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NORCET-11 Prelims
Medical & Surgical Nursing
Medium

If a pressure transducer or central venous pressure manometer zero-level is placed above the phlebostatic axis, what type of reading is expected?

Appeared in: NORCET-11 Prelims

Explanation

  • Transducer above phlebostatic axis causes hydrostatic underestimation.
  • Results in a falsely low central venous pressure reading.
  • Waveform remains present; only the value is affected.
  • Key differentiator: Only numeric value changes, not waveform.

Why Other Options Were Wrong

  • Option A: Placing the transducer above the phlebostatic axis does not cause a falsely high reading. High readings occur if the transducer is below the reference point.
  • Option C: There will be a change in the CVP reading due to the altered hydrostatic pressure. No change only occurs if the transducer is exactly at the phlebostatic axis.
  • Option D: The waveform is not lost by changing the transducer level; only the numeric value is affected. Loss of waveform suggests technical or catheter issues, not transducer height error.

Related Visual

Illustration showing a patient in supine position with a CVP transducer at, above, and below the phlebostatic axis, with arrows indicating direction of error falsely low or hig...
Clinical Relevance
  • Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Effect of transducer position on central venous pressure readings as background academic context rather than a clinical decision trigger.
  • Accurate CVP readings are essential for fluid management in critically ill patients.
  • Nurses must always level the transducer at the phlebostatic axis before recording readings.
  • What if? If the transducer is placed below the phlebostatic axis, the CVP reading will be falsely high, potentially leading to inappropriate fluid restriction.
How to Approach the Question
  • Identify the reference point for CVP measurement (phlebostatic axis).
  • Recall the effect of hydrostatic pressure on fluid columns.
  • Apply the rule: transducer above = falsely low, transducer below = falsely high.
  • Eliminate options that do not match the mechanism (e.g., waveform loss, no change).
  • Choose the answer that matches the described error in measurement.
Concept Tested & Keywords
  • Concept Tested: Effect of transducer position on central venous pressure readings
  • Stem keywords: pressure transducer, central venous pressure, manometer, zero-level, phlebostatic axis
  • Lead-in keywords: expected reading, type of reading
  • Clinical cues: CVP monitoring accuracy depends on transducer position

Question ID

QR0kzeClCf4qXyAcSLmib0

Reference Book

E6 Nursing Fundamentals Taylor p. 145-147

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