Boyles Law

" Boyles = Balloon=Barotrauma"

The pressure of a gas is inversely proportional to the

Volume of a gas at a constant temperature

P1V1=P2V2

• Affects ETT Cuffs, MAST trousers, Air splints, IV drip rates (increase rate)
• If the pt has a Pneumocephalus (air inside the cranial vault after trauma, usually from direct blow, associated with depressed skull fx)  ICP will increase

Daltons Law

"Daltons Gang"

Law of partial pressures (this is a additive gas law)

• The total pressure of a gas mixture is the sum of the partial pressures of all gases in the mixture

Pt=P1+P2+P3........

• Responsible for soft tissue swelling at altitude (uptake of inert gasses into tissue) 

Charles Law

"Charging Charles"

• At constant pressure the volume of gas is directly proportional to the absolute temperature of gas

V1/T1=V2/T2

• Example- when you charge oxygen tank the tank gets hot 
• This law has very little effect on the human body (we are at a relatively constant temperature)

Gay-Lussac's Law

• Directly proportional releationship between temperature and pressure

P1/T1=P2/T2

• Example- an oxygen cylinder left outside overnight will have a lower pressure reading in the morning due to temperature drops.
• This is the gas lwa that explains the reasin you need to add air to your tires in the winter 

Grahams Law

"Grahams = Grey Matter"

• Law of gaseous Diffusion
• Gas exchange at the cellular level
• The rate of diffusion of a gas through a liquid medium is directly related to the solubility of the gas and inversely proportional to the square root of its density
• Limits gas ability to move trough liquid
• Example- gas bubbles coming out of exposed grey matter when at altitude 

Henry's Law

"Henery=Heineken"

• Solubility of gas in liquid
• the quantity of gas dissolved in 1 cm of liquid is proportional to the partial pressureof the gas in contact with the liquid
• Affects divers can lead to decompression sickness "the bends"

Decompression sickness

"the bends"

Type I

nitrogen related, painful joints, mottled shin, pruritic (itching)

• Pt may also feel like "ants are crawling on thier skin"
• Cutis Marmorata-mottled skin, can often look like a sun burn 

Decompression Sickness

The bends

Type II

Neurologic signs and symptoms, hypovolemic shock

• Ground transport is preferred for all diving injuries/decompression sickness 

Arterial Gas Embolism

AGE

• Related to Boyles Law
•  Caused by breath holding during ascent on a dive, air pushes through the alveoli and enters the skin in the neck/chest
• Causing a Pneumothorax
• Air is forced into blood vessels
• The air bubbles blocks blood vessels, causing ischemia
• Patient presents with stroke like symptoms (altered mental status, syncope, dizziness)
• May also have a cough and epistaxis(nose bleed)
• AGE requires immediate hyperbaric treatment
• fly in a pressurized aircraft (fixed wing) or rotary wing <1000Ft MSL

Pulmonary Overpressurization

• Related to Boyles Law
• Asyndrome that occurs when "breath holding" compressed air during ascent
• The greatest pressure differences are just below the surface of the water
• Cause lung overexpansion and ruptures the alveoli
• Causes pneumothorax or mediastinal emphysema
• Common in inexperienced divers 

Atmosphere Calculations

Every 33Ft below water 33ft = 1 ATM (atmosphere)

Sea leve = 1 ATM

33ft under water = 2 ATM

66 ft under water= 3 ATM

Example: your Pt was diving at a depth of 33ft they were exposed to 2 ATM of pressure.

Physiologic Zone

sea level to 10,000ft MSL

Night vision is decreased begining at 5,000Ft MSL

Physiologically Deficient Zone

10k to 50K MSL

• Oxygen or pressurization required to survive at these altutudes
• If in a pressurized cabin and a sudden decompression occurs time of useful consciousness is cut in half
• sign of compression loss is cooler temp in the cabin and windows fogging
• Normal 90 sec of useful conciousness at 30,00ft
• If rapid decompression occurs TUC is mow around 45 sec
• Example- if you were in an altutude chamber at 30K ft and took your oxygen mask off you would normally have around 90 sec of conciousness.  

Physiologic Zone

Night vision is decreased begining at 5,000 ft MSL

Physiologically Deficient Zone

10k to 50k ft MSL

• Oxygen or pressurization required to survive at these  altitudes
• If in a pressurized cabin and a sudden decompression occurs Time of Useful Consciousness is cut in half
• A sign of compression loss is cooler temperatures in the cabin and windows fogging
• Normally 90 sec of useful consciousness at 30,000ft
• If rapid decompression occurs, TUC is now around 45 sec  

Space Equivalent Zone

50k ft MSL

You are an astronaut

Oxygen Adjustment Calculation

(fiO2xP1)/P2=FiO2 required for ascent

FiO2= fraction of inspired oxygen

P1= the pressure you are at (on the ground)

P2= the pressure you are flying to (crusing altitude)

Pressure (P) Values

sea level 760 torr or mmhg (1ATM)

10k ft MSL 523 toor or mmhg

18k ft MSL 380 torr or mmhg (1/2 ATM)

63k ft MSL 0 torr or mmhg (0 ATM)

Hypemic

"Anemic"

• Reduction in the O2 carrying capacity of blood
• Anemia hemorrhage 

Histotoxic

"poisoning"

• Limits the use of available oxygen due to poisoning of the cytochrome oxidase system
• Cyanide, Alcohol, Carbon Monoxide, Nitroglycerin, Sodium Nitroprusside (Nipride) 

Hypoxic

"not enough Oxygen in the air"

• decrease parttial pressure of oxygen at altitude
• Deficiency in alveolar O2 exchange
• Cardiovascular/Pneumothorax patients are more susceptible to this type of hypoxia 

Stagnant

"Blood isn't moving"

• Reduced cardic output or pooling of blood
• High G forces, cardiogenic shock 

Stages of Hypoxia

"ICDC"

Indifferent       Full reasoning ablilities. some loss  NV

Compensatory  Increase HR, Ventilations, slow judgment

Disturbance     Slurred speech, impared judgment

Critical            No longer able to physiologically function

                       Death

Barondontalgia

(teeth)

• Occurs on Ascent
• Air trapped in fillings expands due to Boyles Law

Barotitis

"Ears"

• Occurs on Desent
• Air trapped in the middle ear cant vent through the blocked Eustachian tub
• Ear block 

Barosinusitis

"Sinuses"

• can occur on both ascent and desent
• Can also cause pain the maxillary teeth (but is not the same as barodontalga; that occurs only on ascent)
• Sinus Block 

Part 91

• No duty day
• No weather minimums (PIC risk) 

Part 135

• Max 14 hours duty day
• 8 hours total flying time/8hours "bottle to throttle" 

Weather Minimums

Non Mountainsous   CC     Mountainous      CC

Day   800'-2miles    800-3      800'-3mile    1000'-3

Night  800'-3mile    1000-3    1000'-3mile   1000'-5

CC- Cross Country

Marginal Weather

Weather that is very close to or at minimums

(cant fly but accepting risk)

Below Minimums

weather that is under weather minimums

(cant fly)

• if bad weather is encountered while enroute, divert to the nearest facility
• #1 cause of crashes is weather (#2 is night flight) 

Visual Flight Rules

(VFR)

You can fly only in weather conditions that you can see where you are flying

• Visual Meteorological Conditions (VMC)
• there is no intended instrument flying under these rules 

Instrument Flight Rules

(IFR)

The weather condition do not allow safe flight by sight alone, and the pilot must be able to use his/her instruments to fly

• Instrumental Meteorological Condition (IMC) 
• if the weather condition allow VFR/VMC, a pilot may still fly under these conditions