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Cardio (A&P) > Test 4 Ch. 6&7 > Flashcards

Test 4 Ch. 6&7 Flashcards

1
Q

How do you calculate the quantity of O2 that dissolves in the plasma?

A

Multiply the PaO2 x dissolved O2 factor (0.003).

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2
Q

What are the major features of HB?

A

4 heme groups and 4 amino acid chains.

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3
Q

How do you calculate the quantity of O2 that binds to HB?

A

Multiply 1.34 (O2 bound to HB factor) x the Hb (g/dl).

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4
Q

How does the percentage of HB bound to O2, O2 pressure, and O2 content relate to the oxyhemoglobin dissociation curve?

A

From 60-100mmHg as O2 rapidly binds to HB the PO2 increases. As the PO2 increases everything else increases. Saturation only increases by 7%.

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5
Q

What is the clinical significance of the flat portion of the oxyhemoglobin dissociation curve?

A
  • If PO2 falls from 100-60mmHg HB will still be 90% saturated.
  • Increasing the PO2 beyond the 100mmHg adds very little additional O2 to the blood.
  • As Hb moves through the alveolar-capillary system a significant partial pressure difference continues to exist between the alveolar gas and the blood.
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6
Q

What are the factors that shift the O2HB dissociation curve to the right?

A
  • Decreased pH
  • Increased PCO2
  • Increased temp
  • Increased DPG (diphosphoglycerate).
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7
Q

What are the factors that shift the O2HB dissociation curve to the left?

A
  • Increased pH
  • Decreased PCO2
  • Decreased temp
  • decreased BPG (Biphosphoglycerate)
  • Decreased Hb F ( Fetal hemoglobin)
  • Decreased COHB (carboxyhemoglobin)
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8
Q

What is the clinical significance of the right shifts of the O2HB dissociation curve with regard to the loading of O2 in the lungs and the unloading of O2 at the tissues?

A

Lungs: If the O2HB curve shifts to the right the HB will only be 75% saturated w/ O2 as it leaves the alveoli. The total O2 delivery will be much lower than indicated by a particular PaO2 value when a disease process is present that causes the O2HB curve to shift to the right.

Tissues: If the curve shifts to the right in response to a pH of 7.1, the plasma at the tissue sites would only have to fall from 60-40mmHg to unload 5mL/dL O2 from the HB.

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9
Q

What is the clinical significance of the left shifts of the O2HB dissociation curve with regard to the loading of O2 in the lungs and the unloading of O2 at the tissues?

A

Lungs: If the O2HB curve shifts to the left (caused by a pH of 7.6) at a time when the PaO2 is 60mmHg the HB will be about 95% saturated with O2 as it leaves the alveoli.

**Tissues: **If the curve shifts to the left because of a pH of 7.6 the plasma PO2 at the tissue sites would have to fall from 60-30mmHg in order to unload 5mL/dL O2 from the HB.

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10
Q

How do you calculate total O2 delivery?

A

DO2= QT x (CaO2 x 10)

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11
Q

If an individual has a cardiac output of 5L/min and a CaO2 of 20mL/dL, the total amount of O2 delivered to the peripheral tissues will be about how much?

A

5L x (20mL/dL x10) = 1000mL O2/min

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12
Q

How do you calculate arterial-venous O2 content difference?

A

C(a-v)O2 = Cao2 - Cvo2

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13
Q

If normal CaO2 is about 20mL/dL and the Cvo2 is 15mL/dL how much is the normal C(a-v)O2?

A

20mL/dL - 15mL/ dL = 5mL/dL

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14
Q

How do you calculate O2 consumption?

A

VO2=QT [C(a-v)O2 x 10]

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15
Q

If an individual has a cardiac output of 5L/min and a C(a-v)O2 of 5mL/dL, what is the total amount of O2 metabolized by the tissues?

A

5L/min x 5mL/dL x 10 = 250mL O2/min

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16
Q

How do you calculate the O2 extraction ratio?

A

O2ER=CaO2-CvO2/CaO2

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17
Q

If the normal CaO2 is 20mL/dL and the normal CvO2 is 15mL/dL what is the O2ER ratio?

A

20-15/20 = 5/20 = 0.25

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18
Q
  1. What is normal mixed venous O2 saturation?
  2. What value is clinically acceptable?
A
  1. SvO2 = 75%
  2. 65%
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19
Q

What are the factors that increase and decrease the O2 transport calculations? Look over Table 6-10

A
  • Increase & decrease O2 loading in the lungs
  • Increase & decrease metabolism
  • Increase & decrease cardiac output
  • Certain poisons
20
Q

What is the difference between hypoxemia and hypoxia?

A

Hypoxemia is low O2 in the blood; hypoxia is low O2 in the tissues.

21
Q

What is hypoxic hypoxia?

A

Inadequate O2 at the tissue cells caused by low arterial O2 tension (PaO2).

22
Q

What are some causes of hypoxic hypoxia?

A

Low PaO2 caused by:
* Hypoventilation
* High alititude

Diffusion impairment:
* Interstitial fibrosis
* Interstitial lung disease
* Pulmonary edema
* Pneumoconiosis

Ventilation-perfusion mismatch
Pulmonary shunting

23
Q

What is anemic hypoxia?

A

PaO2 is normal, but the O2 carrying capacity of HB is inadequate.

24
Q

What are some causes of anemic hypoxia?

A

Decreased hemoglobin concentration:
* Anemia
* Hemorrhage
Abnormal Hemoglobin:
* Carboxyhemoglobin
* Methemoglobin

25
Q

What is circulatory hypoxia (a.ka. stagnant or hyperfusion hypoxia)?

A

Blood flow to the tissue cells is inadequate; thus, O2 is not adequate to meet tissue needs.

26
Q

What are some causes of circulatory hypoxia?

A
  • Slow or stagnant (pooling) peripheral blood flow
  • Arterial venous shunts
27
Q

What is histotoxic hypoxia?

A

Impaired ability of the tissue cells to metabolize O2

28
Q

What are some causes of histotoxic hypoxia?

A

Cyanide poisoning

29
Q

What is the meaning of cyanosis?

A

Blue-gray or purplish discoloration seen on the mucous membranes, fingertips, and toes whenever the blood in these areas contains at least 5g/dL of reduced hemoglobin per dL (100mL).

30
Q

What are the 3 ways in which CO2 is transported in the plasma?

A
  1. Carbamino compound (bound to protein).
  2. Bicarbonate
  3. Dissolved CO2
31
Q

What are the 3 ways that CO2 is transported in the RBCs?

A
  1. Dissolved CO2
  2. Carbamino-HB
  3. Bicarbonate
32
Q

How is CO2 converted to HCO3 at the tissue sites and then transported in the plasma to the lungs?

A

Hydrolysis

33
Q

How is CO2 eliminated in the lungs?

A

When venous blood enters the alveolar capillaries & the chemical reactions at the tissue levels are reversed. The chemical processes continue until the CO2 pressure is equal throughout the entire system.

34
Q

How does the CO2 dissociation curve differ form the O2HB dissociation curve?

A

The O2HB is more S-shaped while the CO2 curve is almost linear which means that there is a more direct relationship between the partial pressure of CO2 content in the blood.

35
Q

How does the Haldane effect relate to the CO2 dissociation curve?

A

Deoxygenated blood will enhance the loading of CO2 while oxygenated blood will enhance the unloading of CO2.

36
Q

Describe the acid base balance and regulation of the body?

A

The acid base balance is regulated by pH. When pH is too high or low the body doesn’t function properly. The normal range for pH is 7.35-7.45 (arterial) and 7.3-7.4 (venous). A pH below 7.35 is acidosis and a pH above 7.45 is alkalosis.

37
Q

Identify the following disturbances on the Pco2/HCO3/pH nomogram?

A

Sudden large changes in H+ ions and HCO3 concentrations regardless of the cause.
Ex. Hypoventilation

38
Q

Identify the following disturbances for acute ventilatory failure with respiratory acidosis?

A

Acute hypoventilation caused by an overdose of narcotics or barbiturates.

39
Q

Identify the common acid base disturbances for acute respiratory failure with partial renal compensation?

A

Hypoventilation due to chronic obstructive disease. Is present when pH and HCO3 both are above the normal red colored PCP2 blood buffer bar and the pH is still less than normal.

40
Q

Identify the following acid base disturbances for chronic ventilatory failure with complete renal compensation?

A

Is present when the the HCO3 increases enough to cause the acidic pH to move back into the normal range.

41
Q

What are some common causes of acute respiratory failure?

A

-COPD
-Drug overdose
-General anesthesia
-Head trauma
-Neurologic disorders

42
Q

Identify some common acid base disturbances on for respiratory alkalosis?

A

Hyperventilation due to pain or anxiety.

43
Q

Common causes of acute alveolar hyperventilation?

A
  1. Hypoxia
  2. Pain, anxiety and fever
  3. Brain inflammation
  4. Stimulant drugs
44
Q

Identify common causes of metabolic acidosis?

A

-Lactic acidosis
-Ketoacidosis
- Salicylate intoxication
- Renal failure
- Uncontrolled diarrhea

45
Q

What are some common cause of metabolic alkalosis?

A

Hypokalemia
Hypochloremia
Gastric suction or vomiting
Excessive administration of corticosteroids
Excessive administration of sodium bicarbonate
Diuretic therapy
Hypovolemia

46
Q

What is base excess deficit?

A

It’s a tool use to calculate how much metabolic acidosis is in the body with a base excess of -7; or metabolic alkalosis with a base excess of 7

Cardio (A&P) (5 decks)

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