Assessment of peripheral blood flow using a pulse oximeter.
We investigated the bar graph on a pulse oximeter as an indicator of peripheral blood flow. Because blood flow is known to increase in the lower extremities during spinal analgesia, we chose patients receiving spinal analgesia as the experimental model. Although they are indirect indicators, we used laser Doppler readings and skin temperature to reflect peripheral blood flow. These measurements were made from each patient's foot and hand before and after spinal analgesia and were compared with the deflection on the pulse oximeter bar graph. After subarachnoid injection of bupivacaine, laser Doppler readings from the foot increased to 620 +/- 120% (P less than 0.05) of the control reading. The pulse oximeter signal amplitude increased from 5.2 +/- 0.4 to 9.4 +/- 0.3 bars (P less than 0.05) and mean skin temperature increased from 24.6 +/- 0.5 to 31.2 +/- 0.8 degrees C (P less than 0.05). No changes were noted in readings obtained from the hand. A Nellcor N-200 pulse oximeter may be used to evaluate the effect of sympathetic nerve block as indicated by an increase in peripheral blood flow.
Department of Anaesthesiology, University Hospital, Linköping, Sweden.
M
M
Vegfors
B
B
Tryggvason
F
F
Sjöberg
C
C
Lennmarken
D000328:Adult; D000368:Aged; D000775:Anesthesia, Spinal; D001340:Autonomic Nerve Block; D002045:Bupivacaine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D012015:Reference Standards; D012039:Regional Blood Flow / Q000187:drug effects; D012867:Skin / Q000098:blood supply* / Q000187:drug effects; D012881:Skin Temperature; D014463:Ultrasonography
D002045:Bupivacaine