Question 1

A patient has a reported CaO₂ of 19 vol% ,cardiac output of 4.8 L/min,and CvO₂ of 14 vol%.What would the oxygen consumption equal?

Accepted Answer

Oxygen consumption (VO2) can be calculated using the formula: VO2 = (CaO2 - CvO2) × Cardiac Output × 10, where CaO2 is the arterial oxygen content, CvO2 is the venous oxygen content, and Cardiac Output is given in L/min. Substituting the given values: VO2 = (19 - 14) × 4.8 × 10 = 5 × 4.8 × 10 = 240 mL O₂/min.

Question 2

Which variable appears on the left side (y axis)of the oxyhemoglobin dissociation curve nomogram?

Accepted Answer

The left side (y-axis) of the oxyhemoglobin dissociation curve nomogram represents the percentage of hemoglobin chemically bound to oxygen, also known as the saturation of hemoglobin (SaO2).

Question 3

During an acute asthma episode,a female patient arrived in ER and on room air was found to have a pH 7.25,PaCO₂ 71 mm Hg,PaO₂ 27 mmHg.What effect would these blood gases have on the oxyhemoglobin dissociation curve?

Accepted Answer

The given blood gas values indicate respiratory acidosis with hypoxemia, which would cause a right shift of the oxyhemoglobin dissociation curve. The lower pH and higher PCO₂ would promote the dissociation of oxygen from hemoglobin, making it easier for the oxygen to be delivered to the tissues. This is beneficial for the patient during an acute asthma episode, as it enhances oxygen delivery and helps to alleviate the hypoxemia. Therefore, option A is the most appropriate choice.

Question 4

Which of the following increase the 2,3 BPG levels?
I.hypoxia
II.anemia
III.blood stored for more than 1 week
IV.decreased pH

Accepted Answer

Hypoxia and anemia both increase 2,3 BPG levels as a compensatory mechanism to enhance oxygen release from hemoglobin. Blood stored for more than 1 week actually decreases 2,3 BPG levels, and decreased pH (acidosis) also leads to decreased 2,3 BPG levels.

Question 5

What is the normal P₅₀?

Accepted Answer

The normal P₅₀, which is the partial pressure of oxygen at which hemoglobin is 50% saturated, is approximately 27 mm Hg. This value reflects the affinity of hemoglobin for oxygen; a lower P₅₀ indicates a higher affinity, while a higher P₅₀ indicates a lower affinity.

Question 6

From 97% and 90% saturation on the oxyhemoglobin dissociation curve,what change occurs in the PO₂?

Accepted Answer

The PO₂ decreases from 100 mm Hg at 97% saturation to 60 mm Hg at 90% saturation as shown on the oxyhemoglobin dissociation curve.

Question 7

Which portion of the oxhemoglobin dissociation curve illustrates that hemoglobin has a safety zone for the loading of oxygen in the lungs?

Accepted Answer

The flat portion between 90-100% saturation illustrates that hemoglobin has a safety zone for loading of oxygen in the lungs. In this portion, small variations in oxygen pressure result in minimal changes in hemoglobin saturation, which allows for efficient loading of oxygen in the lungs and ensures that the tissues receive adequate oxygen supply.

Question 8

A patient has a reported CaO₂ of 19 vol%,cardiac output of 4.8 L/min,and CvO₂ of 14 vol%.What would the oxygen extraction ratio equal?

Accepted Answer

The oxygen extraction ratio (O2ER) is calculated as (CaO2 - CvO2) / CaO2. Plugging in the values: (19 vol% - 14 vol%) / 19 vol% = 5 vol% / 19 vol% = 0.263 or 26.3%.

Question 9

Using the 40-50-60/70-80-90 Rule,what PaO₂ would be predicted if the SpO₂ were 80%?

Accepted Answer

The 40-50-60/70-80-90 Rule suggests that when the SpO₂ is 90%, the PaO₂ is approximately 60 mm Hg; at an SpO₂ of 80%, the PaO₂ is approximately 50 mm Hg; and at an SpO₂ of 70%, the PaO₂ is around 40 mm Hg. Therefore, if the SpO₂ were 80%, the predicted PaO₂ would be 50 mm Hg.

Question 10

What would the DO₂ equal if a patient has a CaO₂ of 18 vol% and a CO of 6 L/min.

Accepted Answer

The DO₂ (oxygen delivery) can be calculated using the formula: DO₂ = CaO₂ × CO × 10, where CaO₂ is the arterial oxygen content in vol% and CO is the cardiac output in L/min. Plugging in the given values: DO₂ = 18 vol% × 6 L/min × 10 = 1080 mL O₂/min.

Question 11

A patient has a reported SaO₂ of 90%,hemoglobin 15 g%,PaO₂ of 61 mmHg,cardiac output of 6 L/min,and CvO₂ of 14.2 vol%.What would the C(a-v)O₂ equal?

Accepted Answer

C(a-v)O₂, the arterial-venous oxygen content difference, is calculated using the formula: C(a-v)O₂ = CaO₂ - CvO₂. Given that the CvO₂ (venous oxygen content) is 14.2 vol%, and knowing that CaO₂ (arterial oxygen content) can be estimated using the formula: CaO₂ = (Hb * 1.34 * SaO₂) + (PaO₂ * 0.003), where Hb is hemoglobin in g/dL, SaO₂ is the arterial oxygen saturation, and PaO₂ is the partial pressure of oxygen in arterial blood in mmHg. Substituting the given values: CaO₂ = (15 * 1.34 * 0.90) + (61 * 0.003) ≈ 18.27 vol%. Therefore, C(a-v)O₂ = 18.27 - 14.2 = 4.07 vol%.

Question 12

How would a PO₂ of 80 mm Hg affect the oxyhemoglobin dissociation curve and hemoglobin's ability to transport oxygen to peripheral tissues?

Accepted Answer

A PO₂ of 80 mm Hg is within the normal range for arterial blood, so the oxyhemoglobin dissociation curve would not shift, and oxygen delivery to peripheral tissues would remain normal.

Question 13

Which variable appears on the horizontal portion (x axis)of the oxyhemoglobin dissociation nomogram?

Accepted Answer

The horizontal portion (x-axis) of the oxyhemoglobin dissociation nomogram represents the partial pressure of oxygen (PaO2) in the arterial blood. It is plotted against the percentage of oxygen saturation of hemoglobin (SaO2) on the vertical portion (y-axis).

Question 14

What impact does the steep portion of the oxyhemoglobin dissociation curve have on oxygen delivery?

Accepted Answer

The steep portion of the oxyhemoglobin dissociation curve indicates that there is a rapid release of oxygen from hemoglobin to tissues when the partial pressure of oxygen falls below 60 mm Hg. This enhances oxygen delivery to tissues, ensuring that they receive an adequate supply of oxygen even in conditions of low oxygen availability.

Question 15

At what lung capacity or right?
I.decreased pH
II.increased body temperature
III.increased PaCO₂
IV.decreased 2,3 BPG

Accepted Answer

The right shift in the oxygen-hemoglobin dissociation curve, which facilitates oxygen unloading to the tissues, is caused by decreased pH (acidosis), increased body temperature, and increased PaCO₂ (partial pressure of carbon dioxide). These conditions signal a higher metabolic activity requiring more oxygen. Decreased 2,3-BPG also causes a right shift, contrary to the common misconception that it causes a left shift.

Question 16

What does a P₅₀ of 30 indicate?

Accepted Answer

A P₅₀ of 30 indicates a higher partial pressure of oxygen is needed for hemoglobin to be 50% saturated, suggesting a rightward shift of the oxygen-hemoglobin dissociation curve. This shift signifies a decreased affinity of hemoglobin for oxygen.

Question 17

What does a hematocrit of 51% indicate for a 50 year old male residing at seal level?

Accepted Answer

A hematocrit of 51% indicates polycythemia, which is an abnormal increase in the number of red blood cells in the bloodstream. In a healthy adult male, the normal hematocrit range is typically 38-52%, so this value is slightly above the upper limit of normal. This condition can be caused by a variety of factors, including chronic hypoxia, genetic mutations, or certain medications. It can lead to complications such as increased viscosity and decreased blood flow, which can increase the risk of thrombotic events like stroke or heart attack.

Question 18

Which of the following shift the oxyhemoglobin dissociation curve to the left?
I.Fetal Hb (HbF)
II.carboxyhemoglobin
III.increased H+ concentration

Accepted Answer

The oxyhemoglobin dissociation curve shifts to the left in the presence of fetal hemoglobin (HbF) and carboxyhemoglobin because both have a higher affinity for oxygen than adult hemoglobin (HbA), allowing them to hold onto oxygen more tightly. Increased H+ concentration (acidosis) actually shifts the curve to the right, facilitating oxygen release to tissues.

Question 19

What is derived when (content of oxygen in arterial blood x 10)is multiplied by cardiac output?

Accepted Answer

When the content of oxygen in arterial blood is multiplied by cardiac output (CO), the result is the total oxygen delivery (DO2). This is the amount of oxygen delivered to the tissues per unit of time, expressed in milliliters of oxygen per minute (mL/min).

Question 20

From 97% and 90% saturation on the oxyhemoglobin dissociation curve,what change occurs in the PO₂?

Accepted Answer

As the saturation falls from 97% to 90%, there is a decrease in the affinity of hemoglobin for oxygen, which means that oxygen is released from the hemoglobin molecules. This typically occurs at a PO₂ of around 60 mm Hg. Therefore, the PO₂ falls from 100 mm Hg (at 97% saturation) to 60 mm Hg (at 90% saturation).

Quiz 6: Oxygen and Carbon DioxideTransport

A patient has a reported CaO₂ of 19 vol% ,cardiac output of 4.8 L/min,and CvO₂ of 14 vol%.What would the oxygen consumption equal?

Which variable appears on the left side (y axis) of the oxyhemoglobin dissociation curve nomogram?

During an acute asthma episode,a female patient arrived in ER and on room air was found to have a pH 7.25,PaCO₂ 71 mm Hg,PaO₂ 27 mmHg.What effect would these blood gases have on the oxyhemoglobin dissociation curve?

Which of the following increase the 2,3 BPG levels? I.hypoxia II.anemia III.blood stored for more than 1 week IV.decreased pH

What is the normal P₅₀?

From 97% and 90% saturation on the oxyhemoglobin dissociation curve,what change occurs in the PO₂?

Which portion of the oxhemoglobin dissociation curve illustrates that hemoglobin has a safety zone for the loading of oxygen in the lungs?

A patient has a reported CaO₂ of 19 vol%,cardiac output of 4.8 L/min,and CvO₂ of 14 vol%.What would the oxygen extraction ratio equal?

Using the 40-50-60/70-80-90 Rule,what PaO₂ would be predicted if the SpO₂ were 80%?

What would the DO₂ equal if a patient has a CaO₂ of 18 vol% and a CO of 6 L/min.

A patient has a reported SaO₂ of 90%,hemoglobin 15 g%,PaO₂ of 61 mmHg,cardiac output of 6 L/min,and CvO₂ of 14.2 vol%.What would the C(a-v) O₂ equal?

How would a PO₂ of 80 mm Hg affect the oxyhemoglobin dissociation curve and hemoglobin's ability to transport oxygen to peripheral tissues?

Which variable appears on the horizontal portion (x axis) of the oxyhemoglobin dissociation nomogram?

What impact does the steep portion of the oxyhemoglobin dissociation curve have on oxygen delivery?

At what lung capacity or right? I.decreased pH II.increased body temperature III.increased PaCO₂ IV.decreased 2,3 BPG

What does a P₅₀ of 30 indicate?

What does a hematocrit of 51% indicate for a 50 year old male residing at seal level?

Which of the following shift the oxyhemoglobin dissociation curve to the left? I.Fetal Hb (HbF) II.carboxyhemoglobin III.increased H+ concentration

What is derived when (content of oxygen in arterial blood x 10) is multiplied by cardiac output?

From 97% and 90% saturation on the oxyhemoglobin dissociation curve,what change occurs in the PO₂?