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. Author manuscript; available in PMC: 2015 Jun 22.
Published in final edited form as: Crit Care Clin. 2015 Jan;31(1):133–164. doi: 10.1016/j.ccc.2014.08.007

Table 1.

Levels of data hierarchy

Data hierarchy Examples Notes
Primary variables HR, MAP, CVP, ScvO2, SV, SpO2

  • Used most frequently in goal-oriented therapy protocols
Secondary (derived) variables HRV measuresa, PPV, SVV

  • Requires high-frequency data collection

  • Increasingly being integrated into goal- oriented therapy protocols
Advanced waveform analyses Morphologic changesb, harmonic analysesb

  • Requires data collection via waveforms (>/= 100 Hz)

  • Can be performed on any variable derived from a waveform (CVP, ABP, etc.)

HR=heart rate; MAP=mean arterial pressure; CVP=central venous pressure; ScvO2=central venous oxygen saturation; SV=stroke volume; SpO2= arterial oxygen saturation measured by pulse oximetry; HRV=heart rate variability; PPV=pulse pressure variability; SVV=stroke volume variation; ABP=arterial blood pressure

a

The term HRV measures represents dozens of independent variables

b

Represent potentially hundreds of variables