Techniques to assess the circulatory system

This came up in Question 13.1 from the second paper of 2012. It was an odd question: no special insight was interrogated; the trainees were asked to simply list the haemodynamic assessment techniques which were known to them. The college answer dutifully performed this task. No attempt was made to comment constructively on the utility of any of the techniques, or to classify them systematically. The techniques appeared to be listed from least invasive to most invasive, and some were labeled as "experimental", but beyond that little processing occurred. The list below is an attempt to improve on this. Its organisation is derived from David J. Sturgess' chapter ("Haemodynamic monitoring") from Oh's Manual. Given the fondness of the examiners for this book and its various little blue boxes, it seemed like a sensible starting point. 

Anyway, without further ado, a dumb but systematic list would look like this:

Techniques for the Assessment of Circulation

Clinical techniques

  • Capillary refill
  • Heart rate
  • Temperature of the extremities
  • Urine output
  • Mental state

Pressure-based techniques

  • Non-invasive blood pressure
  • Invasive blood pressure (arterial line)
  • Central venous pressure

Flow-based techniques

  • Thermodilution cardiac output measurements
    • Right heart (PA catheter)
    • Trans-pulmonary (PiCCO)
  • Trans-thoracic Echocardiography (TTE)
  • Transoesophageal echo (TOE)
  • Continuous oesophageal PW Doppler
  • Transcutaneous Doppler

Static indices of fluid responsiveness

  • ITBV

Dynamic indices of fluid responsiveness

  • Response to fluid challenge
  • Passive leg raise
  • Pulse pressure variation
  • Stroke volume variation

Assessment of circulatory efficacy

  • Lactate measurements
  • Central or mixed venous saturation
  • Oxygen extraction ratio
  • a-A CO2 difference

Assessment of microcirculation

  • Gastric tonometry
  • Sublingual tonometry
  • Microdialysis

Experimental techniques

  • Impedance cardiography


Sturgess, David J. (2013). "Haemodynamic monitoring". In Andrew D. Bersten and Neil Soni (Ed.), Oh's Intensive Care Manual, 7th ed.