Boyal’s Law (Gas Expansion)
Gas Expansion
- NG/OG placed
- ET Cuff pressures - check cuff pressure @ altitude in unpressurized air craft (ex. ET cuff expanding @ altitude)
- Consider lower altitude or higher cabin pressure
Dalton’s Law (Partial Pressure)
Decreased PO2
- Pt desaturating as you ⬆️ altitude
- ⬆️ altitude = air gets thinner (less O2 @ altitude than ground)
** Shunt physiology - desaturation @ altitude
Atmospheric (Barometric) Pressure
Atmospheric (Barometric) Pressure: “weight” per unity area of atmospheric gasses above the reference point
- Surface is 1 Atm
- Every 33ft up or down = 1 Atm
- A diver at 66ft is at THREE Atm (remember surface is 1 Atm)
Atmospheric Pressure - as you go ⬆️ pressure goes ⬇️ (Boyals Law)
- ⬆️ altitude, ⬇️ ambient pressure
- Boyals Law - pressure up, volume down
*Organs with enclosed spaces (eyes, ears, teeth, sinuses
EARS: Barotitis Media
- Air is trapped on ASCENT, as aircraft transitions from high to low pressure
- Pain is felt on DESCENT
Teeth/Sinuses (Barodeontalgia/Barosinusitis)
- Pain is felt on ASCENT.
- Trapped gas not migrating, just expanding
Hypoxia
Hypoxia: Lack of Oxygen entering the blood.
- Increase in Altitude (Dalton’s Law) - Shunt physiology (R to L)
- Increase O2
- Decrease Altitude
- Increase Cabin Pressure
4 Ways to Increase FiO2
- It
- Inspiration Pressure
- Peep
- FiO2
Hypoxia - Histotoxic
Histotoxic: Oxygen there, but cells can’t use it
- Cyanide poisoning (house fires)
- Increase O2
- Decrease Altitude
- Increase Cabin Pressure
Hypoxia - Stagnant
Stagnant: Decreased blood flow/perfusion
- Venous pooling from prolonged seated position in flight
Hypoxia - Anemic (or Hypemic)
Anemic (or Hypemic): Lack of hemoglobin
- Blood loss in trauma patient or malnutrition associated with anemias
- Increase O2
- Increase hemoglobin (transfuse)
Sickle Cell
- Hypoxia triggers sickling
- Pain meds and Oxygen!
- Give IVF and increased need for oxygen do prevent sickling
Temperature Corollay
*Decrease by roughly 1 degree per 100ft gain
* At altitude, take extra precautions to prevent heat loss for patient
Boyle’s Law
- Constant temperature
- Pressure goes ⬇️, volume goes ⬆️ (inverse)
- Decrease altitude. Increase cabin pressure
- Boyle’s Balloon
** Think Pneumo going to TENSION pneumo upon ascent (would need to decrease altitude or increase cabin pressure.)
Charle’s Law
- Constant Pressure
- Temperature goes up, volume goes down (direct)
- Less lift in warm weather. (Density down due to increased volume)
- Charles Celsius (gas law dealing with temperature)
- Gas tank or balloon in the sun
Dalton’s Law
- Total pressure is the sum of the individual pressure
- Increase in altitude = DECREASE in PO2
- Think shunt physiology (cardiac kids) - increase O2 before going up in altitude
- Shunt V/Q mismatch, ARDS - increase O2/Cabin pressure, decrease altitude
- Easiest ways to increase O2 is adjusting FiO2 on vent, can also ⬆️ iT, ⬆️ inspiratory pressure, ⬆️ peep
After liftoff, an intubated patient with multiple stab wounds becomes agitated, has decreasing BP, and develops increased RR. After a needle thoracostomy is performed, the nurse would expect to see:
- Decreasing peak airway pressures
- When you decompress the chest = increase in compliance = decreased plateau pressures
