# Respiratory Quiz #3 Flashcards

1
Q

Describe the Universal Gas Law.

A

The ideal gas law is the equation of state of a hypothetical ideal gas. It is a good approximation to the behaviour of many gases under many conditions, although it has several limitations. It was first stated by Émile Clapeyron in 1834 as a combination of Boyle’s law and Charles’s law.[1] The ideal gas law is often introduced in its common form:

PV=nRT

```P=pressure
V=volume
n=# of moles of gas
R=universal gas constant(8.3 joules/kelvin/mole)
T=temperature```
2
Q

Define Avogadro’s Law and the relationship between gas molecule quantity and volume.

A
• one mole of an ideal gas occupies a volume of 22.4 L at 1 atmosphere and 0’C
• # of molecules in 1 mole = 6.02 x 10^23
• equal volumes of different gases at same temp and pressure contain the same # of molecules with nitrous oxide being the only exception.

SO IF THE AMOUNT OF GAS IN A CONTAINER(E.G., BALLOON) INCREASES, THE VOLUME ALSO INCREASES
THIS GIVES THE RELATIONSHIP BETWEEN VOLUME AND QUANTITY WHEN PRESSURE AND TEMP ARE HELD CONSTANT(PV-NRT)

3
Q

Define Boyle’s law and the relationship between pressure to volume. Given an application of Boyles law.

A

“The volume of a given mass of gas is inversely proportional to the pressure, provided that the temperature remains constant”

• IF PRESSURE DOUBLES THE VOLUME WILL DECREASE BY 1/2
• IF THE PRESSURE IS HALVED, THE VOLUME WILL DOUBLE

application would be a pressurized cylinder is opened and slowly emptied so that temp does not change. The volume of gas released from the cylinder can be estimated from Boyles law.

4
Q

Define Charle’s law and the relationship between temperature and volume

A

“The volume of a given mass of an ideal gas is proportional to the absolute temperature, provided that the pressure remains constant”

• AS TEMPERATURE INCREASES, VOLUME INCREASES AS LONG A PRESSURE REMAINS CONSTANT(i.e.,increased temp, increased volume with hot air balloon)
• V1/V2=T1/T2
5
Q

Define Gay-Lussac’s number and the relationship between temperature and pressure.

A

“The pressure of a given mass of an ideal gas is proportional to the absolute temperature, provided that the volume remains constant”

• AS TEMPERATURE INCREASES, PRESSURE INCREASES(when cylinder is moved from loading dock pressure in the cylinder increases)
• P1/T1 = P2/T2
6
Q

Identify the blood supply to the tracheobronchial tree down to the terminal bronchioles.

A

The aorta and the intercostal arteries supplies blood to the tracheobronchial tree down to the level of the terminal bronchioles.

7
Q

Compare and contrast Bronchial blood flow and Pulmonary blood flow.

A

BRONCHIAL BLOOD FLOW:
-constitutes a very small portion(1-2%) of the left ventricular output
-provides the tracheobronchial tree with arterial blood
PULMONARY BLOOD FLOW:
-constitutes the entire output of the right ventricle
-supplies the lung with mixed venous blood draining the body to oxygenate

7
Q

Describe the lungs as a reservoir for blood volume

A

.

9
Q

Describe the lungs as a reservoir for blood volume

A
• 450 ml(9%) of total blood volume is in the pulmonary circuit
• lungs act as a reservoir for excessive blood volume, especially in heart failure(20-30% increase—>CHF/Pulm Edema)
• increased intrathoracic pressure decreases pulmonary blood volume
• blood volume in each region depends on ventilation to each lung region
10
Q

Compare Pulmonary Vascular Resistance to Systemic Vascular Resistance.

A
• mean systemic pressure is 100 mmHg
• mean pulmonary pressure is 15 mmHg
• SVR is 10 times PVR

The walls of the pulmonary vessels are very thin and compliant. They allow diversion of blood from one region to another, as with recruitment, dissension and HPV.

11
Q

Compare the effects of after load on the right ventricle as compared to the left ventricle.

A

The RV is very sensitive to after load changes(fails with acute pulmonary hypertension). Thin walled, low compliance chamber unless chronic pulmonary hypertension.

12
Q

Describe the effect of airway pressure on zero order capillaries.

A

Order “0” capillaries collapse or destined, depending on the pressure surrounding them.

Pulmonary capillaries form a dense network around the alveoli, much as a parking garage with scattered posts. Branching is asymmetrical.

13
Q

Discuss the role of alveolar collapse in pulmonary vascular resistance.

A

Alveolar expansion or collapse plays a major role in pulmonary vascular resistance.

14
Q

Identify the number of “1” order pulmonary capillaries and their volume.

A

300,000,000 pulmonary capillaries and 151 ml volume

15
Q

Define recruitment and distention as they relate to perfusion.

A
• Recruitment refers to perfusion of previously closed capillaries when a critical opening pressure or blood volume is achieved.
• Distension refers to widening of individual capillaries.
16
Q

Compare and contrast alveolar and extra-alveolar effects on capillary size.

A
• PVR is increased when lung volume is low
• alveolar vessels expand up to FRC then constrict but remain more patent
• Extra-alveolar vessels are pulled open as the lung expands
17
Q

Describe the effect of increased blood flow on pulmonary vascular resistance.

A

PVR becomes even less when pressure and flow increase due to distention and recruitment

18
Q

Describe the effects of increasing lung volume(above FRC) on pulmonary vascular resistance.

A
• PVR may drop even further as the pressure within it rises due to recruitment and distention*
• PVR is increased when lung volume is low
19
Q

List 5 factors that increase pulmonary vascular resistance.

A
1. atelectasis
2. hypoxia
3. hypercapnia
4. acidemia
5. catecholamines
6. histamine
7. serotonin
8. prostaglandins
9. lung inflation or deflation from FRC changes
10. increased perivascular pressure
20
Q

List 5 factors that decrease pulmonary vascular resistance

A
1. isoproterenol
2. milrinone
3. flolan/epoprosterenol
4. acetylcholine
5. bradykinin
6. prostoglandins
7. theophylline
8. nitric oxide
9. increased CO
10. increased pulm blood volume
21
Q

Describe the effects of alpha-1 agonist, beta-2 agonist, and V-1 agonist on pulmonary vascular resistance.

A

Alpha 1—>constrict pulmonary vascular tone
Alpha 2—>dilate pulmonary vascular tone
Beta 2—–>dilate pulmonary vascular tone
V1(vasopressin)—>dilate pulmonary vascular tone

22
Q

Define Hypoxic Pulmonary Vasoconstriction(HPV).

A

Contraction of smooth muscle in the walls of the small arterioles in a hypoxic region. Occurs in response to low alveolar PO2, not pulmonary artery PO2. Directs blood flow away from hypoxic regions of the lungs.

23
Q

Identify the triggering action for HPV

A

Occurs in response to low alveolar PO2(< 70 mmHg), not pulmonary artery PO2.

24
Q

Describe the effect of HPV on PVR and blood flow

A

Directs blood flow away form hypoxic regions of the lungs.

25
Q

List 4 drugs that decrease HPV

A
1. beta-agonists
2. calcium channel blockers
3. inhaled anesthetics
4. minoxidil
5. nitrosovascodilators
6. theophylline
25
Q

What is the pneumonic related to the Gas laws?

A
```Can
These
Guys
Possibly
Be
Violinist?```
26
Q

Describe why lower regions of the lungs receive more blood flow

A

Gravity is the principle reason blood flow is greater to the dependent portions of the lungs.

27
Q

Pulmonary capillaries and arterioles(multiple choice):

• branch symmetrically along with bronchioles
• resistance is unaffected by alveolar collapse
• form a dense network around each alveolus
• have 23 generations
A

Form a dense network around each alveolus

28
Q

List 3 drugs that increase HPV

A
1. almitrine
2. cyclo-oxygenase inhibitors
3. beta blockers
29
Q

Compare V/Q ratios in West’s lung zones 1,2 and 3.

A

ZONE 1:
-pulmonary arterial pressure falls below alveolar pressure
-ventilation is greater than perfusion
V/Q RATIO IS HIGH
ZONE 2:
-pulmonary arterial pressure increases due to hydrostatic pressure(gravity)
BETTER VENTILATION-PERFUSION MATCHING OCCURS
ZONE 3:
-pulmonary arterial pressure increases and exceeds alveolar pressure
-perfusion is greater than ventilation
V/Q RATIO IS LOW

30
Q

Identify two factors that increase the prevalence of zone 1.

A

Hemorrhage and Positive Pressure Ventilation

-In this region alveolar pressure(Palv) exceeds Pulmonary capillary pressure(Ppc) so that no flow occurs(collapse)

31
Q

Describe zone 4 and its significance.

A
• some fluid is forced out of the capillary and into the perivascular space(ISF > PA) or the interstitial space
• this zone is usually very small as alveolar vessels are closed by increased PVR from collapsed alveolus
• may be larger in pathologic states
32
Q

List 8 factors contributing to pulmonary edema.

A
1. increased capillary permeability
2. increased capillary hydrostatic pressure
3. decreased interstitial hydrostatic pressure
4. decreased colloid osmotic pressure
5. insufficient lymphatic drainage
6. unknown
7. ?
8. ?

CLINICAL CAUSES OF PULM EDEMA:

• ARDS, oxygen toxicity, inhaled or circulating toxins
• increased LA pressure from infarct or mitral stenosis, over administration of IV fluids
• rapid evacuation of pneumohemothorax
• protein starvation, dilution of blood proteins by hemodilution, proteinuria
• tumors, interstitial fibrosing diseases
• high altitude pulmonary edema, head injury, drug OD
33
Q

List 4 causes of negative pressure pulmonary edema

A
1. post-extubation laryngospasm
2. epiglottitis/croup
3. choking/foreign body
4. strangulation/hanging
5. ET tube obstruction
6. tumor/goiter
7. near drowning
8. direct suctioning of ET tube adapter
35
Q

List 4 causes of hypoxemia

A
1. hypoventilation(drugs, inadequate MV)
2. diffusion issue(CHF, ARDS)
3. shunt(anatomic, atelectasis)
4. ventilation perfusion mismatch(COPD)
36
Q

Describe the clinical result of V/Q mismatch

A
• hypoventilation
• hypoxemia
• hypercarbia
37
Q

Identify the most common cause of hypoxemia during anesthesia.

A

Ventilation-perfusion inequality is the most common cause of hypoxemia(V/Q mismatch)from slide

?shunt?

38
Q

Describe the typical distribution of perfusion

A
• Lower(dependent) regions of the lung receive greater blood flow that the upper(nondependent) regions.
• Gravity is the principle reason blood flow is greater to dependent portions of the lung(base).
39
Q

Compare the distribution of blood flow and ventilation

A
• Blood flow and ventilation decrease almost linearly from bottom to top.
• Ventilation decreases less, such that V/Q ratio is abnormally high in the apex.
• Distribution of both is affected by posture, exercise and position.
40
Q

Identify the effect of moving from the top to the bottom of the lung on V/Q ratio, perfusion, alveolar PO2 and alveolar PCO2

A
• V/Q ratio decreases top to bottom of the lung.
• Perfusion(Q) increases dramatically from top to bottom of the lung.
• PAO2 decreases top to bottom of lung while PACO2 increases.
41
Q

Describe the effect of anesthesia on FRC, lung compliance and airway resistance.

A

The effects of shunting related to anesthesia is:

1. decreased FRC(functional residual capacity)
2. decreased Clung(lung compliance)
3. increased Raw(airway resistance)
42
Q

Discuss anatomic and physiologic shunt as they relate to ventilation and bronchial/thebesian circulations

A

SHUNT refers to blood that enters the arterial system without entering ventilated areas of the lung.
Bronchial and thebesian circulations constitute ANATOMIC shunt.
Blood passing through poorly ventilated lung represents PHYSIOLOGIC shunt.

43
Q

Describe the effect of shunt on increasing inspired oxygen {} and PaO2

A

Increasing FiO2 increases PAO2/PaO2. Varying degrees of shunt will limit the effect on PaO2 such that eventually increasing inspired O2 HAS NO EFFECT ON PaO2.

44
Q

Discuss expected V/Q ratios in healthy patients

A
• In a healthy patient almost all ventilation and blood flow(95%) go to the compartments close to a V/Q ratio of about 1.0.
• Blood flow and ventilation are matched very evenly.
• Almost no blood flow goes to unventilated regions.
45
Q

Describe the effects of lung disease on V/Q ratios.

A
• In a patient with lung disease, V/Q distribution is not equally distributed.
• Considerable blood flow goes to compartments with V/Q mismatch of 0.03-0.3. This blood will be poorly oxygenated and will depress PO2.
• Considerable ventilation will go to unites without perfusion and so CO2 will not be eliminated.
46
Q

Describe compensation for V/Q abnormalities in patients with lung disease.

A
• Increased minute ventilation via central and peripheral chemoreceptors.
• Dissociation curve for CO2 is linear(favors elimination) and dissociation curve for O2 is flat(favors loading of oxygen).
• Hypoxic pulmonary vasoconstriction and pulmonary bronchoconstriction assist in matching perfusion and ventilation.
47
Q

What are 3 factors affecting V/Q matching?

A
1. Gravity
2. Alveolar/capillary collapse in non ventilated areas
3. Hypoxic Pulmonary Vasoconstriction
48
Q

Describe perfusion in zone 1 of the lungs.

A
• Pressure in the pulmonary artery(Ppa) decreases by 1 cmH2)/cm vertical distance up the lung.
• In this region alveolar pressure(PALV) exceeds Ppc so that NO FLOW OCCURS(collapse)
• Zone 1 is not prevalent but may be increased by hemorrhage and positive pressure.
49
Q

Describe perfusion in zone 2 of the lungs.

A
• Further down the lung, Ppa becomes positive and blood flow begins when Ppc exceeds PALV(zone 2)
• PALV still exceeds Ppc during ventilation(lung volumes above FRC) so that BLOOD FLOW ONLY OCCURS WHEN THERE IS A GRADIENT(waterfall effect)
• FLOW IS CYCLIC, BASED ON RESPIRATORY AND CARDIAC CYCLES.
50
Q

Describe perfusion in zone 3 of the lungs.

A
• Lower in the lung, there is a vertical level at which venous pressure becomes positive and also exceeds PALV.
• BLOOD FLOW IS CONTINOUS as Ppc always exceeds PALV.
• Pleural pressure is less negative and so vessels are distended.