Question 30.2

Created on Tue, 05/12/2015 - 18:14
Last updated on Fri, 04/28/2017 - 18:16
Pass rate: ?
Highest mark: ?

Other SAQs in this paper

Other SAQs on this topic

List the important pieces of information that may be obtained from an arterial waveform tracing.

[Click here to toggle visibility of the answers]

College Answer

  • Systolic, diastolic, mean and pulse pressures
  • Heart rate and rhythm
  • Effect of dysrhythmias on cardiac output / perfusion
  • ECG lead disconnect / problem
  • Continuous cardiac output using pulse contour analysis
  • Specific diagnostic waveform morphologies eg slow rising pulse in AS, pulsus paradoxus in tamponade, dynamic hyperinflation
  • Systolic pressure variation, pulse pressure variation may be useful in predicting fluid responsiveness

Discussion

The section on haemodynamic monitoring contains chapters on arterial line waveform interpretation. Also, Information derived from the arterial pressure waveform contains more detail about the specifics, and has examples of both normal and pathological waveforms.

In brief summary:

Information from amplitude

  • Systolic pressure
  • Diastolic pressure (coronary filling)
  • Mean arterial pressure (systemic perfusion)
  • Pulse pressure (high in AR, low in cardiac tamponade or cardiogenic shock)
  • Changes in amplitude associated with respiration (pulse pressure variation) as a predictor of fluid responsiveness

Information from frequency

  • Heart rate
  • Rhythm
  • Effect of rhythm on MAP

Waveform shape

  • Slope of anacrotic limb represents aortic valve and LVOT flow
  • Slurred wave in AS
  • Collapsing wave in AS
  • Rapid systolic decline in LVOTO
  • Bisferiens wave in HOCM
  • Low dicrotic notch in states with poor peripheral resistance

References

McGhee and Bridges "Monitoring Arterial Blood Pressure: What You May Not Know" (Crit Care Nurse April 1, 2002 vol. 22 no. 2 60-79 )

For those who like hardcore physics, this excellent resource will be an enormous source of amusement. It appears to be a free online textbook of anaesthesia. Nowhere else was this topic covered with a greater depth, or with a greater attention to mathematical detail.