Chapter 16; Extrapulmonary Effects of Mechanical Ventilation

Chapter 16; Extrapulmonary Effects of Mechanical Ventilation

 

Complete Chapter Questions With Answers

 

Sample Questions Are Posted Below

 

MULTIPLE CHOICE

 

1. The mode that causes the greatest reduction in cardiac output during ventilation is which of the following?

a.	CPAP
b.	SIMV
c.	SIMV with PEEP
d.	VC-CMV with PEEP

 

 

ANS:   D

VC-CMV with PEEP causes the highest mean airway pressure; this results in the greatest reduction in venous return and thus cardiac output.

 

DIF:    2                      REF:    pg. 317

 

2. High tidal volumes and/or high levels of PEEP cause which of the following?

a.	Improvement in pulmonary blood flow
b.	Increased right ventricular afterload
c.	Interventricular septum shifts to the right
d.	Increased myocardial perfusion

 

 

ANS:   B

High tidal volumes and/or high levels of PEEP result in increased resistance to blood flow through the pulmonary circulation; this increases right ventricular afterload. In addition, the right ventricle becomes overdistended, causing a decrease in RV output. Dilation of the RV can also force the interventricular septum to move to the left. Left ventricular output may also be decreased because of the expanding lungs. This plus the decreased venous return lowers cardiac output and decreases the amount of blood perfusing the myocardium.

 

DIF:    1                      REF:    pg. 317

 

3. Normovolemic patients experience decreases in cardiac output above what level of PEEP?

a.	5 cm H2O
b.	8 cm H2O
c.	12 cm H2O
d.	15 cm H2O

 

 

ANS:   D

Decreases in cardiac output can occur in normovolemic patients with levels of PEEP >15 cm H₂O.

 

DIF:    1                      REF:    pg. 318

 

4. A patient with which of the following is least likely to experience hemodynamic changes with high alveolar pressures during mechanical ventilation?

a.	ARDS
b.	Emphysema
c.	Kyphoscoliosis
d.	Third-degree chest wall burns

 

 

ANS:   A

Patients with stiff lungs (as in ARDS or pulmonary fibrosis) are less likely to experience hemodynamic changes with high pressures, because less of the alveolar pressure is transmitted to the intrapleural space. Patients with compliant lungs (as in emphysema) or with stiff, noncompliant chest walls (as in kyphoscoliosis and extensive chest wall burns) are more likely to have higher intrapleural pressures with PPV and experience more pronounced cardiovascular effects.

 

DIF:    2                      REF:    pg. 319

 

5. The harmful cardiovascular effects of PPV are influenced most by which of the following pressures?

a.	Peak inspiratory pressure
b.	Mean airway pressure
c.	Positive end expiratory pressure
d.	Transpulmonary pressure

 

 

ANS:   B

The amount and duration of the pressure applied to the airway, the mean airway pressure, ultimately influences the extent of the harmful cardiovascular effects. The lower the mean airway pressure, the less marked the cardiovascular effects. This pressure takes into account the peak inspiratory pressure, the positive end expiratory pressure, the inspiratory time, and the total cycle time.

 

DIF:    1                      REF:    pg. 320