Chem Phys Math Review Flashcards

Question

Gas Laws allows us to

Answer 1

- Allows us to predict gas behavior - Know the variable and the constant - Could these guys possibly be violent?

Answer 2

Pressure P and the volume V of a confined gas held at a constant temperature The volume of an ideal gas is inversely proportional to the pressure- Thus as pressure ↑ the volume ↓ P1 x V1 =P2 xV2

Answer 3

Reservoir Bag on Anesthesia Machine --Applying pressure (squeezing it) causes the volume to decrease e.g. Diaphragm contraction Pneumatic bellows Squeezing bag Bourdon gauge to calculate remaining O2 in tank

Answer 4

A full E cylinder of oxygen will empty 625-650 L into the atmosphere The explanation is based on Boyle’s law: The relatively small volume of gas in the cylinder is at high pressure. When it is released to the atmosphere where there is a relatively low pressure, a large volume results Pressure ↓ and Volume ↑

Answer 5

Spontaneous breathing- When intrapulmonary pressure becomes negative (decreases), intrapulmonary volume increases Bellows on ventilator- As pressure increases, the volume within the bellows decreases

Answer 6

Relationship between the Volume of a gas and how it varies with Temperature Charles's Law states that the volume of a given gas is directly proportional to the Kelvin Temperature provided the amount of gas & the pressure remains constant. Volume is proportional to temperature Thus as temperature ↑ the volume ↑

Answer 7

LMA cuff ruptures in an autoclave

Answer 8

Relationship between the Pressure of a gas and its Temperature. At constant Volume, the pressure of a gas sample is directly proportional to the Kelvin Temperature. Thus as the temperature ↑ the pressure ↑

Answer 9

A full cylinder of compressed gas is moved from the air conditioned hospital (70 degrees) to the loading dock (100 degrees Fahrenheit)- What happens to the pressure in the cylinder??? And visa-versa  if the cylinder is moved from hot to cold environment then the pressure would decrease

Answer 10

PV = nRT Combines Boyle’s, Charles’ & Gay Lussac’s Laws + Avagadro’s Law: n = # moles of gas (A mole (mol) of a pure substance is a mass of the material in grams that is numerically equal to the molecular mass in atomic mass units (amu). A mole of any material will contain Avogadro's number of molecules. For example, carbon has an atomic mass of exactly 12.0 atomic mass units -- a mole of carbon is therefore 12 grams. R= universal gas constant 0.0821 liter- atm/K/mole P= Pressure T = absolute temperature V= Volume Reduce to P= T/V or T/P=V or T/V=P

Answer 11

Avagadro introduced a molecular numbering system known as the mole 1 mole contains 6.02 x 1023 molecules Avagadro hypothesized that if you had 2 different containers containing 2 different gases at the same temp and pressure, then they contain the same number of molecules One mole is one gram multiplied by the molecular weight: e.g. 1 mole 02 = 32 grams. It has been found that 1 mole of any substance occupies 22.4 liters so: 6.02 x 1023 molecules of 02 = 32 grams and occupies 22.4 L.

Answer 12

Calibration of vaporizers is done using Avagadro’s hypothesis. Molecular weight of Sevoflurane is 200, so 200 g Sevo is 1 mole, and would occupy 22.4 l at s.t.p. If we put 20g of Sevo (0.1 mole) into a vaporizer, and allow it all to vaporize, it would occupy 2.24 litres

Answer 13

Total Pressure of a gas mixture is the sum of the Partial Pressure of each gas. Total P = P 1 + P 2 + P3… Dalton’s law states that in a mixture of gases, the pressure exerted by each gas is the same as that which it would exert if it alone occupied the container.

Answer 14

We know that the air is 21% Oxygen and 79% Nitrogen, so we can calculate the partial pressure of each gas by multiplying the total atmospheric pressure by the fractional concentration of each gas: 760 mmHg x 21% = l59 mmHg, this is the partial pressure of Oxygen in the container. What is it for nitrogen??? We know that the air is 21% Oxygen and 79% Nitrogen, so we can calculate the partial pressure of each gas by multiplying the total atmospheric pressure by the fractional concentration of each gas: 760 mmHg x 21% = l59 mmHg, this is the partial pressure of Oxygen in the container. What is it for nitrogen???

Answer 15

Generally, when we provide an inhalation anesthetic, we use a combination of inhaled agents. Commonly used agents might be: 50% N20 + 44% O2 + 6%Desflurane =100% Mix to patient

Answer 16

The definition of MAC is the concentration of the vapor (measured as a percentage at 1 atmosphere, i.e the partial pressure) that prevents the reaction to a standard surgical stimulus in 50% of subjects. Since most of us work at about 1 atmosphere, we can still think in terms of % concentration, but what is physiologically important is the partial pressure (mm Hg), not the concentration. At a higher altitude where the barometric pressure is ½ that at sea level, the amount of isoflurane vapor output increases due to the lower barometric pressure. Therefore, the settings that delivered 2% isoflurane now deliver 4% isoflurane. However, according to Dalton’s law, the partial pressure of isoflurane delivered would be approximately the same at both altitudes since 2% isoflurane at 760mm Hg (15.2 mm Hg) is the same as 4% isoflurane at 380mm Hg (15.2 mm Hg)

Answer 17

Definition: The temp above which a substance goes into gaseous form in spite of how much pressure is applied. A gas cannot be liquefied if the ambient temperature is greater than critical temperature A gas can be liquefied if sufficient pressure is applied at ambient temp below the critical temperature

Answer 18

Critical Temp of O2 = - 119 degree C. Therefore, O2 cannot be liquefied at room temp no matter how much pressure is applied to it Recall: A gas can be liquefied if sufficient pressure is applied at ambient temp below the critical temperature

Answer 19

The main supply of oxygen in a hospital is in liquid oxygen stores. Huge quantities of gas can be stored in this way and is more economical. The containers are insulated from the outside and the temperature is kept at -160 degress C.

Answer 20

Critical temp = 36.5 degrees C Room temp. ~ 25 degrees C Therefore, pressure can be applied to liquefy N2O at room temp Hence, N2O is stored as a liquid at pressure of 745 mmHg and at room temp. Recall: A gas can be liquefied if sufficient pressure is applied at ambient temp below the critical temperature

Answer 21

Occurs when matter changes phase The term adiabatic implies a change in temperature of the matter without gain or loss of heat Clinical Application- N2O cylinder opened fully-> frost can form on the outlet due to cooling

Answer 22

Expansion of a gas causes cooling Clinical Application: As gas leaves a cylinder, the expansion cools the surrounding air causing condensation of moisture on the cylinder

Answer 23

Describes the relationship between rate of flow and: 1) pressure gradient across length of tube – direct 2) radius4 of the tube – direct 3) length of the tube – inverse 4) viscosity of the fluid -inverse

Answer 24

IV Flow Airways Vascular flow – Polycythemia vs. Anemia Thorpe Tubes – at low flows

Answer 25

Viscosity is a determinant of flow when flow is laminar (low flow rates). Density is a determinant of flow when it is turbulent. Density is the ratio of mass to volume. D=mass/volume. Determines the rate of flow in flow meters when rate of gas flow is high through variable orifice flow meter. Example: Heliox

Answer 26

Thorpe tube is an older term for flowmeters. At low flows, the annular-shaped orifice around the float is (relatively) tubular so (according to Poiseuille's Law) flow is governed by viscosity. At high flows (indicated on the wider top part of the float tube), the annular opening is more like an orifice, and density governs flows.

Answer 27

Increased velocity Bend >20 degrees Irregularity in the tube

Answer 28

Reynold’s Number = velocity ∙ density ∙ diameter/ viscosity Reynold’s Number > 2000 = TURBULENT FLOW

Answer 29

Relates pressure and velocity and how they interact The lateral wall pressure is LEAST at the point of greatest constriction and the speed is the GREATEST Thus, flow will be faster through the constricted portions and slower at the wider portions of a tube Narrow Diameter = ↓ Lateral wall pressure = ↑ Speed Wider Diameter = ↑ Lateral wall pressure = ↓ Speed

Answer 30

The lateral pressure of rapidly flowing fluid in a constricted tube can be subatmospheric, hence a sidearm on that portion of the tube can be used to aspirate another fluid into the tube. Nebulizers Venturi Oxygen Masks (24-40% O2) Jet Ventilation

Answer 31

Absorption of radiation by a given thickness of a solution of a given concentration is the same as that of twice the thickness of a solution of half the concentration (Beer) Each layer of equal thickness absorbs an equal fraction of the radiation that passes through it (Lambert)

Answer 32

``` Pulse Oximetry 2 LEDs: One (RED) emits light at 660nm One (INFRARED) emits light at 940 nm Shine across pulsatile tissue bed Measure absorption on opposite side Compare RED vs. INFRARED light Calculate Oxygen saturation OXYHGB 940 nm (IR Light) DEOXYHGB 660 nm (RED LIGHT) ```

Answer 33

Artifact (ambient light, low perfusion, motion) Alternate Species of Hemoglobin Carboxyhgb: FALSE HIGH Methgb: If SaO2 > 85% FALSE LOW If SaO2 < 85% FALSE HIGH HgbF: No Effect HgbS: No Effect Polycythemia: No Effect Methylene & Isosulfan Blue: FALSE LOW Indocyanine Green & Indigo Carmine: Slight Decr. Blue Nail Polish: FALSE LOW

Answer 34

Pressure gradient across the wall of a SPHERE or TUBE/CYLINDER (blood vessel, ventricle, alveolus) is related to: Wall tension (T) – Directly Radius (r) – Inversely T=Pr

Answer 35

Normal Alveoli and the need for surfactant during expiration Vascular Pathology- Aneurysm rupture due to increased wall tension Ventricular volume and work of the heart- a dilated ventricle has greater tension in its wall (end diastolic pressure rises)

Answer 36

That resistance which will allow one ampere of current to flow under the influence of a potential of one volt W(Resistance) = Potential (volt) Current (ampere) OR E (Voltage) = I(current flow or amp) R(resistance) E=IR

Answer 37

Strain Gauges in Pressure Transducers Thermistors

Answer 38

Metal is a good conductor, your patient is lying on a metal bed, surgery causes bleeding, blood is wet, the room is full of electrical equipment RISK TO THE PATIENT = BURNS Macroshock: Current distributed through the body, culprit: faulty wiring, improper grounding Microshock: Current applied in or near the heart, culprit pacing wires, fault equipment during cardiac cath Electrocautery

Answer 39

1 milliamp  skin tingling/perception 5 milliamps maximal “harmless” current 10-20 milliamps  let go of source 50 milliamps  pain, LOC, mechanical injury 100-300 milliamps  V-Fib, resp intact 6000 milliamps complete physiologic damage

Answer 40

50 - 100 microamps  V-Fib

Answer 41

Henry's law

Answer 42

Henry's Law

Answer 43

directly proportional

Answer 44

inversely proportional

Answer 45

The ideal (universal) gas law The cylinder has a constant volume. The number of moles (n) of gas decreases as gas exits the cylinder, so Pressure decreases.