Diving and Altitude Flashcards
What does 10m of water equal
1 atm
What does 10m of depth = 2 atm
0m of depth = 1 atm and add on from there
Describe Henry’s law application to depth
Proportionally more gas dissolves in tissue at depth
If ascend at rate exceeds body’s capacity to clear this excess gas, inert bubbles may form in the tissues and lead to compression illness
Describe apnoea
Breath is held at the surface of the dive
PaO2, PaN2, PaCO2 rises
PaN2 forced into alveoli space. Due to compression of lungs as decrease down pool
What is the diving reflex
Apnoea
Bradycardia
Peripheral vasoconstriction
What is an open circuit scuba
Self-contained underwater breathing apparatus
Pressure will be breathed in at the level they are at
Octopus - additional single hose second stage regulator
Define total pressure
Total pressure excreted by a mixture of gases is equal to the sum of the pressure that would be exerted by each of the gases if it alone were present and occupied the total volume
What is the equation for PiGas
Patm x FiGas
Pressure of inspired gas = atmosphere pressure x fracture of the gas (e.g. oxygen .21)
What is the death zone
Over 8000m
Altitude above which is difficult to sustain life without the addition of O2
What happens to gases at altitude
FiO2 remained the same e.g. oxygen 0.21
PiO2 falls with altitude
What is the normal response to lungs at altitude
Hypoxia which leads to
Hyperventilation
Adaptive changes (over 1 week or more)
Describe hyperventilation due to altitude
Increases minute ventilation
Lowers PaCO2
Alkalosis initially due to CO2 dropping
Tachycardia
pH starts to rise (Henderson-Hasselbach equation)
What happens to pressures when ascending
Decreased
- PAO2
- PaO2
Peripheral chemoreceptors fire
Activated increase ventilation
Decrease - PaCO2
Increase
- PAO2
- PaO2
