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Pulse oximetry plethysmographic waveform during changes in blood volume
M Shamir1, L A Eidelman, Y Floman
1Department of Anaesthesiology and CCM, Hadassah Medical Center, Hebrew University Medical School, Jerusalem, Israel.
British Journal of Anaesthesia
|June 12, 1999
Summary
Pulse oximetry waveform variation can detect mild hypovolemia in mechanically ventilated patients. This non-invasive method estimates intravascular volume changes by analyzing plethysmographic waveform variations.
Area of Science:
- Critical Care Medicine
- Physiology
Background:
- Systolic pressure variation (SPV) and its dDown component are established indicators of intravascular volume status in mechanically ventilated patients.
- Assessing intravascular volume is crucial for managing hemodynamics in critical care settings.
Purpose of the Study:
- To evaluate ventilation-induced changes in pulse oximeter plethysmographic waveform (SPVplet, dUp(plet), dDown(plet)) for estimating intravascular volume.
- To determine if non-invasive pulse oximetry can detect mild hypovolemia.
Main Methods:
- Investigated changes in plethysmographic waveform variation (SPVplet) and its components (dUp(plet), dDown(plet)) after 10% blood volume removal and reinfusion.
- Measured SPVplet as the difference between maximal and minimal waveform peaks during ventilation, relative to the apnoeic plateau.
- Correlated plethysmographic waveform changes with invasive arterial SPV and dDown measurements.
Main Results:
- A 10% decrease in blood volume significantly increased SPVplet (17.0% to 31.6%, P=0.005) and dDown(plet) (8.7% to 20.5%, P=0.0005).
- Changes in plethysmographic waveform parameters correlated strongly with changes in arterial SPV and dDown (r=0.85, P=0.0009).
Conclusions:
- Ventilation-induced waveform variability in pulse oximetry signals is a useful, non-invasive tool for detecting mild hypovolemia.
- This method provides a valuable alternative when invasive arterial pressure monitoring is unavailable.