Pilbeams Chapter 13

Question 1

Improving the ventilatory status in a patient with Hypercapnic RF

Answer 1

-Reducing the partial pressure of PaCO2
-Reducing physiological dead space
-Reducing CO2 production

Question 2

Improving oxygenation

Answer 2

-Administer O2
-Apply PEEP or CPAP
-Patient positioning

Question 3

Hypoxemic hypoxia treatment

Answer 3

Occurs when a person breathes rarefied (high altitudes)
Hypoxemic hypoxia can be reversed by having a patient breathe an enriched oxygen mixture.

Question 4

Hypoventilation induced hypoxia

Answer 4

Increase the minute ventilation

Question 5

Anemia

Answer 5

Blood transfusion to improve the O2 carrying capacity of the hemoglobin.

Question 6

Circulatory hypoxia

Answer 6

When the patient’s cardiac output is reduced
-Treatment would involve fluid resuscitation and pharmacological to normalize the CO. (drugs that increase contractility or decrease vascular resistance. Therefore, increasing O2 delivery to the tissues.

Question 7

Histotoxic hypoxia

Answer 7

The body is unable to utilize oxygen for cellular respiration

Question 8

Parameters used to assess oxygenation

Answer 8

FIO2, SPO2, PaO2, ABG’s, Hb, A-a gradient, PF ratio
-ABG’s should be measured within 15 to 30 minutes
-Every attempt should be made to keep FIO2 below 60% while keeping PaO2 between 60 to 90

Question 9

Normal PaO2

Answer 9

80-100

Question 10

Normal PvO2

Answer 10

40 mmHg

Question 11

Normal PAO2

Answer 11

100-673 (FIO2 range: 21-100)

Question 12

Normal A-a gradient

Answer 12

5-10 (on room air 21%)
30-60 (on 100%)

Question 13

Normal P/F ratio

Answer 13

380-475

Question 14

Normal PaO2/PAO2

Answer 14

80-100

Question 15

Normal oxygen consumption (VO2)

Answer 15

250 mL/min

Question 16

Normal oxygen delivery (DO2)

Answer 16

1000 mL/min

Question 17

Normal oxygen content of mixed venous blood (CVO2)

Answer 17

15 vol%

Question 18

Normal oxygen content of arterial blood (CaO2)

Answer 18

20 vol%

Question 19

Normal saturation of mixed venous oxygen (SVO2)

Answer 19

75%

Question 20

Normal saturation of arterial oxygen

Answer 20

97%

Question 21

Adjusting the FIO2

Answer 21

The ABG obtained after MV is initiated is compared to the delivered FIO2. A linear relationship should exist between the 2.
-The known PaO2 and the known FIO2 can be used to obtain the desired FIO2.
-PaO2 (Desired) x FIO2 (Known)/ PaO2 (Known)
This equation is useful in making appropriate changes to the FIO2 to achieve the desired PaO2.

Question 22

Selection of FIO2

Answer 22

-Maintaining a FIO2 above 60 can cause O2 toxicity
-Breathing 100% O2 can lead to absorption atelectasis and increase intrapulmonary shunting.
-FIO2 should be kept as low as possible.

Question 23

If the PaO2 remains very low while the patient is breathing a high FIO2, what may be ocurring?

Answer 23

Significant shunting, V/Q mismatch, diffusion abnormalities
-In these cases, other methods beside increasing the FIO2 should be considered.
-Increase the Paw (as the Paw increases the PaO2 increases)
-As the PEEP increases, the Paw increases
-HFOV and APRV can increase the Paw

Question 24

The use of PEEP

Answer 24

Increasing the PEEP to increase the Paw is used most frequently.
-The goal of PEEP is to recruit collapsed alveoli while avoiding overdistention of already open alveoli,

Question 25

Goals of PEEP/ CPAP Therapy

Answer 25

-Maintain a PaO2 of 60 or greater SpO2 of 90% -Recruit alveoli and maintain them in an aerated state -Restore FRC -Enhance tissue oxygenation

Question 26

Definition of PEEP

Answer 26

A patient receiving MV, the baseline pressure at the end of expiration is above zero.

Question 27

Application of CPAP and PEEP

Answer 27

Can be applied to a patient's airway with a mask, nasal prongs, or an ET tube or a tracheostomy tube.

Question 28

Mask CPAP

Answer 28

Patient's receiving a CPAP with a mask should have a PF ratio greater than 200 and have a stable cardiovascular status. -The hazards and complications of CPAP are vomiting, aspiration, skin necrosis or discomfort from the mask, CO2 retention, increased WOB and cerebral hemorrhage.

Question 29

Nasal CPAP

Answer 29

Most commonly used in infants because they are mouth breathers. -CPAP pressures of up to 15 can be used with this device -Problems with Nasal CPAP include gastric distention, pressure necrosis, swelling of nasal mucosa, and abrasion of posterior pharynx.

Question 30

Endotracheal Tube or Tracheostomy tube CPAP

Answer 30

May be used for patients who do not meet the requirement for nasal CPAP or mask CPAP.

Question 31

Flow and threshold resistors

Answer 31

The more rapidly a device responds to patient effort, the less WOB that is required.

Question 32

Flow resistor

Answer 32

A flow resistor achieves expiratory pressure by creating a resistance to gas flow through an orifice. -As the diameter of the orifice decreases in size, the pressure level applied increases. -As the diameter of the orifice increases, the pressure level applied decreases

Question 33

Threshold resistor

Answer 33

A constant pressure is applied throughout expiration regardless of the rate of gas flow. -The expiratory valve on most ventilators behave as threshold resistors.

Question 34

Freestanding CPAP and CPAP on mechanical ventilators

Answer 34

Ventilator mode: CPAP/Spontaneous Mode-Adjust the PEEP to the desired pressure level.

Question 35

Freestanding CPAP or EPAP systems (not used often at all, most hospitals use CPAP/Spontaneous mode)

Answer 35

Continuous flow-Closed system Demand flow- Open system On both systems, the patient must be able to comfortably maintain a near normal PaCO2.

Question 36

What are the 2 levels of PEEP?

Answer 36

Physiological PEEP and therapeutic PEEP

Question 37

Minimum or low PEEP

Answer 37

A minimum level of PEEP (3-5) should be used to help preserve a patient's normal FRC.

Question 38

Therapeutic PEEP

Answer 38

Therapeutic PEEP is 5 cm or greater, it is used in the treatment of refractory hypoxemia caused by intrapulmonary shunting and V/Q mismatching. -High levels of PEEP are beneficial for a small number of patients with ARDS. -High levels of PEEP are associated with Cardiopulmonary complications so their response to PEEP must be monitored carefully.

Question 39

Optimal PEEP

Answer 39

The level at which the maximum beneficial effects of PEEP occur. -Not associated with cardiopulmonary side effects. -The PEEP at which static compliance is at its highest as PEEP is decreased after a recruitment maneuver.

Question 40

Indications for PEEP and CPAP

Answer 40

-Patient's with ARDS do not benefit from mechanical ventilatory support without PEEP. -Patient's with ARDS benefit from PEEP because it helps prevent collapse of the small airways and alveoli and aids in recruiting closed lung units.

Question 41

Indications of PEEP therapy

Answer 41

-Bilateral infiltrates -Recruitment of atelectasis with low FRC -Reduced lung compliance -PaO2 below 60 on an FIO2 greater than 50% P/F ratio below 300 for ARDS

Question 42

CPAP vs PEEP

Answer 42

-The patient provides all of the WOB at all times during CPAP. -If a patient is able to breathe spontaneously and maintain an adequate PaCO2 CPAP is appropriate. PEEP allows for the reduction of FIO2 because it improves oxygenation and helps avoid the complications of a high FIO2 in certain disorders.

Question 43

What disorders may benefit from the use of PEEP?

Answer 43

-ARDS -Cardiogenic Pulmonary edema -Bilateral diffuse pneumonia.