PB chp 13

Question 1

Improving the ventilatory status of a patient with hypercapnic respiratory failure can be accomplished how? (3 general concepts)

Answer 1

improving alveolar ventilation
reducing physiological dead space
reducing carbon dioxide (CO2) production

Question 2

Improving oxygenation can be accomplished in what 4 general ways?

Answer 2

administering enriched oxygen
PEEP
CPAP
Patient Positioning

Question 3

An increase in CO2 of 1 mm Hg will reduce the PaO2 by ?

Answer 3

1.25 mm Hg

Question 4

reduction in oxygen in the tissues

Answer 4

Hypoxia

Question 5

reduction in the partial pressure of oxygen in the blood

Answer 5

Hypoxemia

Question 6

What causes Hypoxemic hypoxia?

Answer 6

lower than normal PaO2,
ascent to altitude,
hypoventilation

Question 7

What causes Anemic hypoxia

Answer 7

lower than normal red blood cell count [anemia], abnormal hemoglobin,

Question 8

What kind of Hypoxia does the patient have when they have reduced cardiac output, decreased tissue perfusion?

Answer 8

Circulatory hypoxia

Question 9

What kind of Hypoxia does a patient have when cyanide poisoning is involved?

Answer 9

Histotoxic hypoxia

Question 10

When hypoventilation causes hypoxemia, increasing ____ ______ generally improves oxygenation

Answer 10

minute ventilation

Question 11

A patient with myasthenia gravis is placed on mechanical ventilation. The chest radiograph is normal. Breath sounds are clear. Initial ABGs on 0.25 FIO2 20 minutes after beginning ventilation are as follows: pH = 7.31; PaCO2 = 62 mm Hg; bicarbonate = 31 mEq/L; and PaO2 = 58 mm Hg. What change in ventilator setting might improve this patient’s ABG findings?

Answer 11

The patient has respiratory acidosis. The PaO2 indicates moderate hypoxemia. A common reaction by clinicians in this situation is to increase the FIO2. However, the cause of the hypoxemia is the elevated CO2. The PaCO2 is about 40 mm Hg above normal, therefore the PaO2 will be about 50 mm Hg below its actual value. The most appropriate way to increase the PaO2 is to increase ventilation.

Question 12

What is PVO2 & its normal value?

Answer 12

Partial pressure of mixed venous oxygen

40mmhg

Question 13

What is P(A-a)O2 & its normal value?

Answer 13

Alveolar-arterial oxygen tension gradient

5-10 mm Hg (FIO2 = 0.21)
30-60 mm Hg (FIO2 = 1.0)

Question 14

PaO2/FIO2

PaO2 range = 80-100 mm Hg; FIO2 = 0.21

Answer 14

Ratio of PaO2 to fractional inspired oxygen

380-475

Question 15

What is DO2 & its normal value?

Answer 15

Oxygen delivery

1000 mL/min

Question 16

What is VO2 & its normal value?

Answer 16

Oxygen consumption

250 mL/min

Question 17

Generally in chronic patients, what should you keep the FIO2 Below?

Answer 17

60%

Question 18

100% FIO2 over long periods of time can cause what (3) to happen?

Answer 18

absorption Jo Anne
increase intrapulmonary shunting
o2 toxicity

Question 19

After being supported on a ventilator for 30 minutes, a patient’s PaO2 is 40 mm Hg on an FIO2 of 0.75. Acid-base status is normal and all other ventilator parameters are within the acceptable range. PEEP is 3 cm H2O. What FIO2 is required to achieve a desired PaO2 of 60 mm Hg? Is your answer possible? Can you think of another form of therapy to improve oxygenation?

Answer 19

Desired FIO2 = (60 × 0.75)/40 = 1.13

No, this is not possible. You can’t give more than 100% oxygen. Along with increasing the FIO2 to 1, another method of improving oxygenation is to use PEEP.

Question 20

If the PAW increases, what happens to the PaO2?

Answer 20

Increases

Question 21

Factors that affect PAW during positive-pressure ventilation (5)

Answer 21

include peak inspiratory pressure (PIP)
 total PEEP (or auto-PEEP plus extrinsic or set PEEP [PEEPE]
inspiratory-to-expiratory (I:E) ratios,
 respiratory rate (f)
 inspiratory flow pattern

Question 22

As the percent of pulmonary shunt increases, hypoxemia worsens. What are some pathologic conditions associated with an increased shunt fraction.

Answer 22

atelectasis, pulmonary edema, pneumonia, pneumothorax, and complete airway obstruction.

Question 23

What is the difference between PEEP and CPAP

Answer 23

The term PEEP as it is commonly used implies that the patient is receiving mechanical ventilatory support and the baseline pressure is above zero CPAP is pressure above the ambient pressure maintained during spontaneous ventilation.

With CPAP, expiratory positive airway pressure (EPAP) and inspiratory positive airway pressure (IPAP) are both positive and equal, albeit the ventilator does not provide mandatory breaths