Blood Pressure Monitoring

How do we measure it?

How do we measure it?• Estimate• Auscultate• Oscillation• Invasive• Vascular Unloading and Others

Estimate (Guess)

Radial pulse: SBP >80Femoral pulse: SBP > 70Carotid pulse: SBP > 60mmhg

Estimate (Guess)

Accuracy of the advanced trauma life support guidelines for predicting systolic blood pressure using carotid, femoral, and radial pulses: observational study. Charles D Deakin, J Lorraine Low

Auscultate

Auscultate

Oscillation

Oscillation

Oscillation• Useful for trends• Can be in error in some situations:• Hyper/hypotension• Elderly with calcified arteries• Atrial Fibrillation

Invasive: Intra-Arterial• When to go deep:• Hypotension/Shock• Hypertensive Emergency• Frequent ABG checks (paralysis)• Hypothermia protocol• Expectant (“you have to swell to heal”)

Intra-Arterial Catheter• Where to stick it?

Hand Circulation

The Allen’s Test

Edgar V. Allen

The Barbeau Test

How to Place an Arterial Line

How is Pressure Measured?

The Pressure Wave

Underdamped Waveform

Overdamped Waveform

The Fast Flush Test• Record arterial waveform during several brief flushes• Oscillations after the flush are a reflection of the resonance of

the recording system and of the arterial pressure waveform…the actual physics is beyond me at this point.

• But normal, underdampened and overdampened waveforms all will give a stereotypical oscillation pattern:

The Fast Flush Test

Coming Full Circle

• New devices for measuring arterial pressure are in the works as we try to “devolve” back into non-invasive devices but still maintain the accuracy of an invasive catheter.