03/21/2026
Flight Physiology: Gas Laws That Change Patient Care
Altitude affects pressure, temperature, diffusion, and oxygen delivery — making gas laws essential knowledge for flight clinicians.
🎈 Boyle’s Law — Pressure ↔ Volume
As altitude increases, atmospheric pressure decreases and gas expands. This impacts pneumothorax size, air emboli, bowel gas, sinus pressure, ETT cuffs, and air splints.
🌡️ Charles’ Law — Temperature ↔ Volume
Gas volume increases with heat and decreases with cold. Cooler flight environments may slightly reduce gas volume.
🧯 Gay-Lussac’s Law — Temperature ↔ Pressure
In a fixed container, higher temperature increases gas pressure. Oxygen tank readings can vary with environmental temperature.
🫁 Dalton’s Law — Partial Pressures
Total pressure is the sum of all gas pressures. At altitude, reduced atmospheric pressure lowers the partial pressure of oxygen, increasing hypoxia risk even if FiO₂ remains the same.
🫧 Henry’s Law — Gas in Solution
Higher pressure keeps gas dissolved in blood; lower pressure allows bubbles to form. Important in decompression sickness and air embolism.
🌬️ Fick’s Law — Gas Diffusion
Oxygen transfer depends on membrane thickness, surface area, and pressure gradient. Lung pathology can worsen hypoxia during flight.
⚡ Graham’s Law — Diffusion Speed
Lighter gases diffuse faster. Heliox improves airflow in obstructive airway disease.
Understanding these laws helps flight teams anticipate physiologic changes and improve patient safety.
