Page 79 - Clinical Application of Mechanical Ventilation

Effects of Positive Pressure Ventilation 45

SUMMARY

Positive pressure ventilation is beneficial to support a patient’s ventilatory and oxygen-
ation needs. However, it has many inherent physiologic side effects on organ systems.
When caring for critically ill patients with positive pressure ventilation, it is vital to ob-
serve and monitor the patients carefully and frequently for occurrence of side effects.
Once the side effects are noted, appropriate interventions must be taken to correct
the problems.

Self-Assessment Questions

1. During the inspiratory phase of positive pressure ventilation, gas flows into the lung because the pressure in the:
A. airway is higher than the pressure in the lungs.
B. airway is lower than the pressure in the lungs.
C. lungs is higher than the barometric pressure.
D. lungs and airway are the same.

2. A neonate is being ventilated by a pressure-controlled mode. The physician asks the therapist to adjust
the ventilator to increase the patient’s mechanical tidal volume. The therapist should:
A. increase the tidal volume setting. C. decrease the flow rate.
B. increase the pressure setting. D. decrease the inspiratory time.

3. A postoperative patient is recovering in the intensive care unit on volume-controlled mode. With this
mode of ventilation, the ___ is preset with a variable ___ depending on the compliance and airway re-
sistance characteristics.
A. peak inspiratory pressure, tidal volume
B. peak inspiratory pressure, peak flow
C. tidal volume, peak inspiratory pressure
D. tidal volume, peak flow

4. Positive pressure ventilation decreases the oxygen delivery to a patient with normal hemodynamic status
because it causes all of the following changes except:

A. increase in intrathoracic pressure. C. increase in pulmonary blood flow.
B. reduction in stroke volume. D. decrease in cardiac output.

5. In children with right ventricular dysfunction, the thoracic pump mechanism ___ the outflow of blood
from the ___ ventricle.
A. increases, left C. increases, right
B. decreases, left D. decreases, right

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