If a rectangular (square) pressure waveform is generated during ...

[wrbasek0]

If a rectangular (square) pressure waveform is generated during pressure-controlled ventilation, what type of waveforms will develop for volume and flow?
 
  A. volume waveform: exponential rise; flow waveform: exponential decline
  B. volume waveform: exponential decline; flow waveform: exponential rise
  C. volume waveform: sinusoidal; flow waveform: ascending ramp
  D. volume waveform: descending ramp; flow waveform: rectangular

Question 2

Which of the following terms describe the configuration of a ventilator waveform? I. hyperbolic II. sinusoidal III. rectangular IV. exponential
 
  A. II, III only
  B. I, II, IV only
  C. I, III, IV only
  D. II, III, IV only

[dominiqueenicolee]

Answer to Question 1

ANS: AA. Correct response: A rectangular pressure waveform is accompanied by an exponentially rising volume waveform and an exponentially decaying (declining) flow waveform. The volume rises exponentially to a value equal to the product of the lung compliance and the difference between the PIP and the PEEP. That is,
volume = CL (PIP  PEEP)
L = L/cm H2O (cm H2O)
The inspiratory flow declines exponentially from its peak level, which is equal to the difference between change in airway pressure multiplied by the airway resistance. Hence,
flow = Raw  (PIP  PEEP)
L/sec = cm H2O/L/sec  (cm H2O)

B. Incorrect response: The choice has the waveforms opposite of what they actually are.
C. Incorrect response: When the pressure waveform is sinusoidal, the volume and flow waveforms are also sinusoidal.
D. Incorrect response: See explanation for choice A above.

Answer to Question 2

ANS: DI. Incorrect response: None of the ventilator waveforms is hyperbolic.
II. Correct response: The most common types of waveform produced by mechanical ventilators are:
  Rectangular
  Ramp
  Exponential
  Sinusoidal
III. Correct response: See explanation II.
IV. Correct response: See explanation II

[wrbasek0]

Excellent

[shewald78]

TYSM