Relation between pulse oximetry plethysmographic waveform amplitude induced by passive leg raising and cardiac index in spontaneously breathing subjects.
BACKGROUND
Previous studies suggested that variation of pulse oximetric plethysmographic (POP) waveform amplitude (Delta POP) could predict fluid responsiveness in mechanically ventilated patients. Our objective was to correlate the variations of Delta POP and the variations of cardiac index (CI) induced by passive leg raising (PLR) in spontaneously breathing volunteers.


METHODS
We studied 26 spontaneously breathing volunteers using a pulse oximeter attached to the middle finger. We assessed hemodynamic variables, including Delta POP (%) (POP(max) - POP(min))/[(POP(max) + POP(min))/2] and CI determined by transthoracic echocardiography at baseline (eg, semirecumbent position), during PLR at 60 degrees, and back to baseline.


RESULTS
Cardiac index significantly increased from 2.2 to 2.5 L/min x m(2) (P < .01) at 60 degrees PLR. Conversely, Delta POP significantly decreased from 22% to 15% (P < .01) at 60 degrees PLR. There was a weak correlation between CI and Delta POP variations at 60 degrees PLR (r = 0.40; P < .01). The area under curve of the receiver operating characteristic curve for Delta POP as a predictor of an increase of CI of 15% was not significant (0.67 +/- 0.10; P = .16).


CONCLUSIONS
The variation of Delta POP induced by PLR is not an accurate predictor of increase in CI.
Delerme
Samuel
S
Department of Emergency Medicine and Surgery, Center Hospitalo-Universitaire Pitié-Salpêtrière, 75013 Paris, UPMC Paris 6, France.
Castro
Samuel
S
Freund
Yonathan
Y
Nazeyrollas
Pierre
P
Josse
Marie-Odile
MO
Madonna-Py
Béatrice
B
Rouff
Edwin
E
Riou
Bruno
B
Ray
Patrick
P
D000328:Adult; D001794:Blood Pressure; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D005440:Fluid Therapy; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010991:Plethysmography; D011187:Posture / Q000502:physiology; D012372:ROC Curve; D012119:Respiration; D013318:Stroke Volume / Q000502:physiology; D055815:Young Adult