Module 1: Chemistry & Physics

According to Dalton's Law, if P1 = 30 mmHg, P2 = 40 mmHg, and P3 = 50 mmHg, what is the total pressure of the gas mixture?

The total pressure is 120 mmHg.

(This is the sum of the partial pressures of each gas in the mixture.)

How is volumes percent calculated for a gas when the partial pressure and total pressure are known?

Volumes = (Partial pressure / Total pressure) x 100

Convert an end-tidal isoflurane measurement of 8 mmHg at sea level (760 mmHg) to volume percent.

The concentration is 1% ( 8/760 x 10)

Calculate the partial pressure of sevoflurane if the agent monitor measures 2% at sea level (760 mmHg).

The partial pressure is 15.2 mmHg ((2/100) × 760).

Explain the relationship between temperature and gas solubility in a liquid according to Henry's Law.

Solubility is inversely proportional to temperature; as temperature decreases, gas solubility increases.

(This means that colder liquids can hold more gas compared to warmer ones, making gas solubility higher at lower temperatures.)

Why is anesthetic emergence typically prolonged in a hypothermic patient?

The solubility of the anesthetic gas in blood increases, so less gas leaves the body per unit time.

(This leads to a slower elimination of the anesthetic, thus prolonging emergence time.)

What is the solubility coefficient of oxygen in the blood?

The coefficient is 0.003 mL/dL/mmHg.

(This value indicates the amount of oxygen that dissolves in blood per millimeter of mercury of partial pressure. It reflects how oxygen is transported in the bloodstream.)

What is the solubility coefficient of carbon dioxide in the blood?

The coefficient is 0.067 mL/dL/mmHg.

(This value indicates the amount of carbon dioxide that dissolves in blood per millimeter of mercury of partial pressure, which influences its transport and elimination in the body.)

How much more soluble is CO₂ in the blood compared to O₂?

CO₂ is approximately 20 times more soluble than O₂.

(This higher solubility allows for more efficient transport and elimination of carbon dioxide in the bloodstream.)

Which physical law is applied when a CRNA increases the FiO₂ to increase the PaO₂?

Henry's Law

(This law states that the amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid.)

Which equation is used to calculate oxygen delivery (DO₂)?

DO2 = CO (1.34 x Hgb x SpO₂) + (PaO₂ x 0.003) x 10

(This equation quantifies the amount of oxygen delivered to tissues based on cardiac output, hemoglobin saturation, and dissolved oxygen in blood.)

Describe the clinical technique of 'overpressuring' a vaporizer based on Henry's Law.

Increasing the concentration of volatile anesthetic at the alveolocapillary interface hastens its transfer into the bloodstream.

(By applying higher pressure of the vapor above the liquid, more anesthetic gas dissolves according to Henry's Law, enhancing uptake into the blood.)

Which law describes the transfer rate of a gas through a tissue medium, such as placental drug transfer?

Fick's law of diffusion

(This law states that the rate of gas transfer is proportional to the surface area, concentration gradient, and permeability of the medium.)

According to Graham's Law, what determines how fast a gas can diffuse through a membrane?

The molecular weight of the gas (smaller molecules diffuse faster).

(This law explains that the diffusion rate of a gas is inversely proportional to the square root of its molar mass; lighter gases diffuse more rapidly than heavier ones.)

How does Boyle's Law relate pressure and volume at a constant temperature?

Pressure and volume are inversely proportional (P1V1 = P2V2).

(As pressure increases, volume decreases, and vice versa, provided the temperature remains constant. This fundamental principle of gas behavior illustrates how changes in pressure affect the space occupied by a gas.)

How does the contraction of the diaphragm increase tidal volume based on Boyle's Law?

Contraction increases thoracic volume, which decreases intrapulmonary pressure, drawing air into the lungs.

(This process demonstrates Boyle's Law, where an increase in volume leads to a decrease in pressure, allowing for greater air intake during inhalation.)

Which gas law explains why an LMA cuff might rupture when placed in an autoclave?

Charles' Law

(It states that the volume of a gas is directly proportional to its temperature at constant pressure. As the temperature increases, the gas expands, which could cause the cuff to rupture if it exceeds its capacity.)

Explain the risk of an oxygen tank explosion in a heated environment using Gay-Lussac's Law.

At a constant volume, increasing temperature directly increases the pressure inside the container.

(If the pressure exceeds the tank's limits, it may lead to an explosion. This demonstrates Gay-Lussac's Law, emphasizing the importance of temperature control for gas safety.)

What is the conceptual reduction of the Ideal Gas Law (PV = nRT) used to analyze relationships between P, T, and V?

P = T / V.

(This formula demonstrates the relationship between pressure and temperature when volume is held constant, indicating that pressure is directly proportional to temperature.)

How is a Bourdon pressure gauge used clinically to estimate oxygen cylinder contents?

It measures the pressure in the cylinder, which is proportional to the amount (volume) of gas remaining at a constant temperature (Boyle's Law).

(The Bourdon pressure gauge provides a visual indication of the gas pressure, allowing healthcare providers to estimate the remaining gas volume. As per Boyle's Law, at constant temperature, pressure and volume are inversely related, meaning lower pressure indicates a lower gas volume.)

According to Poiseuille's Law, doubling the radius of an IV catheter increases flow by what factor?

Flow increases by a factor of 16 (2⁴).

(This is due to the fourth power relationship between the radius and flow rate in Poiseuille's Law, meaning even small changes in radius can significantly affect flow.)

According to Poiseuille's Law, tripling the radius of a tube increases flow by what factor?

Flow increases by a factor of 81 (3⁴).

How does polycythemia affect microvascular flow according to Poiseuille's Law?

It increases blood viscosity, which inversely decreases the flow rate.

(This is because increased viscosity leads to greater resistance in the microvasculature, resulting in reduced flow according to Poiseuille's Law.)

List four clinical interventions to deliver Packed Red Blood Cells (PRBCs) faster based on Poiseuille's Law.

• Increase radius (large-bore IV)

• increase pressure gradient (pressure bag)

• decrease viscosity (dilute with 0.9% NaCl)

• decrease tube length

A Reynolds' number (Re) of less than 2,000 indicates which type of flow?

Laminar flow.

(This is characterized by smooth, orderly fluid motion, where fluid flows in parallel layers with minimal disruption between them.)

A Reynolds' number (Re) of greater than 4,000 indicates which type of flow?

Turbulent flow

(This type of flow is chaotic and characterized by irregular, eddy-like motion, where fluid particles move in unpredictable patterns.)

Where in the respiratory tract is Reynolds' number the LOWEST?

Terminal bronchioles

(This area features minimal airflow turbulence, as the network of bronchioles becomes increasingly narrow, promoting smoother, laminar flow.)

In which anatomical area is airflow typically turbulent?

Medium-sized bronchi

(This region experiences greater airflow disruptions due to the branch structure and increased diameter, resulting in more chaotic flow patterns.)

Laminar flow is primarily dependent on gas _____, while turbulent flow is primarily dependent on gas _____.

viscosity; density

Why is Heliox (oxygen/helium mixture) used for patients with status asthmaticus or epiglottitis?

Helium has a lower density than nitrogen, which decreases Reynolds' number and improves airflow when resistance is high.

According to Bernoulli's principle, what happens to the pressure exerted on the walls of a tube when fluid velocity increases?

The pressure exerted on the walls decreases.

(This principle indicates that as the velocity of a fluid increases, its pressure decreases, allowing for airflow optimization in respiratory contexts.)

Which clinical application utilizes the Venturi effect to entrain air into a stream of oxygen?

Venturi mask (or jet ventilator/nebulizer)

The tendency of a jet flow to attach itself to a nearby surface and follow its curve is known as the _____.

Coanda effect.

(This phenomenon occurs when a fluid jet adheres to a surface, demonstrating how the jet bends around obstacles.)

What is a clinical example of the Coanda effect in cardiology?

A wall-hugging jet of mitral regurgitation.

(This occurs when blood flows backward from the left ventricle to the left atrium during heart contraction, creating a fluid jet that adheres to the heart wall.)

What is the Law of Laplace formula for wall tension in a spherical structure like an alveolus?

Tension = (Pressure x Radius) / 2

(In a spherical structure, the Law of Laplace states that tension is proportional to the internal pressure and radius of the sphere.)

What is the Law of Laplace formula for wall tension in a cylindrical structure like a blood vessel?

Tension = Pressure x Radius

(In a cylindrical structure, the Law of Laplace states that wall tension is directly proportional to the internal pressure and radius of the cylinder.)

According to the Law of Laplace, which size of alveolus (without surfactant) has a higher tendency to collapse?

The smaller alveolus (smaller radius equals higher pressure for a given tension).

(This is due to the inverse relationship between radius and pressure as described by the Law of Laplace, leading to increased pressure in smaller alveoli.)

How does pulmonary surfactant prevent the collapse of smaller alveoli?

It decreases surface tension more in smaller alveoli, equalizing pressure between alveoli of different sizes.

(This allows smaller alveoli to maintain stability and prevents collapse by reducing the pressure difference.)

At what gestational age do Type 2 pneumocytes begin producing surfactant?

Between 22 - 26 weeks.

(This production is crucial for reducing surface tension in the alveoli and preventing their collapse at birth.)

When applying the Law of Laplace to the left ventricle, what three variables determine myocardial wall stress?

• Intraventricular pressure

• radius

• ventricular wall thickness

According to the myocardial wall stress equation, how does the heart compensate for systemic hypertension to reduce stress?

By developing left ventricular hypertrophy (increasing wall thickness).

(This adaptation allows the heart to handle increased pressure without excessive stress on the myocardial walls.)

Radiation exposure obeys the _____ law, meaning exposure is inversely proportional to the square of the distance from the source.

Inverse square

(This law states that as one moves further away from a radiation source, the intensity of exposure decreases rapidly, making distance a key factor in radiation safety.)

What is the minimum safe distance from a radiation source in the OR?

6 feet

What is the yearly maximum radiation exposure for adults in the hospital setting?

5 rem

What is the yearly maximum radiation exposure limit for the fetus of a pregnant worker?

0.5 rem (or 0.05 rem/month)

Which two organs are most susceptible to injury from ionizing radiation in a non-pregnant person?

The eye and the thyroid.

In the hospital, most radiation exposure is the result of _____ x-rays rather than direct exposure.

scattered

What is the difference between evaporation and boiling?

Evaporation occurs below the boiling point at the surface; boiling occurs when vapor pressure equals atmospheric pressure.

How does high altitude affect the boiling point of a liquid?

The boiling point decreases because atmospheric pressure is lower.

(This lower pressure means the liquid's vapor pressure reaches atmospheric pressure at a lower temperature.)

Term: Specific Heat

Definition: The amount of heat required to increase the temperature of 1 gram of a substance by 1 degree Celsius.

Why do modern vaporizers use metals like copper or bronze for their construction?

They have high thermal conductivity to transfer heat easily and maintain a constant liquid temperature during vaporization.

(This allows for efficient heating, ensuring that the liquid vaporizes quickly without overheating.)

Term: Latent Heat of Vaporization

Definition: The number of calories required to convert 1 gram of liquid to vapor without a temperature change in the liquid.

(It represents the energy needed for a phase change from liquid to gas.)

Explain the Joule-Thompson effect as it applies to an oxygen cylinder being opened quickly.

Rapid expansion of gas stored at high pressure results in a fall in temperature, making the cylinder feel cool.

(This phenomenon occurs because the Joule-Thompson coefficient of oxygen is negative at room temperature, resulting in cooling upon expansion.)

Term: Critical Temperature

Definition: The highest temperature at which a gas can exist as a liquid, regardless of the pressure applied.

(It marks the point above which a substance cannot be liquefied by pressure alone, indicating the transition into a supercritical fluid.)

Why do Nitrous Oxide and CO₂ exist as liquids in an E-cylinder at room temperature (20 °C)?

Their critical temperatures (36.5 °C and 31 °C, respectively) are higher than room temperature.

(This allows them to remain in liquid form under pressure in the cylinder.)

What is the critical temperature of Oxygen?

The critical temperature is -119 °C.

(This is the temperature above which oxygen cannot be liquefied by pressure alone.)

Term: Critical Pressure

Definition: The minimum pressure required to convert a gas to a liquid at its critical temperature.

What is the formula to convert Celsius (C) to Kelvin (K)?

K = C + 273

What is the formula to convert Celsius (C) to Fahrenheit (F)?

F = (C x 1.8) + 32

Equivalent Units: 1 atm = ___ mmHg = ___ psi.

760; 14.7

Equivalent Units: 1 mmHg = ___ cmH₂O.

1.36

Equivalent Units: 1cmH₂O = ___mmHg.

0.74

How many atoms/molecules are in 1 mole of any gas according to Avogadro's number?

6.023 x 10²³

What is the molecular weight of Diatomic Oxygen (O²)?

32g (16g x 2)

Which component of the oxygen delivery equation is MOST affected by Henry's law?

PaO₂ (dissolved oxygen)