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The peripheral perfusion index in reactive hyperemia in critically ill patients

Introduction and objective

The peripheral perfusion index (PFI), derived from the pulse oximetry signal, permits a quantitative analysis of the peripheral perfusion in patients. However, the relationship between variations of this index and variations in peripheral blood flow in critically ill patients has not been studied. We therefore studied the ability of the PFI to detect the vascular response produced by induced reactive hyperemia in critically ill patients.

Materials and methods

PFI was obtained using a conventional pulse oximetry. The peripheral temperature was measured using a proximal temperature probe (Phillips 21078A) placed on the forearm and a distal probe placed on the middle fingertip of the same arm used for PFI measurements. The skin-surface temperature gradient between the proximal and distal probe (dT) was calculated as a measure of changes in forearm blood flow. Reactive hyperemia was produced by arrest of forearm blood flow with a sphygmomanometer pneumatic cuff placed around the upper arm not used for arterial cannulation. The cuff was inflated to a pressure approximately 30 mmHg greater than systolic pressure for 3 min, after which the cuff was rapidly deflated to 0 mmHg. The hyperemic response was analysed by measuring the maximum increase in PFI relative to baseline PFI. A student's t test was used to assess the differences at baseline and maximum PFI. P < 0.05 was considered statistically significant.


Fifty-six measurements were carried out in 14 patients. In all patients the PFI increased after release of the pneumatic cuff. The changes in hemodynamics, PFI and dT are presented in Table 1.

Table 1 Table 1


PFI can be used to assess vascular reactivity in critically ill patients.

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Lima, A., Bakker, J. The peripheral perfusion index in reactive hyperemia in critically ill patients. Crit Care 8, P53 (2004).

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  • Pulse Oximetry
  • Vascular Reactivity
  • Reactive Hyperemia
  • Forearm Blood Flow
  • Proximal Temperature