As we think of rules that we inadvertently follow every day without even realizing it like speed limits and wearing seatbelts, respiratory therapists must remember that there are gas laws we follow every day without realizing it also. This paper will focus on a gas law called Dalton’s law of partial pressures. For respiratory therapists to fully understand the importance of Dalton’s law, we must explain what this law states, how it applies to respiratory care, and what advancements in technology have been made to modify the use of this law.
In the early 1800’s, a scientist by the name of John Dalton developed a theory which we now refer to as Dalton’s law of partial pressure. John Dalton developed this law by experimenting with the gases in the atmosphere. “Dalton's experiments on gases led to his discovery that the total pressure of a mixture of gases amounted to the sum of the partial pressures that each individual gas exerted while occupying the same space”(A+E Networks, 2013). Mathematically, Dalton explained this law by stating, Ptotal= P1+P2+P3……Pn. These preliminary experiments that Dalton performed were based on the original 760 torr or 760 mmHg that had been earlier discovered by Torricelli. Dalton then realized that the 760 mmHg in the atmosphere is made up of gases such as oxygen, nitrogen, carbon dioxide, and a few other trace gases. The pressure given off by each of these gases is considered to be the partial pressure of the total atmospheric pressure. The percentages of these gases in the atmosphere at sea level are nitrogen 78.08%, oxygen 20.95%, carbon dioxide 0.03 %, and remaining trace gases 0.94% which make up a total of 100% in the atmosphere.
As we think about Dalton’s law of partial pressures, a question arises. How does this law affect us as humans? Well, by considering the available oxygen in the atmosphere is 21%, it must be known that this percentage remains the same regardless of altitude, above or below sea level. Keeping this in mind, you may think that the oxygen available to the human body remains the same, but this could not be any farther from the truth. Truth is, as altitude increases from sea level, the atmospheric pressure decreases, which in turn decreases the amount of oxygen available to the human body. This also can go the other direction as well, as altitude decreases from sea level, the atmospheric pressure increases and the amount of oxygen available to the human body increases. For example, at sea level, the atmospheric pressure is 760 mmHg and the available oxygen is 159.6 mmHg, now if we increase altitude to Blue Knob, Pennsylvania or 3000 feet above sea level, which is approximately 680 mmHg, the available oxygen is only 142.8 mmHg. As noted previously in this paper the percentage of oxygen available remains the same at 21%.
Now that we understand how the amount of oxygen available to the human body can change with altitude, we begin to think of the affects it can have on...