In which of the following situations is volume-controlled ...

[piesebel]

In which of the following situations is volume-controlled ventilation sometimes used?
 
  1. When a precise PaCO2 has to be maintained (some closed-head injuries)
  2. When more even distribution of ventilation is required
  3. When ventilating patients with severe, refractory hypoxemia
  4. When ventilating patients with unstable or changing ventilatory drives
  a. 1 and 2 only
  b. 3 and 4 only
  c. 1, 2, and 3 only
  d. 1, 3, and 4 only

Question 2

In which of the following situations is pressure-controlled ventilation sometimes used?
 
  1. When a precise PaCO2 has to be maintained (some closed-head injuries)
  2. When more even distribution of ventilation is required
  3. When ventilating patients with severe, refractory hypoxemia
  4. When tidal volume in unstable due to leaks
  a. 1 and 2 only
  b. 3 and 4 only
  c. 1, 2, and 3 only
  d. 1, 3, and 4 only

[Joy Chen]

Answer to Question 1

ANS: A
Volume-controlled continuous mandatory ventilation is indicated when a precise minute ventila-tion or blood gas parameter, such as PaCO2, is therapeutically essential to the care of patients with normal lung mechanics. Theoretically, volume control (with a constant inspiratory flow) re-sults in a more even distribution of ventilation (compared to pressure control) among lung units with different time constants where the units have equal resistances but unequal compliances (e.g., acute respiratory distress syndrome ARDS).

Answer to Question 2

ANS: B
Pressure-controlled continuous mandatory ventilation is indicated when adequate oxygenation has been difficult to achieve in other modes of ventilation. The instability of tidal volume caused by airway leaks can be minimized by using pressure-controlled ventilation rather than vol-ume-controlled ventilation.

[piesebel]

Correct answers!

[Joy Chen]

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