Liquid and Humidity

What properties do liquids and gases both exhibit?

Viscosity, pressure, and flow.

What is NOT a property shared by both liquids and gases?

Easily compressible

What happens to gas molecules as temperature increases?

As temperature increases, gas molecules move faster.

What is viscosity?

The property of a liquid that opposes flow.

What is density?

Mass per unit volume.

What is specific gravity?

Compares the density of a substance with the density of a reference substance.

What is buoyancy?

The upward force exerted by a fluid.

What is compressibility?

The ability of a substance to decrease in volume when pressure is applied.

What does a hydrometer measure, and what principle does it use?

A hydrometer measures specific gravity based on Archimedes' principle.

What is surfactant?

A detergent-like complex secreted by Type II alveolar cells. It reduces surface tension and helps prevent alveolar collapse.

What is surface tension?

The attraction of liquid molecules to one another at a liquid-gas interface.

What is Laplace's law?

P = 2T/r

How are pressure, surface tension, and radius related?

Pressure is directly proportional to surface tension and inversely proportional to radius.

Which alveolus has higher pressure if surface tension is the same?

The smaller alveolus has higher pressure and would collapse without surfactant.

How much gaseous oxygen is produced by 1 L of liquid oxygen?

Approximately 860 L of gaseous oxygen.

At what temperature does oxygen boil?

−183°C (−297°F) at atmospheric pressure.

How much does 1 L of liquid oxygen weigh?

Approximately 2.5 lb.

What happens to water-holding capacity when temperature increases?

Increased temperature increases water-holding capacity.

What is evaporation?

Liquid turning into water vapor and increasing relative humidity when temperature stays constant.

What is condensation?

Water vapor turning back into liquid, such as in ventilator tubing when temperature

decreases.

What is absolute humidity?

The actual amount of water vapor in a gas, usually expressed in mg/L.

What is relative humidity?

A percentage comparing the actual water vapor content with the gas's capacity to hold water vapor

What is body humidity?

A percentage comparing water vapor in a gas with its capacity at body temperature.

What is humidity deficit?

The difference between body-temperature saturation capacity and actual absolute humidity.

What is saturation?

The equilibrium condition in which a gas holds all the water vapor molecules it can.

What does BTPS stand for?

Body temperature, ambient pressure, saturated.

What is relative humidity at the carina?

100%.

What is the isothermal saturation boundary?

The point where inhaled gases reach alveolar conditions, normally near the 4th–5th airway generation.

What is the relative humidity formula?

Actual absolute humidity ÷ saturation capacity × 100%.

What is the humidity deficit formula?

Saturation capacity at body temperature − absolute humidity.

What is the saturation capacity at 37°C?

Approximately 44 mg/L.

Which upper respiratory tract structures are selected in the assessment?

The nose, pharynx, and larynx.

What is the primary function of the upper respiratory tract in this assessment?

Heat and moisture exchange.

What percentage of air is nitrogen?

Approximately 78%.

How does helium's density compare with oxygen?

Helium has a lower density than oxygen.

What gas mixture is useful for a patient with a tumor causing airway obstruction?

Heliox, because helium's lower density helps deliver oxygen through an obstruction.

What typical He:O2 mixtures are listed?

60:40, 70:30, and 80:20.

Which He:O2 mixture is not typical among these examples?

50:50.

What does oxygen support?

Combustion.

What is nitric oxide?

A toxic, potent pulmonary vasodilator that is very expensive.

What is laminar flow?

Flow that moves parallel to vessel walls.

What shape does the velocity profile form during laminar flow?

A parabolic shape.

Where does peak velocity occur in laminar flow?

In the center.

What statement is false about laminar flow?

That peak velocity occurs near the vessel walls.

What is the H-cylinder factor?

3.14.

What is the E-cylinder factor?

0.28.

How do you calculate oxygen cylinder duration?

Cylinder pressure × cylinder factor ÷ flow rate = duration in minutes.

What unit conversions are used for oxygen duration?

60 minutes = 1 hour; 24 hours = 1 day.

40 lb liquid O2 at 4 L/min: calculate duration.

40 ÷ 2.5 × 860 ÷ 4 = 3,440 minutes = 57 hours 20 minutes.

Portable E cylinder, 900 psi at 6 L/min: calculate duration.

900 × 0.28 ÷ 6 = 42 minutes, without a safety reserve.

2.5 lb liquid O2 at 5 L/min: calculate duration.

2.5 ÷ 2.5 × 860 ÷ 5 = 172 minutes = 2 hours 52 minutes.

30°C and 21 mg/L: calculate relative humidity.

Answer: 21 ÷ 30.4 × 100 = approximately 69%.

33°C and 22 mg/L: calculate body humidity.

22 ÷ 44 × 100 = 50%.

31°C and 12 mg/L: calculate humidity deficit.

44 − 12 = 32 mg/L.

Once inspired gas moves into the lungs, what does it reach?

BTPS — Body Temperature, ambient Pressure, Saturated.