympanic membrane

89
Q

Severe heart disease

A

Congenital heart defects
Severe valve problems
Severe ischaemic heart disease especially when not fully controlled
Post MI with LV dysfunction
Congestive HF
Dependence on medication to control dysrhythmias

90
Q

Lung problems

A 
Bullae (large air sacs)
Severe asthma
Chronic obstructive pulmonary disease
Certain types of lung surgery
Past history of spontaneous pneumothorax
91
Q

Blood disorders

A

Severe bleeding disorders e.g. haemophilia

Blood cancers e.g. leukaemia

92
Q

Temporary contraindications

A

Any illness requiring drug treatment may constitute a temporary disqualification if either the illness or drug may compromise diving safety
Sedatives, tranquilisers, antidepressants, antihistamines, steroids

93
Q

Saturation diving

A

Diving technique that allows divers to reduce risk of decompression sickness (the bends) when work at great depth for long periods of time
Divers live in pressurized environment
May be maintained for up to several weeks
Diver’s tissues absorb max partial pressure of breathing gas possible for that depth + decompressed to surface pressure only once, at end of their tour of duty
Limit no. of decompressions, so risk of decompression sickness v reduced

94
Q

Saturation diving record

A

Scientific dive in 1992
701m
43 days

95
Q

Saturation diving risk

A

Exposure to high pressure can have negative effects on NS and risk of osteonecrosis

96
Q

Atmospheric diving suit

A

Maintains internal pressure 1 atmosphere
Used for v deep dives up to 700m for many hours
Eliminates majority of physiological disorders associated with deep diving
Divers don’t need to decompress, no need for special gas mixtures, no danger decompression sickness or nitrogen narcosis

97
Q

ADS used by US navy since

A

2006

Sports and Exercise Medicine iBSc (13 decks)

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