KOPP Core Gas Laws in Respiratory

Flashcards covering core gas laws and their applications in respiratory therapy, based on lecture notes.

Boyle’s Law

States that at a constant temperature, pressure and volume are inversely proportional (P x V = k). Clinically explains how lung volume changes with pressure during ventilation, exemplified by mechanical ventilation and chest tube drainage. Pressure UP results in Volume DOWN, and vice versa.

Charles’s Law

States that at a constant pressure, volume and absolute temperature are directly proportional (V/T = k). Important for understanding how temperature affects gas volume in devices, and for ensuring accurate oxygen delivery when warming cold gasped oxygen. Temp UP results in Volume UP, and vice versa.

Gay-Lussac’s Law

States that at a constant volume, pressure and absolute temperature are directly proportional (P/T = k). Helps explain pressure changes in oxygen tanks with temperature fluctuations, which is crucial for tank safety and anesthesia delivery.Temp UP results in Pressure UP, and vice versa.

Dalton’s Law

States that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of individual gases (P{total} = P1 + P_2 + ext{…}). Crucial for calculating partial pressures of gases in inspired air and alveoli (e.g., PAO₂) and understanding hypoxemia.

Avogadro’s Law

States that equal volumes of all gases, at the same temperature and pressure, have the same number of molecules (V/n = k). Supports understanding of molecular quantities in gas mixtures, relevant to diffusion.

Ideal Gas Law

An equation that integrates Boyle's, Charles', and Avogadro's laws, stating that PV = nRT. It is useful for modeling general gas behavior under various conditions in respiratory therapy.

Henry’s Law

Explains that the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid. It is key for oxygen and CO₂ transport in blood and is the principle behind hyperbaric oxygen therapy.

Fick’s Law of Diffusion

Describes how gases move across alveolar membranes, stating that the rate of diffusion is directly proportional to surface area and pressure gradient, and inversely proportional to membrane thickness. Vital for gas exchange, explaining conditions like pulmonary fibrosis, and the effectiveness of PEEP therapy.

Graham’s Law

Addresses diffusion rates, explaining that lighter gases diffuse faster. This principle is relevant in therapy, such as Heliox therapy, where helium's low density reduces airway resistance.

Laplace’s Law

Applies to alveolar stability, stating that pressure is directly proportional to surface tension and inversely proportional to the radius (Pressure ∝ surface tension / radius). It explains surfactant’s role in reducing surface tension to prevent alveolar collapse, especially significant in Neonatal Respiratory Distress Syndrome (RDS).

Poiseuille’s Law

Governs airflow resistance, stating that flow is directly proportional to the fourth power of the airway radius (Flow ∝ radius⁴). This law is essential for understanding how small changes in airway diameter (e.g., in asthma) drastically affect airflow and how bronchodilator therapy works.