An alternative method for calculating changes in arterial calf blood flow at rest. An initial study

Area of Science:

• Anesthesiology
• Vascular Physiology
• Medical Instrumentation

Background:

• Assessing changes in calf arterial blood flow (AF) is crucial for understanding physiological responses to anesthesia.
• Traditional methods for calculating AF using strain gauge plethysmography (SGP) can sometimes yield equivocal results.
• Spinal and epidural blocks are common anesthetic techniques that can influence peripheral circulation.

Purpose of the Study:

• To evaluate a novel method (tVC50) for measuring calf arterial blood flow (AF) changes post-spinal and epidural anesthesia.
• To compare the efficacy of the tVC50 method with the conventional tangent method for AF calculation.
• To determine the statistical differences in AF and tVC50 between spinal and epidural block groups.

Main Methods:

• Studied 20 patients undergoing spinal or epidural blocks.
• Utilized venous occlusion strain gauge plethysmography (SGP) to measure calf arterial blood flow (AF).
• Calculated AF using the conventional tangent method and a new method measuring time to 50% venous capacity (tVC50).

Main Results:

• A statistically significant correlation (rs = -0.85, p < 0.01) was found between the conventional AF method and the tVC50 method in measuring post-block changes.
• Both methods demonstrated comparable results in assessing arterial blood flow changes.
• No significant differences were noted in the correlation between the two methods across spinal and epidural groups.

Conclusions:

• The novel tVC50 variable shows potential as a reliable measure for calculating resting arterial blood flow changes.
• The tVC50 method offers a valuable alternative, particularly when the initial upslope of the SGP curve is ambiguous.
• This new variable can be applied in contexts like surgical and pharmacological interventions affecting arterial blood flow.