Assessment of peripheral blood flow using a pulse oximeter

Area of Science:

• Anesthesiology
• Physiology
• Medical Devices

Background:

• Peripheral blood flow is crucial for monitoring physiological status.
• Spinal analgesia is known to influence blood flow in the lower extremities.
• Pulse oximeters offer a non-invasive method for assessing physiological parameters.

Purpose of the Study:

• To evaluate the pulse oximeter's bar graph as an indicator of peripheral blood flow changes.
• To correlate pulse oximeter readings with established measures of peripheral blood flow during spinal analgesia.

Main Methods:

• Patients receiving spinal analgesia were recruited for the study.
• Peripheral blood flow was assessed using laser Doppler and skin temperature measurements from the foot and hand.
• Pulse oximeter bar graph amplitude was recorded before and after spinal anesthesia.

Main Results:

• Spinal analgesia significantly increased laser Doppler readings (620%) and skin temperature in the foot.
• The pulse oximeter signal amplitude in the foot increased significantly post-analgesia (5.2 to 9.4 bars).
• No significant changes were observed in hand measurements, indicating localized effects.

Conclusions:

• The pulse oximeter's bar graph can effectively indicate increased peripheral blood flow in the lower extremities.
• This non-invasive device may be useful for evaluating sympathetic nerve blockade effects.
• Nellcor N-200 pulse oximeter readings correlate with changes in peripheral circulation during spinal analgesia.